ESE's works engine tuner [Archive] - Page 22

F5 Dave

1st November 2011, 11:20

I agree with Wobbly (I usually do): there is no money in paper books on two-stroke technology (there is little money in paper books period, unless you happen to write Harry Potter stories). But you'll find a lot of present-day info in forums.
ESE's works engine tuner is a good example, and of the numerous other forums that are 'open to the public' I would recommend www.pit-lane.biz (http://www.pit-lane.biz). It's French-based, but yours truly and Jan Thiel are allowed to write in English (and I post all my photos in Dutch without anyone noticing:shifty:).
A good starting point would be here: http://www.pit-lane.biz/t117p246-gp125-caracteristiques-aprilia-rsa.

My there is a lot of good stuff in there & the bonus that it is in english so us colonial offshoots on the other side of the world from Europe can understand it. Thank you so much for opening the portal to view this as we would never have looked in a French site (though I see a few old faces like Seb4lo).

kel

1st November 2011, 12:13

Now that Rob has put a link to pit-lane.biz (my almost secret place for all things techo), I'd encourage anyone who loves race bikes to check it out. Its a French site so you'll need to use something like google translator (which can be amusing) although Jan, Frits and others do post in english, those clever Europeans tend to speak more than one language which does help. There's all kinds of super cool technical info on most racing classes plus pictures of just about everything. Enjoy!

http://www.pit-lane.biz/

Not feeling the love Dave :facepalm:
We really are privileged to have so many of the pitlane contributors watching and contributing to this thread, with their input (and Wobblys of course) theres absolutely no reason 2 strokes wont return to dominate buckets.
:woohoo:

bucketracer

1st November 2011, 16:24

Dunt ewe fullas just bump up da cumpression heaps and polish up all da ports?

Its an industry thing, and can only be done by those in the know, and that also have lots of experience ... don't you know ... Yeah Right ...

Ermmm, polished the ports and raised the primary compression .....

richban

1st November 2011, 16:33

theres absolutely no reason 2 strokes wont return to dominate buckets.
:woohoo:

Insert smart ass comment here ...........:innocent:

husaberg

1st November 2011, 20:05

I managed only a brief look at the Pitlane thread with the interview but firstly amazing pics. I was always intrigued by the rear disk engine but more importantly the drive. Now after seeing it (The early version I realise the later is different). I guess it owes a fair bit to the Koing at least in conceptual design.EDIT I have had a longer look. Pure gold and I am only at pg 18 2 stroke institute my is that so familar?

I spend a while looking in the Kaaden thread again great pics.
I thought you might get a kick out of the Alfred Scott bit I postedhttp://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130150906#post1130150906.
The story below it, is the interview with Kaaden himself he seemed real sincere to me with how it all happened.I realise you were quite scathing of his influence.
But in here he certainly to me seemed to atribute the designs to the right people.
I seen the DR Joe bit posted from a exert from one of my other inspirational figures. Phil Irving I didn't expect that bit of how the copy of MZ worked.

Buckets4Me

1st November 2011, 20:20

Insert smart ass comment here ...........:innocent:
Talent :lol:

richban

1st November 2011, 20:30

Talent :lol:

Exactly what I was going to say.

husaberg

1st November 2011, 22:09

Insert smart ass comment here ...........:innocent:
I am guessing MR 4 stroke hasn't read the Pitlane thread yet. The two stroke is not quite as dead as you have been Mislead to believe MR Ban:killingme

dmcca

1st November 2011, 22:34

I'll start a new thread with a couple of questions later today and put a link to it here for anyone else that's interested

EngMod2T Q & A...
http://www.kiwibiker.co.nz/forums/showthread.php/143620-EngMod2T-Q-amp-A?p=1130187060#post1130187060

That pitlane thread is brilliant, its great to see some amazing minds still working on 2T technology. Makes you wonder how much other stuff is on the net in different languages that we might never find as english speakers.

I reckon if anyone bothered to collate all the info from here and pitlane you'd have a pretty comprehensive and up to date 2T manual.

richban

2nd November 2011, 08:37

I am guessing MR 4 stroke hasn't read the Pitlane thread yet. The two stroke is not quite as dead as you have been Mislead to believe MR Ban:killingme

I love 2 strokes especially the peaky, violent MX engine's of my youth. And my old gt50 of course the first bucket way back in 1987. I also like playing the villain 4 stroke guy. Gives you someone to focus all the energy towards. Lets see some action on the track. I'm a bit worried some 30hp 2 stroke will just smoke us all at the GP, but we will have to wait and see. Its great so many talented people are willing to share there expertise and knowledge. No that common in motor sport really. Especially the pinnacle class's of F4 and F5.:)

wobbly

2nd November 2011, 15:02

I have a few customers on the pitlane threads, and for sure the 2T is alive and well in some classes still.
Im deep into the Rossi hydroplane motor as we speak.
And AMA has just changed a few classes "back" to enable the 2T to run again.

kel

2nd November 2011, 15:35

I'm a bit worried some 30hp 2 stroke will just smoke us all at the GP, but we will have to wait and see.

team ESE seem very quiet :confused:

husaberg

2nd November 2011, 15:48

I love 2 strokes especially the peaky, violent MX engine's of my youth. And my old gt50 of course the first bucket way back in 1987. I also like playing the villain 4 stroke guy. Gives you someone to focus all the energy towards. Lets see some action on the track. I'm a bit worried some 30hp 2 stroke will just smoke us all at the GP, but we will have to wait and see. Its great so many talented people are willing to share there expertise and knowledge. No that common in motor sport really. Especially the pinnacle class's of F4 and F5.:)

I share your views. besides someone has to be the devils advocate. The sharing of information we are seeing from Frits Jan and Wob along with others is unreal.
For years it was like some mysterious form of witchcraft. While the 2 stroke may at first appear to be a simple little device. There is so many variables that are all puzzlingly and at times frustratingly interrelated. So much more than I, ever would of imagined.

Buckets4Me

2nd November 2011, 16:31

team ESE seem very quiet :confused:

I do belive that TZ350 has been in the states thats why there has been only a few posts by him and no work on his bike

wait till he gets back to it with all the new toys he will have brought back with him

I'm a bit worried some 30hp 2 stroke will just smoke us all at the GP, but we will have to wait and see. Its great so many talented people are willing to share there expertise and knowledge. No that common in motor sport really.

I'm afraid that all they guys with big H/P bikes up here are getting on a bit in years
some have been banned from riding there buckets

gav

2nd November 2011, 19:18

http://youtu.be/5xKSbvHRLyU

Al Hoogie on his CBR150!

Results of the race here. A 1.54.8 lap time too :clap:

http://www.mylaps.com/results/showrun.jsp?id=2124606

koba

2nd November 2011, 19:29

Click 'Show results by class' under the Motorcycling Canterbury logo to see who was in each class.

husaberg

3rd November 2011, 17:41

For Fits you FOS engine.

Brillient idee

With the exhaust appearing to gain its time area with its formidable width instead of its height. Does that mean the effective duration of its power stroke is of a much longer percentage of the stroke (I hope this makes sense). Or is this cancelled out but it being positioned higher in the cylinder?
It may well be a silly question so apologies, if I missed that bit in translation.

249965

TZ350

3rd November 2011, 18:36

249970

I have been trying to figure out if the bellmouth on the pumper does anything or not.

249974

After a few dyno runs, apparently not.

249972

28+ hp ... Blue with bellmouth, and Red without the bellmouth.

249973

And the ignition curve.

An interesting thing, on overrun as its winding down on the dyno the bike will kick about if the ignition is too advanced in any particular spot.

By paying attention to when it kicks about on over run and the rpm I can get an idea where the ignition needs to be backed off.

TZ350

3rd November 2011, 18:39

249976

Next step was to try it with an Inlet Manifold.

249977

Performance air filter inlet manifold from a VW car.

249975

Now that lost a hp, Red line. And strangly required a richer H setting.

wobbly

3rd November 2011, 19:57

The exhaust open point has very little to do with creating power due to "pressure" on the piston for "longer" with lower timings.
The gas pressures soon after TDC ,that creates the real power, is up over 80 bar, the pressure at Ex open is a couple of bar at best.
Moving from 200* to say 190* creates jack shit extra exertion of pressure on the piston to create torque, that then creates HP.
But the real issue is that down at 190* duration we get a huge amount of superposition of the gas pulse exiting the exhaust, on top of the residual pressure at the port.
This adding of a new pulse on top of an existing residual pressure means the wave front running down into the header has a huge relative amplitude, and this creates a huge depression at the port around BDC.
This also means we have port/pipe resonance over a much wider range and at a much high higher level than can be achieved at 200* duration.
In a conventional design we are forced into a corner by needing to create as much BlowDown STA as we can, and raising the timing is the only available route.
This pushes us away from the ideal port/pipe interaction timings, but is a compromise we are forced to accept to create the + 200psi bmep's needed, to be competitive.
Just another small detail that many overlook, or are unaware of.

wobbly

3rd November 2011, 20:00

I am a little worried by the ignition curve.
Why is there 30* of base timing, then a "correction" of 15* to this.
If the base timing is correct, then no correction is needed at all.
It may not make any difference to what the engine actually sees, as a real timing, but what we see on the graph is rubbish.
The best way to establish a correct base timing is to use the straight line timing of say 30* btdc, over a wide rpm range, mark this on the rotor/stator, strobe it, and correct the base timing till
the actual 30* lines, line up in real time.

TZ350

3rd November 2011, 21:46

The best way to establish a correct base timing is to use the straight line timing of say 30* btdc, over a wide rpm range, mark this on the rotor/stator, strobe it, and correct the base timing till
the actual 30* lines, line up in real time.

That’s exactly how we do it. Here is a video clip of Bucket using the dyno to check and adjust the base advance.

<iframe src="http://www.youtube.com/embed/JKt9OWnYdsQ" allowfullscreen="" width="420" frameborder="0" height="315"></iframe>

.I got the job of setting up NedKellys IgniTech programmable Ignition.

First step is to find TDC.

Mark TDC and the Advance you want, we chose 15 degrees BTDC. and marked them on the fly wheel, the flywheel turns ant-clock wise so the advance is marked to the left of the TDC mark.

This does not have to be that accurate as its only needed as guide so you can see that the ignition is firing somewhere near the right place. The ignition will be optimised on the dyno later.

The next move is to find the base advance.

Ours was about 10 Degrees.

The base advance is entered into one of those little box's in the program and initially the real advance is setup as a straight line in the curve part of the IgniTech program.

With the ignition programmed and the spark plug out, (but plugged into the HT lead and resting on the head) you can then use the Dyno's starter to spin the engine over. Then with the motor spinning over you can use a timing light to see if you have got the initial advance more or less where you want it.

If the advance lines don’t line up, you simply adjust the base advance setting and cylinder correction until they do.

With the initial advance setup more or less where you want it, you are ready to rock and roll on the dyno optimising the ignition curve.

The IgniTech software is very clever as changes to the ignition curve can be made on the fly and the Ignition itself re-programmed while the engine is still running............

Lots of pictures on Buckets original post.

Why is there 30* of base timing, then a "correction" of 15* to this.
If the base timing is correct, then no correction is needed at all.

Mine was the first one we set up and were not to sure what all the bits and bobs did, and how the correction and base advance interacted, it works so we have left it.

I think the initial problem was we needed more base advance than the 30 the Igni program allows. We may also have swapped the triggering from the heal of the rotor to the toe. It was a while ago so its all a bit hazy.

The programmable replaces a fixed ignition that ran best on this engine at 16 deg advance.

I am still not sure about the relationship between base advance and correction.

Is it.

Base Advance plus Correction, ie 30 + -15 = 15 deg Real Base Advance

or

Base Advance minus Correction, ie 30 - -15 = 45 deg Real Base Advance

dmcca

3rd November 2011, 22:50

wobbly

4th November 2011, 06:46

Not sure with your setup, as you should always be firing off the lobe trailing edge ( a dropping voltage) as rising edges are prone to read
spikes ( ie noise) as a control signal.
The procedure is to pick a known advance and mark this on the stator/rotor.Then change the base advance to get the lines coinciding.
Some use TDC and programme a straight line with 0* advance, its easyer to use the flat line in most curves between 2000 and 6000 that should be around 28* = 3.9mm in a 54 stroke.
Advancing the base, retards the firing point.
The correction factor is used for aligning the two channels of the ecu when firing both cdi off one trigger, as used in a Rotax tandem twin.
Due to pipe differences, they need up to 2* of retard on the rear cylinder in relation to the front one.
Your setup "works" but the graph bears no visual relationship to what the engine is actually seeing.
The CR250 race file attached is the advance the engine actually sees, as soon as you apply correction what you read, on screen isnt what you get.
The base advance firing of the lobe trailing edge is the timing seen at kickover ( up to 300rpm),then the map takes effect.
Thus its advisable to have a base advance that is in the range of 10 to 20* for easy starting, and then smooth idle.

F5 Dave

4th November 2011, 09:10

yeah I was going to say that's the queerest ign curve. was expecting to see scads more advance around 4thou if it were a road bike. might help you get out of the pits with less clutch slip.

TZ350

4th November 2011, 13:21

Your setup "works" but the graph bears no visual relationship to what the engine is actually seeing.

What are you saying, the shape is different or that there is a consistant offset. Please elaborate on what you mean by "bears no visual relationship". Any more info would be a help.

My understanding is there are three essential things.

Base Advance tells the Ignitec how far before TDC the timing trigger pulse is.

Correction tells the Igni how much lead or lag to give a particular cylinder in degrees.

The ignition curve tells the Igni the firing point in relation to TDC (plus/minus any correction) and it fires one revolution after the trigger signal.

And on the surface, its all additive/subtractive arithmatic, nothing fancy from the users point of view.

as soon as you apply a correction what you read, on screen isnt what you get.

I don't understand what you mean. Are you talking about an offset or a change in the curve shape itself?

I would like to get to grips with what your trying to tell me. So please, lets start with the basics.

Is it.
Base Advance plus Correction, ie 30 + -15 = 15 deg Real Base Advance
(which means I could drop the -15 correction and use a 15 deg base advance like you suggest)

or

Base Advance minus Correction, ie 30 - -15 = 45 deg Real Base Advance (and may have been what I was aiming for).

It was a while ago when we set this bike up (and our first) so not to sure about the details now. But its possible that we needed more base advance (like 44 deg) than the Ignitec program allowed for and that we used the correction value to extend the base advance.

I could have machined something off the rotor heal or shifted the trigger coil but at the time this was the most practical. After Taupo I will have another look at it to see if it can be tided up, but any software/hardware setup changes require a runup on the Dyno and that will have to wait until I have more time.

TZ350

4th November 2011, 15:32

250008

If this works on your bike, use it I recon, but its not a goer for mine.

250007 250018

I have put some real dyno time into my ignition trying different curve options including ones like the top picture and this straightish one is what works for me, and I know this because the dyno tells me so.

I am fairly confident that the curve shown is the one that works best with my engine. (Speedpros is very similar, others less so).

I know that 15 on the screen may not be 15 in reality but the offset error will be consistantly the same all the way through the curve and so I am expecting the shape of the curve we see to be the shape of the curve the engine sees.

As far as I can see, Base Advance and Correction add up to a consistant offset, not a change in curve shape, but the Ignitec manual is a bit vauge about some things so anything is possible. If the shape of the curve we see in my pic is not the curve shape the engine sees I would be very interested to know more about why.

bucketracer

4th November 2011, 18:52

The procedure is to pick a known advance and mark this on the stator/rotor.Then change the base advance to get the lines coinciding.

The way you describe it, its pretty much how we do it, maybe you missed the original post complete with pictures, link below.

I got the job of setting up NedKellys IgniTech programmable Ignition.

F5 Dave

4th November 2011, 20:40

PS it would be interesting to see your power curve from x/y origin. It looks super fat displayed with 7.5k as the start point, I've only just clicked onto that. Hey my 100 doesn't start to produce power till 9k so I'm not dissing or anything, just interested.

TZ350

4th November 2011, 20:57

The Dynojet graphs the range thats recorded, if the Sampling was started at 5k and finished at 12 the graph would cover that range. My bike starts to get into its stride at 8 and signs off at 12 or so, so sampling from 7 ish covers the range of practical interest.

PS it would be interesting to see your power curve from x/y origin. It looks super fat displayed with 7.5k as the start point, I've only just clicked onto that.

As the bike idles at 3k or so, sampling from the origin (0 rpm) would be an interesting feat indead.

There must be graphs some where on this thread with dyno runs from the Vetec inlet experiments that start much lower than 7k. The Vetec cleaned up the carburation and made the area between 3 and 7 useable, you made comment about how little power there was.

And I found changes in the ignition curve did not improve it. My great hope is that I can make a practical working ATAC system like Wobbly discribes and extend the lower end of the power spread down to 7 or even 6k ish.

My 4k power spread is 1/3 of the total rpm range and I suspect a flat 4k rpm power spread will still be a flat 4k whatever the range the graph printout covers.

F5 Dave

4th November 2011, 21:02

I'm running with much older DJ sw, so used to seeing whole graph, even if starts higher in the range & lets face it I'm used to the 50's curve & 10thou is considered midrange.:blink:

TZ350

4th November 2011, 21:27

lets face it I'm used to the 50's curve & 10thou is considered midrange.:blink:

10k is still midrange for a 4k power spread that starts at 8.

Here is a Vtec graph that starts at 4 ish. In fact the engine with the Vtec fitted could drive from 3.

250023

Blue line, Vtec inlet showing a smother graph between 4 and 7. With the Vtec cleaning up the carburation the area between 4 to 7 became useable but I was disappointed I could never lift the power here whatever I tried including ignition curve changes.

The Vtec combined with the ATAC could be the answer here.

speedpro

4th November 2011, 21:41

I'm running with much older DJ sw, so used to seeing whole graph, even if starts higher in the range & lets face it I'm used to the 50's curve & 10thou is considered midrange.:blink:

and a 300rpm powerband is good

Buckets4Me

4th November 2011, 21:48

and a 300rpm powerband is good

for the clutch supplier :facepalm:

husaberg

4th November 2011, 21:54

The Dynojet graphs the range thats recorded, if the Sampling was started at 5k and finished at 12 the graph would cover that range. My bike starts to get into its stride at 8 and signs off at 12 or so, so sampling from 7 ish covers the range of practical interest.

As the bike idles at 3k or so, sampling from the origin (0 rpm) would be an interesting feat indead.

There must be graphs some where on this thread with dyno runs from the Vetec inlet experiments that start much lower than 7k. The Vetec cleaned up the carburation and made the area between 3 and 7 useable, you made comment about how little power there was.

And I found changes in the ignition curve did not improve it. My great hope is that I can make a practical working ATAC system like Wobbly discribes and extend the lower end of the power spread down to 7 or even 6k ish.

My 4k power spread is 1/3 of the total rpm range and I suspect a flat 4k rpm power spread will still be a flat 4k whatever the range the graph printout covers.

Devils advocate here. Please no one take offense as its not intended a slight on anyone
posted as I am a little bored.
I do have to say. That for all the sexyness of the dynographs (of a lot of the bikes I have seen here.)
Shouldn't most of the final testing of concepts be done at the track?
I am just asking because I guess thats where most of the racing is still done these days?:whistle:

I don't often see the stories of how much the lap times are improved by many of the mods or additional HP gains?

bucketracer

4th November 2011, 22:17

... the final testing of concepts be done at the track? I am just asking because I guess thats where most of the racing is still done these days?

No, not Dyno Racing, never has been .....

... the final testing of concepts be done at the track? I don't often see the stories of how much the lap times are improved by many of the mods or additional HP gains?

I think TeeZee has been pointing out for sometime now that more outright HP has not been much help at Mt Wellington and that he thinks ease of riding and developing power spread with drive out of the corners is where its at for him there, horses for courses so to speak.

I guess when he gets things working to his satisfaction he will let us know how they went for him. In the mean time if you see any ideas that interest you, you are welcome to see what you can make of them for yourself. I am sure TeeZee would be delighted.

Gigglebutton

5th November 2011, 07:07

Devils advocate here. Please no one take offense as its not intended a slight on anyone
posted as I am a little bored.
I do have to say. That for all the sexyness of the dynographs (of a lot of the bikes I have seen here.)
Shouldn't most of the final testing of concepts be done at the track?
I am just asking because I guess thats where most of the racing is still done these days?:whistle:

I don't often see the stories of how much the lap times are improved by many of the mods or additional HP gains?

TZ tuned my RG50 on the ESE dyno. I had tuned it on the track and thought it was well tuned, as did any one else that rode it. I had the timing and jeting well out. A couple of hours later we gained 1.3 hp and .7ft-lbs of torque all through the curve.
So much easier to ride now and my lap times have dropped. Im not getting any quicker, but with Robs expertise in reading the dyno graghs, the bike is.

F5 Dave

5th November 2011, 12:56

10k is still midrange for a 4k power spread that starts at 8.

Here is a Vtec graph that starts at 4 ish. In fact the engine with the Vtec fitted could drive from 3.

250023

Blue line, Vtec inlet showing a smother graph between 4 and 7. With the Vtec cleaning up the carburation the area between 4 to 7 became useable but I was disappointed I could never lift the power here whatever I tried including ignition curve changes.

The Vtec combined with the ATAC could be the answer here.

ahh, that looks a little more like what I'd expect to see. But it pulls up nicely from down low so that looks good & probably a whole lot easier to ride than my creations to date.

TZ350

5th November 2011, 14:09

Comparison of Speedpros 30hp (green) bike and TeeZees 28+ hp. Both have much the same flat ignition curve.

husaberg

5th November 2011, 22:36

.... I cannot explain either what else it could be (I hardly expect Honda experimented with a water-cooled motor control unit) but then I can't see any sense in cooling that pipe injection water either; its container was built into the gas tank where the water will never pick up any heat.
And I know for a fact that the pipe injection system was total-loss. Honda (and Aprilia six years before them) already had a problem with the cooling effect not wearing off quickly enough once you got into the power band; the problem would have been far worse with double-walled light-alloy headers.

I found this snippet of information whilst looking for Rs125 specs.
It would appear to have come from Shigeru Hattori NSR500 project leader. I am now more confused than ever about how it worked.

Frits Overmars

6th November 2011, 03:05

Aaaargh! I'm having big issues viewing this thread. I can look at anything else on KB but For several days now when I try to visit this thread I get an 'http500' error. Finally able to get on using my phone now but can't do it from either computer at home. Am I alone?? Any suggestions.I had exactly the same problem for a couple of weeks. Everything is fine now, without me changing anything. No clue what caused it.

....With the exhaust appearing to gain its time area with its formidable width instead of its height. Does that mean the effective duration of its power stroke is of a much longer percentage of the stroke (I hope this makes sense). Or is this cancelled out but it being positioned higher in the cylinder? It may well be a silly question so apologies, if I missed that bit in translation.Don't you pull my leg, Husaberg. All my contributions to pit-lane are written in English (or at least that is what I tried to do). You are not going to tell me that your native language is Swedish, as your nickname might suggest, huh?:devil2: Well, in case you simply overlooked it, here is a link right to the answer you asked for:
http://www.pit-lane.biz/t117p333-gp125-caracteristiques-aprilia-rsa

I (http://www.pit-lane.biz/t117p333-gp125-caracteristiques-aprilia-rsaI) will also attach some pics of the 50 cc version of my cylinder, including a vertical journey through the model that shows the layout of the various ports and ducts and especially the cooling system.Try casting that!

EDIT: I just discovered I can't attach ZIP-files. The file I tried to upload contains 34 pictures; 2.27 MB in total. Any suggestions?

Dutch Fisher

6th November 2011, 05:35

You'd be better off registering here http://www.photobucket.com and placing the pictures there with a link

Frits Overmars

6th November 2011, 10:24

You'd be better off registering here http://www.photobucket.com and placing the pictures there with a linkThanks Dutch, but there are some problems. First of all, I have seen pictures appear in the open, that could only have come from a restricted forum, where they were posted through photobucket. I want to have some control of who is getting what.
Secondly, the 'vertical journey through the model' I was talking about, would only function as it is supposed to when you can swiftly leaf through the pics instead of having to download them one at a time.

husaberg

6th November 2011, 10:49

I had exactly the same problem for a couple of weeks. Everything is fine now, without me changing anything. No clue what caused it.

Don't you pull my leg, Husaberg. All my contributions to pit-lane are written in English (or at least that is what I tried to do). You are not going to tell me that your native language is Swedish, as your nickname might suggest, huh?:devil2: Well, in case you simply overlooked it, here is a link right to the answer you asked for:
http://www.pit-lane.biz/t117p333-gp125-caracteristiques-aprilia-rsa

(http://www.pit-lane.biz/t117p333-gp125-caracteristiques-aprilia-rsaI)

Sorry Frits
My first language, indeed my only language is English (Although many years ago on occasion I have tried a little Swedish and attempted to get my tongue around the odd other euro .
I guess Its just I don't read that well.
:spanking:
I even had to read it another couple of times before I twigged to it and are still not sure I totally get it.
This says a lot more about my comprehension skills than your explanation though Frits.
I should possibly reread the whole forum again.
Yes my puns are pretty bad to. Much like my grammar and spelling and punctuation and capitalisation.

With regards to the forum The techy people have been making a lot of changes to it over the last couple of weeks which may account for your problems with logging on. With a bit of luck they may make it possible to insert larger images and files to the thread .

Hint hint to kiwibiker.

Either that all you could post them in pit-lane? with a link here leading to them?

Buckets4Me

6th November 2011, 12:02

Well I didn't let of any fireworks and I never made it to taupo
I did get very dirty
and I found a nice new 2 stroke I want KTM380
250102250103
250104
now I can see why people are going over to MX for fitness

teriks

6th November 2011, 23:27

Looks like a fun place to ride!
Only donwside with MX is the cleaning afterwards...

Frits Overmars

7th November 2011, 00:41

gamma500

7th November 2011, 03:29

Awesome cylinders, Frits! :niceone:

Have you already tested those cylinders on dyno?

Frits Overmars

7th November 2011, 06:00

Awesome cylinders, Frits! :niceone:. Have you already tested those cylinders on dyno?Not yet, Gamma. I have deliberately postponed building crankcases until the cylinders were finished (otherwise you'll always find that you have to make unforseen changes).
At the moment we are working on ultralight, ultrashort pistons and conrod bearings that will stand the extreme rpm that the cylinder's angle*areas permit.
Other necessities, like piston pin plugs that prevent short-circuiting between transfer and exhaust ports, are being tested in other engines. So far so good.

casal-fan

7th November 2011, 07:02

wobbly

7th November 2011, 07:32

Rob,re the Ignitech curve "issue".
As I said the correction factor was put into the program to allow a split to be setup in a twin cylinder engine that fires off a single trigger, as thats what I asked for.
But say if you have 15* of base advance with a curve that ramps up to say 30*, then drops to 15* at full noise.
Apply 15* of minus correction, you will still see 15-30-15 on the graph, but the actual timing seen by the engine will be 0-15-0, so what was the point of having a graphical interface
showing what the timing curve looked like in the first place.
If you need 15* of negative correction, then this is the same as having 30* of base timing ( adding 15* to the original 15*), as increasing base advance in effect retards the timing.
You see this when programming 15* base, but the strobe says its advanced by say 1*, apply 16* base and the real timing will drop back to the correct number you are looking for.
But using 30* of base timing isnt a good idea, as this is the "starting" timing seen by the engine.
It will "work" and will start with that timing - I have used the max of 39* on a RS250, as I couldnt move the lobe or recut the keyway), but it was very prone to kicking back, and
was all but impossible to push start and needed a roller.
It kicked back during practice and started in reverse at Bonneville, very embarrassing when he dropped the clutch and it shot of backwards, dropping it on the salt.
I think the Race unit only allows 30* but the normal P2 allows 40* max base advance.
One small point is that in the area off the pipe, I have found that the engine will not make much if any more power, as shown by the dyno load it will pull, but by adding a heap more timing, it will for sure
operate much , much better on part throttle response, on track.
Here is a 125 kart engine curve that made 50RWHp,and won 3 back to back 125 National titles easily.
This thing would deto like mad on part throttle at 6000 if held there, but on track it would pull out of 1st gear hairpins hard enough to spin the tyres on full throttle from the same
rpm, then rev out to 14200.
A TPS and a 3D map would achieve a better result, but I didnt have a RS125 Honda carb at the time.

Frits Overmars

7th November 2011, 08:20

Very interesting Frits. Is this endeavour directed to a specific aplication, or is it just pushing the line on 2stroke alternative scavenging systems?
Awsome thread. A must read for all 2stroke fans. Big thanks to all intervenants.I did not intend to go alternative; I was just looking for a way to increase the angle*areas. And I had planned to build a 125 cc roadracer because if you want to show what you're worth, go for the strongest competion.
Alas, Dorna killed the 125 cc GP-class, so I decided to scale the design down to 50 cc.
It was the easiest conversion I ever performed: I just told SolidWorks to multiply all dimensions by 0.737 :cool:.

dmcca

7th November 2011, 11:05

Not sure with your setup, as you should always be firing off the lobe trailing edge ( a dropping voltage) as rising edges are prone to read
spikes ( ie noise) as a control signal.

The CR250 race file attached is the advance the engine actually sees, as soon as you apply correction what you read, on screen isnt what you get.
The base advance firing of the lobe trailing edge is the timing seen at kickover ( up to 300rpm),then the map takes effect.
Thus its advisable to have a base advance that is in the range of 10 to 20* for easy starting, and then smooth idle.

A couple of questions about the ignitech...

When you referred to firing off the trailing edge... is that set by the check boxes circled in red in the setup window below? What is the Max Advance for? Should both of these be set to second edge? I have a CR250 that im setting up with an ignitech and have been having some issues with kickback at startup so my setup must be wrong... im wondering if its to do with this synchronisation window... there is no explanation of this setting in the manual.

250224

Also the CR250 map you posted, is that for a kart engine? heavily modified or not? Looks like its revving out a decent amount.

wobbly

7th November 2011, 12:29

kiwifruit

7th November 2011, 13:24

kel

7th November 2011, 13:36

[QUOTE=Frits Overmars;1130190161]I did not intend to go alternative; I was just looking for a way to increase the angle*areas. And I had planned to build a 125 cc roadracer because if you want to show what you're worth, go for the strongest competion.
Alas, Dorna killed the 125 cc GP-class, so I decided to scale the design down to 50 cc.QUOTE]

Frits if your revolutionary cylinder is supplied as an AM6 aftermarket kit then it would be legal for our F5 racing class ;), perhaps 29hp is achievable from 50cc after all.

kel

7th November 2011, 13:42

dmcca

7th November 2011, 13:55

The tick box for start advance means the trailing edge of the lobe is used for triggering, and is the advance used at first kick up to 300rpm.
If you tick the maximum advance box above, the most advance you get is the base advance PLUS the lobe length, no matter what the curve says.
This isnt normally needed, but is a safety where you have alot of noise giving false triggering.

Kicking back at startup usually means you have too much advance initially.
I try to get no more than 15* of base timing, and even retard from that after 300rpm - up to say 1500rpm, before ramping up if kickback is an issue.
If you are reversing the trigger polarity, I would go back and change the wires on the ecu, and delete the software reversal.
The ECU works better this way by using a real dropping voltage to detect the lobe trailing edge and it is more reliable.

The CR250 curve is a nearly 65Hp on PumpGas engine for an open kart and revs to 11,000 + all day - then blows to pieces.

My Cr250 is actually a CR280 with B x S of 68.5 x 76mm and a longer 130mm rod, also the centre of new bore is offset to the rear by 1mm... all this adds up to a very different tdc position of the rotor,with tdc now being much earlier than the stock setup... tdc pretty much now coincides with the pick up being directly over the top of the trailing edge of the lobe (on second thoughts, maybe even just before the trailing edge...)

Ive currently got 2 degrees of base advance up to 1500rpm, but still playing with settings. The bike starts very easily with the stock ecu, always first kick with a half hearted effort, however plug the ignitech in and its a prick to start...

I need to get back into the shed, double check everything...

***EDIT... just double checked base advance... it is 5 degrees after the trailing edge of the lobe, will keep testing from here.

TZ350

7th November 2011, 15:35

Rob,re the Ignitech curve "issue". I think the Race unit only allows 30*

Yes the Race unit only allows 30 deg base advance, thanks for going into more detail, as I work through it I may have to ask more questions.

TZ350

7th November 2011, 16:16

The Bucket GP at Taupo.

My Laps:- http://www.mylaps.com/results/showevent.jsp?id=733033

Qualifying (Dry Track), best laps for:-

Andrew A 49.553
Alistair Hoogenboezem 49.567

TeeZee 53.312

So having a big hp bike did not make me a GP winner but it was sure fun to ride.

The GP was run in very wet conditions. Best laps for:-

Andrew A 49.212
Alistair Hoogenboezem 48.743

Both went faster in the wet than they did in Qualifying how good is that ....... that might happen in superbikes too, possibly, maybe.

F5Dave went faster in the wet on his 50 than I did in the dry on my 125, a big hats off to him ..... respect.

Me I completely bottled out in the wet and pulled in, while all my friends in the pits made the chicken clucking noise, bastards. ....

If the big hp team ESE bikes have to prove themselves on the track, then they need someone way better at riding than me to do it.

Av and Speedpro started about 32-36 on the grid and cut their way through the field to finished 8th and 9th both had to ease up a bit in the last laps, Speedpro because his engine was getting hot and Av was having trouble shifting gears towards the end.

It was great watching them out accelerating other bikes along the back straight. The front running FXR's of Andrew, Richban, Gavin, Alistair Hoogenboezem's CBR and I am sure a few other FXR's have been well tuned as they were very fast. In practice and pre-lim my bike did not seem that fast, it struggled past bikes that I thought it should easily take down that long back straight.

After the pre-lim Andrew A came over and gave me a few tips about a still air box and suggested I setup some sort of wind shield in front of the carb so the wind did not blow directly across the bell mouth.

While I was trying to fashion something out of a Tupperware container I broke the fuel barb of the top of the Tillotson plastic carb cap, bugger. I thought may day was over but John Steer and Warwick Head came to the rescue with a fitting, drill and glue and in half an hour it was fixed.

The wind break must have been what the carb needed because when I went out on the track again the bike sounded real sharp and made short work of some of the bikes that I could berley get past before.

It was a great time catching up with old friends, and meeting new ones. Roll on the next GP, can't wait, big hp is fun fun fun even if I can't ride for nuts.

explode64

7th November 2011, 18:12

Shorty_925

7th November 2011, 18:23

The Bucket GP at Taupo.

My Laps:- http://www.mylaps.com/results/showevent.jsp?id=733033

Qualifying (Dry Track)

Andrew A 49.553
Alistair Hoogenboezem 49.567

TeeZee 53.312

So having a big hp bike did not make me a GP winner but it was sure fun to ride.

The GP was run in very wet conditions.

Andrew A 49.212
Alistair Hoogenboezem 48.743

Both went faster in the wet than they did in Qualifying how good is that ....... me I completely bottled out and pulled in, while all my friends in the pits made the chicken clucking noise, bastards :bleh:

F5Dave went faster in the wet on his 50 than I did in the dry on my 125, a big hats off to him.

Av and Speedpro started about 30-32 on the grid and cut their way through the field to finished 8th and 9th both had to ease up a bit in the last laps, Speedpro because his engine was getting hot and Av was having trouble shifting gears towards the end.

It was great watching them out accelerating other bikes along the back straight.

Time to get a 4 stroke?

speedpro

7th November 2011, 18:41

Time to get a 4 stroke?

Far cough

TZ350

7th November 2011, 18:51

Time to get a 4 stroke?

Year Right ........ :rolleyes: ...... might just have to help Chambers with building a decent engine for Av's bike.

husaberg

7th November 2011, 19:00

Time to get a 4 stroke?

:psst: More than two strokes in a Wan.

err..........:tugger:

Then again if you are so convinced of the four stroke superiority. I guess you wont mind if we up the cc limits on the 2 strokes then will you.

Bert

7th November 2011, 19:31

Rather than start a new thread i thought i'd just ask in here:

Sleeving down a water cooled TZR125 to 100cc. Anyone got any experience doing this? Any advise / direction etc gratefully received. :cool:

A couple have been done. The limiting factor is the blowdown associated with the single exhaust port. Check with Bert.

Depends what version your got.
but, Kel is right blow down is the killer;
I'll let the cat out of the bag. if I was to re-sleeve again; I would seriously think about putting a bridge and opening the exhaust up. My Sleeve is about >8mm (I'll measure it up) which i think might get quite hot, but that should be thick enough to put a bridge in (with a little dishing??)..
Give up on the power valve just lock it open.
big end bearings... stupid size yamaha crap. followed Wooblys instructions and modified the crank (machined by ~1mm) to take off the shelf C3 bearings (floating).

Other than that, the little end pin (on the 4dl version; I assume that the more common 2RH is the same) is 16mm (not 14 or 15mm like most other 100-125); which makes it hard to find 50mm pistons for. But Yamaha did make a YZ100 1981-82 (50-52mm) with a 16mm gudgen (wiseco & woosner still produce them) but with a 1.5m ring:mad:... Conrods are the same as 250 so easily sourced.

Got my cylinder done in Whanganui half/Third the price of elsewhere and really impressed with the quality and workmanship (Through Brain Thorley Motorcycles)
Griffiths engineering (PN) has done some amazing work on the head (like a homemade VHM) and most other bits that are beyond me...

take the time to read through BusaPetes thread on his build (he bet me by a year and a half even though we started around the same time; work sucks..):
http://www.kiwibiker.co.nz/forums/showthread.php/105446-Yamagama-100

kiwifruit

7th November 2011, 20:03

Depends what version your got.
but, Kel is right blow down is the killer;
I'll let the cat out of the bag. if I was to re-sleeve again; I would seriously think about putting a bridge and opening the exhaust up. My Sleeve is about >8mm (I'll measure it up) which i think might get quite hot, but that should be thick enough to put a bridge in (with a little dishing??)..
Give up on the power valve just lock it open.
big end bearings... stupid size yamaha crap. followed Wooblys instructions and modified the crank (machined by ~1mm) to take off the shelf C3 bearings (floating).

Other than that, the little end pin (on the 4dl version; I assume that the more common 2RH is the same) is 16mm (not 14 or 15mm like most other 100-125); which makes it hard to find 50mm pistons for. But Yamaha did make a YZ100 1981-82 (50-52mm) with a 16mm gudgen (wiseco & woosner still produce them) but with a 1.5m ring:mad:... Conrods are the same as 250 so easily sourced.

Got my cylinder done in Whanganui half/Third the price of elsewhere and really impressed with the quality and workmanship (Through Brain Thorley Motorcycles)
Griffiths engineering (PN) has done some amazing work on the head (like a VHM) and most other bits that are beyond me...

Thanks Bert. I'll pass this on to my old man. he has a 1990(? - it's water cooled with 17 inch wheels) TZR125 and is looking to turn it into a bucket.

Buckets4Me

7th November 2011, 21:12

:psst: More than two strokes in a Wan.

err..........:tugger:

Then again if you are so convinced of the four stroke superiority. I guess you wont mind if we up the cc limits on the 2 strokes then will you.

hay I walked into a new bike shop today . It was new about 2 weeks old and full of ktm's and there in the back corner in nice new blue paint was a half dosen HUSABERG's

koba

7th November 2011, 21:18

take the time to read through BusaPetes thread on his build (he bet me by a year and a half even though we started around the same time; work sucks..):
http://www.kiwibiker.co.nz/forums/showthread.php/105446-Yamagama-100

Did he really? Does it go? I saw it was for sale ages ago but was it actually fully functional?

Thanks Bert. I'll pass this on to my old man. he has a 1990(? - it's water cooled with 17 inch wheels) TZR125 and is looking to turn it into a bucket.

Fantastic!

husaberg

7th November 2011, 21:38

hay I walked into a new bike shop today . It was new about 2 weeks old and full of ktm's and there in the back corner in nice new blue paint was a half dosen HUSABERG's

I am going to sell mine now as they are obviously common as muck these days.
I will have to get my self a TM or something.
Don't you FXR150 riders hate it, when you get to a party and some other chick is wearing the same dress as you.:nya:

speedpro

7th November 2011, 21:51

Got my cylinder done in Whanganui half/Third the price of elsewhere and really impressed with the quality and workmanship (Through Brain Thorley Motorcycles)
Griffiths engineering (PN) has done some amazing work on the head (like a VHM) and most other bits that are beyond me...[/url]

Years ago there was a bunch of Griffiths racing buckets and they had a machine shop or some sort of engineering business. Probably the same guys.

Bert

7th November 2011, 23:37

Years ago there was a bunch of Griffiths racing buckets and they had a machine shop or some sort of engineering business. Probably the same guys.

Yip. and they still have shed loads of very cool buckets & bucket sidecars.

teriks

8th November 2011, 08:50

Here are some of the pictures. Most of them have not been shown on an open forum before.
Pictures 1 and 2 show development stages; both are several years old now.
Picture 3 shows doctor of physics Denis Klemm (left) and myself with the first 50 cc FOS cylinders. Denis was of vital importance in applying the Selective Laser Melting process that allowed me to produce the shapes I wanted.
Pictures 4, 5 and 6 show these cylinders from some different angles.

Now this is really interesting, not only the port arrangement, but the manufacturing method as well!

It just happens I spoke briefly with a colleague about the possibility using laser-sintering/melting for cylinder prototyping. For me it will probably stay stay just like that, discussing and dreaming.
Anyway, his main concerns were surface accuracy and less than full density of the resulting material. That, and to find someone who had developed for an useable aluminium alloy.

-After seeing your cylinder today, the colleague said that it had some of, or even the best surface quality he had seen. Seems you have it all covered.

F5 Dave

8th November 2011, 09:16

The Bucket GP at Taupo.
. . .
F5Dave went faster in the wet on his 50 than I did in the dry on my 125, a big hats off to him ..... respect.

. . ..

ahhh, actually I think you read the wrong session & it was a dry one, in the 50 race I was on slicks in the wet so had well modified lines to just stay on board & bring it home.

Frits Overmars

8th November 2011, 09:39

Now this is really interesting, not only the port arrangement, but the manufacturing method as well!
It just happens I spoke briefly with a colleague about the possibility using laser-sintering/melting for cylinder prototyping. For me it will probably stay stay just like that, discussing and dreaming.
Anyway, his main concerns were surface accuracy and less than full density of the resulting material. That, and to find someone who had developed for an useable aluminium alloy.
-After seeing your cylinder today, the colleague said that it had some of, or even the best surface quality he had seen. Seems you have it all covered.I think we have. We used AlSi12 material; the melting resolution was 20 micron. The result is a dense, hard workpiece, better than the best casting quality.
If there is a downside to all this, it would be that building these two 50 cc cylinders took 25 machine-hours; great for prototypes, but forget about mass production.

TZ350

8th November 2011, 11:17

The Bucket GP at Taupo.

My Laps:- http://www.mylaps.com/results/showevent.jsp?id=733033

F5Dave went faster in the wet on his 50 than I did in the dry on my 125, a big hats off to him ..... respect.

ahhh, actually I think you read the wrong session & it was a dry one, in the 50 race I was on slicks in the wet so had well modified lines to just stay on board & bring it home.

OK ... so ... F5Dave went faster on his 50 than I did on my big hp 125, in practice/qualifing and I was giving it a real good go too, so, how does he do it?

Henk

8th November 2011, 15:39

Don't you FXR150 riders hate it, when you get to a party and some other chick is wearing the same dress as you.:nya:

No, because at least we have a conversation starter while all you big boys stand in the other corner comparing lubricants.

TZ350

8th November 2011, 19:49

Neels van NieKerk auther of EngMod2T

As far as squish is concerned whether it helps or not depends on the residual turbulence at the time of combustion. As for squish quenching the flame at the edge of the squish band to stop detonation is not looking very likely. http://home.earthlink.net/~scloughn/id21.html

250292 Tail pipe entry geometry http://www.google.co.nz/#sclient=psy-ab&hl=en&source=hp&q=engmod2t+simulation&pbx=1&oq=engmod2t+simulation&aq=f&aqi=&aql=&gs_sm=e&gs_upl=12692l12692l0l14059l1l1l0l0l0l0l290l290l2-1l1l0&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=7b5dd5d7c296b0b3&biw=1024&bih=574

250284 (2004) EngMod2T manual :- http://www.rddreams.com/neels/engmod2t.pdf

This manual is a bit dated but worth a look, hopefully someone can find a more recent version for us to look at.

Obtaining the EngMod2T suite of programs
The software price is $400.00. To purchase it email Neels van Niekerk at
vannik@mweb.co.za with a request. The software will then be emailed to you after which you
install it on your PC. The pre and post processors together with all the help files should then
work. EngMod2T requires a licence file to run. A one month evaluation license can be
provided. If after reading the help files you should decide to purchase the software contact
Neels van Niekerk to obtain banking details. Once proof of payment has been received the
licence file will be sent to you. The licence is for one computer only.

husaberg

8th November 2011, 21:28

No, because at least we have a conversation starter while all you big boys stand in the other corner comparing lubricants.
I know you are right. Women seem to always have something that requires conversation.

Question for Frits

With regards to adjustable length pipes For (Expansion chambers). I seem to have picked up that they at least mostly lengthening for low end power.
Has anyone tried ones that just shorten for top end or a least over rev potential to me that would be a more logical solution?( I am not always logical mind you)
I know Cagiva ran a hydraulic system and someone posted a solution you like on pit-lane but I can't access the pic I have a log in and it would let me in?

Frits Overmars

8th November 2011, 23:43

...With regards to adjustable length pipes For (Expansion chambers). I seem to have picked up that they at least mostly lengthening for low end power. Has anyone tried ones that just shorten for top end or a least over rev potential to me that would be a more logical solution?You have to stay within certain length percentage limits for all elements of the exhaust system; you cannot make one part a lot longer or shorter in relation to the others without losing power somewhere.
It is best to concentrate on getting all dimensions correct for maximum power. In the high gears you don't ride low revs and in the low gears you'll have enough low-down power left to pull a wheelie or spin out the rear wheel (I'm not talking about buckets though, so you might want to reconsider your case).
If you have a decent setup for angle*areas, pipe, carburation and ignition, the necessary overrev potential will come naturally; no need to sacrifice maximum power in order to make it rev a little higher.

teriks

9th November 2011, 06:59

I think we have. We used AlSi12 material; the melting resolution was 20 micron. The result is a dense, hard workpiece, better than the best casting quality.
If there is a downside to all this, it would be that building these two 50 cc cylinders took 25 machine-hours; great for prototypes, but forget about mass production.
Should be a bit faster for a 6.6cc cylinder, might even be affordable, for a prototype that is.
Then again, I think I'm better of sticking to my loose plan of using Rob's cylinders and making my own crankcases.

Frits Overmars

9th November 2011, 09:09

Should be a bit faster for a 6.6cc cylinder, might even be affordable, for a prototype that is.
Then again, I think I'm better of sticking to my loose plan of using Rob's cylinders and making my own crankcases.In my cylinders it was mainly the complicated cooling ducting that forced me to find a way around casting limitations. For an air-cooled cylinder like you want, there is no need to resort to selective laser melting.
Rob Metkemeijer's MB40 prototype engines are cast using the lost-wax method. Below you see a mold with exhaust and transfer cores, a wax cylinder and the end product. A mold like this for an air-cooled cylinder is relatively easy to make.

richban

9th November 2011, 17:33

It was a great time catching up with old friends, and meeting new ones. Roll on the next GP, can't wait, big hp is fun fun fun even if I can't ride for nuts.

Was great catching up again. I think after being on track with the fast 2 strokes again. If it was dry it would have been a lot closer. The level of bikes and riders just keeps on climbing. I know that to win this race you need more than a fast bike. You need a fast bike a very focused rider and a bit of luck. Looking forward to next year already.

TZ350

9th November 2011, 18:27

Was great catching up again. Looking forward to next year already.

"Looking forward to next year", me too and breakfast at Tiffany’s again.

I have purchased a copy of EngMod2T and will see what improvements I can make before the next GP and Chambers is pretty interested in what hp improvements he can make to Av's bike.

TZ350

9th November 2011, 20:58

Tried each of the centre section inserts in turn.

250361 250362

You have to stay within certain length percentage limits for all elements of the exhaust system; you cannot make one part a lot longer or shorter in relation to the others without losing power somewhere.

250360

That explains what we found (and suspected). We tried header and mid section extensions, neither on their own or in combination moved the power spread lower in the rpm range. The longer the extension the less top end power and a pronounced double hump. But no significant low end improvement.

And I suspect slippery pipes will behave much the same but water may work because I think it would change all the sections of the pipe proportionaly.

250364

The power came back as the pipe was progressively shortened to its proper tuned length.

husaberg

9th November 2011, 21:23

250361 250362

250360

That explains what we found (and suspected). We tried header and mid section extensions, neither on their own or in combination moved the power spread lower in the rpm range. The longer the extension the less top end power and a pronounced double hump. But no significant low end improvement.

And I suspect slippery pipes will behave much the same but water may work because I think it would change all the sections of the pipe proportionaly.

250364

The power came back as the pipe was progressively shortened to its proper tuned length.

You have to stay within certain length percentage limits for all elements of the exhaust system; you cannot make one part a lot longer or shorter in relation to the others without losing power somewhere.
It is best to concentrate on getting all dimensions correct for maximum power. In the high gears you don't ride low revs and in the low gears you'll have enough low-down power left to pull a wheelie or spin out the rear wheel (I'm not talking about buckets though, so you might want to reconsider your case).
If you have a decent setup for angle*areas, pipe, carburation and ignition, the necessary overrev potential will come naturally; no need to sacrifice maximum power in order to make it rev a little higher.

Thanks for the info Frits and TZ

What i was thinking was to have the proper tuned length with the resultant mid range and the ability to control the carb. But as well have te ability to shorten the tuned length a little for the very top end. As the icing on the cake as it were.
Would not shortening the header a little say 15mm give the potential for a little more over rev and possibly more power? in broad sense. i realise as usual i am making a broad generalisation here.

Brian d marge

10th November 2011, 01:30

In my cylinders it was mainly the complicated cooling ducting that forced me to find a way around casting limitations. For an air-cooled cylinder like you want, there is no need to resort to selective laser melting.
Rob Metkemeijer's MB40 prototype engines are cast using the lost-wax method. Below you see a mold with exhaust and transfer cores, a wax cylinder and the end product. A mold like this for an air-cooled cylinder is relatively easy to make.

While lost wax in this case is still one of the cheapest ways. I use rapid prototyping and almost day bt day the cost is comming down alowing one to really explore !

CFD the ports the literally cut paste into the printer! ( well there are more steps , but this is so exciting ( for me anyway !)

There has been some very creative work here fellas , world class , keep it up

Stephen

TZ350

12th November 2011, 13:24

Team ESE's new EngMod2T software.

I am still at the garbage in garbage out stage, finding out how the modules connect together. But my first impression of using EngMod2T is that it’s a very fragile application, prone to falling over at the slightest data entry mistake. Like a field might display a zero as a default entry and if you backspace to clear it before entering the value you want the program suffers a fatal error and falls over, this happens a lot, well has happened a lot to me anyway.

This sort of untidy logic error is not a problem with the MOTA software I have been using previously. MOTA seems a lot more refined from a user point of view but the EngMod2T approach has some user features I very much like. Like displaying the power potential of the various ports as you develop them. I think this is very handy, saves say, over cooking the exhaust port and then being limited for what can be done with the transfers. This feature alone puts its usefullness ahead of MOTA for me.

Because of the history of the author and the time over which EngMod2T has been developed I expect the underling simulation algorithms are pretty good and in spite of its user interface problems I am looking forward to modelling my engine and seeing what improvements can be made.

After learning how to use the modules and going about inputting the data I will model my motor as is and compare it to a recent dyno graph. If it’s a good match then we can be pretty confident that any changes in the model will reflect what I can expect to see on the dyno.

EngMod2T is already suggesting a 30+ rwhp air cooled engine is possible, now that alone won't make me a GP winner but it sure will be fun to ride.

NordieBoy

12th November 2011, 14:02

What do you 4-stroke guys use to model your engines?

Buckets4Me

12th November 2011, 15:11

What do you 4-stroke guys use to model your engines?

a spade. no wait thats changing tyres.

wobbly

12th November 2011, 15:16

dmcca

12th November 2011, 17:52

NordieBoy

12th November 2011, 19:10

There is EngMod4T that is used by many of the V8 Supercar teams, but probably the best program I have seen is what I use to develop
4T headers.
The pipes I did with it were then modelled and used with Fluent at Ch Ch Uni, to finally come up with the best pipes ever dynoed for FF1600.
It has a huge amount of additional info about the flow data etc needed to support the power that you are looking for.
Its called PipeMax Pro Version by MaxRace Software.

I had a play a while ago trying to model my '79 XR250 engine on Lotus's free engine package (http://www.lotusfiles.com/engineering/lesoft/freeware_software.exe) but couldn't get it above 12hp :headbang:
Knowing nothing about engines probably had something to do with it but it kept me off the streets.

TZ350

12th November 2011, 19:13

interesting... I haven't experienced any stability issues at all... Seems quite stable to me.

Thats good to hear as the crashes were driving me nuts while trying to find my way around a new application.

The sequence leading to a typical crash is.

In the Dat2T application.

Create a New Project.

On the Pipe Types screen.

In the Header Pipe Restriction field
Deleting the default “0” provokes a Visual Fortran Run Time Error.

In the Header Pipe Restriction field
Backspacing to remove the “0” provokes a Visual Fortran Run Time Error.

In the Header Pipe Restriction field
Entering any number without deleting the “0” first results in a Dat2T error message.

On the next page of the module backspacing to clear a field before entering a value invokes a Dat2T error.

I can’t try to enter a value here without either crashing the program or getting an error message that I have to work around. The data entry logic could do with some fine tuning.

As an easily confused newbe just starting out these data entry problems right at the beginning were a real frustration but now that I am getting more familiar with the program it’s not such an issue.

teriks

13th November 2011, 10:19

TZ350, I can repeat most of the problems you are describing.
Might be a good idea to send Neels a bug report.

teriks

13th November 2011, 10:28

In my cylinders it was mainly the complicated cooling ducting that forced me to find a way around casting limitations. For an air-cooled cylinder like you want, there is no need to resort to selective laser melting.
Rob Metkemeijer's MB40 prototype engines are cast using the lost-wax method. Below you see a mold with exhaust and transfer cores, a wax cylinder and the end product. A mold like this for an air-cooled cylinder is relatively easy to make.
I'm quite lost when it comes to casting, but I can see that once you have the mold done, changing cores for different configurations would be quite straight forward.
Thanks for the pictures, at least two of them are new to me.

Ill stick to the bottom end for now though, I want rear induction.

wobbly

13th November 2011, 19:26

TeeZee I have never had a runtime error using the program since it was first created by Neels???
What version of Windoze are you running?
When you have created the project, do you go thru and spec the pages in sequence.
ie the pipe program will need the Ex Port duct length created before the pipe, as its a prerequisite to calculate the complete tuned length.
Dont know but just maybe this is an issue???

Talking about TeeZees, the setup I did for Trevor Discombes TZ350 worked a treat today - he broke the Pre 82 lap record at Puke.
I got sunburnt to hell, dumb.

TZ350

13th November 2011, 20:32

The sequence leading to a typical crash is.

In the Dat2T application.

Create a New Project.

On the Pipe Types screen.

In the Header Pipe Restriction field
Deleting the default “0” provokes a Visual Fortran Run Time Error.

In the Header Pipe Restriction field
Backspacing to remove the “0” provokes a Visual Fortran Run Time Error.

In the Header Pipe Restriction field
Entering any number without deleting the “0” first results in a Dat2T error message.

On the next page of the module backspacing to clear a field before entering a value invokes a Dat2T error.

I can’t try to enter a value here without either crashing the program or getting an error message that I have to work around. The data entry logic could do with some fine tuning.

TZ350, I can repeat most of the problems you are describing.

TeeZee I have never had a runtime error using the program since it was first created by Neels??? What version of Windoze are you running?

Did you try the sequence described in my post?

Windows, XP pro ver 2002 service pack 3 and yes I work down the page in order when creating a new project.

I very much like the EngMod2T programe, lots of great features and after two days and a bit I can create a project, process it and display sensible graphs. Modelling the carb and inlet tract and accuratly measuring the theta angles of the transfers are a bit of a trick. I havn't been able to produce a graph that accuratly matches my existing motor yet, that might take a bit of time but I expect I will get there.

Wob, Great work on Trevors engine, its great to see someones bringing the old TZs into the modern age.

pete 2

14th November 2011, 07:33

Sorry guys a bit off topic,but this thread has some very knowageable people, could i just ask what they think about this?
at the entrance to the transfers the rsa aprilla has very wide dividers between each one while most tuners would narrow these down, i wonder what people like frits think about this or does it not matter.
great thread by the way

wobbly

14th November 2011, 08:07

The wide septums between the transfer ducts is there for two reasons.
One it reduces the duct entry area, and thus the ratio between the port and entry areas.
This drops the volume of the duct.A smaller volume sitting at the port has less inertia that the pressure ratio across the port has to accelerate into the cylinder.
Also consider that if you calculate the delivery ratio at full power and compare this to the cylinder swept volume of the cylinder, the air/fuel mixture sitting in the ducts
is more than enough to fill the cylinder - the is very little "flow" from the case, around the duct and into the cylinder in reality.

Secondly, the front and rear wall radial angles of the ducts are maintained all the way from the port, out to the duct entry.
As in 4T ports, trying to "bend" flow in two dimensions concurrently,lowers the bulk flow rate considerably.
Thus the ducts taper all the way from entry to exit, but only change direction in the one plane, around the short turn to give the correct axial entry angle.
The old bullshit you see of sharp divider edges is just that.
Only supersonic aircraft have sharp leading edges on the wings,and we certainly arent dealing with supersonic flow in transfer ducting.
Any flow loss due to the corners on the flat topped septums is way offset by the better directional control and reduced volume of the duct acting to fill the cylinder quicker.

teriks

14th November 2011, 09:09

Did you try the sequence described in my post?

Windows, XP pro ver 2002 service pack 3 and yes I work down the page in order when creating a new project.

I very much like the EngMod2T programe, lots of great features and after two days and a bit I can create a project, process it and display sensible graphs. Modelling the carb and inlet tract and accuratly measuring the theta angles of the transfers are a bit of a trick. I havn't been able to produce a graph that accuratly matches my existing motor yet, that might take a bit of time but I expect I will get there.

Wob, Great work on Trevors engine, its great to see someones bringing the old TZs into the modern age.

Yup, same sequence, only I stopped after
In the Header Pipe Restriction field
Entering any number without deleting the “0” first results in a Dat2T error message.
Using the same Windows version as well.

I find that I have made a habit to mark the initial number and enter the new without deleting the initial value.
Guess that's why I don't notice these things..

Frits Overmars

14th November 2011, 10:47

at the entrance to the transfers the rsa aprilla has very wide dividers between each one while most tuners would narrow these down, i wonder what people like frits think about this or does it not matter.It matters, Pete, as a lot of Italian kart engine manufacturers and tuners will reluctantly confirm. They all copied the Aprilia cylinder and while they were at it, they could not resist correcting the 'errors' that Jan Thiel had left behind. And then they were surprised when the engine made less power instead of more :bleh:.
It's not that simple to improve the best two-stroke cylinder in history :rolleyes:.

TZ350

14th November 2011, 16:29

EngMod2T

One of the inputs required is the transfer duct angles across the bore. Working them out had me stumped for a while but in the end this is how I went about measuring them, simple as.

250654

Take one piston, cover it with masking tape and mark out some reference lines.

250655

Put the piston in the cylinder and using a wire bent to fit inside the transfer ports mark out the angles using the wire as a guide.

250656

I coloured the segments to make them easier to see.

250657

Measured the angles and off sets and entered the data.

250653

And yes I think I got it right as the software gave me the numbers I was expecting and it has drawn a picture of the ports that look like the shapes on my piston top.

koba

14th November 2011, 17:01

Jeebus that's a big Exhaust port.

Is that the 75% one that went clank?

TZ350

14th November 2011, 18:51

Jeebus that's a big Exhaust port. Is that the 75% one that went clank?

The transfer ducts screen only deals with the transfers, the exhaust pictured on it, is only there so you know which way is up.

If you mean the cylinder, Yes ... and soon to be resurrected too.

dmcca

14th November 2011, 22:54

It matters, Pete, as a lot of Italian kart engine manufacturers and tuners will reluctantly confirm. They all copied the Aprilia cylinder and while they were at it, they could not resist correcting the 'errors' that Jan Thiel had left behind. And then they were surprised when the engine made less power instead of more :bleh:.
It's not that simple to improve the best two-stroke cylinder in history :rolleyes:.

Frits, first of all, thanks for your willingness to share info with us... Your ideas have inspired me:niceone:

It sounds like a lot of the development of the RSA cylinder went into transfer duct geometry... are there any more secrets you can share about the key characteristics that led to such huge power...

Is there any single aspect of transfer duct geometry that offers greater gains than others??... inner duct radius, window/port ratio, radius at bore edge, widening factor just before the port exit, etc. Or is it simply a case of 'the whole being greater than the sum of the parts'.

***EDIT... just been looking more closely at the RSA cylinder transfer ducts... it looks like the inner duct radius is different between secondary and main transfer ducts... Also it seems that the window/port ratio is very different between secondary and main transfers... Im assuming that the flow in the secondary ducts accelerated faster as a result?... were both ports opened at the same time or were staggered transfer timings used?

Sorry for all the questions, just trying to understand the efficiency of the design.

Engmod2T question...

On the topic of transfer geometry, when modelling the transfer window/port ratio, I have been measuring this at the horizontal plane of the base gasket surface (ie measuring the entry to the ducts as shows in the photo Frits posted above) while the drawings in the help files seem to show that it should be modelled along the vertical plane where the cases widen either side of the crank. It has a significant affect on the length of the port depending on which one is chosen (and therefore affects duct volume and crankcase comp ratio).

Which is correct?

Ignitech/starting advance question...

Ive been playing with base advance after experiencing hard starting on my CR280 build... it was kicking back, backfiring and was very hard to start... i quadruple checked everything and determined that base advance was 8 degrees which i though should be fine, however after playing with the stator plate i have now settled on 2 degrees base advance (the minimum i can physically go to) and starting is much easier, much less kickback and very smooth idle. I tried it at 10-15 and it nearly broke my ankle.

Im still trying to account for why it is hard to start at even 8 degrees base advance...Im running a custom toroidal combustion chamber at 13:1 compression ratio... Jetting seems ok. Im wondering if the toroidal head has sped up combustion to the point that even 8 degrees advance is too much for starting, resulting in kickback... or possibly the fact that the bore centre is offset 1mm to the rear, could that resulting change in crank angle at tdc make it that much more susceptible to kickback??...

Just trying to get my head around why it needs so little advance to start?? Once running it is very strong at 25+ degrees advance and shows no sign of detonation even when experimenting with advance up to 35 degrees and super lean jetting.

Dave.

Frits Overmars

15th November 2011, 01:05

Frits, first of all, thanks for your willingness to share info with us... Your ideas have inspired me:niceone:. It sounds like a lot of the development of the RSA cylinder went into transfer duct geometry... are there any more secrets you can share about the key characteristics that led to such huge power...
Is there any single aspect of transfer duct geometry that offers greater gains than others??... inner duct radius, window/port ratio, radius at bore edge, widening factor just before the port exit, etc. Or is it simply a case of 'the whole being greater than the sum of the parts'.
***EDIT... just been looking more closely at the RSA cylinder transfer ducts... it looks like the inner duct radius is different between secondary and main transfer ducts... Also it seems that the window/port ratio is very different between secondary and main transfers... Im assuming that the flow in the secondary ducts accelerated faster as a result?... were both ports opened at the same time or were staggered transfer timings used?
The outer transfer duct radius is utterly unimportant; there the charge has no option but to go where the duct wall leads it. But the inner duct radius is very important: it should be as large as possible to avoid flow detachment. If you manage to keep the flow clinging to the inner surface (the Coanda effect), there will be less pressure-absorbing turbulence, so the flow will meet less resistance, transport more mass and deliver it where you want it to go.
The golden rule of flow: look for sharp inner edges and remove them. It always works.

The radii at the bottom bore edges, as visible in the picture above, yielded 1 HP; that's about 2% of the total power. The egdes where the transfer port windows cut the bore, should not be radiused; you do not want to promote inflow of waste gas into the transfer ducts. Here only the top and bottom edges should be chamfered lightly to make life easier for the piston ring.
There should be no widening just before the port exit; the duct cross-section area should gradually move from entry area to exit area. And with the inner curvature of the duct fixed, this more or less lays down the shape of the outer curvature.

Assuming that the flow in a duct will accelerate faster as a result of narrowing that duct is an ineradicable misconception. If it were true, it would mean that a duct narrowing to zero would yield an infinite flow velocity......
Flow velocity depends on the pressure difference between entry and exit of a duct, and in the case of an engine, where the flow constantly accelerates and decelerates, it also depends on the column length of the mass in the duct. It does not depend on the column's cross-area; twice the area would mean twice the mass per mm column length, but it also means that the cross-area exposed to the pressure difference is twice as big.
A smaller cross-area can have the effect that because of the reduced mass flow the pressure in the crankcase does not fall as quickly, which in turn may lead to a longer-lasting acceleration of the flow and thus a slightly higher top speed. But it will also mean less mass transport during the transfer phase.

The duct entry area of the Aprilia cylinder's B-ports is slightly smaller than their port exit area. This stems from the old obligation to develop cylinders that had to fit the existing crankcases of the Aprilia RSW engine, of which there are hundreds around. the RSA engine did not have this limitation, but simply enlarging the B-duct entries disturbed the scavenging, so the ducts were left as they were (and remember: while the B-ports' exit areas are only open part of the time, the entry areas are open all the time).
The transfer timing is 130° for the A-ports (they are really close to the auxiliary exhaust ports) and 132° for the B-ports and the C-port.

Dutch Fisher

15th November 2011, 03:19

Thats good to hear as the crashes were driving me nuts while trying to find my way around a new application.

The sequence leading to a typical crash is.

In the Dat2T application.

Create a New Project.

On the Pipe Types screen.

In the Header Pipe Restriction field
Deleting the default “0” provokes a Visual Fortran Run Time Error.

In the Header Pipe Restriction field
Backspacing to remove the “0” provokes a Visual Fortran Run Time Error.

In the Header Pipe Restriction field
Entering any number without deleting the “0” first results in a Dat2T error message.

On the next page of the module backspacing to clear a field before entering a value invokes a Dat2T error.
.

You need to reinstall XP. Those errors are from the Windows DLL that DAT2T uses to display dialog boxes.

pete 2

15th November 2011, 03:19

Thanks frits,
so would their be a (correct) ratio between c/case volume and transfer duct volume for a high performance engine?
also on the rsa cylinder the liner has an opening in front of the boost port, while the honda 250 production racer has not,in the honda this is directly infront of the inlet from the reed block and appears to be an obstruction to the flow.
250700

NordieBoy

15th November 2011, 06:13

You need to reinstall XP. Those errors are from the Windows DLL that DAT2T uses to display dialog boxes.

Errors in the visual fortran runtime mean you have to reinstall windows?

Frits Overmars

15th November 2011, 06:18

Thanks frits,
so would their be a (correct) ratio between c/case volume and transfer duct volume for a high performance engine?Not really. The RSA's TDC crankcase volume is 675 cc (for a 125 cc engine!) but most of this volume is in the transfer ducts.
also on the rsa cylinder the liner has an opening in front of the boost port, while the honda 250 production racer has not,in the honda this is directly infront of the inlet from the reed block and appears to be an obstruction to the flow.Over the years Honda has produced cylinders with and without the lip that your picture shows, sometimes both types in the same production year. But flow through the C-port is not the most important item of a fast cylinder.
Another point to help you make up your mind: compared to a Honda RS125 or RS250 the Aprilia RSA125 produces about 20% more power per cylinder....

wobbly

15th November 2011, 07:09

Re EngMod2T question on ducts and entry areas.
Depends upon the geometry of the duct in the case and that of the cylinder where the duct begins at the bore edge.
In many designs the inner wall is very short ( above the gasket plane ), and the case extension of the duct outer wall drops away very sharply - with the floor being miles away from the gasket plane.
In this case I would use the area/length at an angle from the bore edge out to just below the gasket plane.
Some engines have a longer inner wall, and also have the case floor close to the gasket surface.
In this design the duct really does "go around the corner" into the case and the ( vertical ) window forms the entry area, as shown in the help files.
Truth be known the main effect is to change the case volume, but this spec is always MUCH better to model accurately by drilling a hole in a piston at TDC, and calculating with the ducts included.
The case volume total has a bigger effect on the real power produced by the sim, rather than duct length.
Duct length, has a bigger effect on the sim run times, not power.
I tried to replicate the run time error as you found TeeZee, and yes my system does the same - I never found that issue as I have never changed the zero figure before.
None of the pipes I have done have a "step", always an oval to round transition in the flange, that is modelled as a short taper in the pipe screen.
So yes, send a report to Neels, it is a "fault".
He is working now on creating a "button" that will collect all the files used by a project, into one file, so its easy to send each other sims to check, making it much quicker for others to review projects already created.

Re Ignitech starting issues, and base advance.
Post up a screen shot of the "Bike" page and advance curve, I may be able to help with that.

TZ350

15th November 2011, 16:40

250727

I measured my old RS125 pipe tonight ...

250725
and it turns out to be the same dimensions as the bracketed ones in the picture.

250726

The numbers on the left (Tuned Pipe Dimensions) are for the pipe itself. The numbers on the right (Tail Pipe Dimensions) are for the venturi restrictor at the end of the convergent cone and the tail pipe (stinger) length.

250729

Then you can get a look at what the pipe will look like and check the tuned length.

250730

The object is to simulate my existing engine and get a simulated graph that is the same as the real dyno graph, well similar as the simulator is crank hp and the dyno is rwhp. Then I can be pretty confident any changes I make in the simulation should be reflected on the dyno.

I am a bit of a newbee with the EngMod2T simulation package but getting there.

Yow Ling

15th November 2011, 19:43

TZ350

15th November 2011, 21:18

One of the local bucket guys came round tonight with the bike he has been building. We just checked the squish and admired his work. This is RG150 bottom end with VJ22 barrel with sleeve. Wish mine was this far done!
250747
250748
250749
250750

Its what I thought after the GP, the writing is on the wall for the 4-stroke boys no matter how fast they can ride as the whole playing field seems to be moving up a notch or two.

TZ350

15th November 2011, 21:27

250768250769

Not there yet with the simulation but its starting to look similar to the real thing.

dinamik2t

16th November 2011, 01:04

Hey TZ, would you mind exchanging combustion files?
I am very interested in seeing what afr and comb.efficiency values do you guys use in your simulations.

I get akwardly good results from mine and I would like to compare my values.
Here's a couple of pics. It's an 118cc engine.

<a href="http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Untitled-1.png" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Untitled-1.png" border="0" alt="Photobucket" ></a><a href="http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Untitled2.png" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Untitled2.png" border="0" alt="Photobucket" ></a>

Also a short introduction and a few comments.. My name is Vagelis, I come from Greece and I am a student of Physics (more into electronics though than thermodynamics or mechanics)

I have been reading the topic at pitlane and now saw the TFR timings of the RSA mr. Frits gave away.
I have ended up in the same concusion through sim testing. If rear TFRs open earlier than the front ones, more power is gained than the opposite combination!
Yet, in a couple of Honda port maps I've seen, fronts open earlier than the rears..:wait: Does the latter serve any particular cause? (eg a different power/torque delivery)
Or is it just a pattern in older Honda cylinders?

And about the books you discused in earlier posts: Has anyone read "The high performance two stroke engine", by John Dixon?
I found it online at a very low price and got it a while ago. It does (rather .. "he does") a great analysis of the physics throughout the engine and does not offer much "tuning tips". Actually, that's more preferable in my opinion. Intelligent people should learn "how stuff works" and decide their own modifications afterwards, instead of "do that, that and that". :)

Here's the front cover of the book:
250770

TZ350

16th November 2011, 05:48

Hey TZ, would you mind exchanging combustion files?
I am very interested in seeing what afr and comb.efficiency values do you guys use in your simulations.

Hi dinamik2t thank you for letting us see your combustion file. I have only just learnt how to enter basic data like the engine file, transfers and pipe and have been using what other default files or copying stuff that looks close so my files wont be much use.

My posts are the journey of a newbee learning to use a simulation software package. Hopefully someone with more experience than me will post some interesting files and comments as I am keen to learn more about them too.

koba

16th November 2011, 06:43

Intelligent people should learn "how stuff works" and decide their own modifications afterwards, instead of "do that, that and that". :)

Most of us can only wish we were that intelligent!

dinamik2t

16th November 2011, 06:54

I don't have any problem letting people see what I "play" with. There isn't any commercial issue or profit, from my files at least.. Mr Frits and mr Jan gave away info freely, that many people used in commercial ways!

To be honest am not much into becoming a paid engine mechanic (an engineer, that we can discuss). I like learning and searching stuff and I occasionally port (as much as my abilities/knowledge permit me of cource -not much:rolleyes:) some cylinders for engines similar to my own. Just for an extra income. Anyway..

Here is the whole file of the above pics: http://users.uoa.gr/~sph0800108/modenas_dinamik_forum/EngMod2T/OneHalf54-EngMod2T_%20setup_15-11-2011.rar
I would be gratefull if people with more experience than my own checked these files and told me where I am wrong or suggest a couple of things!
I would have many things to say encore (gratitute, enthusiasm, questions, more enthusiasm, more questions), but it will be too much blah-blah! :D

As for the engmod file, I concentrate my attention for possible inaccuracies in combustion efficiency, temperature and AFR values. I have no idea what real-life values would be achievable.

dinamik2t

16th November 2011, 06:57

Most of us can only wish we were that intelligent!

Yes! To explain myself, I didn't want to imply that I am the intelligent one to do thus. I believe though, that an average clever person can achieve that quality through learning and that's what I aim for. Until (a) God appears in front of us, everything is a matter of science. Since something is already discovered, we can only learn it, not reinvent or rediscover it (unless it's wrong, but we still have to know the wrong to find the right).
The more you know, the more you can understand. And the more intelligent you are, the more innovations you can build into the 'understood'. :)

Frits Overmars

16th November 2011, 08:11

.... I have been reading the topic at pitlane and now saw the TFR timings of the RSA mr. Frits gave away. I have ended up in the same concusion through sim testing. If rear TFRs open earlier than the front ones, more power is gained than the opposite combination! Yet, in a couple of Honda port maps I've seen, fronts open earlier than the rears..:wait: Does the latter serve any particular cause? (eg a different power/torque delivery) Or is it just a pattern in older Honda cylinders?It is a pattern in all Honda cylinders, Vagelis. Even the cylinders of their last (2009) 250 cc works racer (and don't ask how I got my hands on it) had high A-ports, somewhat lower B-ports and an even lower C-port. We call this the Dalton Brothers-configuration. If you know the Lucky Luke strip albums, you will know what I mean.

dinamik2t

16th November 2011, 08:51

gamma500

16th November 2011, 08:56

Frits,

I have used ''simple'' pipe calculations you posted on pit-lane.biz, and found out that those calculations give bigger expansion chamber diameters for lower exhaust port timings.

I have been wondering why engines with lower exhaust port timings need ''fatter'' pipes?

Frits Overmars

16th November 2011, 09:41

Yes, indeed! And Joe is also shorter by 2-3 degrees than the B-ports (even shorter than Averel!):laugh:
Mr Frits, I have noticed one more thing that looks strange to me. Here are two photos of the stock port layout of my cylinder.

http://i736.photobucket.com/albums/xx5/Vag1-2/th_PSC02115-1.jpg (http://s736.photobucket.com/albums/xx5/Vag1-2/PSC02115-1.jpg)http://i736.photobucket.com/albums/xx5/Vag1-2/th_PSC02110.jpg (http://s736.photobucket.com/albums/xx5/Vag1-2/PSC02110.jpg)
Encircled in green there is a sudden bent in the A port duct. I understand this must be to give the incoming mixture a backwards angle. It is very sudden though and I have noticed this in other cylinders also, even some older Honda RS cylinders. My guts tell me that this angle should be more gentle and the duct should follow that bent all the way from the cylinder base (like the red sprayed right duct).
Say, my cylinder has small ducts (for a certain mass production reason), they needed that size of port window and that angle, so it was designed that way. But other cylinders with decent port duct/window sizes have the same bent.
Is there a particular purpose of such a design?The backward angle of the port flank nearest the exhaust (the green line in your drawing) is important, but I agree that your duct is not a thing of beauty.
But the right-side duct, though it may look more attractive, is even worse. The backward angle of the green line may be somewhat exaggerated, but the blue line is not sufficiently angled backward, which will result in short-circuiting: fresh charge from the A-ports will make a U-turn and escape directly into the exhaust duct. And it will do so as soon as the transfer ports open, which means it will be too far down the exhaust pipe by the time the return pulse tries to shove escaped charge back into the cylinder.
I can only guess as to the purpose of such a design. Maybe it is not even a deliberate design but just the result of using existing casting cores for a new cylinder.
Or maybe the cylinder studs were in the way...

By the way, I appreciate you calling me Mr. Frits, but there is no need; just Frits will do fine :shifty:.

I have used ''simple'' pipe calculations you posted on pit-lane.biz, and found out that those calculations give bigger expansion chamber diameters for lower exhaust port timings. I have been wondering why engines with lower exhaust port timings need ''fatter'' pipes? Remember what I said about those simple calculations: they are only meant to help beginning tuners on their way and a lot of more or less important facors, like compression ratio, ignition timing, type of fuel, carburetter diameter, crankcase volume and angle*areas, are not taken into account.
In your example the important thing is that lower exhaust timings need bigger header diameters. But explaining why this is so, might be beyond the scope of this forum (and it would certainly be beyond the time I have at my disposal).
But come to think of it: the least I can do is post the same simple calculations here. Instead of all those factors I left out, I included one variable, the speed of sound. Starting with 550 m/s will get you in the right ballpark, after which you can vary this value according to your findings.
Final remark: the calculation of the tailpipe restrictor diameter is critical: you can only apply it to engines that are thermally sound. Air-cooled engines are not...

gamma500

16th November 2011, 09:58

Remember what I said about those simple calculations: they are only meant to help beginning tuners on their way and a lot of more or less important facors, like compression ratio, ignition timing, type of fuel, carburetter diameter, crankcase volume and angle*areas, are not taken into account.
In your example the important thing is that lower exhaust timings need bigger header diameters. But explaining why this is so, might be beyond the scope of this forum (and it would certainly be beyond the time I have at my disposal).
But come to think of it: the least I can do is post the same simple calculations here:[/QUOTE]

Thanks for the answer. :niceone:

I have simulated some pipes designed with those calculations, and the results have been excellent.

dmcca

16th November 2011, 10:21

There should be no widening just before the port exit; the duct cross-section area should gradually move from entry area to exit area. And with the inner curvature of the duct fixed, this more or less lays down the shape of the outer curvature.

Thanks Frits. After looking at the CAD image of the RSA transfer ducts (attached) that has already been posted it appears that the B ducts (and im assuming the A ducts) widen sideways just before they exit into the cyllidner so I assumed that the cross sectional area was increasing here also... I had made the assumption it was something to do with controlling or slowing the flow just as it enters the cylinder

We call this the Dalton Brothers-configuration. If you know the Lucky Luke strip albums, you will know what I mean.
:laugh:

Re Ignitech starting issues, and base advance.
Post up a screen shot of the "Bike" page and advance curve, I may be able to help with that.

Thanks Wobbly... they are attached.
The bike is running very well now with this curve so im just trying to understand the need for such low base advance... whether its an ignitech issue or a mechanical characteristic of the engine.
Also the curve above 5k really needs to be tested on a dyno... its just a guess at the moment as i havent had much chance to ride it flat out, i tend to do slower, technical stuff at lower revs. It does currently rev out well though.

wobbly

16th November 2011, 10:58

Here is a comb file for a very fast RS125, where the sim is all but perfectly reflecting reality.
The difference between the sim and RWHp is around 10 to 12% as you would expect - despite what many say about the fudge factors in a Dynojet.
The comb file has afr as measured on the dyno - and shows the correction of the ratio naturally going rich over the pipe, by the powerjet switching at 12200.
Without the powerjet it would go very rich, and would not make any power past 12600 - as in reality.
But for most sims, you will be in the ballpark simply running 12:1 in all fields.
The comb efficiency is good for full house racing 2T at 0.92,less well tuned engines will be down between 0.87 and 0.9
And the combustion variables are as calculated by the program using the turbulent model - you use burnrate prescribed until the model is well refined,then run turbulent ( very slow)
and transfer the results from that run manually,to speed up later sims by using real burnrate numbers.
Re the question of cylinder temp.The important factor is TUbMax - the temp of the end gases trapped in the squish.Optimum is around 1000*, but if its too high, the sim will automatically
show a warning on the screen - "deto" as the run is progressing.
Too lean, and or too much timing or compression and this warning comes up, believe it and change something to fix it, or your computers piston will sieze.
PS - I need your .pjt file to make it easy to open the sim.
Neels is working on a "pack and go" button that will collect all files for a project and put them in one file to send out for review.

Re the A and B port stagger.
Honda have always run the A port higher approx 0.7mm giving timings of 132/130/129.
This works OK using the big T port,but in the Aprilia 3 port layout, when pushed to the extreme as Jan did, the A port is lower to allow more area for the huge Aux ports needed to give sufficient blowdown.
Then the B port is raised to get back the needed transfer TA.

Re the ignition problems at starting.
Two things, firstly reverse the wires from the trigger and delete the reverse polarity button in software.Many times the trigger wired backwards gives very odd results when strobed.
Secondly, look at the "number of programmings" no way have you done 33,000 changes - this means the ECU is being corrupted by RF noise, you need to check the resistor plug cap and plug, as well as
ensure that the hot wire to the coil is well away from the trigger wires etc.
Also the curve is very odd.
Any tuned engine will like 28* advance in the mid under the pipe, then where the bmep starts to rise as the pipe works, around 8000 in your engine, you start pulling out timing, heading for around 15* at peak torque.
Depending upon how its set up, then less advance may be needed at peak power and beyond to make it rev out.
Below is a curve for similar rpm as your example.

TZ350

16th November 2011, 15:52

TZ350

16th November 2011, 15:59

250785

An interesting look at a Kreidler transfer passage.

250786

Supercharged DKW

husaberg

16th November 2011, 16:18

http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Untitled-1.png (http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Untitled-1.png)http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Untitled2.png (http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Untitled2.png)

Also a short introduction and a few comments.. My name is Vagelis, from Greece

Yet, in a couple of Honda port maps I've seen, fronts open earlier than the rears..:wait: Does the latter serve any particular cause? (eg a different power/torque delivery)
Or is it just a pattern in older Honda cylinders?

And about the books you discused in earlier posts: Has anyone read "The high performance two stroke engine", by John Dixon?

Here's the front cover of the book:
250770

Hello Vagelis

I can't speak for if its right or wrong, but both Bell and I think Robinson as well do offer an explanation on the staggered transfer timings in both directions.
I had not seen the book before, are you able to show some exerts of its content.

PS I loved the movie, great sound track. .:rockon:sorry
.250806

On a different subject has anyone ever seen a map of the KTM50 ignition curve, because they would have to be the most petite set up ever.

They are also relatively inexpensive if not totally reliable.
They also have what would be the smallest easy to add water pump to an Air cooled crank or oil pump set up to convert to liquid cooled.
250813

TZ350

16th November 2011, 17:20

Page 360 interesting posts to be collected here.......

... simple calculations: they are only meant to help beginning tuners on their way and a lot of more or less important facors, like compression ratio, ignition timing, type of fuel, carburetter diameter, crankcase volume and angle*areas, are not taken into account.

250970

the important thing is that lower exhaust timings need bigger header diameters ... the speed of sound. Starting with 550 m/s will get you in the right ballpark, after which you can vary this value according to your findings.

Final remark: the calculation of the tailpipe restrictor diameter is critical: you can only apply it to engines that are thermally sound. Air-cooled engines are not...

TZ350

16th November 2011, 20:43

250804250805

My simulation is getting closer to the real thing, most of the difference was adding realistic rpm related pipe temperatures and running the simulator using the turbulent option.

Frits Overmars

16th November 2011, 21:53

250785
An interesting look at a Kreidler transfer passage.The Kreidler engine shown by TZ350 was cutting edge technology in 1962, but I do not think any of you want to copy transfer passages that, together with twin rotary disks and a twelve-speed gearbox, produced all of 10 HP out of 50 cc.
In case you wonder: the transfer timing was 142°; the single exhaust was way over 200°. Don't try this at home....
Below are some more pictures of the same engine, showing the twin carbs and the screwed-in caps that gave access to the transfer ports for easy modification.
You can also see the hand-operated three-speed gearbox behind the foot-shifted four-speed box.

Grumph

17th November 2011, 07:18

First off, Frits, thank you very much for sharing your knowledge and experience with us.

Following the Kreidler pics, when i was looking at your 50cc cylinder, i did wonder about inlets...and thought maybe the kreidler dual disc setup may be in your mind....

I'm an old guy whose days of working with state of the art cylinders are way behind him, but I was looking at pics of a 70's Rotax 125 cylinder recently and it's very apparent how it has evolved into the Aprilia. The amount of wall between ports has shrunk noticebly over the years which leads to one question...where on the Aprilia cylinder is the ring peg/gap ? In that maze of ports i can't see room.

The Honda cylinder previously mentioned with the obstruction to flow apparent brought to mind one I did on a customers instructions...he wanted it removed so I did. End result - gained 2 hp in the midrange - lost 2 hp off the peak...

Greg

Frits Overmars

17th November 2011, 08:23

First off, Frits, thank you very much for sharing your knowledge and experience with us.
Following the Kreidler pics, when i was looking at your 50cc cylinder, i did wonder about inlets...and thought maybe the kreidler dual disc setup may be in your mind....Yeah, as a nightmare. Just think of any error you can come up with: Kreidler had it. Both disks were axially fixed on the crankshaft; they could not nestle against their covers and it took hours to press (!) them into a position that would not yield too much leakage or too much friction.
And take a look at the inlet tracts between carbs and disks. Nice tight U-turn, wouldn't you say? No, for my cylinder I thought up something completely different:
the 24/7-system. I've got no time to elaborate now, but you may find some more info here: http://www.pit-lane.biz/t117p376-gp125-caracteristiques-aprilia-rsa .

I'm an old guy whose days of working with state of the art cylinders are way behind him, but I was looking at pics of a 70's Rotax 125 cylinder recently and it's very apparent how it has evolved into the Aprilia. The amount of wall between ports has shrunk noticebly over the years which leads to one question...where on the Aprilia cylinder is the ring peg/gap ? In that maze of ports i can't see room.The devil is old, Greg. Below left is a drawing I did when working on a Rotax cylinder in 1980, and next to it the 1980 cylinder itself and a recent Aprilia cylinder.
You are quite right: not that much difference in over 30 years.

The ring peg is right opposite the exhaust: the only decent place for it. Each time the ring passes over the exhaust port, it bulges out a little and then gets shoved back in its groove when it runs over the top and bottom port edges. If the ring peg is not diametrically opposite the exhaust port, this shoving back will cause the ring to rotate in its groove and every time it will hit the peg from the same side until the peg works loose....
Don't worry about the ring gap running over the C-port. The Aprilia's C-port is now 15 mm wide, but it has been as wide as 22 mm and even then there were never any ring problems.
Generally speaking you can say that the ring gap is safe over a C-port width of up to 40% of the bore. For steel rings that is; I never tried it with cast iron.......

F5 Dave

17th November 2011, 09:42

Frits, thank you for your time & knowledge. We have been talking a lot about the RSA & cylinder transfer ducts and learning a lot. Looking under the sheets a little further one wonders what the crank would look like? If super lightweight stuffers would be employed to reduce the crank area so more volume could exist outside of the turbulent area yet retain a suitable case compression ratio?

I have read about charge in the duct area being most important, - this would tend to indicate that the reed entry was not so critical, but I heavily suspect having seen (and produced) some less than successful full reed conversions that the reedblock angled into the crank area is not desirable. Thus the thoughts above. Pity there is that damn awfully inconvenient rod thrashing about the interface else you could separate the two areas:rolleyes:.

dinamik2t

17th November 2011, 10:32

_

Thank you for the explanations (plain) Frits :)
In some cylinders the A ports have a reducing width from top to bottom, without any aux or bridged exhaust ports being over them. Is that the same reason for this shape? Avoid short-circuiting when A-port open - one that cannot allow mixture to return to the cylinder?

_

Thank for all the info either. It seems every configuration has its purpose at some point and each engineer has his own approach.
By the way, I uploaded some new files, plus the .pjt file so that everyone can open it right away. :niceone:
http://users.uoa.gr/~sph0800108/modenas_dinamik_forum/EngMod2T/OneHalf54-EngMod2T_%20setup_17-11-2011.rar

_

I think it might not be legal to scan/upload content from the book. Plus, I am not sure if it's allowed do thus on this board. On the other hand it would be a promotion gesture :bleh:
Here's the index page from another site. If I'am allowed, I can find a couple of pages from a specific subject that might interest you! As a demonstration of the content..

250824

Grumph

17th November 2011, 12:05

Thanks for the link Frits - i see now what you're trying to achieve.

Reminds me of an incident a few years back when a friend of mine was running an "E" model TZ 250 Vtwin. One meeting it went exceptionally well - when he checked it proved to have a broken reed petal. He asked my opinion so I advanced the suggestion that he start cropping reeds back until he found the optimum amount of reed required for satisfactory starting and midrange....
He never followed up on the idea but I offer it here for what it's worth....

wobbly

17th November 2011, 12:12

Re power graph for Dynamik2T.
This is where you need experience to dictate if the sim result is realistic or not.
Having a 82.5* Ex with a pipe 895 long will NEVER have peak power at 12500.
I ran a baseline with all your inputs, except changed the comb to prescribed ( turbulent is very slow).
Then changed pipe wall temp to 50* as I usually do.
This gives max power around 11500 as I would expect.
There are a heap of other issues to look at, including the warning about the transfers being too close to floor of the Aux ports.
Drop the transfers as they are too big now, this will increase blowdown,and that is what it needs more of.
Bottom line here is, what rpm peak power do you want, and what max rpm do you want to limit to.

Myron

17th November 2011, 14:02

dinamik2t

17th November 2011, 14:18

Thanks for checking the file :)
This exhaust is actually an RS125 exhaust, with about 55mm of length added and a few minor diameter changes to keep the angles the same. It was a custom made pipe by a friend with a TIG a long time ago, as an improvement over a crappy pipe from some local dealer. The reason why we added that length back then was to bring the power down to that RPM point from the 12.5k.
I started simulating at about 11.8 and by altering specs, advance and afr it went that high, which was curious but pleasant. I didn't know it wasn't right!

To confirm from my side also, here's the result when changing pipe wall temp to 50C. It's Turbulent model result (bless 4-core cpus, less than 10min for a run :cool:)
I then lowered by 1.5deg the TFRs and played with advance and afr. In short, top power went up a little and overrev improved much. I 'll keep experimenting.
I think I am fine with the lower rpm top power. Could it go up to 12.5 or even 13 with decent overrev (say, over 21-22kW)? That's about my rpm limit.
Gearing isn't close-ratio and rpm drop a lot in first gears. It could benefit from the extra power in overrev, right?

<a href="http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Untitled-2.png" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Untitled-2.png" border="0" alt="Photobucket" ></a>

If I used a thermal wrapping on the pipe would the results went closer to the previous curve? Or is it a matter of length? I woudn't like to ask for a complete explanation (given your free time), but could you guide me on where to look for the answer here? Or give a hint perhaps..

One last thing. I have noticed that modern MX-125class crankshafts are very wide (>54mm), while kart cranks are wery thin (~48mm). Both for the same stroke of course. Say we used a 5 or 6 speed shifter kart with a typical clutch for the comparison, so that are both "models" equal on the transmission part.
Could you explain the physics here?
I say there would be bigger momentum for the heavier crank and bigger inertia also. So, it would be harder to rev on the one hand, but also harder to 'unrev' (good thing)?

ps. I know it's wrong, but it's actually dinamik. that's the name of the bike (http://www.modenas.com.my/v2motorcycle.asp?id=46)! I have been using it a long time as a username, so I kept it here also so as not to forget it. :D

TZ350

17th November 2011, 16:47

TZ350

17th November 2011, 17:50

And the combustion variables are as calculated by the program using the turbulent model - you use burnrate prescribed until the model is well refined,then run turbulent ( very slow) and transfer the results from that run manually,to speed up later sims by using real burnrate numbers.

Hi Wob, after running the sim in turbulent mode where do I find the real burn rate numbers?

dinamik2t

17th November 2011, 21:30

TZ, you will have to get them from Post2T. Instead of selecting 'power' graph, you should select 'Delay', 'Durat' (duration), 'VibeA' and 'VibeB'. Then manually transfer the values to the respective columns in the Combustion file. It takes some time...:sleep:

Wobbly, could you tell us after which alterations the Turbulent numbers change? For example, if I make a minor EXpipe dimension change or a port TA change, do I have to run turbulent again to get new-correct delay/duration/vibe numbers? From what I remember from the manual, it's only affected by the main combustion variable themselves (adv,afr), but I am not sure.

Frits Overmars

17th November 2011, 22:01

Frits, wondering if you would be willing to comment further on the RSA125. My question at present is in the downsweep of the exhaust duct. I believe you are at roughly a 30 deg downsweep from center of exh port to center of the exh duct outlet. Was there any testing on varying this angle flatter or steeper? How important do you view this angle? I have a significant library of cyl specs from all different forms of two stroke applications, and it seems to run the gammit. I have some hunches but cant really prove or disprove any of them with my available resources. Does this angle affect the looping direction of the transfers? It would seem to me a flatter angle would obviously give a better time area, but would also tend to "bend" the charge from the transfers in a short circuiting manner quicker. Or maybe you view the roof of the exh port as more important? Any experiences or thoughts?
MyronI am willing allright, Myron; I am trying to promote two-stroke knowledge. But I'm short of time as it is.
Regarding testing: if you can think of anything at all, you can be sure it was tested.
Maybe the picture below will answer some of your questions. There is a lot more where this came from and I am willing to share, but you would have to convince your forum governor to allow uploading ZIP-files.

teriks

17th November 2011, 22:11

The yellow trace is the pressure at the exhaust port.

Wob am I reading this right?

250838

On the left the pipe is sucking the cylinder down to late for the transfer port opening TPO.

And on the right the exhaust pulse is arriving back to early, before the transfer port has properly closed TPC.
Now this will be interesting.. testing my knowledge.

"On the left": Id say you need to increase exhaust blowdown, not fiddle with the pipe. If anything the lowest pressure in "Pexport" should occur later, around BDC.
"On the right": I agree.
As it is simulated, the pipe seems tuned for max power at higher rpm than simulated, but you may lack blowdown time*area to run such rpm's.

dmcca

17th November 2011, 22:15

Re the ignition problems at starting.
Two things, firstly reverse the wires from the trigger and delete the reverse polarity button in software.Many times the trigger wired backwards gives very odd results when strobed.
Secondly, look at the "number of programmings" no way have you done 33,000 changes - this means the ECU is being corrupted by RF noise, you need to check the resistor plug cap and plug, as well as
ensure that the hot wire to the coil is well away from the trigger wires etc.
Also the curve is very odd.
Any tuned engine will like 28* advance in the mid under the pipe, then where the bmep starts to rise as the pipe works, around 8000 in your engine, you start pulling out timing, heading for around 15* at peak torque.
Depending upon how its set up, then less advance may be needed at peak power and beyond to make it rev out.
Below is a curve for similar rpm as your example.

Thanks for this info:niceone:

I did the things you suggested and spent a couple of hours re-routing wiring and checking all connections, etc... and... it wont start at all now with the ignitech, even when reinstating the previous settings... however i discovered the following...

- with the plug out while cranking the kickstarter by hand the ignitech gets a single spark very occasionally, not enough to start though, regardless of polarity of the trigger. This must be what has been happening to produce hard starting.
- with a 12v battery connected to the system it sparks every revolution, even with very slow turning of the flywheel, regardless of polarity of the trigger.
- the stock ECU still works fine, sparks every revolution without a battery and always starts extremely easily.

Seems like the ignitech is not getting the power it needs at startup and therefore is sparking intermittently causing difficult starting. Does the ignitech have a higher power requirement at startup than a stock ECU?? Otherwise it looks like a bad stator or elec system.

With the "number of programmings" from brand new it read around 32,000?!?!? I found this a little strange.

With the ignition curve i will adjust it accordingly. Going by some sim results peak torque should be around 7500-8000 and max overrev about 9500... thats where ive set the limiter anyway.

Myron

17th November 2011, 23:38

I am willing allright, Myron; I am trying to promote two-stroke knowledge. But I'm short of time as it is.
Regarding testing: if you can think of anything at all, you can be sure it was tested.
Maybe the picture below will answer some of your questions. There is a lot more where this came from and I am willing to share, but you would have to convince your forum governor to allow uploading ZIP-files.

So.... I take it you tried flatter and steeper angles on exh duct than whats in the pic? What were you learning?

Frits Overmars

18th November 2011, 02:08

So.... I take it you tried flatter and steeper angles on exh duct than whats in the pic? What were you learning?I didn't; Jan Thiel did. And we learned that the result in the pic is the best. I also learned that you won't stop asking questions :msn-wink:.
I don't mind; I would do the same if I were you. But answering them would require more time than I have available right now. There's an engine design waiting.....

TZ350

18th November 2011, 06:45

http://www.trademe.co.nz/Browse/Listing.aspx?id=424848013

A copy of MOTA 6.10 2-Stroke engine development software.

Sold this software sold through the buynow option within an hour of going on Trademe.

speedpro

18th November 2011, 06:56

Seems like the ignitech is not getting the power it needs at startup and therefore is sparking intermittently causing difficult starting. Does the ignitech have a higher power requirement at startup than a stock ECU?? Otherwise it looks like a bad stator or elec system.

I have a MB100 powered bucket with an Ignitech CDI. I'm running a Honda CRF250F, I think, generator and reg/rec and power capacitor. It starts in a couple of steps. With the plug out and in gear with it on the stand just pulling the rear wheel will cause a spark. From that I think the Ignitech starts operating pretty quickly once supplied power.

quallman1234

18th November 2011, 07:17

http://www.trademe.co.nz/Browse/Listing.aspx?id=424848013

A copy of MOTA 6.10 2-Stroke engine development software.

Yoink, thank you very much.

wobbly

18th November 2011, 07:55

If the stator has trouble supplying enough power, quickly enough,you can increase the "turns before firing" to say 5 or 10.
This gives the system a chance to ramp up, before the ECU starts to fire sparks.

Re your sim printout TeeZee.
Lots to be seen there.
Starting at the top, you are about 500 rpm below peak power in the sim at 11500.
The whole engine isnt very efficient as the D.Ratio is low for the rpm being close to peak.
The TexAv is very high ,over 600
The TuMax is low.
With the depression in the cylinder starting early, then dropping away, the pipe shape is wrong for that rpm.
The pipe is too short for that rpm, as the return pulse has dropped away before the piston is close to closing.
The port timing and the pipe length are not working together, you have no superposition on the far left.
Look at this 40 odd crank Hp RGV100 just over peak, read all the numbers,and note the pressure wave shape, this is as good as it gets.

Edit - you can see the effects of low blowdown, if you get a big jump in Transfer pressure ratio when they open.

TZ350

18th November 2011, 14:55

I am willing ... but you would have to convince your forum governor to allow uploading ZIP-files.

The mods are looking into it and also asking, how big are the zip files? apparently there is a limit.

TZ350

18th November 2011, 15:08

Hi Wob

D.Ratio
TexAv
TuMax
PexPort

there are lots of these abreviated names, I can guess at a few like D.Ratio for delivery ratio but most are a mystery to me, is there a list of definitions/explinations some place?

wobbly

18th November 2011, 16:55

yes DR is delivery ratio.
TexAv = average temp in middle of the pipe.
TuMax = max temp of unburnt gas in the squish.
PexPort = pressure ratio at the exhaust port.

Go into help from the Post 2T screen,then plot options, then performance traces, also go to thermo traces for those terms.

F5 Dave

18th November 2011, 23:32

Hmm, well I think I've had answered most of my questions on prev page by finally finding the time to trawl through the pitlane thread (oops how did it get to be tomorrow?). But haven't seen any crank pics of RSA, just curious.

Myron

18th November 2011, 23:52

I didn't; Jan Thiel did. And we learned that the result in the pic is the best. I also learned that you won't stop asking questions :msn-wink:.
I don't mind; I would do the same if I were you. But answering them would require more time than I have available right now. There's an engine design waiting.....

Fair enough. That is the second time Ive pushed for your thoughts on this. Thanks anyway for your response and willingness to share.
Myron

husaberg

19th November 2011, 07:53

I know the real answer is to get a programmable ignition

But how do you produce/record a map a plain analogue ignition. I guess you mark the rotor and use a strobe and possibly a camera and a tacho but how do you do it say on a KTM 50 where the rotor drives the water pump and is inner rotor.

There must be an easier way? I have had a look on the net for a map of one and for how to do them but no joy so far.

Bert

19th November 2011, 08:27

I know the real answer is to get a programmable ignition

But how do you produce/record a map a plain analogue ignition. I guess you mark the rotor and use a strobe and poibly a camera and a tacho but how do you do it say on a KTM 50 where the rotor drives the water pump and is inner rotor.

There must be an easier way? I have had a look on the net for a map of one and for how to do them but no joy so far.

make up a router test bench. lathe up a shaft to suit the router and magneto (bearings to hold it all steady)
and a solid bracket to hold it all together (earth your spark plug well away from you).

timing light, hold/set the router at fixed RPM (measure that, easiest way is using a multimeter on the strobe measuring the frequency of pulses and do the maths)
and visually record the advance etc; then adjust the router RPM etc... bobs ya uncle.:woohoo:

Good way to test the entire system.

I got the idea from here:

http://www.sportdevices.com/ignition/ignition.htm#ignition_test_machine

---> full desings for CDI's and TCI's

Interesting article here on modifying a KDX200 cdi (which some might find interesting; I think I've posted it before...):
http://www.geocities.com/a57ngel/moto/CDI.html

husaberg

19th November 2011, 09:08

make up a router test bench. lathe up a shaft to suit the router and magneto (bearings to hold it all steady)
and a solid bracket to hold it all together (earth your spark plug well away from you).

timing light, hold/set the router at fixed RPM (measure that, easiest way is using a multimeter on the strobe measuring the frequency of pulses and do the maths)
and visually record the advance etc; then adjust the router RPM etc... bobs ya uncle.:woohoo:

Good way to test the entire system.

I got the idea from here:

http://www.sportdevices.com/ignition/ignition.htm#ignition_test_machine

---> full desings for CDI's and TCI's

Interesting article here on modifying a KDX200 cdi (which some might find interesting; I think I've posted it before...):
http://www.geocities.com/a57ngel/moto/CDI.html

Thanks Bert.

I was thinking of measuring the delay or advance with time. Of course a sparky may have another way I guess.

Bert

19th November 2011, 09:21

Thanks Bert.

I was thinking of measuring the delay or advance with time. Of course a sparky may have another way I guess.

in the KDX link he talks about a test circuit at the bottom of the page;
looks electrically plausible if you have the right input AC pulse frequency generator (easily enough to build) i.e the input AC voltage frequency will change with RPM...

wobbly

19th November 2011, 09:24

Here is a pic of cranks for Aprilia 250.
Full circle, full width, plenty of Mallory, high inertia, very low in cycle speed variation, lots of power and overev - why isnt your crank like this??

Also pic of my Ignition rig.
A vacuum cleaner motor with light rheostat, also reversable, has protractor on the other end.
I use a cheap kart rev counter and a strobe.
Doing curves on anything is easy, once its set up.

husaberg

19th November 2011, 09:33

Thanks both Bumslap on the KDX one I had seen it but obviously not read it, that well.

I guess the frequency generator is a function generator.

I was always going to try a build a simple Fi system with one back when injection was expensive.

Wobs crank pic above
What is the notch in the crankwheel at 9 oclock for?

Also for Fits
Oval and knife shaped rods.
they were all the rage in the 60"s.
Are there any advantages today?
I guess possibly not on a disk valve unless for comp, but on a reed?

Frits Overmars

20th November 2011, 13:43

Oval and knife-shaped conrods are better streamlined and meet a little less resistance when cutting through the contents of the crankcase. But I doubt whether they have any structural advantages.

The notch in the crankweb triggers the ignition. There's a Hall sensor at the crankcase looking at the crankshaft circumference. That gives a more accurate timing signal than a sensor looking at the end of a swaying shaft.
Below are some pictures of the Aprilia RSA125; the red arrows indicate the ignition sensor.

wobbly

20th November 2011, 18:28

That notch for timing reminds me of one of the cleverest triggering setups I have seen.
In the SwissAuto/Pulse flying web engine there were two magnets at 180* in one crank web with only 1 sensor, setup much as the pic of the RSA125.
I spent ages trying to figure out how it worked, untill one day I grabbed another magnet and discovered that each one inside the crank
was orientated N & S pole outward.
The trigger sensed the N pole as cylinders 1,3 and the S pole as 2,4, bloody clever and as simple as it could be made.

speedpro

20th November 2011, 19:57

husaberg

20th November 2011, 20:27

TZ350

20th November 2011, 22:04

TZ, you will have to get them from Post2T. Instead of selecting 'power' graph, you should select 'Delay', 'Durat' (duration), 'VibeA' and 'VibeB'. Then manually transfer the values to the respective columns in the Combustion file. It takes some time...:sleep:

yes DR is delivery ratio. TexAv = average temp in middle of the pipe. TuMax = max temp of unburnt gas in the squish. PexPort = pressure ratio at the exhaust port. Go into help from the Post 2T screen,then plot options, then performance traces, also go to thermo traces for those terms.

Thanks dinamik2t and Wobbly, I have been able to find that info and use it, it sure changes things and with a bit more polish I recon I will have a good working model (pic1 crank hp simulation) soon of the real thing (the 28.9rwhp graphs in pic2).

wobbly

21st November 2011, 07:05

Sorry I didnt see the question about transferring the Comb info.
The engine mechanical configuration such as pipe dimensions have no effect on the results.
So I always refine the model as best I can, then run turbulent, tabulate the results , and transfer the data.
Once its been transferred,you can run prescribed from then on, that is much faster to run the sim.
I get pissed when just making a small change to a pipe, then having to wait any more than a minute for the result.
To make the sim run faster use a 64bit Windoze system, and its processor speed that then dictates the run time.
The code doesnt fully support multi threading yet, so using a 4 core isnt faster.
But I got a 2 core that is based on the 4 core die, and overclocked it to hell.
This can handle the heat no problem and runs at 4.4GHz with 16GB ram.

dinamik2t

21st November 2011, 08:33

The code doesnt fully support multi threading yet, so using a 4 core isnt faster.
But I got a 2 core that is based on the 4 core die, and overclocked it to hell.
This can handle the heat no problem and runs at 4.4GHz with 16GB ram.

Thanks for the info!
I did some testing too a few weeks ago. As you say multi threading isn't fully supported, but there is some sharing. When I change affinity to a single core it went 100% load, while with all 4 a have an average of 35%. I 've set specific program specs and overclock 2 cores to run the engmod2t.exe at 3.5 through 'fsb' hehe :D Lucky you, can reach 4.4 on air?? Brand new 32nm CPU ??:shifty:
Ram doesn't seem to be needed in this sim.. 16gb is huge!:shutup:

Well, that's all with the off topic.
Wobbly, could you give some more info on the inlet tuning through intake wave observing?
I remember saying something about intake length tuning @ the 3rd harmonic, while crank pressure droping and in rising.
I did some testing but best results didn't always appear at the above situation. Actually, I always tried to tune at top-power rpm. :confused:
I got the best results in here:
<a href="http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Z61-georgio-InTraces-20112011.png" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Z61-georgio-InTraces-20112011.png" border="0" alt="Photobucket" ></a><a href="http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Z61-georgio-ExTraces-20112011.png" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Z61-georgio-ExTraces-20112011.png" border="0" alt="Photobucket" ></a>

F5 Dave

21st November 2011, 09:18

Here is a pic of cranks for Aprilia 250.
Full circle, full width, plenty of Mallory, high inertia, very low in cycle speed variation, lots of power and overev - why isnt your crank like this??
. . .
ahh, yeah that looks just like my std MB crank.:confused:
Thanks for posting the pic. Are the singles cranks different?

wobbly

21st November 2011, 11:18

I only use 16MB ram for running SolidWorks - it needs all of it.
The intake tuning is shown in this thread. - http://www.kiwibiker.co.nz/forums/showthread.php/143620-EngMod2T-Q-amp-A?p=1130187153#post1130187153.
The 3rd harmonic gives the best spread of power for a 2T, as it has a higher frequency but lower amplitude than the lower harmonics.
From messing about I have found that a length from the bellmouth correction to the 2/3 reed end length of around 135mm is good for a 125 running up past 12000
And another example being the RZ400 F3 engine the total length is 205 for tune at 10,000.

teriks

21st November 2011, 11:18

EDIT: Beaten by wobbly by a few seconds it seems ;)

Well, that's all with the off topic.
Wobbly, could you give some more info on the inlet tuning through intake wave observing?
I remember saying something about intake length tuning @ the 3rd harmonic, while crank pressure droping and in rising.
I did some testing but best results didn't always appear at the above situation. Actually, I always tried to tune at top-power rpm. :confused:
I got the best results in here:
<a href="http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Z61-georgio-InTraces-20112011.png" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Z61-georgio-InTraces-20112011.png" border="0" alt="Photobucket" ></a><a href="http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/Z61-georgio-ExTraces-20112011.png" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_Z61-georgio-ExTraces-20112011.png" border="0" alt="Photobucket" ></a>

Some info from Wobbly in the other EngMod2t-thread (http://www.kiwibiker.co.nz/forums/showthread.php/143620-EngMod2T-Q-amp-A), but maybe not what you are looking for?.

wobbly

21st November 2011, 12:27

The intake in the example is the wrong length for 12000, the intake wave crosses zero pressure ratio, going positive, way too soon.
This appears to be tuned to the second harmonic, with only one pulse in the intake.
Also look at the RZ400 trace, it has twice the frequency of pulses and crosses zero at the same time as the case goes negative.
Fine tuning makes a big difference.
The pic shows a TM125MX kart motor with a standard Honda RS125 intake rubber, then a 15mm shorter one from an early model RS125.
2 Hp, just by shortening the intake length, real numbers off my dyno.

TZ350

21st November 2011, 15:32

TZ350

21st November 2011, 20:09

Simulation Time ....

251102

The simulator tells me that those nifty little side exhaust ports I made before are not going to do much for me. I suspect the 24mm carb is starting to choke the engine and the effort of tripple exhaust ports for more blowdown is not worth the trouble unless I can find a way to induct more air into the engine.

251101

A comparison of the 24mm carb vis a 30mm one confirms for me that I am getting close to whats easily possible with the 24mm carb at 12.000 rpm and its becoming the bottle neck. I now have to start looking for any further gains to come from fine tuning the rest of the engine and pipe, thank goodness for a good simulator.

251103

Wobbly I would be interested to know what are good numbers for TexAv, average exhaust temperature and TUMax, maximum temp of the end gases in the squish area.

Dratio delivery ratio, what sort of numbers do you expect to see here on a mildly well tuned engine and PurCyl purity of the fresh charge, 97.7% has got to be good, hasint it?

I am particuarly interested in how to blowdown the cylinder quicker so that I can get rid of that pressure hump in the transfer port (left side of graph).

Any pointers here would be very helpfull.

speedpro

21st November 2011, 20:46

That's really interesting. To get rid of the transfer port pressure hump it "looks" like you need more blowdown. Also looking at the reduction rate of pressure in the transfer I wonder what effect a change in crankcase volume would have.

teriks

21st November 2011, 21:05

Increased blowdown time*area is my take on it as well.
Have you compared this curve for your different exhaust ports?
-You mention some nifty side exhaust ports, those could be the key.

PS: You do know that you can plot both results in a single chart this using Post2T, right?

kel

21st November 2011, 21:16

Work faster guys, the premier Auckland F4 meeting was run over the weekend and there were no 2 strokes in the top ten :facepalm:

TZ350

21st November 2011, 21:23

Work faster guys, the premier Auckland F4 meeting was run over the weekend and there were no 2 strokes in the top ten :facepalm:

will be :soon: ....... and congrats I hear you managed a third against some realy stiff compitition ......

TZ350

21st November 2011, 21:40

That's really interesting. To get rid of the transfer port pressure hump it "looks" like you need more blowdown.

Increased blowdown time*area is my take on it as well.

251116

STA numbers for the graph, looks like plenty of Blow Down Time Area, I think it must be something to do with the exhaust tract/pipe.

The inlet port (rotary valve port) is good for 39hp but it requires a 34mm carb, the 24 is holding it back.

Have you compared this curve for your different exhaust ports?
-You mention some nifty side exhaust ports, those could be the key. PS: You do know that you can plot both results in a single chart this using Post2T, right?

No ... just learning, thanks for the tip.

TZ350

21st November 2011, 21:49

I wanted to see what could be done with a dash of DihydrogenMonoxide.Unfortunatly I did the runs with the 30mm carb so max power is overstated.

This is a 30mm carb and tripple exhaust port (blue line) with DihydrogenMonoxide.

251117

Look at the predicted improvement to the torque curve, those FXR's could be in trouble yet ... :laugh:

With a slightly better airflow through the carb, triple exhaust ports and a touch of DihydrogenMonoxide (Hydric Acid) and I could get to here.

As DihydrogenMonoxide has a much higher latent heat of evaporation than Methanol I would not need to induct much with the fuel to get the Methanol effect. Read more here about DihydrogenMonoxide:- http://www.dhmo.org/facts.html

251118

This looks promising and I won't have to use much to get the same latent heat effect as Methanol.

koba

21st November 2011, 21:54

When I was a kid I almost died because of that Dihydrogen Monoxide. Dangerous stuff.

husaberg

21st November 2011, 21:54

I wanted to see what could be done with a dash of DihydrogenMonoxide.Unfortunatly I did the runs with the 30mm carb. So this is a 30mm carb with (blue line) DihydrogenMonoxide.

251117

Look at the predicted improvement to the torque curve.

With a slightly better airflow through the carb, triple exhaust ports and a touch of DihydrogenMonoxide (Hydric Acid) and I could get to here as DihydrogenMonoxide has a much higher latent heat of evaporation than Methanol I would not need to induct much with the fuel to get the Methanol effect. Read more here about DihydrogenMonoxide:- http://www.dhmo.org/facts.html

251118

This looks promising and I won't have to use much to get the same latent heat effect as Methanol.

ban it i say. It already killed heaps of people. Its use is on the rise according to stats. It has already done untold damage to my bikes.

koba

21st November 2011, 22:02

'snot a fuel in most forms but it is arguably illegal for a 125. Not to mention irresponsible and dangerous.

Frits Overmars

21st November 2011, 23:23

Someone was asking about an Aprillia 125 crank.

251080251081

These are photos taken by Chambers looking inside an Aprillia125 at Phillip Island during the last Moto GP. Chambers took them to show me that Aprillia don't bother to champer the inlet side flywheel edge, in this engine anyway and they use a fairly solid I beam conrod.Here are some other pics, from an RS250 and an RSW125. As you can see, inlet flow is not hindered too much by the flywheels.
By the way, the RSA125 does not have chamfered flywheels because its inlet is at the rear, not the side.

cotswold

22nd November 2011, 02:20

[QUOTE=TZ350;1130199606]251116

STA numbers for the graph, looks like plenty of Blow Down Time Area, I think it must be something to do with the exhaust tract/pipe.

The inlet port (rotary valve port) is good for 39hp but it requires a 34mm carb, the 24 is holding it back.

Would the GP100 offer more as it has no restriction on the carb ?

dinamik2t

22nd November 2011, 02:42

To Wobbly:
I am probably asking something you take as a given. By "3rd harmonic" we mean the third oscillation from EPO? I get confused with the physics terminology we use at college.:mellow:
In the RZ400 example in the other topic, the 'tuning spot' it at approximatelly 120 degrees or after ~1.5 period of oscillation after EPO. According to what we use to say in physics, that would be ~ one harmonic (oscillation) and a half.

The snaps of the traces I presented were from a 61X54.7 engine actually. I can't even get to 12nbars of BMEP :facepalm:<_<

To TZ350:
Aren't the time areas you show a little too much?? Especially those tfr numbers are huge! For an 125cc engine, with 50mm stroke. Except if I am not using correct input in all my calculations..
Good requests by the way! It would be very interesting to know a fine setup numbers. Not to copy it, but to have a point of comparison.
In these sim there are so many interdependant variables, that you can sim and sim and sim for months!

After Wobbly gave us some info on how to interprate these graphs, I tried to study the results from the two GP engines coming along the sim, an RS125 and a TZ250G. But I got even more confused. Especially the inlet traces are a lot different at max-power-rpm, than what the ideal situation described above.
Another strange point is that RZ400 example, at EPO the inlet pressure is atmospheric and descends, while in all my graphs it's atmospheric and ascends.

I would like to summarize a couple of the info until this far:

Inlet traces:
> Inlet pressure should rise above 1, at the same point where case pressure falls below 1. That's best to be at the "3rd harmonic".
> Transfer pressure shouldn't rise too abruptly after TPO. That would mean a need for more blowdown.
> (on a question mark - that's a personal observation) Reeddisp shouldn't rise to be too close to the crank/inlet pressure.

Exhaust traces:
> (on a question mark also) Cylinder pressure should start falling from peak at TPO and reach peak again at EPC.

teriks

22nd November 2011, 03:21

251116

STA numbers for the graph, looks like plenty of Blow Down Time Area, I think it must be something to do with the exhaust tract/pipe.
I'm anything but an experienced tuner myself, but I believe you will always see more or less of that pressure spike around max-power-rpm on a useful engine. How much is too much is another question.

Re. the pipe, wobblys comment

The port timing and the pipe length are not working together, you have no superposition on the far left.
applies to this one as well. Compare the pressure in the exhaust port, "Pexport", at EPO with wobbly's pic here (http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250859&d=1321559702)

No ... just learning, thanks for the tip.
So am I, after plenty of time behind the screen. It's kind of humbling... :)
Let's see what the more experienced have to say.

wobbly

22nd November 2011, 08:33

Dont get hung up on Bl - STA, thinking its good to get rid of the transfer blip..
Any well developed race engine is ultimately Blowdown restricted, and you will always see the Tr Port pressure ratio rise when they open.
That effect is what makes port stagger work.
The first port to open, initially has backflow, it must, as there is more pressure above than below.
Then the rest of the ports open and eventually begin to flow into the cylinder due to the depression created by the pipe diffuser.
Thus the port that opens first, flows last.
Counter intuitive, but reality, proven on motored, instrumented engines in the lab and reported in a raft of SAE papers - and now shown in the sim.
Getting a balance between the blowdown needed to achieve the power you want, and the transfer area available is the tuning trick most valuable.

Superposition at ExPort opening is loosely referred to as pipe/port resonance, and is best achieved over the widest range with low Ex durations down at 192*.
Unfortunately this is countered by needing alot more blowdown than these numbers allow, and around 198 is needed to achieve the best bmep numbers.
In this scenario we try to achieve resonance at peak and beyond, to give plenty of overev power.

Next issue that is my favorite hobby horse for today is Ex duct exit area.
You will find a heap of free power, when using a T port or a Tripple port configuration, by limiting the duct exit area to around 75% of the Total Ex Port Effective.
Then make the header start at the area = to the Total Effective.
Join these with an oval to round adapter in the spigot or flange, where the width = the header dia all the way thru, to enhance the flow from the blowdown area,and
the height at the flange face forms an oval to give the correct 75% area.

The Temp Av in the pipe should be around 500 as in any fast engine you would measure around 600 in the header.
The TuMax should be around 1000,any more and you get deto, alot less and it means the temp/pressure rise in the chamber isnt high enough, and you are restricting the "push" on the piston.
But can also mean that you are using retarded timing to get heat into the pipe, not create pressure on the piston.

Lots more stuff, so little time.

bucketracer

22nd November 2011, 08:57

Great info, thanks Wobbly, I am learning more all the time.

dinamik2t

22nd November 2011, 09:12

As an addition to what Wobbly said about the exhaust duct-flange diameter, there is this quote from pitlane.biz:

One wants the pressure wave coming back into the cilinder but NOT the burned gases that are hot and can cause detonation!

and the photos of RSA's duct/flange

251236
251237

F5 Dave

22nd November 2011, 09:16

Indeed. Makes the staggered port make more sense now.

Thank you Frits, lovely cases, esp the water channel presumably as a neat to barrel to barrel water transfer & taking heat out of the cases as well. Never was sure how much cooling the cases did. Seemed popular ages back & then just sort of went quiet (But I'm obviously not poking around high end GP bikes).

kel

22nd November 2011, 12:55

Below are some pictures of the Aprilia RSA125; the red arrows indicate the ignition sensor.

Wow that RSA has some different bits attached? Frits is that a temp sensor in the exhaust header flange and if so was it connected to the engine management or just the data acquisition system?

Frits Overmars

22nd November 2011, 13:08

Wow that RSA has some different bits attached? Frits is that a temp sensor in the exhaust header flange and if so was it connected to the engine management or just the data acquisition system?Yes, it was a kappa-type thermocouple and it was just for data acquisition.
In fact its position is much too close to the cylinder; there should be room for at least one cylinder volume of 125 cc in the header between cylinder and sensor to avoid fresh charge hitting the sensor. But mounting the sensor further down the pipe proved impractical because there it was quickly destroyed by vibrations.

dinamik2t

22nd November 2011, 14:59

Here are some results regarding inlet length tuning, to add to what Wobbly described in previous posts.
I am speaking of a 118cc with max hp at 11.8k rpm.

Firstly, an inlet pipe of total length of 136mm. (2/3 of reed cage included) Fine tuned at the "3rd harmonic", with inlet pressure rising and case pressure falling. Would be a charm, unless I would have to skip the whole intake rubber.:shifty:
251365

Then, same setup with the shorter intake that can fit into my chassis. Total L of 186mm. Tuned at nowhere (?) Same peak power, but of this more to the end.
251366

I tried to tune it half-period earlier and here there are the results for inlet pressure droping while case pressure does too. At 161mm. Slightly decreased peak-power.
251367

Finally, if I wanted to achieve the inlet-fall/case-drop situation with a realistic intake, I had to tune at the "2nd harmonic", with a length of 221mm. A small decrease of peak power here too. [Notice here that reed pressure rises significantly more than in the other two setups. I guess this might have an impact on reed life. - That is not correct, REEDDISP is Reed Petal Tip Lift, as Wobbly corrected]
251368

I wanted to do an overlay image but there are too many graphs and it would be more confusing than helpful.
Anyway, those were the results at peak-power rpm only. And differences there where not very serious.
If we look at the whole curves though, things are very different. (the 3rd result is missing, I didn't run it)
251369

-------------

Also have a question for you Wobbly, whenever you find the time to answer.

I though of simulating the Flange to Pipe Header transition, so I added a small part in front of the exhaust.
Starting diameter is the duct exit diameter and end diameter the header diameter. The length of the transition, I used to add it to ex duct length in Exhaust data, as the flange base thickness.
Is this thought correct or not?

251370

I experimented a little with lengths and the setup in the image worked best for me.
Generally, comparing transition with no transition, there was a loss in overrev power and a small gain just before peak power.

wobbly

22nd November 2011, 15:34

Firstly you are misguided re the reed trace - this represents reed tip lift, there is no "pressure ratio" being shown.
The reeds will flat line at the max lift if you use a stop plate.
The length of about 135 for a 12,000 rpm engine has an effect over a much wider range, than the longer intakes, as the pulse frequency is greater, and the crossing point doesnt
move as much with a change in rpm.
That length is what was achieved in the dyno graph I posted back a bit for the TM125MX - just taking 15mm off the rubber gave 2 Hp in 50, and worked over a wide range.
It used a SPJ short carb from a HRC RS125, and a very short rubber off a earlyer model with the same bolt pattern.

Re the Ex duct nozzle.
The area at the cylinder duct exit should be around 75% of total Ex effective, simply change this in the Ex Port page.
Then you should have at least 30mm or so of "flange" to increase the dia up to the header size ( this would be an oval to round CNC transition).
Your small taper is way too steep, and kills energy in both directions.
This flange is part of the pipe, as you have done.
When done right this is the result - no nozzle = a 45mm duct exit straight into the header.
The curves above had a 39mm dia duct exit, with a 30mm long flange going up to 45 dia at the header.

k14

22nd November 2011, 15:45

As an addition to what Wobbly said about the exhaust duct-flange diameter, there is this quote from pitlane.biz:

and the photos of RSA's duct/flange
Makes me remember when I was racing 125GP and plenty of guys got the devcon out on the header flange to correct Hondas "mistake" :facepalm:

dmcca

22nd November 2011, 18:34

Re the Ex duct nozzle.
The area at the cylinder duct exit should be around 75% of total Ex effective, simply change this in the Ex Port page.
Then you should have at least 30mm or so of "flange" to increase the dia up to the header size ( this would be an oval to round CNC transition).
Your small taper is way too steep, and kills energy in both directions.
This flange is part of the pipe, as you have done.
When done right this is the result - no nozzle = a 45mm duct exit straight into the header.
The curves above had a 39mm dia duct exit, with a 30mm long flange going up to 45 dia at the header.

Sorry if this is a stupid question... but do you want to have a step at the top and bottom where the flange/duct meet?? I imagined the CNC oval/round transition to be smooth but it looks like its not the case in the RSA photos above???

This seems like a key bit of tuning advice so i want to be 110% sure i get it. Ive mostly worked with MX motors and most have this 'step' top or bottom or both

husaberg

22nd November 2011, 21:30

Question for the panel

In the Bell book he mentioned modifying the two crankcase ports in a CR125 cylinder (the old cylinder reed model which has two small ports with link the reed cavity with the crankcase)
He closed them with filler and then shortened the piston skirt to achieve 230 degrees inlet duration.

I did the same mod on my old H100 which has similar ports and a windowless piston but never got around to testing it.
I always wondered how much difference it would actually make and why.

Has anyone ever tried it?
He said he achieved an extra HP or so with the mod.

dinamik2t

22nd November 2011, 23:11

Woobly, merci. I read "reeddisp" -displacement probably- but then again, all Y-axis was pressure. Thanks for making that clear.
-I edited the previous post so as not to mislead anyone. :)

I have a 37 efficient diameter at ExP and duct exit was 36. Before the above sims, I have used every duct exit size from 28(~75% of 37) till 36 - 2mm stepping. Best results in my opinion were at 32mm. I have the graph for the 28~34 testing testing. At 28 there was a huge overrev gain, but power decreased everywere else.

<a href="http://s736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/DuctExitDiameterTesting.png" target="_blank"><img src="http://i736.photobucket.com/albums/xx5/Vag1-2/EngMod2T/th_DuctExitDiameterTesting.png" border="0" alt="Photobucket" ></a>

Actually, now that I look back at your post about RZ400 numbers, considering that header dia. is the same as ExP effective dia., then 39 is ~85% of 45.
About 85% is the 32 of the 37, which gave better results in my scenario also. Perhaps you are too busy these days :D

Sorry if this is a stupid question... but do you want to have a step at the top and bottom where the flange/duct meet?? I imagined the CNC oval/round transition to be smooth but it looks like its not the case in the RSA photos above???

I remember Jan (Thiel) or Frits (Overmars) -:bleh:- saying that duct volume should be as small as possible. Plus the quote of Jan's words earlier.
I don't think this gives you the answer you want, but anyway. We should try and think how a wave behaves to understand further of this configuration.

dmcca

22nd November 2011, 23:24

We should try and think how a wave behaves to understand further of this configuration.

Thats what ive been wondering... taking the quote earlier from Jan Thiel into account (about wanting the return pressure wave but not the returning gasses) I would guess that the step hinders the reverse flow of the burnt gasses , possibly by bouncing back a small wave back down the pipe as the reverse wave returns to the exhaust duct??

*** on second thoughts the 75% oval to 100% round transition will create a reverse wave just fine by itself (even without the step) as the initial wave returns though it.

teriks

22nd November 2011, 23:55

I cant really come to terms with the step either, but it would hinder _flow_ from the pipe to the cylinder somewhat.

The effect of duct volume, or rather duct cross sectional area, I think I have some kind of grasp on.
-Decreasing the duct cross section area would increase the length of the fresh gas column for a given volume.
This could increase power when the return pulse otherwise arrive too early.

I'm sure Frits or wobbly will correct me if I'm wrong :)

Grumph

23rd November 2011, 05:24

A stepped transition at the header joint is common on fourstrokes for just the reason Jan Thiel stated.

If I remember correctly it will flow just like a cone section for outward gases. The step has no effect on the return wave activity but does resist returning "solid material".

wobbly

23rd November 2011, 07:25

The areas of a header transition is whats important - a 39 duct exit is 75% AREA of a 45 header,39 isnt 75% of 45 obviously.
The 75% isnt set in stone - just a guide.
I have noticed that the best ratio seems to be when you use the header area the same as the full Total Effective Area of the Ex Port, along with a duct exit restriction
nozzle about the area of the main port.

Re the smooth transition nozzle Vs a stepped design.I started to experiment with this after getting hold of a genuine A Kit Honda spigot.
I did a series of dyno tests using a late model HRC RS125, when beta testing Luytens cylinders.
The cylinder as first produced had a 40 by 35 duct exit oval.And as a reference any dummy that removes the oval and makes it simply 40 dia round, just lost 2 Hp and all the overev power.
This was first tested with a simple 40 dia round spigot, thus having a step - top and bottom.
Next I bolted on an early model A kit RS250 spigot, this is a cast oval to round transition from the factory.This test immediately gained around 1.2 Hp, and alot more power past peak.
Then I ground the duct out to 41, and welded the duct up inside as far as I could, to enable a 32 high oval shape.
Hondas later model RS250 A Kit has this size spigot but with the oval 35 high, so I welded that and reshaped it as well to 32 high.
A new pipe with the bigger header was built to suit.
This gained another 1.5 Hp, so as a last test I made a simple 41 round spigot - and this lost all the power just gained.
The 41 by 32 oval was right on 76%.

So - I can say definitively with a T port that the transition is better than a step, but all the 3 port engines I have done have made alot more power as well, though not as well tested back to back ( I was paid to do the T port testing ).

I believe that the Aprilias slightly different system can work just as well, maybe even slightly better - as im sure Jan Thiel would have tested it to death, as it promotes the flow from the triple ports right up to the header.
But when you are modifying an existing design, the CNC oval to round setup is quite easy to implement, on a T port or a triple port design, especially as I have tested it to death on 50cc up to 500cc cylinders,and given you the basic numbers to follow.

Edit - re the so called "power port" idea.This was developed as a tuning aid back when engines made no power at all, and running a bigger piston port timing, along with forcing inflow to be pushed thru the boost port, just happened to add a Hp or 2 on top of none to start with.
What we find now is that cylinder reed engines always end up being power limited by the effective STA that can be obtained by cutting holes in pistons, adding big Boyesen ports and even then adding floor ports.
All this is attempting to get the inflow around and or thru the piston that is in the way alot of the time.
That is why case reed is ultimately better when done properly.

husaberg

23rd November 2011, 16:32

Edit - re the so called "power port" idea.This was developed as a tuning aid back when engines made no power at all, and running a bigger piston port timing, along with forcing inflow to be pushed thru the boost port, just happened to add a Hp or 2 on top of none to start with.
What we find now is that cylinder reed engines always end up being power limited by the effective STA that can be obtained by cutting holes in pistons, adding big Boyesen ports and even then adding floor ports.
All this is attempting to get the inflow around and or thru the piston that is in the way alot of the time.
That is why case reed is ultimately better when done properly.

Case reed sounds interesting i wonder if it will catch on.:whistle: Put Vanessa down for one of those I guess then.:innocent:

Although what is a Boyesen port? I know he had quite a few patents. I will see what Mr Google says.

<tbody>
<center>Auxiliary intake ports</center>
Passages leading to the transfer port tunnels which are extended from the intake area without entering the crankcase. Also called Boyesen ports

</tbody>

251394

So they are like the Kawasaki ones that link the reed cavity with the Transfers or these Cagiva ones

ps I can not be blamed for these sharpened Septums it was not I. (I have sharpened the odd one or two in my youth though.)

Thanks Wob

F5 Dave

23rd November 2011, 16:41

yeah also had the boysen action bar or somesuch which was a wing in the reedblock to try reduce the velocity reduction. Never seemed to catch on so he made teh boysen radvalve. Sort of then got over-taken by Vforce, supposedly. Never been too sure how much of this reedcage titivation alters the real life performance. Usually use lots of hard to quantify anecdotal claims such as throttle response.

Used to be just 'throw the biggest cage you could in there' as it would be an improvement, Husky got a bit silly in that regard.

wobbly

23rd November 2011, 19:06

The oversized reed cage is one of the multiplicity of reasons a TZ125 is a piece of shit compared to an RS.

TZ350

23rd November 2011, 20:46

EngMod2T

251402

Found where I can create and save the prescribed combustion data file. and I was able to edit and save this dummy data file.

251399

Found where I can get the real data to enter into the prescribed combustion data file.

251398

Previously I have had trouble saving this file so this time I added the correct data a bit at a time saving it as I went and when I added the 100 deg duration’s it fell over again.

251400

Now I dont mind getting an error message, in fact welcome it if I can go back and edit the data, even better if it tells me which fields are wrong.

251401

But this program kicks me right out and worse deletes my previous work forcing me to start over. now that’s just plain stupid and frustrating as it's a lot of data to have to keep re-entering until I get it right.

Now an experianced person might recognise bad data before they try to save it, but a newbee like me won't. One should be given the chance to edit it and not just have all of the combustion data dumped and then made to start over.

I know the algorithms have been developed over a long period of time and I have every confidence in them and their coding.

But the data input and editing side of this application can make this a frustrating package to use. Hopefully with time these things will get sorted and made more crash proof for dummies, as I believe this package is realy worth it .......

But if it pisses me off too much Bucket will get the job ....... :D

husaberg

23rd November 2011, 21:20

But if it pisses me off too much Bucket will get the job .......

All the Best managers delegate Rob.

After-all the CEO of KFC doesn't Kill the chickens.:laugh:

Team ESE is becoming a large operation now.
What with Project Managers and IT team leaders. development riders. researchers, PR consultants. Overseas development consultants. Merchandiser, R&D, Dyno Operators and Umbrella Girls.

Yes I am Jealous.

dinamik2t

24th November 2011, 00:17

The areas of a header transition is whats important - a 39 duct exit is 75% AREA of a 45 header,39 isnt 75% of 45 obviously.
The 75% isnt set in stone - just a guide.
I have noticed that the best ratio seems to be when you use the header area the same as the full Total Effective Area of the Ex Port, along with a duct exit restriction
nozzle about the area of the main port.

Sorry, my mistake. Seems I'm too excited and overlook things, not you too busy! :scratch:
Reminded me of the fault about squish percentage reference. It is the area, not diameter that is compared.
[Trying to save my a** :P] As area calculation has no other variables than diameter, the relation between those can be expressed by the 85% (86.7% to be accurate). 0.75 square rooted is 0.867 :D

----

About the steps in ExP duct exit. Does is have anything to do with how waves & pressure pulses behave on convergent (while exiting) and divergent (while returning) cones??
I was thinking that since duct diameter is larger at Port than at exit, it behaves like so. Is this the right route to continue thinking?

----

Hey TZ, I think you are being way NOT accurate with the inputs in Vibes. You should choose only one variable at a time to copy the values. Futhermore, you should use the "Supplied" option in X/Y-axis limits (it's on the window for choosing perf. data) to limit the range and get even more accurate values.
A small trick I use is this: say I see the value of delay at 10500 is between 10 and 12. I limit the Y-axis between these two, and set the X-axis to start at 10500. It says the exact value right on the Y-axis scale. :)

Basically, now that I think about it, while you keep using Prediscribed, there is no need for too great an accuracy, since you are only looking for differences between modifications. I like to keep an accuracy of 1 decimal point in short-ranged variables (i.e. not duration) and 2 for VibeM.

Here's the latest predicribed model I use. Look at the accuracy I am talking about. It gives me about 0.5hp inaccuracy over the turbulent.

251408

If you have problems copying the values, I can help you if you send me your files. It's no big deal. :yes:

TZ350

24th November 2011, 05:41

Hey TZ, I think you are being way NOT accurate with the inputs in Vibes. You should choose only one variable at a time to copy the values. Futhermore, you should use the "Supplied" option in X/Y-axis limits (it's on the window for choosing perf. data) to limit the range and get even more accurate values.
A small trick I use is this: say I see the value of delay at 10500 is between 10 and 12. I limit the Y-axis between these two, and set the X-axis to start at 10500. It says the exact value right on the Y-axis scale.

Thank you for your suggestions, I will try them. I notice the top (options) on your graph screen looks different to mine.

I think this is a great program, I like what it can do when the data input is right ....

wobbly

24th November 2011, 06:55

Just a couple of things to note - the program will crash with an entry greater than 100 for duration - its not a "real" entry.
And your ignition timings are very wierd - never ever seen any 2T that will run 40* at any rpm.
But for example running straight Methanol in a 125, the dyno testing has been done a hundred times, and won dozens of titles.
Run 18.5:1 com ( 17.5 in air cooled ) and a "normal" ignition curve for petrol, ie around 28* in the mid and 15* at peak torque.This sort of setup gives the best power every time.
Its a long drawn out fallacy that you can make big power by taking a petrol based engine, pour in a high latent fuel, and simply wind in timing - it doesn't work.
Its best to run an "average" input for the variables until you are confident with the other inputs, then run turbulent,then transfer the calculated data.
These are 12 for AFR, 9 for delay,50 for Duration,6 for VibA, 1.25 for VibM.
This always works well as a baseline.

F5 Dave

24th November 2011, 08:32

. . .
After-all the CEO of KFC doesn't Kill the chickens.:laugh:
. . .I doubt he eats them either.

teriks

24th November 2011, 09:45

wobbly, now that you mentioned methanol, could you share some numbers on critical temperatures for a methanol engine?
-Or anything else methanol specific to watch out for for that matter.

Now, I don't have the luxury of a programmable ignition, heck, I cant even set a static ignition timing with the glow plug ignition I'm using.
Avoiding getting too much off topic with glow-plug stuff, I might be able to use at least something like Max unburnt from a "normal" engine as a guideline.

251412251413

wobbly

24th November 2011, 10:45

Sorry Teriks, methanol is banned here now so I havnt done any work on it to help you.
I am about to get all the parts for a Rossi hydroplane engine that uses methanol,to design a pipe for it, so I will be working on that soon.
Your pipe trace looks very good, except the peak ratios are low, maybe the pipe needs to be fatter to create more wave action.

teriks

24th November 2011, 11:28

Hydroplane, thats funny, my dad just got nostalgic and got a hydroplane again after 30 years or so off.
Had a quick glimpse on his CMB45, seems there are quite some room for improvement.

I'd be happy to discuss and share my models etc. if you are interested, but it might not be right to clutter up this thread with miniature engine stuff.
TZ350, your opinion on the cluttering-up-your-thread part?

EDIT: Thanks for the comment on the pipe, have spent way too much time on the simulator on that one. -Now I just need to have it made, that, and wait for some decent outdoor temperatures.

Frits Overmars

24th November 2011, 12:38

...I am about to get all the parts for a Rossi hydroplane engine that uses methanol,to design a pipe for itFrom what I've seen you can gain 20 HP right there if you can convince Rossi to shield his pipes from the boat's rooster tale. Talk about water-cooled exhausts....

wobbly

24th November 2011, 13:13

Im sure you are right Frits, I saw the water spraying all over them in a video.
Then they tell me they only have 420* in the header.
They run absolutely mental compression ratios, then drown the engine with fuel, and use extra big stingers to stop it blowing up.
Even on jungle juice they make way less power than you guys were on unleaded, the pipe design is a joke.
Much to do.

teriks

24th November 2011, 19:15

Ohhh, _that_ Rossi hydro plane, talk about jumping to conclusions.. :facepalm:
-There are model hydro planes as well, and Rossi miniature engines.

TZ350

24th November 2011, 19:36

Just a couple of things to note - the program will crash with an entry greater than 100 for duration - its not a "real" entry.
And your ignition timings are very wierd - never ever seen any 2T that will run 40* at any rpm.

Thanks for the 100 tip ...... being a newbee I was just taking the duration data from the performance display screen as is.

With a sensible ignition timing and 100 duration the burn went past the ex opening point, the 40* timing was to get past that issue.

251437

Now I think I understand the real problem, with 99 duration the program handles the data string ok and saves it but with a 100 or greater the program crashes.

To me it looks like, its not that the number is a 100 or greater or even plain wrong, its that the number is three digits long and that pushes out the length of the data string and the end de limiter is lost.

Some data input checking for string length and format on these fields as they are enterd would cure this and give the data entry operator a chance to correct any mistakes without losing all of their input work on this screen.

I did not know what I was doing wrong before but now that little issue is sorted, I am off again looking for a new way forward for my engine and modelling stuff to see how it might work out, sure I expect there will be other little issues, but who cares.

Up and running again ..... :D .....total happiness

husaberg

24th November 2011, 21:51

dmcca

24th November 2011, 22:00

Up and running again ..... :D .....total happiness

EngMod2T is a roller coaster ride thats for sure! One minute you think you know it and the next you realise you dont.

Frits Overmars

24th November 2011, 22:48

EngMod2T is a roller coaster ride thats for sure! One minute you think you know it and the next you realise you dont.Is that so? Then it's a perfect imitation of a competition two-stroke :rolleyes:.

Strokerhaus

25th November 2011, 08:00

I found these in the Haynes published the Two stroke engine design and Tuning KG Draper

That Kobas and I were discussing earlier there is some interesting design features here old hat yes outdated yes but interesting nevertheless.
Well to me anyway.

Interesting yes, I have a peripheral valve Alpha, but the big issue is inlet area at flywheel is some what restricted. Now rebuilding a Centuri which was a good machine in its day but will be a challenge to match the modern Ariel Arrows in UK CRMC but you have to try. The biggest issue with that is twin disc valves with one carb, 180 deg crank and limited room between disc valves.

Keep up the great work, love the forum.

TZ350

25th November 2011, 09:47

modern Ariel Arrows in UK CRMC

I would love to know more tech details about the Ariel Arrows ......

husaberg

25th November 2011, 15:17

Interesting yes, I have a peripheral valve Alpha, but the big issue is inlet area at flywheel is some what restricted. Now rebuilding a Centuri which was a good machine in its day but will be a challenge to match the modern Ariel Arrows in UK CRMC but you have to try. The biggest issue with that is twin disc valves with one carb, 180 deg crank and limited room between disc valves.

Keep up the great work, love the forum.

You have both. Wow.
I found finding info on the twin a little daunting. There are few pics i had seen that show the disk set up in detail, and one of the museum ones was burnt destroyed can't remember if it was a twin or single. Is one of these yours perchance?http://www.lortim.demon.co.uk/alpha/index.htm

I do have this which was similar era and more conventional in design.post later

husaberg

25th November 2011, 18:27

You have both. Wow.
I found finding info on the twin a little daunting. There are few pics i had seen that show the disk set up in detail, and one of the museum ones was burnt destroyed can't remember if it was a twin or single. Is one of these yours perchance?http://www.lortim.demon.co.uk/alpha/index.htm

I do have this which was similar era and more conventional in design.post later

One more page sorry will fill in gaps with Ariel or Alpha for the nostalgic types.

Yes Rob I did find some Ariel stuff in the book library. But the stuff from England would be much more interesting remember the Arrow was slightly based on the Addler as was the original Yamaha.

husaberg

25th November 2011, 21:59

One more page sorry will fill in gaps with Ariel or Alpha for the nostalgic types.

Yes Rob I did find some Ariel stuff in the book library. But the stuff from England would be much more interesting remember the Arrow was slightly based on the Addler as was the original Yamaha twin

A beautiful GP5

Sorry no more old dungers for a week after this. Rob made me do it.:innocent:

Although I must admit the thought of a old Ariel 2 stroke stuffed full of TZ internals sucking on Methanol with 2011 porting technology socking it to $50,000 dollar Manx Nortons does give me a little wood.:Punk:Does that make me a bad person or just demented?

Strokerhaus

25th November 2011, 22:31

Yes a couple of my single cylinder Alpha bottom end's are on that web site, and the picture you attached of the Alpha test bike with the very early single cylinder engine is one of my bikes although it no longer looks like that. The Alpha twin on the web site is one of 4 machines that "survive", but its not mine. That is the sister bike of the one damaged in the fire, which is being rebuilt slowly by its owner, the frame is now straight thanks to young Sprayson, there is now a replacement gearbox sourced from New Zealand, he has a spare engine, so heading in the right direction. I'm now making a replica Centuri engine since I do not want to trash another original Alpha engine on the race track, heads and crankcases already cast I still have to finish the core boxes for the cylinders, but that could take a week or two yet! My bike is one of the two DMW versions used in the 68 TT, neither of which managed a lap during the race. Another little snippet is the bikes run on a 29 mm Delorto with an 1800 main jet, yes not a miss print, one of the short falls of using a single carb and twin disc valves, however having said that, the final version did manage to produce 48 bhp at the crank, and had an amazing appitite for primary chains.

The Merlin engine in your photo's was very popular with the Kart people, there were 3 versions to my knowledge a 200cc, 250cc and a 350ish cc engine. A very good little engine, but sadly not developed like so many other good ideas.

The Arrow engine is now becoming popular again in Classic Bike racing in the UK, as you said the engine is very similar to both the Adler and TZ, with the same bore and stroke. The bikes currently racing in the UK are much more like the TZ internally, than an Ariel. The Ariel came in multiple shapes and sizes, 200cc, and 250cc with the latter available with the standard single carb, or the twin carb sports version. All bikes had the basic very stiff pressed steel spine from, which was very advanced for its time and trailing link front forks which are very heavy, the Leader had the extra body work for every day transport, and the Arrow was the bare sporty bike. Good machines.

Another interesting British engine was the Royal Enfield GP5 designed by Hermann Meier, which I think was one of the first 4 transfer port engines around, and way ahead of the Yamaha versions, and not counting the MZ boost ports. Hermann was a very clever engineer who also tuned the very succesful TT Arrow ridden by Mike O'Rourke.

Enough now lets get back to modern stuff, so I can revise my designs for the Centuri core boxes!

Frits Overmars

25th November 2011, 23:00

Just one more picture of an Ariel Arrow before returning to the 21st century. Note the clever crankcase 'cooling' fins right behind & above the headers...

bucketracer

26th November 2011, 07:09

Local bike, Taupo track, Wobbly pipes, bikes from Tauranga I think, I have seen it at Puki during the Classic Festival.

wobbly

26th November 2011, 07:47

Yes, the Arrow in that pic lives just down the road from me.
Its got Yamaha crank parts, CR125 pistons, PVL Ignition, twin carbs on Methanol, my pipes, a 6 speed box in the original gearcase ( Shhhh ) and about a months worth of
porting and machining.
Got to make a living somehow - stealing money off classic nutters is one way.

husaberg

26th November 2011, 13:03

247722

When TeeZee first talked about fuel passing the main jet three times. SS90 was most adamant that it couldn’t possibly happen as he had never seen a carb fog at max power on a 2-stroke, you know, real life experience and all that.

And he made his usual song and dance about having to have real Industry experience to know what your talking about.

<iframe src="http://www.youtube.com/embed/KcNfci9OruU" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>

This is TeeZee’s bike making 27-28 hp complete with carb fog at max power. If its not fuel passing the main jet at least three times then what is it, maybe SS90 the Industry Man himself could tell us.

247723

After seeing the fuel line being sucked down in the vid, TeeZee added the filter/header tank, it works a treat and keeps the line full.

I have posted the first one already but here are two other examples of three times past the Mainjet

Everyone must sure miss Neil :ar15: . :dodge:
Because no doubt there have been a lot of shots fired at time over the years.

First one is Speed and how to obtain it (Most likely Phil Irving) (RIP)
The second one is John Robinson (RIP)
The third one is A Graham Bell (NIR)

AS all three are from Books and Not the new fangled internet they might even be true? (Unless Neil disagrees that is)

Then again they were not the industry respected man Neil is!!!

Just because they designed a lot over world beating motorcyles and F1 car engines as well and sold a few hundred thousand books and countless Mags.
WTF would they know about Vespa's. Pah likely mere amateurs at best aye Neil.

That doesn't make sense at all. It is not a Vespa

TZ350

26th November 2011, 17:57

Somebody asked about the Aprilia's inlet disk diameter. From memory I would say it was 126 mm.

Optimized disk inlets do not generate pulses: you open the disk when the crankcase pressure is equal to the pressure just outside the disk. Opening it any sooner would cause a loss of mixture to the outside world; opening it any later would be a waste of time*area.

You close the disk when the inlet flow has come to a stop. At that moment the pressure at the outside face of the disk will be equal to the pressure in the crankcase, but it will be higher than the atmospheric pressure, so there will be some blow-back, but that does not come out of the crankcase (assuming your closing timing is spot-on); it is just mixture feathering back from the high-density zone outside the disk.

For that matter, every conventional inlet system (disk, piston, reed) will show the same blow-back tendency. And it may not be even visible from the outside; maybe the cloud of blow-back moves just a few centimeters and never really exits the inlet tract.

By the way, closing an inlet disk too early (or revving the engine higher than the inlet system's frequency would like to) will generate serious blow-back because then the closing disk interrupts an inward-bound flow which will violently bounce off the disk.

You can observe this very nicely on a dyno: looking into the carburetter you can see the fuel spray exiting the mixing tube and curving towards the crankcase. But rev it high enough and you will see this curving change into a steep front of mixture.

I have posted the first one already but here are two other examples of three times past the Mainjet

Frits has given a good explanation of the reasons for fuel stand off in a rotary valver. Its also a clue to more power too, because if the stand off is at max power rpm, then it points to the possibility of closing the inlet a little later.

... closing an inlet disk too early will generate serious blow-back because then the closing disk interrupts an inward-bound flow which will violently bounce off the disk. You can observe this very nicely on a dyno ...

I too was surprised Neil wasn’t onto this himself, as its such an obvious thing when you think about it, particuarly if you have had a bit of time on a dyno.

husaberg

26th November 2011, 18:19

Frits has given a good explanation of the reasons for fuel stand off in a rotary valver. Its also a clue to more power too, because if the stand off is at max power rpm, then it points to the possibility of closing the inlet a little later.

I too was surprised Neil wasn’t onto this himself, as its such an obvious thing when you think about it, particuarly if you have had a bit of time on a dyno.

Possibly just possibly. Frits is a teeny tiny bit more clever than Neil. It could be errr...........possible :yes:

He does (SS unspoken) have the fall back position available in NZ for the Race Relations Conciliator (http://race relations conciliator/) if the Scooter thing doesn't pan out with the Vespa's

But on to more productive things.

Remarks in the Disk valve Merlin single suggest it was suffering from stagnation in its original test and the the jetting was only put right on the modern version after a session with the Late Leon Moss on the Dyno. It is said in both accounts that no reliance could be placed on the plug for correct jetting. mmmm.....

I will add an article that most Kiwi's will be familiar with and no doubt Mr Wayne Wright (sounds like a character from are you being served.
"Are you free Mr Waynewright")will be able to shed some light on a few bits like the 36HP more highly effective power valve.

wobbly

26th November 2011, 18:46

Aww shit, come on you guys.
Its bloody obvious - Frits is a dead set Industry Man,working as a senior employee of the biggest bastion of 2T insanity on the planet.
Can you imagine what it must have been like to have to work full time, trying to find something useful for 100 people to do in the race dept at Aprilia.
Must have been a bitch, at the least a worry.
What I dont understand is why Niel ( who the hell is he by the way) wasnt working as Jans right hand man, so much to contribute, no one to listen.

husaberg

26th November 2011, 20:09

Can you add any info to the BSL story above Wob. Or highlight any errors.
I always thought for some reason there was a twin that they started with first. Many years before the Triple.

Ps does anyone know why. No mater how careful you are loading the attachments. They end up in random orders sometimes?

Strokerhaus

27th November 2011, 01:59

As an addition to what Wobbly said about the exhaust duct-flange diameter, there is this quote from pitlane.biz:

and the photos of RSA's duct/flange

251236
251237

These changes in section at the exhaust, I have been trying to understand why they work. I lost 1 bhp on one of my old engines, after I had modified a port and a step in the exhaust, yes typical idiot, but no time no money so go for it! Unfortunately the engine granaded itself in the next meeting so could not go back to check out the changes. The port mod I have since repeated on another engine, and I'm reasoably certain it was not that. The exhaust port was round with just a step at the manifold. In checking out potential reasons I have noticed in a HRC tuning manual for the RS125 that you can remove the top mismatch on the port to manifold joint but not the lower one. So it suggests that oval is not mandatory but a step is.

Not certain if I have been sniffing too much Avgas/Castrol R, but I was wondering if the step sets up a sonic shock wave across the port, so engine side is sub sonic, and waves still go up and down pipe at supersonic speed. Therefore the width of the step and its proximity to the open port is critical, just like a jet engine intake. The advantage being possibly that it stops the shock wave going into the cylinder, from my understanding if a shock wave goes into a cavity it cause chaos to any flows (jan's comment keeping exhaust and inlet seperate). Has anyone any thoughts about this or am I off my head?

wobbly

27th November 2011, 06:38

Most of the article is crap,with alot of misguided ego's and selectively faulty memory involved.
For example Harden had nothing to do with the alternator design,he soldered the coils together, collected the magnets from F&P and had them epoxied.
The original CAD files are on a disc in my draw next to me.
I could spend a month dictating the reality of what happened and why at BSL.
First off the tripple was 59.6mm square,not 56, and the cylinder swept volume has absolutely nothing to do with the pistons "falling into" the exhaust ports.
The 120* V layout had a very clever firing order and balance shaft arrangement, the right hand upper, and middle lower cylinder fired together,the LH upper firing 120* later.
This was developed by Simon Longdill with a program he wrote for his BE project.
It worked a treat, being very smooth, but the crank took an age to make reliable due to very strong torsional harmonics.
The carbs were not anything like $10,000, they were SPJs off a Honda RS125 and cost about $800 each.
As they were on the front of the engine,facing back to front, they flooded under hard braking.
The float levers would force the needles off the seats, so I had some new bowls made using the needle and seats out of a Mikuni TMX.
These used a rod to support the floats - worked fine after that.

The extra mid range power was all down to using ATAC chambers on the top two cylinders, as well as the original PV blades.

Piston reliability was finally nailed when Vertex did some pistons with the correct cam shape to suit the bore when it was hot, this took 4 attempts,each attempt taking about 6 months from me sending
the CAD file, to getting the part to test.
All 3 were the same by the way.
Very frustrating, but we had no other way of getting the job done, being very small fish in a very big pond.

The CNC machined frame and swingarm spars were a work of art,we were the first to do this,as were the rapid prototyped cylinders.
These were cast directly off the CAD files by a company called Soligen - their web site still has our cylinder as an example of their CAD casting expertise.

The real shame at the end of the day, was that we finally cracked the reliability problems, running 100s of laps at Sepang with no breakdowns of the two test bikes.
The lap times there put us mid grid of the previous years GP, and this was documented by the Sepang Clerk of the Course.
When we applied to race at Philip Island that year,Dorna realised we had a chance of gaining points, and this would have given us the right to a "franchise" the following year - that could be sold for a fortune.
They took our "development team" status away, gave it to Ducati, who didnt even have a bike on the drawing board at the time, and told us to piss off.

The case CAD pic is the raw file used to craete the tool path.
The finish cuts were with a ball nose - leaving radi in all the corners by default.
Second shot shows the finished engine with carbs - the third a rendering of the tiny alternator, using NdFeB magnet material out of a F&P Smartdrive.

TZ350

27th November 2011, 08:35

I always thought for some reason there was a twin that they started with first. Many years before the Triple.

There was an earlier bike, on a visit once, upstairs in a storage area above the old resonator assembly room in the original Bowden rd workshop Bill showed me a dust covered hand made (rolling?) frame and a bunch of new engine parts from 125 YZ MXr's. Bill gave me one of the ignitions off it for something I was running at the time.

I can't remember the intended engine configuration of this earlier hand built Buckly race bike, not sure but I don't think it had actually ever been finished and run. Our real interest in ratting through the loft was to find some of his old Vincent speedway engine parts for a special he was building. A year or so later he started up the BSL project.

There was another hand made special about the place, I have only ever seen pictures of the rolling chassis and engine pinned on the wall at Gigglebuttons workshop but Nigal Duff was building a 500-4 stroker and I think that made it to the track, maybe the frame I saw at Bucklys and the pictures on the smoko wall at Giggles is the same bike.

husaberg

27th November 2011, 08:54

There was an earlier bike, on a visit once, upstairs in a storage area above the old resonator assembly room in the original Bowden rd workshop Bill showed me a dust covered hand made (rolling?) frame and a bunch of new engine parts from 125 YZ MXr's. Bill gave me one of the ignitions off it for something I was running at the time. I can't remember the intended engine configuration of this earlier hand built Buckly race bike, not sure but I don't think it had actually ever been finished and run. Our real interest in ratting through the loft was to find some of his old Vincent speedway engine parts for a special he was building. A year or so later he started up the BSL project.

I seem to think a twin with cr250 cylinders or such like it was in Kiwibiker along time ago around 91 I think I could have been someone else but it was a father and son?

Most of the article is crap,with alot of misguided ego's and selectively faulty memory involved.
For example Harden had nothing to do with the alternator design,he soldered the coils together, collected the magnets from F&F and had them epoxied.
The original CAD files are on a disc in my draw next to me.
I could spend a month dictating the reality of what happened and why at BSL.
First off the tripple was 59.6mm square,not 56, and the cylinder swept volume has absolutely nothing to do with the pistons "falling into" the exhaust ports.
The 120* V layout had a very clever firing order and balance shaft arrangement, the right hand upper, and middle lower cylinder fired together,the LH upper firing 120* later.
This was developed by Simon Longdill with a program he wrote for his BE project.
It worked a treat, being very smooth, but the crank took an age to make reliable due to very strong torsional harmonics.
The carbs were not anything like $10,000, they were SPJs off a Honda RS125 and cost about $800 each.
As they were on the front of the engine,facing back to front, they flooded under hard braking.
The float levers would force the needles off the seats, so I had some new bowls made using the needle and seats out of a Mikuni TMX.
These used a rod to support the floats - worked fine after that.

The extra mid range power was all down to using ATAC chambers on the top two cylinders, as well as the original PV blades.

Piston reliability was finally nailed when Vertex did some pistons with the correct cam shape to suit the bore when it was hot, this took 4 attempts,each attempt taking about 6 months from me sending
the CAD file, to getting the part to test.
All 3 were the same by the way.
Very frustrating, but we had no other way of getting the job done, being very small fish in a very big pond.

The CNC machined frame and swingarm spars were a work of art,we were the first to do this,as were the rapid prototyped cylinders.
These were cast directly off the CAD files by a company called Soligen - their web site still has our cylinder as an example of their CAD casting expertise.

The real shame at the end of the day, was that we finally cracked the reliability problems, running 100s of laps at Sepang with no breakdowns of the two test bikes.
The lap times there put us mid grid of the previous years GP, and this was documented by the Sepang Clerk of the Course.
When we applied to race at Philip Island that year,Dorna realised we had a chance of gaining points, and this would have given us the right to a "franchise" the following year - that could be sold for a fortune.
They took our "development team" status away, gave it to Ducati, who didnt even have a bike on the drawing board at the time, and told us to piss off.

The case CAD pic is the raw file used to craete the tool path.
The finish cuts were with a ball nose - leaving radi in all the corners by default.
Second shot shows the finished engine with carbs - the third a rendering of the tiny alternator, using NdFeB magnet material out of a F&F Smartdrive.

LInk to Soligen with cylinders http://www.soligen.com/parts/motorcycle-eng.shtml

I have done a couple of interviews with the media and had a little to do with press realeses and such like. One interview I did I found out all sort of interesting information about myself that I never knew before after reading the article. It is very interesting how different a story becomes by the change of a few words or a coma or full stop here or there.

The bore and stroke threw me a bit when i read it as it wouldn't have been 500 and 56mm pistons would have been common although maybe a little short.that and all the stuff i tried to highlight as well thanks Wob. Was the designer of the styling right? I always though John did his own styling.Although the name is sure familiar.

The MNZ was clearly not as friendly to BSL as it was to the Britten either. B.stards. At least they are consistent with there inconsistency's anyway.

wobbly

27th November 2011, 17:03

Bill built a V4 - 500 that used YZ125 parts, with a pressed and welded frame.
It wasnt very clever, and he didnt like it when I said to him in the tent at Manfield that the guy who made the pipes should be shot.
I was with Mike Sinclair, Mike Webb and the other Mike the suspension guy from here in Tauranga.
They all told Bill to start again, and eventually he did.
When Loren and I turned up to start the project, he wanted us to finish the prototype, but as I pointed out there was no place to put the water pump,so that sealed its fate - bin it.

Another laugh I had was over Briggsy designing and building all the pipes, more rubbish.
I was so busy trying to get the engine rework done - I taught him what to do, and gave him the laser'd pattern designs and he welded and hammered some of the final few sets up, including some Ti ones.
Made some real nice ones too.
Jason Monopoly worked for John B, then came to us at BSL for 6 months.
He did all the glass styling/design work, and off that Roly made some stunning bodywork that worked well in the wind tunnel testing we did at AK Uni.
But alot was changed when Mike Sinclair mused about sidewind effects at 300Km/H

Nigels bike we worked on and off for about 10 years,going in fits when he had some money.
It was a pretty thing, as you can see from the pipes,but Nige finally gave up on trying to finish it - its gone to Rodent in Queenstown