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Grumph
30th July 2012, 15:47
SS90's poisonous pen ..... regular as clockwork ... :laugh: ... talks cheap, lets see a dyno graph of your own work.

Yeah, he was an obnoxious bastard when here...yeah, I know, pot, kettle....but at least he got out on track and did it.

Personally, I'm curious about the Manx Norton in your signature Fred...Protar kit is it ?

F5 Dave
30th July 2012, 15:57
:killingme Now that just wasn't called for. What you failed to appreciate is that with my tinted visor down I look as young as the next guy :lol:

edit - I believe young Arron would be a third of my age. Kids have no respect for their elders these days.
hey buddy I'm drinking from the same well, or getting there:weep:

F5 Dave
30th July 2012, 15:58
Why don't you pop in & see Fred's Manx, I'm sure he wouldn't mind, you're both in Chch I think.

Grumph
30th July 2012, 16:10
Why don't you pop in & see Fred's Manx, I'm sure he wouldn't mind, you're both in Chch I think.

I'd love to....but if he had one I'd already know him.....and he'd know me.

bucketracer
30th July 2012, 17:10
... you can produce an immense amount of torque from a two stroke, with-out any of the crap that thing has bolted on to it.

SS90, I know you claim to be an experianced industry insider but your opinions often don't seem to stand any sort of scrutiny.

SS90 Maybe you have achieved a torqe monster, but I doubt it, a dyno graph of your own work could change my mind but I am not holding my breath.




267321


My opinion is that a 28PS 25 NM air cooled two stroke 125 would currently clean up in NZ buckets.

Sure it might clean up but first lets use BMEP calcs to see if a F4 legal 28PS 25NM air cooled 125 two stroke is possible.

267320

SS90 28PS is easy, TeeZee has done more than that, its the 25NM from a 125 thats making only 28ps that might be the problem as that means the RPM is low and the BMEP high. If you can follow the maths you will understand how 25NM may not be possible from a lower powered engine.

Converting metric to imperial:-

28PS = 27.6BHP (1PS = 0.987BHP)

25NM = 18.4Ft/Lbs (1NM = 0.737Ft/Lb)

Finding the RPM that 28PS 25NM relates to from the formula for HP.

HP = (RPM*Torque)/5252

transposing for RPM gives :-

RPM = (HP*5252)/Torque
RPM = (27.6*5252)/18.4
RPM = 144,955.2/18.4
RPM = 7,878

Now to find the BMEP needed for a 125 2-Stroke to make 25PS at 7,878RPM

BMEP = (HP*6500)/(L*RPM)
BMEP = (27.6*6500)/(0.125*7878)
BMEP = 179,400/984.75
BMEP = 182.2 PSI

Converting PSI to Bar. 1PSI = 0.06895Bar

182.2 PSI = 12.6 Bar

That's a higher BMEP than Wobblys water cooled F3 400 or the Honda 500 V Twin GP bike.

SS unless you know more than Wob and Honda I am not sure you could make a 28PS 25NM 125 F4 legal 125 air cooled 2-Stroke let alone finish a race or even start one.

267319

The idea of a high 25NMs of torque from a 125 aircooled making only 28PS is ... Busted

wobbly
30th July 2012, 18:42
What several are failing to recognise is that the big issue is the torque required AT WHAT RPM.
As above - making any sort of useable torque down at 7000 odd rpm in a 125 engine is simply a friggin joke - its absolutely impossible to achieve GP levels of bmep at 1/2 the rpm those engines turned.
Crank the rpm up to over 12,000 and the 28PS becomes easy, but then the torque needed drops commensurately.
My efforts with the 400 F3 engine in context are pretty impressive,working around a pair of cylinders on 102mm centres that came originally from a 250 design
a hundred years ago.
But in reality getting around 100 RWHp from a 400 is nothing great at all, if the design wasnt severely limited by road based cases then 30% more would be easily attainable - again,do the numbers.
The math and the dyno never tell lies.

TZ350
30th July 2012, 18:43
Theres still an issue with a delay coming back onto the throttle but Im sure we can sort this out.

Kel went realy well, it was exciting to watch. Hopefully it will be dry for him at the next meeting and he will have the traction to get some real power to the ground.

Kel reports that when the engine is reved right out and then after shutting off there is a delay coming back on the throttle. But by using the IgniTecs rev limiter he found this delay is not there if the engine is shut down earlier, like just a smiggin after peak power.

The delay coming back on the throttle had us looking at fuelling in the closed to quarter open area. but as it only happens when the engine is reved well past peak power I am starting to think that the problem is the fixed power jet going way over rich and loading up the engine, so that it takes a bit of clearing before coming back on song again.

Time to fit an electronic power jet then we can have the IgniTec shut it off in the over rev area, hopefully that will cure the delay and extend the over rev at the same time.

All said and done, Kel did pretty well I think.

richban
30th July 2012, 18:53
hey buddy I'm drinking from the same well, or getting there:weep:

Me 2. Plenty of us old boys going ok. The skinny kids will have to work for their wins.

speedpro
30th July 2012, 19:36
Hopefully it will be dry for him at the next meeting and he will have the traction to get some real power to the ground.

Traction control??

You know you want it.

bucketracer
30th July 2012, 21:44
Personally, I'm curious about the Manx Norton in your signature Fred...Protar kit is it ?

267323

Here you go ..... Freds Manx.

SS90
30th July 2012, 22:01
So what's your point SS? Fastest bike doesn't get the win? It isn't a drag race & to be fair Kel isn't a young buck or anything. pointy end of field often is inhabited by such bods (some like Young Nat would be less than 1/2 his age & then some). That said, I found he was a damn sight faster than I thought he might be first time in wgtn.

My point is that it seems that for all this effort, the bike in question just seems to be being tuned to a standstill,
Earlier incarnations of this engine where reliable, and, by all accounts enough power to win.
I am curious as to how much power the engine Avalon Biddle used when she did the only winning Teram ESE has had (in the RS chassis) that apparently Chambers built.

People can jump up, Lay eggs, and wave pitch forks about all they like, I feel this is a valid point.

bucketracer
30th July 2012, 22:15
My point is ...... Mostly Sourgrapes ......

wobbly
31st July 2012, 08:42
I remember that it was reported on here that Avalons engine was 24RWHp.
She dicked everyone.
Fast bike,fast pilot,average engine.

But the real point is, that if you put her up against say NoMates RS100 on 28 Hp and she will get dicked every time ( but for sure wont smile as she normally would in that situation ).
Then put Hassan on 32 Hp and NoMates would crash into him to stop that easy win.
Forget a million ft/lbs, even around the goat track - a WELL EXECUTED full house 14,000 rpm engine with 32 RWHp and a 4000 wide powerband when used to its potential, is a forgone conclusion.
Why would this sport be different than EVERY other where a 2T has been well developed - fast and reliable.

The screaming 2T isnt easy to get right, but when enough people finally "get it " that lots of rpm and lots of power to suit the limited gear ratios available can be done,
then easy to tune and ride Diesels, would soon be a long forgotten dim memory.

None of the technology needed for 32RWHp is remotely spectacular or clever.
We had electronic powerjets on the TZ racebikes over 20 years ago,Honda gave in finally in 1998,no one in buckets has one yet????
Its simply a matter of climbing up the exponential learning curve of power and reliability hand in hand,and I reckon TZ is learning both,in public, very gracefully considering the sniping wankers on the sidelines giving forth
no REAL help at all.

ief
31st July 2012, 08:58
and I reckon TZ is learning both,in public, very gracefully considering the sniping wankers on the sidelines giving forth
no REAL help at all.

That's only about 0.2 % wob, 98 % leaches this thread like there's no tomorrow, the other ones you 'know' :2thumbsup

ps: Am I the only one with engmod witch, once in a while, decides to mysteriously change some stuff only to leave you baffled for a while thinking what stupid thing have I done this time only to find out the port timings went from 128 to 140 or whatever? :lol:

Haufen
31st July 2012, 09:29
Kel reports that when the engine is reved right out and then after shutting off there is a delay coming back on the throttle. But by using the IgniTecs rev limiter he found this delay is not there if the engine is shut down earlier, like just a smiggin after peak power.

The delay coming back on the throttle had us looking at fuelling in the closed to quarter open area. but as it only happens when the engine is reved well past peak power I am starting to think that the problem is the fixed power jet going way over rich and loading up the engine, so that it takes a bit of clearing before coming back on song again.


So the problem is just ocurring after rolling with closed throttle? Or does it occur when accelerating through the gears, also?

TZ350
31st July 2012, 09:46
So the problem is just ocurring after rolling with closed throttle? Or does it occur when accelerating through the gears, also?

Good question.

Around Mt Welly Kel can get away with only two gear changes, one down at the end of the sweeper and one up along the front straight.

But whether its also a problem when just rolling off through the infield, I will have to ask.

kel
31st July 2012, 10:33
So the problem is just ocurring after rolling with closed throttle? Or does it occur when accelerating through the gears, also?

No problem changing up through the gears i.e. no problem when the throttle is closed for fraction of a second (Im that quick on the change). The problem is when the throttle is completely closed for a couple seconds after revving out such as when braking, if you then blip the throttle when changing down through the gears its as if there is no spark and then when you hammer it back open nothing happens again as if theres no spark, delay, then it hits and its off again. My uneducated guess is that the crankcase pressure drops so much that the exhaust gases travel into the transfer ducts and theres a delay while things equalise and burnt gases are flushed out, part of the reasoning being that this doesnt happen at lower revs i.e. if I only rev to say 10k I can shut the throttle for a couple of seconds and when opened it picks up immediately.

Haufen
31st July 2012, 10:47
I once experienced something similar. When in idle for too long, the engine would die or almost die as soon as I opened the throttle again, but the jetting at idle was far from being rich.

Found out my inlet manifold went downwards just a bit and the other half upwards just a bit, so at low throttle openings with too weak suction from the engine I had like a little puddle in the inlet manifold. As soon as I opened the throttle, all of that mixture got pulled in at once causing a very rich condition. Your problem sounds like something similar, only that your puddle might be caused by something (blowback?) that only occurs at very high revs.

TZ350
31st July 2012, 10:53
... if I only rev to say 10k I can shut the throttle for a couple of seconds and when opened it picks up immediately.

This suggests to me that the low end carburation is not the problem, and the problem is someplace else like a crankcase full of exhaust gas or loaded up from an over rich power jet. The simplist thing to try next is an electronic PJ.

Anyone with any thoughts on other possibilities... :scratch:

TZ350
31st July 2012, 10:57
Found out my inlet manifold went downwards just a bit and the other half upwards just a bit, so at low throttle openings with too weak suction from the engine I had like a little puddle in the inlet manifold. As soon as I opened the throttle, all of that mixture got pulled in at once causing a very rich condition. Your problem sounds like something similar, only that your puddle might be caused by something (blowback?) that only occurs at very high revs.

Actually come to think of it, like yours did, there is a place in our inlet manifold that a puddle can form and I often see a lot of oil collected there. Also Dave D told us he had a similar problem coming back onto the throttle, for him it was an over rich low end carburetor setting that was loading his motor up.

So a temporary over richness might very well be the problem. Thanks for the idea.

F5 Dave
31st July 2012, 12:39
267323

Here you go ..... Freds Manx.
That really is fantastic, spoke nipples & everything. Though there has been some damage on the rear shock springs, presumably where someone picked it up;).

FastFred
31st July 2012, 12:52
there has been some damage on the rear shock springs, presumably where someone picked it up ;).

Rough Bastards :crazy:

diesel pig
31st July 2012, 13:28
- a WELL EXECUTED full house 14,000 rpm engine with 32 RWHp and a 4000 wide powerband when used to its potential, is a forgone conclusion.
Why would this sport be different than EVERY other where a 2T has been well developed - fast and reliable.


*We had electronic powerjets on the TZ racebikes over 20 years ago,Honda gave in finally in 1998,no one in buckets has one yet????
.

When you say 14,000rpm engine do you mean that is where max power would be made OR do you mean useful power starting at 10,000rpm with max power between 12,000rpm and 13,000rpm and a overev of 1000rpm or so to 14,000rpm? I am sorry if this is obvious to you Wobbly but I am abit slow:( if you hadn't pointed out what I was doing wrong with the keihin mainjet and powerjets I would problely still be trying to sort it!

*My igntech showed on the computer that the electronic powerjet was working when I rev up the bucket the other night so there is a bucket with a electronic powerjet in NZ Wobbley.

2T Institute
31st July 2012, 13:36
No problem changing up through the gears i.e. no problem when the throttle is closed for fraction of a second (Im that quick on the change). The problem is when the throttle is completely closed for a couple seconds after revving out such as when braking, if you then blip the throttle when changing down through the gears its as if there is no spark and then when you hammer it back open nothing happens again as if theres no spark, delay, then it hits and its off again. My uneducated guess is that the crankcase pressure drops so much that the exhaust gases travel into the transfer ducts and theres a delay while things equalise and burnt gases are flushed out, part of the reasoning being that this doesnt happen at lower revs i.e. if I only rev to say 10k I can shut the throttle for a couple of seconds and when opened it picks up immediately.

Don't shut the throttle :lol: Sounds more like a combination of carburation and ignition, most help would be the TPS, do you have a tacho? What rpm is it happening? How high is the idle set at?

For iphone owners check out 'Harry's Lap timer' impressive stuff.

TZ350
31st July 2012, 17:04
267354

This is a 38 electric power jet carb I tried a while ago on the dyno. It has a 24mm venture fitted behind the slide and flowed well on the bench but did not make any more power on the dyno.

I figured the hold up must have been some place else in the engine and it also would flat spot if opened to quickly and in the end after a lot of dyno time I figured a taper bored OKO would be a better all round carb.

But I liked the electric PJ so the next mission is to fit a electronic power jet to the OKO.

F5 Dave
31st July 2012, 17:18
I went for the PWK KX carb to get the soil PJ but have to remote the TPS as the Mik one pictured would have clashed with the shock. I'll fit it in stage 2 but needs the ignitech fitted at same time or just prior.

I have thought about doing a mod Soil onto older carb (ie my 32 Mik VJ21 carb) which might be the go for Kart tracks.

wobbly
31st July 2012, 17:34
Useable power around 9,000 with peak around 13.000 and will rev to 14,000 without falling off the cliff.

TZ350
31st July 2012, 17:52
Useable power around 9,000 with peak around 13.000 and will rev to 14,000 without falling off the cliff.

267356

Not quite 9 to 14 but getting there, an electric PJ and a bit of ignition fiddling might strech it out more.

richban
31st July 2012, 18:07
267356

Not quite 9 to 14 but getting there, an electric PJ and a bit of ignition fiddling might strech it out more.

Bloody hell. OK stop now, its not fare.

Yow Ling
31st July 2012, 18:40
Bloody hell. OK stop now, its not fare.

Just get an old GP125, soon they will be the new FXR

richban
31st July 2012, 19:04
Just get an old GP125, soon they will be the new FXR

Yeah nah can't do it. Plenty of development to do on the FXR. If i went 2 stroke my sponsor would beat me up and cut off all factory support. Be like going from a protype ride down to CRT. Anyway the new engine will smoke that for sure.:bash:

TZ350
31st July 2012, 20:04
Found out my inlet manifold went downwards just a bit and the other half upwards just a bit, so at low throttle openings with too weak suction from the engine I had like a little puddle in the inlet manifold. As soon as I opened the throttle, all of that mixture got pulled in at once causing a very rich condition. Your problem sounds like something similar,

267359

There is a hollow in there that collects a lot of oily mixture that could be evidence of something similar to the puddle you describe.

richban
31st July 2012, 21:16
Stumbled onto this guy today. Amazing bike build. No need to speak the language just start from the beginning and look at the pics.

http://www.2t-special.it/forum/viewtopic.php?f=14&t=498&start=1310

husaberg
31st July 2012, 22:10
The wife mentioned he was getting excited, glad it was entertaining.
We had a bit of a shocking start to race day with the bike and I having a number of disagreements, stalling on the line was all me though :facepalm:. Thankfully my prediction that we'd got all the bad luck out of the way was correct and things went better for the points races. TZ had installed a TPS, altered the ignition curve to 3D map, installed the deto regulator and set a soft and hard rev limiter, all of which seemed to be working well as there were no mechanical issues and the bike was still clearly the quickest thing on track. Theres still an issue with a delay coming back onto the throttle but Im sure we can sort this out. Chassis wise we installed a new shock Friday night which worked out really well, even with my that looks about right approach to setting preload and dampening the handling improved immensely.
First race went well with a good start and managing to get through traffic reasonably quickly, as is often the case luck played a part in finishing 3rd but with that said second was a real chance with just a .9 sec gap separating us.
Second race and the start was a shocker (thought I'd got to terms with getting off the line but more practice required), by the time I got through to 5th the front 3 were long gone so just settled in behind the 4th place rider and played it safe, passing with 2 laps to go to finish 4th. The bike and I probably could have gone as much as 2 seconds a lap quicker but there seemed little point.
I was hoping to have my new bike ready for the next round but TZ's GP125 is getting so good I might try for a ride next round as well. :clap:

No problem changing up through the gears i.e. no problem when the throttle is closed for fraction of a second (Im that quick on the change). The problem is when the throttle is completely closed for a couple seconds after revving out such as when braking, if you then blip the throttle when changing down through the gears its as if there is no spark and then when you hammer it back open nothing happens again as if theres no spark, delay, then it hits and its off again. My uneducated guess is that the crankcase pressure drops so much that the exhaust gases travel into the transfer ducts and theres a delay while things equalise and burnt gases are flushed out, part of the reasoning being that this doesnt happen at lower revs i.e. if I only rev to say 10k I can shut the throttle for a couple of seconds and when opened it picks up immediately.


This suggests to me that the low end carburation is not the problem, and the problem is someplace else like a crankcase full of exhaust gas or loaded up from an over rich power jet. The simplist thing to try next is an electronic PJ.

Anyone with any thoughts on other possibilities... :scratch:

Its a bit left field but as it 's overrun the simple as suggested is overly rich condition, and then it clears
But i see you said about how TZ has just set the rev limiter .
So could this be contributing to the problem as on overrun it will likely be shutting off the spark and not therefor the engine wouldn't be clearing the unburnt fuel? well maybe?

Not applicable to your problem much but i have suffered a far worse condition on a pumper carb equipped MB100 sure it was a rocket in the straight line yet unriddle out of a harpin's.
As the pumper carb pumps fuel regards as long as the engines turning the results were a best a large delay and stutter power then coming in rather abrupt or at worst power Bog then power in with bang and high-side. It can be cured on an old pumper with mods described by Jenning from his work with the Kawasaki disk twin McCollochs. I guess its not a problem with the Karts as the throttle is barely ever off. The fuel injected Cagiva allegedly suffered from the same problem as it kept on pumping fuel on overrun as well from what i have read about it.

Haufen
31st July 2012, 23:44
Actually come to think of it, like yours did, there is a place in our inlet manifold that a puddle can form and I often see a lot of oil collected there. Also Dave D told us he had a similar problem coming back onto the throttle, for him it was an over rich low end carburetor setting that was loading his motor up.

So a temporary over richness might very well be the problem. Thanks for the idea.


267359

There is a hollow in there that collects a lot of oily mixture that could be evidence of something similar to the puddle you describe.


I've got another idea also. I assume you were cornering when off the throttle. So it could be the float (whose level might be a bit lower after reving hard) that falls open when leaning into the corner and thus flooding the engine.

C_Wolf
1st August 2012, 08:38
The bike is for sale

http://www.ebay.de/itm/DKW-SUPERCHARGED-1936-EX-KLUGE-THOMAS-WUENSCHE-OTTO-STEINBACH-FACTORY-WORKSRACER-/160851407103?pt=AU_Motorcycles&hash=item25737db0ff

TZ350
1st August 2012, 09:00
The bike is for sale

http://www.ebay.de/itm/DKW-SUPERCHARGED-1936-EX-KLUGE-THOMAS-WUENSCHE-OTTO-STEINBACH-FACTORY-WORKSRACER-/160851407103?pt=AU_Motorcycles&hash=item25737db0ff

267383

............

F5 Dave
1st August 2012, 09:18
267359

There is a hollow in there that collects a lot of oily mixture that could be evidence of something similar to the puddle you describe.
ya know? I can't see that puddle forming at past say 5000 rpm.

Drew
1st August 2012, 09:23
Stumbled onto this guy today. Amazing bike build. No need to speak the language just start from the beginning and look at the pics.

http://www.2t-special.it/forum/viewtopic.php?f=14&t=498&start=1310

At page 17 when he starts making his own radial calliper mounts, I began thinking, "this dude doesn't fuck about"!

Did you notice the other bikes in his shed? TZ750 gave me wood.

wobbly
1st August 2012, 10:03
I agree with Dave re the puddle, its gota be an issue with off idle tuning ( those 4 stroke holes in the tube ) ,or the float height.

bucketracer
1st August 2012, 10:56
ya know? I can't see that puddle forming at past say 5000 rpm.

5000 and WOT, agreed but 5000 and closed throttle? maybe the pilot jet is to big and excess fuel is getting sucked in on a closed throttle.


I agree with Dave re the puddle, its gota be an issue with off idle tuning ( those 4 stroke holes in the tube ) ,or the float height.

The problem is, how does TeeZee modify an emulsion type Keihin or OKO to take a GP125 primary type pilot jet?

Looks like a tricky machining job.

F5 Dave
1st August 2012, 12:14
So the pump is turning the same speed, but the orifice is restricted. Opening near the point of the port depression. I'm still happy with that.

TZ350
1st August 2012, 19:56
Am I the only one with engmod witch, once in a while, decides to mysteriously change some stuff only to leave you baffled for a while thinking what stupid thing have I done this time only to find out the port timings went from 128 to 140 or whatever? :lol:

I have not seen that myself but if its happening to you, it might mean, I am not entering the data in the same sequence as you do.

If you can get a clear picture of what data capture screens and data entry sequence the problem follows then Neels would be very interested.

EngMod2T is a very well supported package data entry/retention issues seem to get sorted quickly.

TZ350
1st August 2012, 21:32
267422

Winner (4-Stroke) of the second A grade points race, number 88 (2-Stroke) won the first. Both races were run in wet and very slippery track conditions.

I think I am missing the third place finisher in race 2 but these are the other top placers in the two A grade points races. Kel is riding No 14, and it was an even mix of 4 and 2-Stroke bikes at the sharp end.

From Damion Tomans photos http://www.flickr.com/photos/dty1/sets/72157630799237432/

husaberg
1st August 2012, 23:34
5000 and WOT, agreed but 5000 and closed throttle? maybe the pilot jet is to big and excess fuel is getting sucked in on a closed throttle.



The problem is, how does TeeZee modify an emulsion type Keihin or OKO to take a GP125 primary type pilot jet?

Looks like a tricky machining job.


chuck some tape around the holes and try it out. prick the tape in a few areas to suit the area you wish to change.
Yes i know Wob:pinch: if it helps fill them up permanent. What do you have to lose.
i thought i had posted the Jennings bit looks like i hadn't. Worth maybe re read,

TZ350
2nd August 2012, 02:16
chuck some tape around the holes and try it out. prick the tape in a few areas to suit the area you wish to change.
Yes i know Wob:pinch: if it helps fill them up permanent. What do you have to lose.
i thought i had posted the Jennings bit looks like i hadn't. Worth maybe re read,

Thanks for the tape idea and the Jennings bit on carbs, I have read through it carfully.

ief
2nd August 2012, 05:57
I have not seen that myself but if its happening to you, it might mean, I am not entering the data in the same sequence as you do.

If you can get a clear picture of what data capture screens and data entry sequence the problem follows then Neels would be very interested.

EngMod2T is a very well supported package data entry/retention issues seem to get sorted quickly.

Could be sequense, could be OS related (win7 64), dunno, have informed Neels and more to come, not so much performance wise as ergonomics wise, long time since i felt a mouse finger emerging (used to like quake 2 and 3 a lot :) )... have to say, I did go over the edge on using it perhaps, haha. It's to great and verrrry addictive.

TZ350
2nd August 2012, 07:53
... have to say, I did go over the edge on using it perhaps, haha. It's to great and verrrry addictive.

Yes me 2 ... I have found it very usefull, and learnt a lot about the direction to take when tuning a 2-Stroke from playing with the engine simulation program.

kel
2nd August 2012, 08:29
I think I am missing the third place finisher in race 2

No, you have it covered. Same top 5 in both races, just a different finishing order. Nathaniel was 3rd in race 2.

F5 Dave
2nd August 2012, 10:16
Oop, Disqualify DaveD, - he has his visor part up & by Kartsport national rules. . . .;)

F5 Dave
2nd August 2012, 12:26
chuck some tape around the holes and try it out. prick the tape in a few areas to suit the area you wish to change.
Yes i know Wob:pinch: if it helps fill them up permanent. What do you have to lose.
i thought i had posted the Jennings bit looks like i hadn't. Worth maybe re read,

Ha the very first post I made on this thread coming on 4 years ago is contained in this article, though I have never read it before[edit maybe it was in his early book, too long ago. . .]. Pretty basic stuff though & not Brain Science:wacko:.

excerpt:
". I have found that this matter can be settled very simply by lowering the needle to its last notch, which maximizes the flow restriction at the needle jet, and then removing the main jet entirely from the carburetor. The engine should then run, if none-too-well, on part-throttle, but flood as the throttle is opened fully. Should the engine be willing to run on full throttle, you may be sure that a larger needle jet is required"

twotempi
2nd August 2012, 12:49
F5 Daves idea is good, but why not solder up the holes and remove a variable from the jetting equation as per Wobblys advice.

TZ350
2nd August 2012, 14:23
Stolen from another thread but its so good I had to do it.


This is probably old hat to many but not for me so.

I had a problem with my bikes exhaust which led me to remove it from the cylinder, whilst drilling the stud thread out I spotted that my piston was badly scored.

267462 267463

I was told it was a lubrication problem which is fairly plain to see but what worried me is why or how could it have a lube problem when i had 20:1 Motul 800 in the fuel?

After a bit of research i found this article and it seems to make sense


piston Seizure Vs Piston Scoring - Piston “seizure” and piston “scoring” are two different stages of the same problem. When the oil film on a cylinder is momentarily burned or brushed away, the bare metal surfaces of the piston and the cylinder wall will actually touch. When this happens, there is a sort of scraping that takes place between them. If the oil film is quickly resumed, the marks from this scraping will often remain on the piston and (or) the cylinder wall. A momentary scraping or "scoring" seldom causes any permanent or performance robbing damage. In a momentary scoring event like this, no significant damage takes place because the oil film is resumed before the piston and cylinder have a chance to start exchanging material onto one another.

Scoring is commonly seen on the piston face directly below the piston ring end gaps. The blast of combustion can get between the large end gap of a worn out ring and burn the oil off the piston and cylinder in that area...Hence the surface scoring. In most cases, score marks can simply be sanded off of the piston and cylinder. However when ever you see scoring, it's a good idea to find the source so that it doesn't develop into a full blown seizure.

Piston seizure is a case of scoring where the oil film does not immediately return. After a few moments of constant scoring, the piston and cylinder will scratch each other hard enough to remove material from each other. This floating material grinds itself into the piston and the cylinder as it continues to grow in size. As this snowballing material grows, it will drive the opposite side of the piston against the cylinder wall with a pressure so terrific that scoring on the other side of the piston begins to take place. While all this is going on, your engine is still running wonderfully at full throttle. However if there is a momentary lifting of the throttle, the force of this scoring can cause the piston to “seize” in the bore. In a “light seizure” event like this, the rings often escape any damage, and the engine will easily re-fire as soon as the engine cools down slightly.

The death blow of a “power-on” seizure comes when the mass of material between the piston and the cylinder wall finds it's way to the piston rings. This nearly molten mixture of aluminum and iron can lock the ring in it's groove. This ring locking, not the piston surface scoring, is what actually causes your engine to quit when you experience a “throttle-on” seizure. When the piston ring becomes locked back in it's groove, it's incapable of providing compression sealing against the cylinder wall. This instant loss of compression, while the engine is at speed, causes a dramatic loss of power. That power loss, along with the added drag of the badly scoring piston, makes the engine quit or lock up in a nanosecond. In fact this entire seizure process, from the first scoring scratch to the piston locked solid, takes less than a second at full rpm. In such a failure, a single cylinder engine will seldom restart.

I have decided to go with Grump and bought some Klotz R50 to see if this behaves.


About Two Stroke Oils and Premixes

One of the best “general” information articles about current two stroke oils is at the link below. While this article was originally authored with a specific view towards two-stroke personal watercraft oils, we consider the info to be very current and well written … it is “highly recommended reading” for any vintage two-stroke owner.

http://www.sea-doo.net/techarticles/oil/oil.htm
For those not wanting to muddle through the entire text, we consider the two excerpts below to be far and away the most important with respect to vintage two strokes.

Castor Based Oils

Mr. Robert Verret wrote : I mentioned a third category of base oils earlier, vegetable or Castor (not Castrol, that’s a manufacturer) bean oil. This oil is derived from pressing oil out of castor beans and distilling it. ‘Bean Oil’ as it is often referred to, has some very unique characteristics; some very good, others not so good. The good is that it is an excellent lubricant. It seeks out hot spots in the engine and clings to those hot surfaces much better than petroleum type oils. The bad is that it does not mix with gasoline easily and it burns ‘dirty’ (excessive carbon/varnish deposits). In the early 70s, before power valves were used, castor bean oil was very popular in racing 2-strokes. Now that power valves are common and we have improved petroleum and synthetic oils, castor bean oil is seldom used anymore. Several companies still market it in the form of a degummed castor oil for racing applications only. It should be avoided for recreational use unless you enjoy tearing your engine down for a top end cleanup fairly often. Several manufacturers formulate their oil with castor bean oil as an additive (antiwear agent) rather than base oil. They blend it with their petroleum and synthetic base oils. When castor bean oil burns, it has an unmistakable ‘sweet’ smell. (end of excerpt)

Like the author of the above text (Mr. Robert Verret) we too have been involved with two-strokes for 30+ years, and we have also spoken with many well educated and well informed folks in the lubrication business. All the experienced and reputable folks we have ever spoken to agreed on the basic qualities of Castor oils. That is, castor bean based oils are not particularly clean burning, do not mix homogonously with virtually any fuel, and are very expensive to manufacture …. But they offer a film strength and lubrication quality that is not matched by any other oil…. Period.

Like Mr. Verret, we also understand that many folks get very emotional about the particular oil brand they use. For us, choosing a 2-stroke oil is all about the science and results … emotion doesn’t matter. For air cooled two-strokes being run at high rpms and high loads, there is no better choice than a castor based oil. During our stint of running the DG Performance race team from 1975-1979, we ran ONLY 20:1 Castrol “R” in every Team DG machine raced out of our shop. The sheer film strength of the bean oil allowed us to run tighter than normal piston clearances, and thereby netting better performance and long term piston life (as a result of less piston "rattling” in the bore).

Castrol “R” was certainly a bit dirty, but it was the best stuff of the day. Of the castor bean oils currently available, we prefer Maxima 927. While it is not “perfectly clean” we have found it to run cleaner than any other bean oil we have used (and we have used plenty). In addition, the film strength of “927” is every bit as good as the Castrol “R” of the 1970’s, with a lot less mess.

In 2010, we built and road raced two 1970 Kawasaki 350 Bighorn Production Class enduros in the western AHRMA road race events. We ran these machines on a 20:1 mix of “927” and 105 octane race gas. While stock Bighorns redline at 6000rpm, ours turned 8500rpm and ran a bit over 100mph. At the Willow Springs track in Southern California, we lapped at 1:52 (an average speed of 80mph). At Willow, our Bighorns were constantly at peak rpm in 4th & 5th gear for every moment of each 15 minute practice session and race. Our race weekend entailed 4 outings for each of 2 days … a total of 120 operating minutes at peak rpm in high gear (per machine) … with not one mechanical issue at all. We respectfully submit that there isn’t any way to subject a vintage two stroke to any more intense abuse than this, and we feel that the lubrication abilities of the Maxima “927” were a fundamental contributor to our weekends of trouble free racing.

After our race season was done, we fitted our Bighorns with street-lighting, and ran the exact same machines on the 100 mile Hansen Dam classic motorcycle ride north of Los Angeles. At this event, we ran the Bighorns on a 40:1 mix of “927” and 91 octane pump gas (most of the ride was done at 3000-5000rpm). The bikes never put out any visible smoke (except at long stop lights) and never came close to fouling a spark plug.

Despite all this very positive experience with a Castor based oil, we openly acknowledge that Castor oils “ARE NOT” necessarily the best choice for all vintage two-stroke applications. Robert Verret’s excerpt below explains that.

API – TC Oils

Mr. Robert Verret wrote: The API-TC standard was developed for Air-cooled, high rpm, high output 2-stroke engines operating under severe load conditions. Although this standard is no longer reviewed and updated since 1993 b the API, it still is in effect today. This standard most accurately addresses the condition Rotax and 2-stroke racing motorcycles and snowmobiles operate under. Almost all these oils are formulated with synthetic or synthetic blend base oils and all use a low ash type detergent. If you walk into a store that handles a variety of 2-stroke oils, it is relatively easy to find TCW3 certified oil. The manufacturer proudly displays that certification on each container. API-TC certified oils, on the other hand, are very difficult to find. There are two main reasons for this. First, many small API-TC oil manufacturers can’t or won’t spend the money (about $75,000) for the testing and certification process. Second, most engines requiring API-TC oils are for racing applications (Motocrossers and Crosscountry motorcycles) and don’t offer warranties with their engines anyway. The owner/operators of these machines know what oils work and don’t work. They do not need the API-TC certification on the bottle to help them decide what oil to use. (end of excerpt)

The truth is that API-TC oils are also top level lubricants that have excellent film strength, and are much easier to “live with” than Castor oils. Besides being somewhat cleaner than bean oils, the API-TC oils will also mix “homogonously” with gasoline, and have little or no tendency to separate. For vintage machines that spend very little time held at peak rpm (in the higher gears), API-TC oils are the better choice. Among these oils, our favorites are Yamalube R, Kawasaki K2, and Maxima Super M.

About the Engines Lubrication “Needs” - A two-stroke engine actually has two very different kinds of lubrication needs. The lower end crank and rod bearings prefer a slow drip of a very heavy viscosity oil, while the top end parts wear best with a deluge of a very lightweight oil. Since these are two very opposite lubrication needs, you have to choose whom you want to please. For most two-stroke owners, it’s a no brainer. You can buy 100 cranks and crank bearings that will all offer the same performance, but every owner wants to do whatever can be done to preserve a good running piston / cylinder set. Given all this, heavier premixes of lighter viscosity oils are more desirable to most owners.

About Premix Ratios and “Oil Migration Time” - Oil Premix ratios are another subject that some folks tend to get emotional about … and like oil brand choice, our choices are about science and results…not emotion.

The objective of the premix ratio is to maintain a certain level of “oil-presence” in the engine interior during it’s average “operating-use” cycle. But how does one measure or assess the “oil-presence” … The most effective way has been with a radioactive additive. We explain below.

Trying to keep it simple…here is how it works. A test lab sets up an engine on a dyno stand, and begins feeding the engine a premix of an oil that has a specific level of mixed-in radioactive additive. As the engine is run, a Geiger counter at the exhaust exit measures the amount of radioactive material being eliminated. In this way, it is possible to factor the amount of radioactive material being put into the engine, verses the amount being sent out the exhaust. The net result is the amount of “oil-presence” inside the engine. In short, these tests showed that the oil-presence in the engine is a function of the operating rpm. That is, the “oil-presence" inside a two stroke drops significantly as the operating rpms increase. What this means is that an engine being run at 4000 rpm can maintain a very healthy and happy level of oil-presence with a 40:1 premix. However that exact same engine being run at 8000rpm needs to have a 20:1 premix to maintain the exact same level of oil-presence inside. This is why our 350 Bighorn road racers ran happily on the public roads on 40:1, but needed 20:1 for our sustained high rpm racing use. It bears noting that in both the 40:1 street and 20:1 racing situations, our Bighorns made no visible exhaust smoke at all, except when they were held at idle speeds for a long time.

A further example of this is shown in the carbureted two-stroke 951cc SeaDoo watercrafts of the early 2000s. In an effort to reduce the smoking during initial take-offs, SeaDoo engineers setup the oil injection systems to deliver no oil at all at idle speeds (and we mean zero oil). The logic was that at idle speeds there is virtually no oil migration at all. The high oil presence from the previous high speed runs was enough to allow the engine to run happily at idle for 10+ minutes with no oil at all being added…. And it worked great.

The lesson here is that your premix ratio should be a function of the average operating rpm that your vintage two stroke runs at. If you are at peak rpm all the time, 20:1 is a good idea. However for recreational level riders that don’t “scream” their engines constantly, leaner premixes will yield excellent long term wear.

About Oil “Film Strength” and Piston Seizures - Many people believe that piston seizures occur when engine heat causes the piston to expand larger than the size of the cylinder bore.... but surprisingly this is not true.

If you could freeze your engine "in motion" in the middle of a long full throttle pass, and disassemble it for micrometer measurement, you would find the piston to measure at a .0005" to .001" press fit into the bore. That's right, a slight press fit! The reason that it doesn't seize is because the premix oil has such a terrific film strength that it acts as an irremovable buffer between the piston and the cylinder. That is, the bare metal surface of the piston never actually touches the bare metal surface of the cylinder because the oil stays between them. Many mechanics have experienced this phenomenon while cleaning a freshly bored cylinder in a solvent tank. Completely dry without any cleaning solvent, the piston moves through the bore with difficulty. However while rinsing a cylinder bore with cleaning solvent, the piston glides all the way through with no resistance at all. This is because the solvent acts as a film between the piston and cylinder.

A piston seizure can only occur when something burns or scrapes away the oil film that exists between the piston and the cylinder wall. Understanding this, it's not hard to see why oils with exceptionally high film strengths are very desirable, and why maintaining a proper oil-presence is also desirable. Good quality oils can provide a film that stands up to the most intense heat and the pressure loads of a modern high output engine. Here again, we mention that “absolutely no oil” has a stronger film strength than castor based oils.

About 100:1 Premix Oils - Since the 70’s there have been repeated advertising claims made by various oil brands claiming that their oils can offer suitable lubrication for competition two-stokes on a 100:1 or 80:1 premix. In many cases, these claims are “supported” by testimonials from various users. Despite the oil makers claims, and the sincerity of the testimonials … it’s not so. Running a 100:1 premix would be much like running only 2 quarts of oil in your truck, expecting that the quality of the oil can make up for the quantity …. It cannot….. no matter how good the film strength is “claimed” to be. The truth is, many two-stroke engines can “operate” on a 100:1 pre-mix so long as rpms are kept very low (as might be the case on a novice class open bike). But the first time that 100:1 engine makes an extended higher rpm run … it will lose the mathematics of oil migration, and score a piston. There is just no way around the math.

About Oil Injection - A majority of vintage street and recreational based 2strokes were manufactured with an oil injection system that eliminated the need for pre-mixing fuel. Oils made for oil injection use have a considerably thinner viscosity than oils intended for premix. It is unwise to use a premix type oil in an injector because a premix type oil can have difficulty passing through the small orifices in many oil-injection systems. On the same tack, it is a very bad idea to use an "oil-injection" oil in a premix application because the reduced viscosity will not offer the lubrication needed in a pre-mix situation

Within oil-injection systems, there are two types. The first is a simple "fixed feed" oil injection pump that is driven entirely by the varying rpms of the engine. At low rpms, the pump rate is slow, and at higher rpms, the pump delivers more oil simply because it is being spun faster. Unfortunately, pumps like this generally deliver much more oil than is needed at idling speeds. This is a particular problem for street bikes that often sit at stop lights in street traffic.

To relieve the excessive low speed over oiling of a fixed feed pump, manufacturers fitted, "cable operated" oil injection pumps whose oil feed was varied by a cable-driven valve connected to the throttle. The cable operated pumps have a much broader range of oil output ability. The average cable operated pump will feed an 80:1 - 100:1 oil ratio at idle speeds, and a 32:1 -50:1 ratio (depending on that particular engine's peak rpm) at full throttle. At the same time, many of these cable-driven oil injection systems had "divided feed" lines that delivered some of the oil to the inlet port near the carburetor, and other lines that fed oil directly to lower end bearings. With this, split feed system, less total oil could be injected because less oil was being lost via atomization with the fuel/air mixture.

In truth, many of the cable driven injection systems did a great job of delivering adequate lubrication, along with very minimal smoking. But sadly, these injectors had several significant down sides. Those are (in order of importance):

1) No warning system if the pump failed or stopped delivering oil
2) No warning system if the cable connection malfunctions or becomes disconnected
3) Air Leak risk at fitting bolts that become loose
4) Reduced oil delivery caused by a leaking fitting
5) Oil delivery blockage at one of the many small orifices

For these reasons (and more) many owners opted to remove their problematic oil injection system and simply pre-mix the fuel. This worked fine for Enduro/off-road applications where long idling and low speed smoking are not issues. However for street machinery, the problem of low speed smoking was still a problem that had to be dealt with.

About Oil injection Oils and Smoking - It's important to understand that there is no such thing as a "straight petroleum" oil, nor a "synthetic" oil.... those are just industry "buzz" words. With the exception of castor bean oils, all 2stroke oils are a mixture of the chemical components needed to do the respective job at hand .... and it has been that way for many decades. In the 70's a very common component of most 2stroke oils was "bright stock". Bright stock was very inexpensive, and offered decent lubrication qualities, but it contributed greatly to excessive smoking, no matter how lean the oil ratios got.

Nowadays, most "quality" two stroke oils have long since replaced bright-stock with Poly-Butane. Poly-butane is roughly triple the cost of bright-stock, but it smokes much less, and still offers great lubrication qualities. All that said, there are still several 2stroke oil makers that use bright-stock instead of Poly-butane ... simply to cut costs. The bummer is that there is no labeling that allows you to know which is being used, and very few oil makers that will give you an honest answer if you ask them. This same scenario applies for several other primary components of current 2stroke oils. But There's more.....

99% of all two-stroke oils containers say "smokeless" or "low smoke". The truth is that there is no engineering nor industry standards for varying levels of "smoke-free-ness". The oil makers can print anything they want on the bottles without ever having to meet or comply with any industry standards or limits.
As a result of all this, we use exclusively Maxima Oils products, because the folks at Maxima are very open and up-front about what their oils are made of. In the genre of Maxima 2cycle oils, their 927 castor oil is by far the best for high-temperature competition engines. However if you try to use this castor oil in a street (premix) application, you can experience excessive smoking in engines that do not run particularly hot. The most smoke-free oil that Maxima makes is their "Super M" which comes in a premix and oil-injection viscosity. Super M contains no bright-stock, and instead uses the much more smoke free poly-butane. Maxima also offers a purpose made "scooter" oil that is slightly more smoke free than Super M, however this scooter oils doesn't offer the lubrication needed for a high temperature air-cooled vintage engine.

TZ350
2nd August 2012, 14:45
Ha the very first post I made on this thread coming on 4 years ago is contained in this article, though I have never read it before[edit maybe it was in his early book, too long ago. . .]. Pretty basic stuff though & not Brain Science:wacko:.

excerpt:
". I have found that this matter can be settled very simply by lowering the needle to its last notch, which maximizes the flow restriction at the needle jet, and then removing the main jet entirely from the carburetor. The engine should then run, if none-too-well, on part-throttle, but flood as the throttle is opened fully. Should the engine be willing to run on full throttle, you may be sure that a larger needle jet is required"

And after reading it, it became one of the first things we do when trying to setup a new carb. Thanks.

The problem we have now, although seemingly a small irritation, when sorted will make the bike much more ridable. I think Kel did very well in the wet and this hesitation coming back on the throttel must have been a real handycap.

husaberg
2nd August 2012, 16:25
Stolen from another thread but its so good I had to do it.

http://klemmvintage.com/oils.htm


And after reading it, it became one of the first things we do when trying to setup a new carb. Thanks.

The problem we have now, although seemingly a small irritation, when sorted will make the bike much more ridable. I think Kel did very well in the wet and this hesitation coming back on the throttel must have been a real handycap.


Ha the very first post I made on this thread coming on 4 years ago is contained in this article, though I have never read it before[edit maybe it was in his early book, too long ago. . .]. Pretty basic stuff though & not Brain Science:wacko:.

excerpt:
". I have found that this matter can be settled very simply by lowering the needle to its last notch, which maximizes the flow restriction at the needle jet, and then removing the main jet entirely from the carburetor. The engine should then run, if none-too-well, on part-throttle, but flood as the throttle is opened fully. Should the engine be willing to run on full throttle, you may be sure that a larger needle jet is required"
Its also on the first page of this thread or close to it i think. It is also repeated in Bell plus the Mikuni manual as well. Sure some of it is basic but some of it is stuff i have not seen else where in 2 stroke stuff anyway "like for the stuff on the holes in the emulsion tube' :whistle:


And after reading it, it became one of the first things we do when trying to setup a new carb. Thanks.

The problem we have now, although seemingly a small irritation, when sorted will make the bike much more ridable. I think Kel did very well in the wet and this hesitation coming back on the throttel must have been a real handycap.


.

This is Thomas a Vietnamese race mechanic, you know that place where they have all those hot 50's and 125's are big bikes.

Thomas, ESE's Race Team's Tuner is fettling number 9. adjusting the port timing for Taupo.

Its hard to see but he has taped a degree wheel to the magneto flywheel so he can mark out the exhaust port height he wants.

None of this raise the port 3.5mm for a gazillion HP nonsense. He knows what timing he needs and sets the crank position there before marking the port and then doing the hells death port job that we all dream of.

You should see him setting up a carb. Talk about pain staking, he starts with a main jet so big the bike floods at about half throttle (apparently this proves the oriface of the needle/needle jet combo is big enough) and then he slowly step by step works back until it runs clean.

Most people start at the bottom with a carb and work up, He starts at the top and works backwards.

Never seen him blow one up. But then he is intelligent with the throttle and does not ring its neck when the engine is in distress.

Boy o Boy am I Looking forward to Taupo.

.



F5 Daves idea is good, but why not solder up the holes and remove a variable from the jetting equation as per Wobblys advice.
With "Daves" Clever Idea :whistle:for the tape I guess was, so you could prick additional holes which is easier than removing solder once its right if it works fill them up permanent. or as wob said try to get a more normal one if OKO do them. Or if there is a Keihin one that fits?

F5 Dave
2nd August 2012, 17:26
erm I never said anything about tape. no matter, will be interesting to see what fixes the issue Kel complained of, I was not offering any fix for it, just responding to Husi's posted article, as it rang a Bell (sic).

richban
2nd August 2012, 17:33
erm I never said anything about tape. no matter, will be interesting to see what fixes the issue Kel complained of, I was not offering any fix for it, just responding to Husi's posted article, as it rang a Bell (sic).

I think you might find that some of the problem is that he is riding a 30hp 2 stroke on a very small kart track with some very slow corners. Sorry didn't read the pages. What rpm was it happening? Also riding in the wet on a very slippery track. I would think it might not be as much of a problem when its dry.

Drew
2nd August 2012, 18:08
The problem we have now...the wet

Now, I'm no where near up with the play on what you guys do to these motors, but could you possibly not be over thinking it?

TZ350
2nd August 2012, 18:48
.... could you possibly not be over thinking it?

Always possible but I dont think so as its a definit problem thats hurting our chances and is not as simple as finding the right main jet or needle clip position, its something more subtle, but I am sure your right it will be something simple.

The problem happens when shutting of from 13500 rpm but not 11500.

If we can use 9,500 to 13,500rpm then we can run corner to corner without changing gears, thats a big advantage but if there is a big hesitation getting back on the gas ..... well people get away or past you, and you cant go diving up the inside if the engine then just stops.

With the Beasts power spread it can run around Mt Welly on two gear changes and thats a big advantage but the engine not picking up again after each straight is a handycap thats worth looking into.

richban
2nd August 2012, 19:01
Always possible but I dont think so as its a definit problem thats hurting our chances and is not as simple as finding the right main jet or needle clip position, its something more subtle.

The problem happens when shutting of from 13500 rpm but not 11500.

If we can use 9,500 to 13,500rpm then we can run corner to corner without changing gears, thats a big advantage but if the is a big hesitation getting back on the gas ..... well people get away or past, you cant go diving up the inside if the engine then stops.

Fuel starvation? Maybe try a runwith out the fuel filter if you are still running an external one. Do you have one in the tank as well. Can you replicate it on the dyno? Vibration? Cavitation? Does the tank have good rubber mounting. You could chuck some of that sponge stuff in the tank and see if that helps? Longer fuel line.

TZ350
2nd August 2012, 19:09
Can you replicate it on the dyno?

Thanks for the ideas and not so marked but yes, it does show up on the dyno.

richban
2nd August 2012, 19:29
Thanks for the ideas and not so marked but yes, it does show up on the dyno.

I know its unlikely but maybe there is some sort of vibration thing happening at that rpm. Can't imagine you would be riding at that rpm for more than a second on that track. ignore me I have been drinking. But then Kel said it was really bad at Taupo. Ok of to the shed to sort my own problems.

TZ350
2nd August 2012, 21:39
<iframe src="http://www.youtube.com/embed/UNVqcFvoRq4" allowfullscreen="" frameborder="0" height="315" width="560"></iframe>

Worth a look to see just how big these English race meetings can be, takes a while to get out on the track but the sound of a 2-Stroke in full flight is just ..... well worth the wait. Engine pulls from 6K and runs to 12.

Frits Overmars
2nd August 2012, 21:40
....I have found that this matter can be settled very simply by lowering the needle to its last notch, which maximizes the flow restriction at the needle jet, and then removing the main jet entirely from the carburetor. The engine should then run, if none-too-well, on part-throttle, but flood as the throttle is opened fully. Should the engine be willing to run on full throttle, you may be sure that a larger needle jet is required"You just re-invented the Lectron carb :D.

husaberg
2nd August 2012, 23:16
I wonder if anyone Picked (Sic) up it says in the Jennings attachment
3 times past the mainjet.

ps it looks like the Pwk 28 has removable jets that may suit you needs

=bucketracer;1130166597]
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="" width="420" frameborder="0" height="315"></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

wobbly
3rd August 2012, 08:44
Had a thought that the issue might be carb orientation, when its tipped over the float level may be changing due to the lever arm
facing across the bike instead of front to rear as its designed to.
The Dellortos usually have the floats on rods.
But I did use a pair of TMX carbs on a Rotax twin in a kart that did exactly the same thing, even with the float rods.
It would not blip to change gears, and would die after the overun into corners.
I set it up to idle,and played with the air screw, eventually found that the idle jet and slide were a big mismatch.
The idle jet was way big and the slide was way lean, so the rich idle was masked by horrible lean on the transition onto the needle4 circuit..
Changed them a couple of sizes each way, and for the first time I could snap the throttle off idle, and it would spin up faster than my hand and hit the limiter.
Suddenly it would blip on the down change correctly, and spun up the tyres off slow corners.
So my guess is to ditch the emulsion tube holes and get the snap response correct off idle.

Re Frits comment about reinventing the Lectron - its been done already..
I have been working with APT in USA and that is exactly what they have done, developing small carbs for generators etc to meet CARB regulations.
The first Billet big set was used at Pikes Peak on a 500 version of my 400, same pipes and ports etc, was easily the fastest,with perfect jetting over a 4000 ft elevation rise.
I have the first pair of die cast 40mm on the way now to test on the next F3 bike.

TZ350
3rd August 2012, 10:45
Had a thought that the issue might be carb orientation, when its tipped over the float level may be changing due to the lever arm facing across the bike instead of front to rear as its designed to.

It happens on the dyno to, same symptoms but depends on how far it is revved out.


It would not blip to change gears, and would die after the overun into corners. I set it up to idle,and played with the air screw, eventually found that the idle jet and slide were a big mismatch.

The idle jet was way big and the slide was way lean, so the rich idle was masked by horrible lean on the transition onto the needle4 circuit..

Changed them a couple of sizes each way, and for the first time I could snap the throttle off idle, and it would spin up faster than my hand and hit the limiter.

Suddenly it would blip on the down change correctly, and spun up the tyres off slow corners.
So my guess is to ditch the emulsion tube holes and get the snap response correct off idle.

Yes the pilot jet is big #50, air screw 1/2 turn out, slide a number #3, needle diameter rich.

Also I have shortened the needle jet so it doesn’t protrude into the throttle bore so much and cut the back away like a regular primary jet thinking that would richen up the transition.

The air correction orifice was to small and had to be drilled out, so it could be the orifices in the pilot jet circuit are to small too and masking the pilot jet.

Anyway its handy it does it on the dyno, I will get some spare bits and bobs and have a play.

TZ350
3rd August 2012, 10:46
re Frits comment about reinventing the Lectron - its been done already.. I have been working with APT in USA and that is exactly what they have done, developing small carbs for generators etc to meet CARB regulations. The first Billet big set was used at Pikes Peak on a 500 version of my 400, same pipes and ports etc, was easily the fastest,with perfect jetting over a 4000 ft elevation rise.

I have the first pair of die cast 40mm on the way now to test on the next F3 bike.

Thats very clever, great to see new stuff ...

dmcca
3rd August 2012, 22:28
Sorry to be the bearer of bad news but it turns out that four strokes are actually good for something after all...
84Sm9w65dmo

TZ350
3rd August 2012, 23:12
Now that is clever .... thats real bloke stuff ....

husaberg
3rd August 2012, 23:58
Sorry to be the bearer of bad news but it turns out that four strokes are actually good for something after all...
[/YOUTUBE]


Gee "At a cost of nothing from the scrap yard" i wonder how much the lathe cost him then?


266969

OKO Needle Jet .....


OK........ As i said earlier the PWK28 has a removable needle jet and holder.
It also (err maybe i should'nt mention it hasa dedicated foul stroke version.)

If you look at the pics below you will see why i think the OKO carb TZ uses, is based on the PWK 28.

Why, because it is the only 2 stroke std Keihin that seems to have this feature removable needle jet and holder.(Not counting the FCR and CR and PE)

Can you see where i am leading with this...............?
Some info from here http://www.splatshop.co.uk/sherco-lower-sprey-jet-small-keihin-2t.html

some from here http://www.motorcyclecarbs.com/Keihin_PWK28_Parts_Cart__C1281.cfm

MMM... the extra bits on the dedicated foul stroke .....Wallace?

Grumph
4th August 2012, 06:26
It happens on the dyno to, same symptoms but depends on how far it is revved out.



Yes the pilot jet is big #50, air screw 1/2 turn out, slide a number #3, needle diameter rich.



I reckon Wob's called it on this one...that is a VERY lean slide IMO. Every 2 stroke I've ever tuned has at some point needed the slides machined to reduce the cutaway hence go richer at that point.
With this done the ide jet comes back to something reasonable.
As an aside I remember Dick Hurdeman complaining to me that the idle jets he was using in the BMS Ducai on nitro were so big that raw fuel was running into the motor on braking.

speedpro
4th August 2012, 07:45
I've devconned the bottom of a slide with good results. Reduced the cutaway by probably 50% and it made the transition from off - 1/4 throttle work

TZ350
4th August 2012, 08:28
OK........ As i said earlier the PWK28 has a removable needle jet and holder.It also (err maybe i should'nt mention it hasa dedicated foul stroke version.)

If you look at the pics below you will see why i think the OKO carb TZ uses, is based on the PWK 28.

Why, because it is the only 2 stroke std Keihin that seems to have this feature removable needle jet and holder.(Not counting the FCR and CR and PE)


Definatly based on the PWK28 but is it 4 or 2 stroke? is it the 4-stroke version, how do you tell.


I reckon Wob's called it on this one...that is a VERY lean slide IMO. Every 2 stroke I've ever tuned has at some point needed the slides machined to reduce the cutaway hence go richer at that point.

Agreed, also I think I may have cut the protruding part of the needle jet away to much and left to much area exposed to the air stream at idle. I will fit a new one and modify some slides.


I've devconned the bottom of a slide with good results. Reduced the cutaway by probably 50% and it made the transition from off - 1/4 throttle work

Good idea Thanks ........

Will get a chance to look at this when I get back to work next week (been away for a few days). Kel has offered to help and Thomas is putting an electronic det sensor stethoscope thing together so hopefully we can setup the IgniTechs detsensor properly and develop the ignition curve some more and sort this hesitation.

With any luck it will be sorted for Kel to ride at the next meeting.

husaberg
4th August 2012, 13:48
Definatly based on the PWK28 but is it 4 or 2 stroke? is it the 4-stroke version, how do you tell.

The foul stroke version i posted were for a Scerco trials bike
the Normal Keihin PWK28 sold were for a two stroke (Cr85 and so on)
My thoughts are your OKO is a carb made to work on 2 strokes and four Strokes.
So there is a compromise try getting a needle holder for a PWK28 from a 2 stroke have a go. What can it hurt.(Make sure it flows enough of course)

But didn't the symptoms only first appear when you set the rev limiter up?

The other parts i linked may be an option for Wallace (Marsheng) with is Diesel

TZ350
4th August 2012, 14:15
My thoughts are your OKO is a carb made to work on 2 strokes and four Strokes. So there is a compromise try getting a needle holder for a PWK28 from a 2 stroke have a go.

I have a genuine PWK28 Keihin that I was told was from a 2-Stroke, RM125??? is that possible? and the internal parts look the same as the OKO's.


But didn't the symptoms only first appear when you set the rev limiter up?

No no ... by using the rev limiter we found that if the engine was prevented from being reved right out it didn’t hesitate so much coming back on the throttle but if it was maxed out it was a dog to get going again. We need to fix this as we want the widest rev range possible.

husaberg
4th August 2012, 14:25
I have a genuine PWK28 Keihin that I was told was from a 2-Stroke, RM125??? is that possible? and the internal parts look the same as the OKO's.



No no ... by using the rev limiter we found that if the engine was prevented from being reved right out it didn’t hesitate so much coming back on the throttle but if it was maxed out it was a dog to get going again. We need to fix this as we want the widest rev range possible.

Def not a 125 but could be a KR1s or cr85 Rm85 etc.

actually strip a kr1s and have a look one of the threads linked below say the hole are different on a oko (for a Foul stroke anyway)
http://www.rzrd500.com/500phpBB2/viewtopic.php?t=10089&highlight=srx250+petcock
http://www.kawasakitriplesworldwide.com/phpBB2/viewtopic.php?f=17&t=55329&start=15
http://www.miniriders.com/tech-talk/26815-keihin-pwk-copy-carb-mods.html
http://i91.photobucket.com/albums/k315/1crazypj/Carburettors/Primarychokeandairbleedneedlejets.jpg
<img src=" http://i452.photobucket.com/albums/qq243/ferrariron58/Early%2072%20H2/3tubes.jpg" width="640px"/>
Not sure i understand what you mean in regards to the limiter though?

TZ350
4th August 2012, 14:52
Not sure i understand what you mean in regards to the limiter though?


The problem happens when shutting of from 13500 rpm but not 11500.


Thanks for the pictures and your help with this.

TZ350
4th August 2012, 14:59
267549267550

I was told the original 28mm Keihin I started with was off a 2-stroke, the internal parts look the same as the 24mm OKO.

267552267553

Because I have bored the OKO out in the slide area I shortened the needle jet and cut it back to look like jet (1) but may have taken it to far.

TZ350
4th August 2012, 15:10
Just looking at that link you posted. http://www.rzrd500.com/500phpBB2/viewtopic.php?t=10089&highlight=srx250+petcock

I see:- Tuning data: Jetting specs and tuning results will be posted as the bike is set up.
Baseline will be what the KX85 comes stock with ie. 45/#3 NAPE/140 which should be close. (Keihin jetting is different than Mikuni's) Based on what people run on the KR1(125)/KX100, it will prob be around 42/#2 NAPF/135 but we'll see.

Which is pretty much where I am on the OKO.

husaberg
4th August 2012, 15:13
267549267550

I was told the original 28mm Keihin I started with was off a 2-stroke, the internal parts look the same as the 24mm OKO.



So they have the same number of holes in the holder in same places?

TZ350
4th August 2012, 15:24
So same number of holes in the holder and in same places?

I will have to re check that but yes I think so.

I read through your links and people report that after a bit of a fiddle they did get their OKO's to work well on their strokers so thats encouraging.

husaberg
4th August 2012, 16:05
I will have to re check that but yes I think so.

I read through your links and people report that after a bit of a fiddle they did get their OKO's to work well on their strokers so thats encouraging.

Bummer it also looks like the CR85 has at least 4 Holes as well. Not sure re the KX100.
Anyone got a PWK off a KR1s?

Chucked in the Sudco Mikuni stuff as well.

kel
4th August 2012, 20:23
Not sure i understand what you mean in regards to the limiter though?


The soft rev limiter is currently set at 12500rpm. Previously there was no rev limiter allowing the motor to rev through to 14k or so (no rev counter so this is all going by ear and power drop off and knowing the old dyno curve). The delay coming back onto the throttle is noticeably worse the harder the bike is revved, so while the problem existed last weekend it was almost minor compared to how it was with no rev limiter.
Now before some says "why dont you set the rev limiter at 10500" ...

husaberg
4th August 2012, 21:11
The soft rev limiter is currently set at 12500rpm. Previously there was no rev limiter allowing the motor to rev through to 14k or so (no rev counter so this is all going by ear and power drop off and knowing the old dyno curve). The delay coming back onto the throttle is noticeably worse the harder the bike is revved, so while the problem existed last weekend it was almost minor compared to how it was with no rev limiter.
Now before some says "why dont you set the rev limiter at 10500" ...

I'll say it i was thinking it before anyway couldn't the rev limiter be set to work to a lower level at a per-determined TPS position (say 25%)
That way it should only effect over run.
But my thoughts were there was a excess of fuel (Rich mixture condition)that needed to be burned off before thew engine would respond when coming back onto the power from a slower corner high over-run revs condition?

Below Bert or Burt 1972 ish

TZ350
4th August 2012, 21:34
I'll say it i was thinking it before anyway couldn't the rev limiter be set to work to a lovwer level at a per-determined TPS position (say 25%)That way it should only effect over run.

No, the IgniTec software does not allow for tying the revlimiter to a TPS position and rpm, its rpm only.


Bummer it also looks like the CR85 has at least 4 Holes as well. Not sure re the KX100.Anyone got a PWK off a KR1s?

267607

The OKO has four holes each side.

Voltaire
5th August 2012, 11:35
No, the IgniTec software does not allow for tying the revlimiter to a TPS position and rpm, its rpm only.

Unrelated but I bought an Ignitech ignition off a KB member for my BMW R90, had a few questions about why the program would freeze up.....no replies to email or PM.....got it sorted thanks to Ducati forum.
Nice bit of kit though.

TZ350
5th August 2012, 12:17
I bought an Ignitech ignition off a KB member for my BMW R90, had a few questions about why the program would freeze up.....no replies to email or PM.....got it sorted thanks to Ducati forum.

What was the answer to yours freezing up? I am still struggling with ours.

Voltaire
5th August 2012, 13:28
What was the answer to yours freezing up? I am still struggling with ours.

PM sent.

Are you the guys with the dyno Darren told me about.....?
My BMW needs some dyno time to get the jetting/ignition right.

wobbly
5th August 2012, 16:00
I am sorry I didnt reply to the questions about the software freeze ups.
I emailed Ignitech about it, as I have been having this issue of late, only since Ignitech have supplied a "one for all " Windoze driver for usb.
Never had a problem previously, except when using USB in real time with the motor running.
That is always to do with RF noise going down the usb, and is usually fixed easily enough.
But I have had no real helpful info from them about constant freezing up for no reason, I havnt been able to solve it myself, so if there is a "fix"
then many of us would love to hear about it.

Voltaire
5th August 2012, 17:07
I am sorry I didnt reply to the questions about the software freeze ups.
I emailed Ignitech about it, as I have been having this issue of late, only since Ignitech have supplied a "one for all " Windoze driver for usb.
Never had a problem previously, except when using USB in real time with the motor running.
That is always to do with RF noise going down the usb, and is usually fixed easily enough.
But I have had no real helpful info from them about constant freezing up for no reason, I havnt been able to solve it myself, so if there is a "fix"
then many of us would love to hear about it.

A reply would have been nice......even just acknowledging you were following up...anyway :hug:

OK, fitted the unit , my mate made up a mount for the pick up...set gap to .6-.9 mm
Bought a usb to serial interface from Jaycar for $34.00
Set up the base advance, set up the laptop , you could see the crank speed on the screen,
As soon as the motor started the screen went " no pc connection' and froze.
Tried all sorts, running unit of separate 12 volts to starter motor
After what seemed like hours gave up.....
Next day as a last resort went to Repco and bought 2 RESISTOR plugs.....like that was going to make a difference......
Well it did and it works.:2thumbsup

http://i129.photobucket.com/albums/p235/rednzep/crankpickup.jpg

http://i129.photobucket.com/albums/p235/rednzep/cpu.jpg

Running dual output coils as was going twin plugs....so earthed at the moment as not needed.

http://i129.photobucket.com/albums/p235/rednzep/coils.jpg

So there you go....its in the Ignitech FAQ but only as an aside....

Now I just need my FXR 150 to magically transport itself from Napier to Auckland and I'll be sorted...:killingme

wobbly
5th August 2012, 20:13
OK, that is what i was saying about it is easy to fix usb communication issues when the motor is running - I didnt realise that was what you were having as its easy to fix.
I usually tell everyone that you MUST run resistor plugs AND resistor caps, must have forgotten with your project.
Or I have tested using spiral wound coil wires,this works real well and means you dont have issues with unreliable resistor caps - but you still must use resistor plugs in any case.
What is hard to figure out is why we are getting freeze ups without the engine running.
Still dont know.

Voltaire
5th August 2012, 20:35
I had no issues with comms engine not running, I bought a jaycar converter that comes with a CD.
http://www.jaycar.co.nz/productView.asp?ID=XC4834

F5 Dave
6th August 2012, 09:55
Bummer it also looks like the CR85 has at least 4 Holes as well. Not sure re the KX100.
Anyone got a PWK off a KR1s?
. ..
Um yeah, a couple + one meant for a KX80/5. At home I think (Bert has the other one that was in my tool box as a spare for my 50).

TZ350
6th August 2012, 15:59
267724

Took apart the PWK 28 and found the diffuser has the same hole arrangement as the OKO, no surprise realy as the OKO is a copy of the PWK.

F5 Dave
6th August 2012, 16:48
What might be interesting is the replaceable needlejet in the Oko could be used to recondition a Keihin. I have worried about that for the 500 (do they make a 35mm Oko & sell needle jets I wonder). . . . On the other hand at this rate the 500 will never wear out.


What are the float jet seats like? Just into ally on the pwk.

husaberg
6th August 2012, 16:59
What might be interesting is the replaceable needlejet in the Oko could be used to recondition a Keihin. I have worried about that for the 500 (do they make a 35mm Oko & sell needle jets I wonder). . . . On the other hand at this rate the 500 will never wear out.


What are the float jet seats like? Just into ally on the pwk.

If you go back a few pages there are some links that spell out the differences.
With TZ's oko, The one thing i have noticed with Mikunis of Disk vave engines is there ultra short needle jet ie the shound with vey little cut away where as the the reed and piston ports are longer and have a lager cut away.
The Holes are a bit of a surprise though i wonder why the pictures of some of them show no holes for the 2 stroke trials bike.
Care to whip your one open (The trials bike) if it has a PWK28 Dave...

Whoops i may not have posted the OKO vs PWK 28. It was from a Aussie pitbike thread.
I will find it again the float valve i think was smaller than the PWK28 i think but fixable.

OK here it is..........http://www.miniriders.com/tech-talk/26815-keihin-pwk-copy-carb-mods.html


AS a side note Dave on MY cr500 i used a different Diameter and taper (i think )needle to accommodate the wear it is common on the CR500 and is a real bitch as it leaves the 500 with a 125 like powerband and is the direct reason why some of my fingers are not as long as they used to be.........
(Always wear gloves and Always cover the rear brake, kids and Always make sure you really are in third gear )

F5 Dave
6th August 2012, 18:05
Sadly I had to sell the trials bike, but that was a 200 GG & had a Dellorto. . .26mm I think. Fitting a Jap carb was supposed to be good for better more power, but got it fueling real nice. An aside, I'll dig out the spare PWK carb.

The problem with wear is it ovalises the hole so you get rich blobuals of gas. Going to a larger needle may end up with too lean + wet hard to burn. With my old Touring bus which had Mikuni CV carbs they ovalised the emulsion tubes, I had bought factory brand plated ones, but it did it again as the bodies were worn enough to rattle the slides.

Built wear up with epoxy & bored the tubes 5mm & glued in inserts that looked largely like the Oko needle jets, just plain sleeves (5mm long) & drilled the right point drill dia.

Same careful boring & gluing an Oko jet should do it. If I ever need to. . . :crazy:

husaberg
6th August 2012, 18:21
Sadly I had to sell the trials bike, but that was a 200 GG & had a Dellorto. . .26mm I think. Fitting a Jap carb was supposed to be good for better more power, but got it fueling real nice. An aside, I'll dig out the spare PWK carb.

The problem with wear is it ovalises the hole so you get rich blobuals of gas. Going to a larger needle may end up with too lean + wet hard to burn. With my old Touring bus which had Mikuni CV carbs they ovalised the emulsion tubes, I had bought factory brand plated ones, but it did it again as the bodies were worn enough to rattle the slides.

Built wear up with epoxy & bored the tubes 5mm & glued in inserts that looked largely like the Oko needle jets, just plain sleeves (5mm long) & drilled the right point drill dia.

Same careful boring & gluing an Oko jet should do it. If I ever need to. . . :crazy:

I had real trouble with my second CR500 (the first had a Mikuni fitted) ;)
The fueling was so rich mid range it was just about impossible to rev through with dipping the clutch (How i brought it) the effective rev range when it cleared was about 1500 RPM.
It smoked so so bad plus and the pipe was choked full of oil and carbon crud.
It had been diagnosed as haven a blown crankseal and sucking gearbox oil.
I found this thread was hapily surprised i knew the needle jet holder was not replaceable.
But i followed the direction of the thread, only i used a Cr125 needle from a 1993 or so and it was 1000 times better.
The cost $0 as i had one in the shed.(needle)
The pilot i never got fully sorted to many other projects and the hot starting was shit but the bike was ridable without much effort.

Degner possibly a more balanced story than the normal write up.

The second bit i see those Euro types are still copying the Japanese;)
I had read that Yamaha twin were based a bit on the Adler twins but i had never seen the race version.
Wow..... way ahead of there time.

Fourth attachment DKW's 4 piston 2 cylinders twin cranked supercharged 2 stroke 1940

TZ350
7th August 2012, 05:31
What are the float jet seats like? Just into ally on the pwk.

267776

My OKO float jet/needle valve had a brass washer like seat that fell out and was lost now its just a rubber tipped needle in an alloy hole like the original Keihin. It was easy to re set the float height.

F5 Dave
7th August 2012, 09:24
oh, ok thanks.

So I took apart the KR1S PWK 28mm. I won't bother to post a pic as it is prexactly like the pics above. Even the needle jet is removable. i'm sure they aren't in my GasGas 39mm PWK or the 35s on my 500. Cost saving I guess.

TZ350
7th August 2012, 14:49
Over the weekend Thomas put together the Det Ear.

267793

The essential parts.

267794

The pickup is sensitive enough to listen to a watch tick. The padded 80's stereo headphones act like earmuffs as well as headphones, I brought them at a garage sale for $5, like new and still in their original box.

267791

Closeup of the inside.

Now that we will be able to hear detonation we can have another go at setting up the IgniTecs det sensor and optimizing the timing.

F5 Dave
7th August 2012, 16:15
So have you run the Knockgauge as is? Do you think it needs adjustment?

Couldn't you just run it on the dyno & advance the ign until the power JUST starts falling off & turn the dial till it reports det there?


Pity you can't run the knock gauge on small batteries, everything 12V is huge.

TZ350
7th August 2012, 16:45
So have you run the Knockgauge as is? Do you think it needs adjustment?

Yes, but I don't know where in its adjustment range it sees det or not, and I want to find out. It would give me some confidence if I can hear det and see the Knock Gauge detecting it.


Couldn't you just run it on the dyno & advance the ign until the power JUST starts falling off & turn the dial till it reports det there?

I think you might be able to get detonation of the end gases in the squish area before you see any real loss of topend power on the dyno, anyway it was detonation in the midrange on part throttle that killed the engine last time and we sure missed that on the dyno.

There is quite a range of adjustment of the Knock Gauges sensitivity. I am sure someone who is familiar with these Knock detectors can set one up easily, but I am new to this.

And I feel I need to hear det and see the Knock Gauge detecting it before I can have any real confidence in the detector, anything else would just seem like guessing.

Bert
7th August 2012, 18:18
.....
And I feel I need to hear det and see the Knock Gauge detecting it before I can have any real confidence in the detector, anything else would just seem like guessing.

Good thinking Batman... nothing better than seeing it for yourself with your own eyes.
in one of those earlier articles (the source of your project); there was a section on connecting it up the pickup mic to a PC and looking at the full acoustic range using mixing amp software. My thinking was it might be useful to record this every so often (one the dyno say every couple of hours use) and see if (when) a part fails there is an acoustic signature (or change etc) that change be identified. kind of like a CSI trace analysis for noise; if you get my drift. it would be very useful for future use and resolving issues before they turn out to cost $$$$.

Many of us have heard and felt changes in engine tone/vibration (usually right before one ends up on one's a55) i.e. main bearings, big ends & new knocks etc. each will have a different signature....

husaberg
7th August 2012, 21:07
Am i the only one who has experienced the death silence.

No, not the one from the significant other in your life.:mad:

But just before the engine nips up.

It seems to go quiet is it just the clearances closing up or something else or is it just in my head:scratch:

Is this a real phenomena.

Oh yeah i just watch 6 vidoes on Youtube describing the difference between an OKO and a Genuine PWK don't watch the vids.
He found there is not much difference the oko casting and slide are a it rougher but as TZ has said they seem to machine better.

All the rest was how you should clean the carb and use a filter and not get Carbclean in your eyes.

Yow Ling
7th August 2012, 21:27
Am i the only one who has experienced the death silence.

No, not the one from the significant other in your life.:mad:

But just before the engine nips up.

It seems to go quiet is it just the clearances closing up or something else or is it just in my head:scratch:

Is this a real phenomena.

.

I had 2 seizures at the weekend, does go quiet, and the back gets queer till you get your shit together, maybe my brain just stops listening while its yelling at my clutch hand. getting closer with the jetting I think !!

husaberg
7th August 2012, 21:32
I had 2 seizures at the weekend, does go quiet, and the back gets queer till you get your shit together, maybe my brain just stops listening while its yelling at my clutch hand. getting closer with the jetting I think !!

Yeah go way leaner till it is one piece;)
Funny but No i was meaning just before it seizes. Maybe its just me.

Me mum always says i'm special:drool:
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=267753&stc=1&thumb=1&d=1344248255
Not so sure about the queer rear though not my area.:buggerd:

wobbly
8th August 2012, 07:56
One thing you wont get is deto of the end gases without loosing power.
The phenomenon of deto is caused by temp/pressure creating free radicals,this process eliminates a huge amount of the available energy in the combustion fuel.
And once the radiacals are formed, they are self sustaining,and cause a runaway reaction process - consuming more energy.
This is exactly why the egt drops when you are too lean, and deto starts - no energy left to create heat - ie no power.

F5 Dave
8th August 2012, 10:28
So the method of calibrating on the dyno with tiny timing changes till the power just drops off would seem doable.

If I understand correctly from what Wob has said (I haven't had gauge on running engine yet, maybe next week -ho ho) then:


Peak power you get the 'warning' just chiming in a little,
& with a bit more timing that the power just starts to drop off = Deto.
If you get deto at another rev range it should still show on the gauge.

If you never see 'warning' then you are not close enough with the timing in that area, but caution, as have to build a TPS aided model to get it that close for all conditions.

TZ350
8th August 2012, 12:08
So the method of calibrating on the dyno with tiny timing changes till the power just drops off would seem doable.

Running blind through rush hour traffic is doable too, but I don't like your chances but on the other hand I like your independent spirit ....... go for it I say.

Hopefully I will get a chance tonight to see how well the Det Ear idea works and if I can hear anything worthwhile with it, will let you know.

F5 Dave
8th August 2012, 12:33
But you'll run it up on the dyno & that should tell you if the earpiece is telling you any more or if the curve changes are sufficient. Would be interested as I'll be doing the same soon.

diesel pig
8th August 2012, 18:35
There are commercial det ear makers who have videos on youtube with recordings of actual deto. It may be useful.

TZ350
8th August 2012, 20:24
267851


But you'll run it up on the dyno & that should tell you if the earpiece is telling you any more or if the curve changes are sufficient. Would be interested as I'll be doing the same soon.

267850

Kel and Giggles came around and we ran the beast up on the dyno, and I could hear a lot of mechanical noise with the Det Ear, but deto???????

With only one green light showing, the Knock sensor only spasmodically flashed orange during a pull and with the sensitivity wound up a bit so two green lights were on when the bike was running it would flash orange and then red during a pull and red on the over run but I never heard any det sounds in the headphones.

So was the Knock sensor seeing detonation and I couldn't tell what it sounded like over the engine noise or could the pickup on the head be tuned for the wrong cylinder diameter and was sending false signals to the Knock sensor.

I was sure I was going to hear detonation if it was happening, now I am none the wiser.


There are commercial det ear makers who have videos on youtube with recordings of actual deto. It may be useful.

Thanks I will have a look at them.

kel
8th August 2012, 21:08
with the sensitivity wound up a bit so two green lights were on when the bike was running it would flash orange and then red during a pull and red on the over run

Yep had it lit up like a christmas tree on over run, but you failed to mention the other area we were working on. Hope Im not getting ahead of myself but the throttle on after closed delay is well and truely gone (when running on the dyno anyways) :banana:

husaberg
8th August 2012, 22:01
267851



267850

Kel and Giggles came around and we ran the beast up on the dyno, and I could hear a lot of mechanical noise with the Det Ear, but deto???????

With only one green light showing, the Knock sensor only spasmodically flashed orange during a pull and with the sensitivity wound up a bit so two green lights were on when the bike was running it would flash orange and then red during a pull and red on the over run but I never heard any det sounds in the headphones.

So was the Knock sensor seeing detonation and I couldn't tell what it sounded like over the engine noise or could the pickup on the head be tuned for the wrong cylinder diameter and was sending false signals to the Knock sensor.

I was sure I was going to hear detonation if it was happening, now I am none the wiser.



Thanks I will have a look at them.

on the Autospeed page it had to from memory to listen to a car engine it went through a procedure.
But there is a quote which i can't quite remember that went something like
Sometimes for the good of many. some individuals must be sacrificed............
Maybe a TF125............
The only limits on scientific progress are those imposed by society. Nikola Tesla

TZ350
8th August 2012, 22:23
the other area we were working on. Hope Im not getting ahead of myself but the throttle on after closed delay is well and truely gone (when running on the dyno anyways) :banana:

Yes it took a bit of work and I couldn't have done it without your patent help but the way it comes back on is truly frightening, I think we will have to refine (tame) it for the track. But if it leaps out of corners as fast as it picks up on the dyno its going to be a rocket ship.

richban
8th August 2012, 22:36
I was sure I was going to hear detonation if it was happening, now I am none the wiser.

When I was using Andrews phones you could hear it loud and clear just over idle when the slide gasket on my cheap carb gave up. Sounded like a man with a hammer bashing my engine apart. All that normal engine noise was totally drowned out. It was loaded on a dyno with a break at the time but really minimal load. Will soon be doing it agin so will keep you posted on how I go. New engine finished and sitting on the bench.

Haufen
9th August 2012, 03:51
Yes it took a bit of work and I couldn't have done it without your patent help but the way it comes back on is truly frightening, I think we will have to refine (tame) it for the track. But if it leaps out of corners as fast as it picks up on the dyno its going to be a rocket ship.

Now I am curious, what was the reason?

TZ350
9th August 2012, 06:48
When I was using Andrews phones you could hear it loud and clear just over idle when the slide gasket on my cheap carb gave up. Sounded like a man with a hammer bashing my engine apart. All that normal engine noise was totally drowned out.

Thats what I was expecting, to be able to clearly hear detonation when it happened but the Knock Sensor was lighting up like a Xmas tree and I could not hear anything with the Det Ear other than lots of engine noise so something must be missing from the equation.


Now I am curious, what was the reason?

267902

Needed a longer shroud on the needle jet, a leaner pilot, richer slide (like Wob said) and a needle that was leaner in the parallel part, took a while and I am sure that at the track we will have to refine it some more yet.

And at idle there looks like there is a low part in the inlet tract where a puddle might be forming (like you said there could be). I will have to take the RV cover off and see what can be done about draining it into the RV cavity. I figure if it drains into the RV cavity the RV blade will churn it up and fling it back into the moving air stream in the inlet tract.

F5 Dave
9th August 2012, 09:16
So did you alter the timing and note the power falling off? Maybe it is set over sensitive & you aren't getting det yet.

Kickaha
9th August 2012, 09:18
Anyone know what this engine is?
http://www.steveenglish.com/forum/download/file.php?id=6806&mode=view

F5 Dave
9th August 2012, 09:25
If that's the only clue(ie none you turkey), then no.

Try posting a pic or a description;)

Kickaha
9th August 2012, 10:02
If that's the only clue(ie none you turkey), then no.

Try posting a pic or a description;)

If I had a clue i wouldn't have needed to post it:bleh:

edit: can't you see the pic?

Yow Ling
9th August 2012, 10:05
Anyone know what this engine is?
http://www.steveenglish.com/forum/download/file.php?id=6806&mode=view

Is it a Doxford 58JS3 ?

Kickaha
9th August 2012, 10:07
Is it a Doxford 58JS3 ?
I think you'd need a bigger chassis to fit one of those in

Haufen
9th August 2012, 10:54
267902

Needed a longer shroud on the needle jet, a leaner pilot, richer slide (like Wob said) and a needle that was leaner in the parallel part, took a while and I am sure that at the track we will have to refine it some more yet.

And at idle there looks like there is a low part in the inlet tract where a puddle might be forming (like you said there could be). I will have to take the RV cover off and see what can be done about draining it into the RV cavity. I figure if it drains into the RV cavity the RV blade will churn it up and fling it back into the moving air stream in the inlet tract.

Thanks, good to know. Is the off idle throttle response of the engine any different after idling for a longer period of time? I guess with the taper bored carb and the shape of the inlet port, just filling the floor of the port (and carb) is not an option.

TZ350
9th August 2012, 11:22
Thanks, good to know. Is the off idle throttle response of the engine any different after idling for a longer period of time?

It loads up if left idling ......


I guess with the taper bored carb and the shape of the inlet port, just filling the floor of the port (and carb) is not an option.

No, but I expect to be able to drain it into the RV cavity.

TZ350
9th August 2012, 11:32
So did you alter the timing and note the power falling off?

Kel would back off as soon as he saw the det light so we didn't get any comparative runs.


Maybe it is set over sensitive & you aren't getting det yet.

It could be that alright or we have made some mistake in constructing the Det Ear and if that's the case, the way we put the pickup together might be the problem.

F5 Dave
9th August 2012, 12:11
. . .

edit: can't you see the pic?

err, no, can you? Is this an Emperors new clothes sort of thing? In which case I can see it:eek5:.

Its clearly a Sterling engine with a candle so choosing the right grade of wax is important for long trips. Don't go over 3kph or it might blow out.

F5 Dave
9th August 2012, 12:13
Kel would back off as soon as he saw the det light so we don't get any comparative runs.
. . .
Remove it, do some runs with safe timing & tweak it more advance until improvement stops & starts to fall off. You've just calibrated your engine to be detoing slightly, but its standard fare dyno tuning of course & you've done it many times.

Then plug the gauge back in & the det ear.

Kickaha
9th August 2012, 12:38
err, no, can you?

Yes it also shows up where Yow Ling quoted me

http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc7/s720x720/306475_10151023365237825_1952728429_n.jpg

This isn't as good as the other shot, the other one shows the rear of the engine

Kickaha
9th August 2012, 12:45
Ok, see how this works then

267905

F5 Dave
9th August 2012, 12:53
Ahh, odd. Disc valve 3 cyl. interesting.

TZ350
9th August 2012, 15:02
Remove it, do some runs with safe timing & tweak it more advance until improvement stops & starts to fall off. You've just calibrated your engine to be detoing slightly, but its standard fare dyno tuning of course & you've done it many times. Then plug the gauge back in & the det ear.

Good suggestions, I will give them a try ....

TZ350
9th August 2012, 16:31
267911

Some good news, after fitting a 5k Ohm resistor plug cap and changing to a new USB serial converter with its own USB driver I did not suffer any of the freezing problems during the last dyno session that had been a real pain before.

TZ350
9th August 2012, 17:26
Found out my inlet manifold went downwards just a bit and the other half upwards just a bit, so at low throttle openings with too weak suction from the engine I had like a little puddle in the inlet manifold.

267912

And yes, like yours, a puddle forms in the inlet tract .....

Drew
9th August 2012, 19:05
And yes, like yours, a puddle forms in the inlet tract .....Is it possible that just happens when you shut it down?

I know fuck all, but if a two stroke isn't firing, the draw through effect stops happening I would think. So the mixture would just stall there wouldn't it?

TZ350
9th August 2012, 19:18
Is it possible that just happens when you shut it down?

I had wondered about that, bleading float valve and fuel dribbling into the engine while sitting, that sort of thing, but tonight I checked straight after a brisk dyno session and the puddle was there.

TZ350
9th August 2012, 19:24
I found the adjustment on the Knock Sensor to be very sensitive and when I took my time to carefully adjust it according to the instructions and use very small movements it seemed to work OK and gave me some confidence that it was detecting even small det.

267917

Three runs at different throttle settings 100-80-60% and the TPS map adjusted so no det red light was seen.

Then for extra on track safety I set the IgniTec to automatically retard 5 deg if the Knock Sensor detected any detonation.

Not a 100% optimised but should get through the next race day with any luck .....

The carburation seems to be realy good now too.

Drew
9th August 2012, 19:51
I had wondered about that, bleading float valve and fuel dribbling into the engine while sitting, that sort of thing, but tonight I checked straight after a brisk dyno session and the puddle was there.I'm more meaning on over run with the ignition off when turning it off.

I know very little about these things, and would appreciate if someone knows why it wouldn't be the case.

The puddle looked quite dark also, had it been in the crank cases and sorta...floated (only term I could come up with to fit what I mean) down after cooling. You know, like the opposite of evapourating. The word is fuckin gone from my head, I've done a refridgeration course, I should know it.

Buckets4Me
9th August 2012, 20:35
so who was saying that post classics was cheaper than buckets

http://www.trademe.co.nz/motors/motorbikes/motorbikes/classic-vintage/auction-501542957.htm

I nearly got one of these 10 years ago for $5000 but my DAD said it was a waste of money :( (and he was right)

http://www.trademe.co.nz/motors/motorbikes/motorbikes/classic-vintage/auction-501542957.htm

267919

bucketracer
9th August 2012, 20:44
Is it possible that just happens when you shut it down?


I'm more meaning on over run with the ignition off when turning it off.

For the same throttle opening whether the ignition is on or turned off, the same amount of air/fuel is sucked in and passes through the motor.

Turn the ignition off and its kinetic energy thats spinning the crank and with the ignition on, its the energy in the fuel thats spinning the crank.

If the crank is spinning air and fuel is sucked in regardless of whether it then gets burnt or not.

Frits Overmars
9th August 2012, 21:02
For the same throttle opening whether the ignition is on or turned off, the same amount of air/fuel is sucked in and passes through the motor.It is the exhaust pipe that is doing 75% of the sucking, provided that there is combustion....

bucketracer
9th August 2012, 21:13
It is the exhaust pipe that is doing 75% of the sucking, provided that there is combustion....

I hadn't thought to figure the effect of the 2-Strokes exhaust into it, yes true, unlike a simple 4-stroke a tuned 2 with an expansion chamber would have more suck at the right rpm with the ignition on.

Drew
10th August 2012, 07:36
It is the exhaust pipe that is doing 75% of the sucking, provided that there is combustion....Yeah, that's what I was getting at.

F5 Dave
10th August 2012, 09:56
. . . In a reed valve setup,tuned for peak power around 12000 rpm, we find that the best tuned length is around 135mm from the reed tip, to the end of the bellmouth works best.
What this does is hard to explain but easy to show you.
The wave bouncing up and down the intake length, when its "in tune", will arrive at the reeds as a + going pressure ratio, at the same time as the case drops below atmospheric, due to the piston rising - plus the pipe diffuser sucking like hell on the Ex Port around BDC.
When this happens the reeds have + on one side and - on the other.They open real fast, with little "flow energy" being waisted, and Hp is made big time for free..
With this & Frits advice on keeping the tract as short as I could(ish) I have flowed a control reedblock (the differing epoxy makes it look like there is a bad match but I used Kneedit as its easy to form & then Devcon over the top to smooth it out. Then I ground & sanded it back. Needs more but will do for now. Next block will incorporate a fin & test against this one.

But then I measure it & it is 160mm from reed tip to bellmouth (photo makes it hard to see but it is squared up).

I want to peak faster still than 12, probably 13,000, but I'm no where near even 135mm to the Bell mouth. I could perhaps find a shorter manifold rubber, but only by a few mm & mill into the 10mm ally plate. But I'd only find 10mm tops. The manifold is only about 30mm long. Going to the 36mm PWK makes the assembly even longer.

currently an early TZR block (only just fits) with VJ21 32mm Mik.

HPbyGD
10th August 2012, 10:22
Hi Guys
Has anyone hooked a deto sensor, the piece that is used on the block of a car to a set of head phones to see if it would work like the pickup with the microphone glued to a clip ? The other thing that would be interesting is to use some recording software to see what the deto looks like.

Gary

Grumph
10th August 2012, 12:23
[QUOTE=Buckets4Me;1130373684]so who was saying that post classics was cheaper than buckets

http://www.trademe.co.nz/motors/motorbikes/motorbikes/classic-vintage/auction-501542957.htm

Saw that at the Burt Munro last year...let's just say he's a tad optimistic......

F5 Dave
10th August 2012, 12:34
Hi Guys
Has anyone hooked a deto sensor, the piece that is used on the block of a car to a set of head phones to see if it would work like the pickup with the microphone glued to a clip ? The other thing that would be interesting is to use some recording software to see what the deto looks like.

Gary
The deto sensor is a piezo so will always produce voltage (noise), but its the big spikes so you'd have to filter. But that is what the Knock gauge plugs into.

TZ350
10th August 2012, 14:30
so who was saying that post classics was cheaper than buckets

http://www.trademe.co.nz/motors/motorbikes/motorbikes/classic-vintage/auction-501542957.htm

Saw that at the Burt Munro last year...let's just say he's a tad optimistic......

Hi Grumph ... so, if its not 16K, what is a TZ350G in really nice condition worth then?

Yow Ling
10th August 2012, 17:41
You know, like the opposite of evapourating. The word is fuckin gone from my head, I've done a refridgeration course, I should know it.

Nevapourating ?

Kickaha
10th August 2012, 18:01
The puddle looked quite dark also, had it been in the crank cases and sorta...floated (only term I could come up with to fit what I mean) down after cooling. You know, like the opposite of evapourating. The word is fuckin gone from my head, I've done a refridgeration course, I should know it.

Condensing?

Drew
10th August 2012, 18:53
Condensing?Not the word we use when refering to refridgerant in a split system, but correct none the less I suppose.

Cheers.

TZ350
10th August 2012, 19:30
The puddle looked quite dark also ...

It did look dirty and it shouldn't be, I was puzzled by that, I will have a better look when I get back to work.

Drew
10th August 2012, 20:36
It did look dirty and it shouldn't be, I was puzzled by that, I will have a better look when I get back to work.

It must be from floating around in the cases, giving some weight to the ignitionless over run of shutting down.

husaberg
10th August 2012, 22:48
With this & Frits advice on keeping the tract as short as I could(ish) I have flowed a control reedblock (the differing epoxy makes it look like there is a bad match but I used Kneedit as its easy to form & then Devcon over the top to smooth it out. Then I ground & sanded it back. Needs more but will do for now. Next block will incorporate a fin & test against this one.

But then I measure it & it is 160mm from reed tip to bellmouth (photo makes it hard to see but it is squared up).

I want to peak faster still than 12, probably 13,000, but I'm no where near even 135mm to the Bell mouth. I could perhaps find a shorter manifold rubber, but only by a few mm & mill into the 10mm ally plate. But I'd only find 10mm tops. The manifold is only about 30mm long. Going to the 36mm PWK makes the assembly even longer.

currently an early TZR block (only just fits) with VJ21 32mm Mik.

I sent you a picture of a straight reed manifold from a YAM Phazer snowmobile that was shorter a while back.
<center><img src="http://i.ebayimg.com/t/Yamaha-Phazer-Snowmobile-Intake-Boots-/19/!CCYSLlgCGk~$(KGrHqJ,!hQE0fiJjwSIBNK5)Gy!dQ~~_3.JP G" width="355px"/><center> http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=267944&stc=1&thumb=1&d=1344549372
<img src="http://i.ebayimg.com/t/Yamaha-Phazer-Snowmobile-Intake-Boots-/22/%20CCYSPl!EGk~$(KGrHqR,!gwEz)PCQ7nuBNK5)RmSMw~~_3. JPG"355px"/>
http://img.auctiva.com/imgdata/5/9/8/0/3/8/webimg/301390612_tp.jpghttp://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=267945&d=1344549373
BOLT HOLES ON CENTER: WIDTH = 70MM, HEIGHT = 57.5MM

Also if there is enough meat in the RGV carb the spigot recess could be moved inwards like on a TZR250 TMSS28 carb vs STD Mikuni VM
Then the rubber shortened with a scalpel

But i have seen a thread some where that shows how to make a rubber manifold as on the Japanese bikes do.
Can't remember where, ....OK not the one but like this anyway
http://www.precisiontradingsystems.com/inlet_videos.htm

Failing that you could replicate a old Amal or four stroke flange mount cemented direct to the carb with a thin insulting piece.
Much like a MB100 or RD125/200 or Suzuki RG500
http://images.cmsnl.com/img/partslists/yamaha-rd200c-1976-carburetor_mediumyau1178b-2_4982.jpg<img src="http://3.bp.blogspot.com/-hpjd7FYBfuk/T9igjziioKI/AAAAAAAAAqU/8oQ9Mk4xWXc/s1600/HPIM5381.JPG" width="437px"/>

There is a Short PWK 36 from the KX125 from around 99 ish but i guess that's what you may already have?

<img src="http://i.ebayimg.com/t/1999-99-KAWASAKI-KX125-KX-125-STOCK-OEM-CARB-CARBURETOR-/00/s/MTIwMFgxNjAw/$(KGrHqJ,!qYE+nMeQoJWBQJHQ2KGf!~~60_57.JPG" width="340px"/><center><img src="http://img248.imageshack.us/img248/959/09062009316.jpg" width="340px"/><center>
These are 73mm long overall as opposed to 91mm for the std large Keihin PWK.
(Yes have to be modded to suit the angle But Wob has outlined this before)
As a comparison the TA22 Keihin from a NSR250 is about 95mm.
So what are the Mikunis from the VJ21?

Yow Ling
11th August 2012, 08:13
With this & Frits advice on keeping the tract as short as I could(ish) I have flowed a control reedblock (the differing epoxy makes it look like there is a bad match but I used Kneedit as its easy to form & then Devcon over the top to smooth it out. Then I ground & sanded it back. Needs more but will do for now. Next block will incorporate a fin & test against this one.

But then I measure it & it is 160mm from reed tip to bellmouth (photo makes it hard to see but it is squared up).

I want to peak faster still than 12, probably 13,000, but I'm no where near even 135mm to the Bell mouth. I could perhaps find a shorter manifold rubber, but only by a few mm & mill into the 10mm ally plate. But I'd only find 10mm tops. The manifold is only about 30mm long. Going to the 36mm PWK makes the assembly even longer.

currently an early TZR block (only just fits) with VJ21 32mm Mik.

V Force reeds may be shorter

Haufen
11th August 2012, 23:14
Have tried the remote hose to the Lambda thing and although the probe lasted better it was slow responding.to the extent that it is impossible to log the Lambda
output against rpm/Hp on the printout.
The reading I think was about 2000 rpm behind the engine when accelerating at 300 rpm/sec.
Dynojet has an expensive add on kit that uses a pump to draw the gas thru a tube that goes in the muffler, this has a filter element in it so should make the probe reliable.
But it doesnt work on a 2T - even apart from having something affecting the test by altering the outlet area of the muffler itself..
I have seen one Dynojet session where the customer had to pay for 2 probes in a 4 hour test cycle. NFG.

Re using EGT and CHT.
The only probes that are worth shit come from Exhaust Gas Technologies.They guarantee them for 2 years,and I have had no problems since changing to them.
They sell probes to Nascar/IRL/F1/MotoGP teams with a guarantee - the only guys to do this with exposed tip,high speed temp sensors.
The company sells Digatron gauges on Ebay,and having just started to use one with 2 screens and 5 functions - im sold.
The ones sold by Mychron etc for kart use are crap, seen several brand new setup last two laps.


Thanks for the information, I guess with that being said, a Lambda probe is (can be) useful when step testing only.

I looked up Exhaust Gas Technologies on ebay, but found that there are many different probes by that seller there. Are the exposed tip high speed probes all the same and the only difference is the connector and the probe diameter (.25 & .187 in)? My gauge uses K-type thermocouples and no connector, the cables are clamped directly to the gauge. So is this (http://www.ebay.com/itm/Heavy-Duty-EGT-Stinger-Probe-Sensor-Hyper-Tip-NEW-/120780063487?pt=Race_Car_Parts&hash=item1c1f0d82ff) the right probe for me? Or are there any better probes by EGT (faster, more durable, cheaper etc)?

Frits Overmars
12th August 2012, 04:02
Thanks for the information, I guess with that being said, a Lambda probe is (can be) useful when step testing only.A normal car-type Lambda probe lags only about 0.1 sec; that's fine for inertial testing.

TZ350
12th August 2012, 08:50
No need to have a peaky engine. Here are Two Very useful Tools. EngMod2T a 2-Stroke simulation package and a handy (and cheep) Porting Calculator from:- http://www.porting-programs.com/ which is based on Blairs work.

There are over 3,500 images on this thread. To find the interesting ones use Thread Tools near the top of this page and View Images, then sort them from the Beginning and 70 to a page. Click on the Image to view it and the little N/A sign to go to the Post about it.

268048

A handy little tool put together by Bucket for checking the BMEP of different Engines.

You change the values in the yellow squares and the answers appear in the green ones. Its a great tool for compairing different bikes and what development potential they may have left and who's telling porkies.

wobbly
12th August 2012, 16:56
That K probe is the good one,is fast and reliable and cheap.

F5 Dave
12th August 2012, 21:02
Thanks Husi, but that Yam one doesn't look any shorter, except maybe the plate, but I could take that down, but I'm not going to find 25mm. Rubber is needed to isolate from vibes. Just checking if that really meant 135 to the bellmouth which is tricky.

husaberg
12th August 2012, 22:04
Thanks Husi, but that Yam one doesn't look any shorter, except maybe the plate, but I could take that down, but I'm not going to find 25mm. Rubber is needed to isolate from vibes. Just checking if that really meant 135 to the bellmouth which is tricky.

So what is the RGV carb length? is your PWK a shorty?
A long while back i posted a length of inlet rubbers its on a decade page somewhere.http://www.allensperformance.co.uk/products-manifolds.html
but the inlet rubber of the Phazer looks shorter than just your inlet rubber (which acually looks long). <center>http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=267944&d=1344549372<center>

Re the inlet vibes the RG500 and RD200 seem to cope? As Mike said the Vforce seems shorter. I am sure Frits said somewhere if the tract is smaller it can be longer I think? assuming the length Wob posted is to do with the Helmoltz frequency?

Mr Frits..... But I claim that in a normal reed-valved engine you have no real Helmholtz frequency; once the flow direction wants to reverse, it is blocked by the reed. It would be the same as a brake that stops the bouncing mass in your animation once it has reached its highest position.
Only two things can go wrong in a reed-valve engine. With too low a Helmholtz frequency the mixture column in the intake tract has no chance to convert all of its kinetic energy into pressure before the next cycle starts. Or the frequency can be so high that the flow already reverses before the crankcase volume has reached its maximum value (piston in TDC). Between these two extremes there is a broad frequency range that functions well in combination with reed valves......... We need a certain Helmholtz frequency, but there are several ways to achieve it:
via the volume, via the tract length and via the tract diameter.

TZ350
12th August 2012, 22:17
Just checking if that really meant 135 to the bellmouth which is tricky.

268067

Yep 130-135 to bellmouth edge. By loosing 15mm (145 down to 130) we gained 1hp on top.

Frits Overmars
12th August 2012, 23:30
... I am sure Frits said somewhere if the tract is smaller it can be longer...And I am sure I didn't. Quite the opposite in fact: if the tract diameter has to be small for some reason (rules), you can diminish its negative effect by making it as short as possible. And because it's a lovely day, here is my solution of making it really short.
I slip a plate (P in the drawing) around the carb. The hole in this plate is about 2 mm larger than the carb's outer diameter. Then I slip a thick O-ring O around the carb. Then I slide this composition into a hole in the disk valve cover D and fasten it with two bolts B.
Plate P compresses O-ring O which centers the carb in the disk valve cover so there is no metallic contact anywhere. With this solution I manage to fit the carb at 2 millimeters from the disk valve. It works with reed valves too.

You can play with the O-ring size and the rate of compression to vary the flexibility of the carb mounting. You can also fit a second, smaller O-ring at the bevelled end of the carb, next to the disk valve, to keep the carb from sagging when applying a light rate of compression on the large O-ring.
The ideal would be an O-ring with a sleeve. Maybe you can produce something like that with 'liquid rubber'.

husaberg
13th August 2012, 00:17
I am sure Frits said somewhere if the tract is smaller it can be longer I think? assuming the length Wob posted is to do with the Helmoltz frequency?

OK maybe not so sure but i did have a Question mark:facepalm:


And I am sure I didn't. Quite the opposite in fact: if the tract diameter has to be small for some reason (rules), you can diminish its negative effect by making it as short as possible.

Can you expand on the text i misquoted Frits?


"Frits Overmars"
But I claim that in a normal reed-valved engine you have no real Helmholtz frequency; once the flow direction wants to reverse, it is blocked by the reed. It would be the same as a brake that stops the bouncing mass in your animation once it has reached its highest position.
Only two things can go wrong in a reed-valve engine.
With too low a Helmholtz frequency the mixture column in the intake tract has no chance to convert all of its kinetic energy into pressure before the next cycle starts. Or the frequency can be so high that the flow already reverses before the crankcase volume has reached its maximum value (piston in TDC). Between these two extremes there is a broad frequency range that functions well in combination with reed valves.........
We need a certain Helmholtz frequency, but there are several ways to achieve it:
via the volume, via the tract length and via the tract diameter.

PS your carb looks a lot like a Suzuki one in profile rather than design

Frits Overmars
13th August 2012, 04:25
Can you expand on the text i misquoted Frits?I could, if I had the time. But I haven't.
What I can do, is pester you with an article that I wrote for a German two-stroke forum. It's in German (they like that in Germany)...

Frits Overmars
13th August 2012, 04:28
Here's some more Helmholtz-encouragement:

Regarding induction systems: build a short induction tract and visit a test bench.
You can forget about calculations. The formulas you find in various books are all based on the Helmholtz resonator. It made me write a simple story, called:
Helmholtz blues
"A Helmholtz resonator consists of a volume connected to a duct". That is what Wikipedia tries to tell you.
But that is a Helmholtz resonator in its simplest form; one that you won't find anywhere in an engine.
What you do find in an engine is an intake tract with a variable cross-sectional area. This tract is from time to time connected to a variable volume (the crankcase) through a very variable window (the intake port / reed valve / rotary inlet).
The crankcase is connected to a number of transfer ducts with variable cross-sectional areas, which are from time to time connected to a very variable volume (the cylinder) through a number of very variable windows (the transfer ports).
The cylinder is from time to time, through a very variable window (the exhaust port), connected to an exhaust pipe with a very variable cross-sectional area who at the same time doubles as a volume. This pipe volume is constantly connected to a big volume (the outside world) through a tailpipe with a constant cross-sectional area and constant entry and exit windows (thank God, finally someting that's not variable).
We call this a compound Helmholtz resonator .
The various papers also tell us how to calculate the resonator's frequency:
" frequency = speed of sound / (2*pi)* Sqr ( cross-sectional area of the neck / ( volume of the resonator * effective neck length ) ) ".
O yes, the speed of sound... It is dependent on temperature, which is not really constant in the intake tract and the crankcase, rather variable in the transfer ducts and very variable in the cylinder and the exhaust pipe.
Now the above frequency formula is not exact; it is an approximation that is usable as long as the volume of 'the' tract is very small compared to the resonator's volume.
So when engines are concerned, that formula goes very far out the window.
Who said gas dynamics is simple dull?
PS:
It's a similar story with acoustics. That is a sub-branch of gas dynamics, simplified with a lot of assumptions that are acceptable as long as the sound pressure does not exceed a certain limit. The wave pressures in a two-stoke exhaust exceed that limit by a factor of thousand. Bye bye, acoustics...

Frits Overmars
13th August 2012, 04:34
Why does all text on this page self-center? I tried overriding it with advanced editing and clicking 'align left', but to no avail. It is beginning to annoy me....

jasonu
13th August 2012, 05:39
And I am sure I didn't. Quite the opposite in fact: if the tract diameter has to be small for some reason (rules), you can diminish its negative effect by making it as short as possible. And because it's a lovely day, here is my solution of making it really short.
I slip a plate (P in the drawing) around the carb. The hole in this plate is about 2 mm larger than the carb's outer diameter. Then I slip a thick O-ring O around the carb. Then I slide this composition into a hole in the disk valve cover D and fasten it with two bolts B.
Plate P compresses O-ring O which centers the carb in the disk valve cover so there is no metallic contact anywhere. With this solution I manage to fit the carb at 2 millimeters from the disk valve. It works with reed valves too.

You can play with the O-ring size and the rate of compression to vary the flexibility of the carb mounting. You can also fit a second, smaller O-ring at the bevelled end of the carb, next to the disk valve, to keep the carb from sagging when applying a light rate of compression on the large O-ring.
The ideal would be an O-ring with a sleeve. Maybe you can produce something like that with 'liquid rubber'.

That is really similar to how I mounted my RG400 flatslide to the KE125 disk bottom end. I did it more to keep the carb tucked in but if it gave me a power gain then double good.

husaberg
13th August 2012, 06:55
Why does all text on this page self-center? I tried overriding it with advanced editing and clicking 'align left', but to no avail. It is beginning to annoy me....

<center>The self center may be my fault. If you quoted me. but i guess you figured that out.<center>

wobbly
13th August 2012, 07:51
I discovered the 135mm inlet rule of thumb on a TM125 MX engine used for 125 class kart shifter racing .
It had a VF2 with a late model RS125 rubber manifold along with Kehin SPJ solenoid carb.
The old Dynamation sim I was using said shorter was better.
I really wanted 50 Hp and found an old model RS125 intake rubber - 20mm shorter, fitted that in a back to back,Voila more power everywhere in the useable range.
Each test is 3 pulls averaged.
That length is for a reed - the RV needs to be alot shorter again.

Frits Overmars
13th August 2012, 07:52
My Helmholtz Blues contained no quote at all. And neither does this post. But they get centered just the same....

ief
13th August 2012, 08:05
Doesn't look centered to me, browser issue?

TZ350
13th August 2012, 08:30
My Helmholtz Blues contained no quote at all. And neither does this post. But they get centered just the same....

268088

Looks OK 2 me 2 .....

TZ350
13th August 2012, 08:34
That length is for a reed - the RV needs to be alot shorter again.

Oh no ..... :facepalm: ... it was hard enough to get down to 130 and EngMod2T points to 85mm

Now I will have to look at Fritz's Idea.

Frits Overmars
13th August 2012, 08:42
Doesn't look centered to me, browser issue?It would seem so. With Windows 7 + Internet Explorer 8 everything gets centered. With Mozilla Firefox it doesn't, but Firefox is terribly slow; too slow to use on a regular basis. Suggestions anyone?

@TZ350: sooo sorry :devil2:.

TZ350
13th August 2012, 08:52
@TZ350: sooo sorry :devil2:.

You don't sound very sorry ... LOL ... it took me months to get it as short as it is now, but at least you have given me a way forward, otherwise I might have been a bit stuck.

268089

Frits thanks for the idea ..... I need to get down to 85mm from RV to Bellmouth.

ief
13th August 2012, 09:19
It would seem so. With Windows 7 + Internet Explorer 8 everything gets centered. With Mozilla Firefox it doesn't, but Firefox is terribly slow; too slow to use on a regular basis. Suggestions anyone?

@TZ350: sooo sorry :devil2:.

I'm an opera adept since like forever but that has it's quirks to here and there... I just stick with it :baby:

F5 Dave
13th August 2012, 09:40
Hello Frits

Thank you for the manifold idea, that is brilliant & will chop a heap off. Hope my carb now clears the cases, but that can be fixed. Thank heavens for nice days;).

Haufen
13th August 2012, 09:56
It would seem so. With Windows 7 + Internet Explorer 8 everything gets centered. With Mozilla Firefox it doesn't, but Firefox is terribly slow; too slow to use on a regular basis. Suggestions anyone?

@TZ350: sooo sorry :devil2:.

You might want to try Opera (http://www.opera.com/). Browsing with Internet Explorer is like driving a four-stroke (to me). I try to avoid it as often as possible.


I discovered the 135mm inlet rule of thumb on a TM125 MX engine used for 125 class kart shifter racing .
It had a VF2 with a late model RS125 rubber manifold along with Kehin SPJ solenoid carb.
The old Dynamation sim I was using said shorter was better.
I really wanted 50 Hp and founded an old model RS125 intake rubber - 20mm shorter, fitted that in a back to back,Voila more power everywhere in the useable range.
Each test is 3 pulls averaged.
That length is for a reed - the RV needs to be alot shorter again.

Did you have to rejet to achieve that result? When playing around with intake lengths on reed engines I found that the shorter length liked a smaller main jet. But then again the lengths were 190 and 165mm or thereabouts.

Grumph
13th August 2012, 12:04
Why does all text on this page self-center? I tried overriding it with advanced editing and clicking 'align left', but to no avail. It is beginning to annoy me....

Oh, I don't know Frits, it made the Helmoltz Blues read like a Haiku...very artistic.

It seems to be unique to this thread - and happend after a Husaberg post so I'd blame him....

mike schmidt
13th August 2012, 12:23
Just a dumb boat racer, but several years ago I built a new 250 Kawasaki boat engine. A pair of KX 125 cylinders on billet case. I used KX 250 reed cages and had them kicked at an angle so that the upper reed pedals were almost 90 degees to the bore centerline. Problem was that I could not fit the two Mikuni 38 flatslides on as they crashed into one another. I welded up two real nice aluminum manifolds that moved the carbs outboard, so they would fit. Modeld them after a "Pro Stock" car manifold. The motor was a dog at best. Several MPH slower than my other ones. Only change was to epoxe up the crankcase, move the reeds so that the mounitng surface was parellel to the centerline of the cylinder bore and mounted the Mikuni mount almost to the face of the reed cage. Became my best motor overnight.

About 25 years ago I did a whole bunch of KT 100 kart motors to help pay for boat stuff....We had a dyno mule motor that we expermented on. Once we found what direction helped, we then pushed the rules in that direction on the "stock" motors. One of the first things we found was that the closer you can get the carb to the cylinder, the more horsepower they made. On our "stock" motors we milled the carb mount on the cylinder to the very min. spec., faced the carb adapter to the min. spec., cut the overall length of the carb to the min. spec. and assembeled them without any gaskets (just Yamabond). We saw almost 1/2 H.P. by shorteneing the intake up about 3mm.

That said, the shorter the better is what we have found.

Fritz: I really like your "O" Ring systen. Will test on our 125 Rossi at next race.

Wayne: This message board is real neat, but until you have posted some amount of posts, you can not reply to private mail......

teammsr@comcast.net

Thanks

Michael D-1

husaberg
13th August 2012, 17:50
My Helmholtz Blues contained no quote at all. And neither does this post. But they get centered just the same....

I just assumed you "replied with quote" then it seems to retain the previous formatting, even if you delete the original post

It would seem so. With Windows 7 + Internet Explorer 8 everything gets centered. With Mozilla Firefox it doesn't, but Firefox is terribly slow; too slow to use on a regular basis. Suggestions anyone?

@TZ350: sooo sorry :devil2:.

The only thing i use Firefox for is his thread and Explorer for everything else and yes it does seem slower for me to(.i'm Just too lazy to log in on initially on another browser though) Gee I only just found the Refresh button (Had to ask Mental)on Firefox as well, so add thick to lazy.
I did try finding the Helmoltz blues in the search part of pitlane it wouldn't work for me at all (In hindsight maybe it had to be in the first Half of the Thread?)
Does the German article you posted Frits Have any more tidbits that is not in the Pitlane thread? As German is even worse than my English.

Oh, I don't know Frits, it made the Helmoltz Blues read like a Haiku...very artistic.

It seems to be unique to this thread - and happened after a Husaberg post so I'd blame him....

Why not, Everyone else is my fault. Just ask My lady, she has a list and all.

TZ350
13th August 2012, 19:41
When I was helping Thomas with measuring air flow through different carbs and looking for ways to improve them he showed me that it was much easier to get good flow with a small step < 1mm between carb and manifold than you usually could by trying to get a perfectly good match.

248015

The flow with a small step and the best match we could make was the same, a slightly imperfect, perfect match flowed noticeably less air than a definite small step did.

248014

TeeZees carb with a small even 0.5mm step all around the edge will make it easy to take off and refit without loosing any air flow at the joint through any slight miss alignment.


Made a small adapter plate tonight to fit the pumper carb hard up against the case, can't get any shorter than that.

Reposted because someone wanted to see how the pumper was mounted. The little white hose thing is a mod for the pulse line from the crankcase. There are more photos on the original post.

Frits Overmars
13th August 2012, 20:39
...Does the German article you posted Frits Have any more tidbits that is not in the Pitlane thread?That article was only published at that German forum and nowhere else. I think it is worth the effort as it is only a short article and it will help you gain a better understanding of the events in a two-stroke engine. I'm sorry I can't find the time to translate it right now.

EDIT: Hey, the self-centering has gone :). You can tell the Missus to strike that from her list, Husa.

Buckets4Me
13th August 2012, 20:48
I could, if I had the time. But I haven't.
What I can do, is pester you with an article that I wrote for a German two-stroke forum. It's in German (they like that in Germany)...

268124


I'd like to tell you about the events in the engine. Without calculating (it already expects
enough), but with logic, in a way that it can understand a 12 year old. This is just in the area
my knowledge of German.
Look at the picture some HFD-1.
There you'll see a cylinder. Above the piston is a volume VZYL and therein a pressure prevails Pzyl.
Then comes an exhaust manifold. It contains a mass of gas. The moves are not enough.
After the elbow is the exhaust volume Vout and the pressure is there Paus.
Now we consider what happens when the engine is running in thousandths of seconds. But we have
not in a hurry, we take the time to step by step to follow closely and rethink.
Case 1: The piston has just released the exhaust port. The pressure in the cylinder Pzyl is higher than the pressure
Paus in the exhaust. This means that the gas mass in the left elbow is more crowded than the right.
The mass will be accelerated on the right night. It flows from the gas cylinder in the manifold and thereby
the cylinder pressure drops Pzyl.
At the same gas flows from the exhaust manifold in volume, thereby increasing the exhaust pressure Paus.
As long as the cylinder pressure of the exhaust pressure Pzyl Paus is the gas mass in the manifold
accelerated and the flow velocity on the increase.
This goes on until Pzyl Paus is the same. Then the gas mass reaches its maximum speed.
Because the flow from left to right, ie running from the cylinder to exhaust, remains in the cylinder always
less gas left, so the pressure drops Pzyl ever. And the exhaust is it just the other way.
There is always flowing into it more gas, so that the pressure continues to rise Paus. Paus is therefore higher than
Pzyl. The right of the elbow will be more crowded than on the left and the flow in the manifold is always
decelerated more, until it completely stops.
The crowd is right now much stronger than the left, so the currently stagnant gas mass in the
Now bend to the left accelerates back to the cylinder.
The acceleration remains active until Pzyl Paus again is the same. Then the mass of gas has reiterated its maximum
Speed ​​is reached, but this time left. After growing Pzyl beyond Paus and after the
left flowing gas mass decelerated again until it stops.
Now we are back at the starting point: the cylinder pressure Pzyl is high, the exhaust pressure is Paus
lower, and the mass of gas in the manifold is stationary. She has now performed a complete oscillation of
left to right and back.
Case 2: Imagine that the cylinder volume is now twice as big VZYL. The cylinder is so much
more gas as in Case 1 Now, if gas from the cylinder flows in the manifold, the cylinder pressure decreases Pzyl
much more slowly. So down it takes longer now to Pzyl up at the Pau-value.
It takes longer to stop the flow. And then when the flow goes to the left, back to the
Cylinder increases, Pzyl at much slower and takes longer to stop this reverse flow.
Everything just takes longer.
Case 3: Let us now before the exhaust volume Vout also made twice as large. If dan
Gas from the exhaust manifold flows in, the pressure Paus also much slower. It takes longer to
the flow is slowed down to the right and the return flow comes to the left in motion. And so on.
Case 4: Now we do the Krümmerdurchmesser much smaller, as in Figure HFD-4.
The piston is released to the exhaust port. The mass of gas in the manifold is on the pressure difference
Pzyl-Paus back to the right and accelerates the flow velocity increases again. But because
the small Krümmerdurchmessers comes despite the gas flow rate less mass per
Second from the cylinder to the exhaust. The cylinder entlehrt So slowly, the pressure drops Pzyl
slower, the pressure rises more slowly Paus, everything is slower.
Case 5: the elbow regains its original diameter, as shown in Fig HFD-1. But now
we make, such as image HFD-5 shows the manifold much shorter.
All other values ​​VZYL, Pzyl, Vout and Pau are the same as in Case 1
The pressure difference Pzyl-Paus of the acceleration provides the mass of gas, is again the same.
But the mass itself is now much smaller! Therefore, it is accelerated harder.
The flow rate increases faster, the cylinder pressure Pzyl decreases faster and the exhaust pressure
Paus is increasing rapidly. The flow velocity reaches its maximum value is more likely, rather slowed down,
rather, the direction changes from right to left, there is also decelerated more. In short, the
whole vibration plays in less time.
Leak
Now to another topic. I have stated several times: gas flows from the manifold in
Exhaust volume, thereby increasing the exhaust pressure Paus. But even in HFD-1 image you can see the hook:
the tailpipe! The exhaust has a leak. It comes in. Although gas, but also some same time escaped.
Therefore, the pressure Paus not nearly as fast as you expect without the tail pipe like it.
The pressure in the exhaust behaves as if the exhaust volume would be larger in reality. And
the larger the pipe diameter increases slower Paus Paus, and the lower is the peak-
be. The final hole acts like a shock absorber in the system.
Far left of the images are somewhat remarkable: the overflow. Once the piston
the scavenging port releases, has not only the exhaust volume, but also the cylinder volume a leak.
The cylinder pressure drops Pzyl though because gas flows away from the cylinder above the elbow, but as soon as
Pzyl comes under the irrigation pressure, fresh gas is refilled. Pzyl decreases less rapidly so as to
closed transfer ports.
Once through the opening of the overflow valve, the cylinder volume is brought into communication with the crankcase volume,
Thus it behaves as if it were greater in reality. The vibration in
this coupled volume and tube-dan system is running slower, and the system frequency drops.
Now you have something to ponder:
An increase in volume of the exhaust system reduces the frequency.
A reduction of Krümmerdurchmessers well.
A shortening of the manifold increases the frequency.
An enlargement of the Spülsteuerwinkels lowers the frequency.
An enlargement of the tail pipe diameter reduces the frequency and weakens the pressure fluctuations in the
Exhaust.

Frits Overmars
13th August 2012, 20:55
O boy, Google Translator at work, isn't it? There are passages not even I can understand. And I wrote the damn article!
Warning: translating via Google may not give you a better understanding, but it will certainly give you a headache!

Buckets4Me
13th August 2012, 20:57
O boy, Google Translator at work, isn't it? There are passages not even I can understand. And I wrote the damn article!
Warning: translating via Google may not give you a better understanding, but it will certainly give you a headache!

aha but i can now understand it like a 12 year old

to lazy but was hoping someone may take up the chalange

TZ350
13th August 2012, 21:36
In 1970 I was doing the grand tour around NZ with a few friends on our bikes. And we visited Burt, Burt liked it if visitors brought a generous meal of fish and chips to share.

His home and workshop was two concrete block sheds side by side, each was about the size of a single car garage. The car and windmill lived in one and Bert, the lathe, workbench and bikes in the other.

We spent an hour or so there chatting and marvelling at the windmill contraption he used for a dyno, the shelf of broken engine pieces and the basic hand tools with which he made everything.

One of my friends still has a match box full of little bits of engine from Burts big blow up at Muriwai.

Pictures were originaly posted by Husaberg

TZ350
13th August 2012, 21:39
Burts comments ”That the engine was blown up on a regular basis and new schemes to extract more speed from the engine often made it slower or just increased the pile of blown parts.” Well that’s familiar to me and probably sounds very familiar to anyone else who has tried their hand at “improving things”.

I guess there is a little bit of Burts spirit in most of us.

Pictures were originaly posted by Husaberg

TZ350
13th August 2012, 21:42
I hesitate to compare ourselves in anyway to the great man, but Team ESE do everything with pretty basic hand tools too.

husaberg
13th August 2012, 21:46
One of my friends still has a match box full of little bits of engine from Burts big blow up at Muriwai.

Pictures were originaly posted by HusaBurg


I hope they don't have any of burts teeth mixed in:shit:

One of the trophies for Cams had (could have be recycled as the Burt Munroe Memorial throphy i guess) a pair of Burts conrods. I will post a pic if i have one.
There is a beautiful story in George Beggs book he wrote on Burt How he used to cajole people (press-gang) into helping with the paddlewheel dyno. It only worked once of course:gob:
If you get the chance, read the book. The Velo is over looked by most people, but that was just as well developed.From what i understand was the Worlds Fastest Velocette as well.

wax
13th August 2012, 21:54
Reposted because someone wanted to see how the pumper was mounted. The little white hose thing is a mod for the pulse line from the crankcase. There are more photos on the original post.
How did you find the pumper carb in comparison to a float style carburetor, Im looking at running one of these on an engine I am building to try and make the intake as short as possible as well

F5 Dave
13th August 2012, 21:59
Well I'll be right into the cases with the carb mounted that close on the shortened mount. So its a project for later, there's room to dig into it so I'm not too swayed by the inconvenience.

TZ350
13th August 2012, 22:04
How did you find the pumper carb in comparison to a float style carburetor, Im looking at running one of these on an engine I am building to try and make the intake as short as possible as well

I thought it was a very good carb and when I got used to it I found it very easy to tune. It took me a while to get used to doing very small 1/16 turn adjustments on the needles. To start with, I would rush it and mess it up.

In the end the problem with it was that as the power increased over 28+ it could not pass enough fuel to keep up, it could be modified I guess but it is now destined for a RG50 where the inlet tract is on quite a steep angle that doesn't suit conventional carbs.

I got my best run from it without any sort of bellmouth, and now think those fancy bellmouths you see for these carbs are more about somewhere for the airbox than air intake.

268146

All the inlet you need for 28 hp.

268147

Air cooled, 125cc rotary valve, 24mm Tillotson HL360A carb, 1979 Suzuki GP125 2-stroke engine with original (ported) cylinder.

TZ350
13th August 2012, 22:09
Well I'll be right into the cases with the carb mounted that close on the shortened mount.

Same here, because the RV cover is behind the clutch cover on the GP engine so it is a bit of a challange, not impossible just difficult and time consuming so it will have to wait till some of the other projects are out of the way.

268149

But I am certainly going to re visit the plenum idea too as that allows for a very easy short inlet.

kel
13th August 2012, 22:38
Oh no ..... :facepalm: ... it was hard enough to get down to 130 and EngMod2T points to 85mm

Now I will have to look at Fritz's Idea.
It will work on the KE using the standard 24mm Mikuni. I got all inspired by Fritz's very clever (why couldn't I see that myself) mounting method.
So I taper bored the Mikuni, 24mm venturi 28mm outlet. Even had to do it myself as that meany TZ350 wouldn't do it :bleh:. The standard inlet length is under 100mm, approximately 30mm shorter than with the PWK. With a small amount of machining the outlet will fit nicely into the valve cover spigot reducing the overall length to wait for it ... 85mm!
268152268154268156

wax
13th August 2012, 22:49
I thought it was a very good carb and when I got used to it I found it very easy to tune. It took me a while to get used to doing very small 1/16 turn adjustments on the needles. To start with, I would rush it and mess it up.

In the end the problem with it was that as the power increased over 28+ it could not pass enough fuel to keep up, it could be modified I guess but it is now destined for a RG50 where the inlet tract is on quite a steep angle that doesn't suit conventional carbs.

I got my best run from it without any sort of bellmouth, and now think those fancy bellmouths you see for these carbs are more about somewhere for the airbox than air intake.

268146

It managed to support 28 hp with the inlet like this.

268147

Air cooled, 125cc rotary valve, 24mm Tillotson HL360A carb, 1979 Suzuki GP125 2-stroke engine with original (ported) cylinder.

Thats great thanks I am using it on an yamaha scooter and its running vertical so easy to fit. They say they dont hold tune well and are very fussy with air density changes.

Rg50 does that by chance run the mineralli am6 cylinder

husaberg
13th August 2012, 22:56
I hesitate to compare ourselves in anyway to the great man, but Team ESE have only pretty basic hand tools to work with too.

I see huge parallels. Burt used a 30 plus year old engine Air cooled and all:yes:

TZ350
13th August 2012, 23:03
With a small amount of machining the outlet will fit nicely into the valve cover spigot reducing the overall length to wait for it ... 85mm!
268152268154268156

Good effort ...... 85mm, I am mildly jellous .... :sick: ... Ok .. green with envy.

TZ350
13th August 2012, 23:04
I see huge parallels. Burt used a 30 plus year old engine Air cooled and all:yes:

I am about the same age as when he was going to Bonneville too.

husaberg
13th August 2012, 23:07
I am about the same age as when he was going to Bonneville too.

I was not mean enough to mention that:innocent:

Bert
14th August 2012, 06:21
Rg50 does that by chance run the mineralli am6 cylinder?

Nope; suzuki special. crankcase reed like the old TS/DF/TF/RM... from what I can see they still make them in the TS&RMX 50s/80s...


its a little weird posting with my nickname; while everyone is posting about Burt...

wobbly
14th August 2012, 08:02
The tuned intake length testing I did with the reed engine was based on Dynamation sim results and as I have shown here before,involves combining the
case pressure ratio dropping below atma,at the same time as the intake length resonates with a + ratio at the reeds.
This opens them real quick,and fast,initiating intake flow early in the cycle.
Having around 135mm from bell to reed tips gives a good result centred around 12,000 rpm so works well on alot of 125s.
This tunes the intake to the 2rd harmonic from memory as it gives the best energy recovery over the widest range.
Using this approach on a 250 power unit gives really good gains ( making the length around 50% longer again ) and proves that the only reason the factories use 125 size carbs and manifolds
on these MX bikes ,is simply that there is no room.
Another pointer is that for example on the old TZ250 piston port.
If you are silly enough to remove the 20mm phenolic spacer fitted by the factory to "get some more top end ", all that happens is the the tuning range moves up past 12,000
and it is impossible to jet the thing at lower rpm.
Same with the tossers selling shortened carbs for the TZ350, simply throwing away a bunch of free mid power with no addition of any top end at all - the factory chose the big/long body Mikuni for a reason..

The RV scenario probably is working on the short 3rd harmonic, with less energy recovery, but also the very short length is mechanically desirable and reduces the deleterious effect
of the standing waves on the fuel delivery from the jets.

dinamik2t
14th August 2012, 10:26
The tuned intake length testing I did with the reed engine was based on Dynamation sim results and as I have shown here before,involves combining the
case pressure ratio dropping below atma,at the same time as the intake length resonates with a + ratio at the reeds.
This opens them real quick,and fast,initiating intake flow early in the cycle.
Having around 135mm from bell to reed tips gives a good result centred around 12,000 rpm so works well on alot of 125s.
This tunes the intake to the 2rd harmonic from memory as it gives the best energy recovery over the widest range.

Based on RS125 pressure graphs, with SPJ/short rubber, it is tuned on the 2nd harmonic -your memory tests great Wob. But intake pressure is a little after its '+' peak and dropping, when case pressure falls below 1atm -> in contrast with the + for the intake/- for the case, which seems to be the case for RVs and the 3rd harmonic.
The latter scenario though looks unachievable for a reed valver, unless a short carb and a zero length rubber is incorporated!

It's the point for best power spread in my files too. Intake flow starts very early!
However, intake length is around 150mm (for RS too).:confused:

268164

edit: actually, on the RS graph, intake pressure wave is a little before its '+' peak (and rising), when crank pressure is at 0-. Sorry, I was mistaken by my pressure waves (I waver{r} too from time to time)

RAW
14th August 2012, 10:27
Just to head off on a different approach, is it possible to have to short of a intake length ? And if so how would one know, what type of characteristics could one expect to see?
Could it be desirable if mechanically possible to have the exhaust length / volume variable so as to achieve a desirable outcome?
With regards to the use of a power jet to switch off as a means to create a desirable overrun effect, what would one expect to see with a variable pipe length / volume, could one expect to see a power increase along with the ability to not have to use a power jet untill somewhere further up the RPM scale therefore having a greater increase in useable torque at what would have previously been the overrun rpm
The wealth of informative education within this forum is unprecedented, I now have a far greater understanding of the way a 2stroke works and as such the way I deduce and implement an idea has now become a thus far a successful one

Frits, wobbly and of coarse all of the others whom have shared there wisdom I have followed and implemented your teachings with a great personal success and relief, I now have a renewed energy to continue on within the racing scene.
A very much appreciated thanks to you all

Frits Overmars
14th August 2012, 10:54
Thanks for the flowers, RAW.
You can have an intake length that is too short in combination with intake diameter, intake timing, crankcase volume and desired rpm, in which case the engine will express its displeasure by blowing back some of the inhaled mixture. I prefer to shorten the intake length as much as possible and shorten the intake timing accordingly.
By varying intake length, intake timing or crankcase volume you can adapt the induction system to different rpms. I think the best way to adapt to low revs is to advance the intake closing; it will make for a docile engine with a clean, easy to set carburation.

Varying exhaust pipe length seems to be a far better way of increasing overrev than retarding the ignition or leaning out the mixture; it would be a waste not to utilize all inhaled oxygen. Varying the pipe length can also markedly lower the beginning of the power band.

wax
14th August 2012, 13:29
Thats a very interesting part of the thread, talking intake length . Is there a rule of thumb of tuned length for rpm.

RAW
14th August 2012, 16:35
Thanks for the flowers, RAW.
You can have an intake length that is too short in combination with intake diameter, intake timing, crankcase volume and desired rpm, in which case the engine will express its displeasure by blowing back some of the inhaled mixture. I prefer to shorten the intake length as much as possible and shorten the intake timing accordingly.
By varying intake length, intake timing or crankcase volume you can adapt the induction system to different rpms. I think the best way to adapt to low revs is to advance the intake closing; it will make for a docile engine with a clean, easy to set carburation.

Varying exhaust pipe length seems to be a far better way of increasing overrev than retarding the ignition or leaning out the mixture; it would be a waste not to utilize all inhaled oxygen. Varying the pipe length can also markedly lower the onset of the power band.

Understand the low revs advanced intake closing, if we were to use an engine configuration all seem to be magnetized to and of which all can see the layout of via various posts, the RSA / RSW 125.

If we were to turn the power jet of at say 12,700 rpm in the RSW / RSA engine to achieve our desired overrev, would it be prudent to alter a variable pipe length so as to raise the torque peak to a higher than previous rpm and follow up with the power jet at some later rpm than previous thus hoping to increase the overall Power of an engines forward propulsion, I'm perhaps misunderstanding this overrev phernomonom and it's link to ignition retard, the power jet lean out and increased pipe heat. as you stated the on set of the power band may also be lowered with a variable pipe, I suppose I'm looking at this with trying to achieve more useable power at the lower rpm range and also at the upper rpm threshold of which maybe in excess of 14,000 rpm

In my situation the lower rpm power I'm happy with, its the 6th gear long straights where it runs out of puff, that is untill several teaching were followed
120mm con rod
42mm carb
Shortened inlet tract
It's happy and fun now

Drew
14th August 2012, 16:58
On the GT125, I've come up with a way to reed feed it(trademark pending on that wee gem). Should I still aim for 130mm even though it's only feeding 67cc?

Frits Overmars
14th August 2012, 18:02
If we were to turn the power jet of at say 12,700 rpm in the RSW / RSA engine to achieve our desired overrev, would it be prudent to alter a variable pipe length so as to raise the torque peak to a higher than previous rpm and follow up with the power jet at some later rpm than previous thus hoping to increase the overall Power of an engines forward propulsion, I'm perhaps misunderstanding this overrev phernomonom and it's link to ignition retard, the power jet lean out and increased pipe heat. as you stated the on set of the power band may also be lowered with a variable pipe, I suppose I'm looking at this with trying to achieve more useable power at the lower rpm range and also at the upper rpm threshold of which maybe in excess of 14,000 rpmWith a variable header length you do not need to artificially raise the exhaust gas temperature, so you need neither the power jet nor the ignition retard.
The 50 cc engine with trombone pipe that I wrote about some time ago, runs strongly from 7,000 to 17,000 rpm without power jet and ignition retard.

Note: the power jet in the Aprilia RSW / RSA is gradually closed and the ignition is gradually retarded till 10° before TDC. These engines rev to 14,500 rpm. But I am convinced that with a trombone pipe they would function much better still.

TZ350
14th August 2012, 22:47
With a variable header length you do not need to artificially raise the exhaust gas temperature, so you need neither the power jet nor the ignition retard.
The 50 cc engine with trombone pipe that I wrote about some time ago, runs strongly from 7,000 to 17,000 rpm without power jet and ignition retard.


... a couple of recent videos from the Dutch 50 cc scene.
http://www.youtube.com/watch?v=mvV4xbFKs0g&feature=relmfu
http://youtu.be/0odVzSgufjk


It was designed and built by Richard Maas http://www.adriaanmeeuwsen.nl/team-pagina.html. Hopefully we will see it in action next monday.
And if I were you, I would make it go shorter with rpm :whistle:.


after playing with EngMod2T again for a bit and with the exhaust port width reduced to a sensible 40mm (70%) and a few other tweeks with the Trombone pipe I find I can pretty much make the same power as before.

262201

And it looks like a useful 5.5k power spread from 9-14.5K, with a 30+ hp peak and a virtually flat 2.5k spread across the top is on the cards using a Trombone pipe. If I can do it.


262505

130mm Trombone Header

After playing with EngMod2T a bit more I found that the interesting thing about the pipe elements needing to stay within certain percentage limits is that when you reduce the headers length, like in the Trombone arrangement the overall tuned length also reduces so the headers percentage of the overall length does not get out of balance as quickly as you might think.

I am very taken with the Trombones possibilities and after using EngMod2T to simulate it, it looks like the Trombone is much better at extending a pipes upper range than plumping up the lower part of the torque curve below the pipes natural operating point.

So if you have an engine with a pipe good for 13K and a mechanical limit of 14 then its not much point in making a 13K trombone that can run 6K from 12 to 18.

After looking at the EngMod simulation results I think it makes better sense to discard my 13K pipe and design a pipe that’s a strong torque monster at 8K with the trombone effect extending its range out 6K to the engines 14K limit.

268214

That’s the approach I am going to take when I make one of these for Beast-2.

A trombone and power valve combination would be even better.

Frits Overmars
14th August 2012, 23:20
....A trombone and power valve combination would be even better...if you have trial riding in mind...
A (partly) closed powervalve will spoil the exhaust pulse and exclude true 180°-resonance, so you will never get a decent torque value.
I think the trombone alone will be a better choice. It will be easier to realize as well. Remember: KISS.

RAW
15th August 2012, 00:13
More news from Richard Maas. Did his trombone pipe give the desired results? O yes. At 10,000 rpm it gives 4 HP more than the same engine with a fixed pipe. It runs over 17,000 rpm without the need for a powerjet and with a fixed ignition timing. It is miles better than an engine with an exhaust power valve. And the mapping of pipe length, ignition timing and powerjet pulse width has yet to be carried out. Maybe the powerjet can disappear altogether.
Only problem so far: the piece of pipe that is fixed to the cylinder, is shrouded by the pipe that slides over it, so it gets very hot. Too hot for the Viton O-ring that is taking care of sealing. Any bright ideas, anyone?

Just been re- reading and couldn't help but wonder if the system is fully functioning, did anyone solve the sealing issue of the sliding surfaces.

Further with the aprilia RSW / RSA exhaust port, the exhaust stub fitted to the barrel is approximately 40mm long and roughly has an internal diameter of 43mm, the port shape within the barrel is not round leaving a large step upon the upper and lower surfaces, how,why what is going on here ? I'm aware this is common to several engines but I have never spent the time to ask myself as to what may be the reason for this, I can only imagine there must be a good reason for this but I'm unable to think of one

Frits Overmars
15th August 2012, 00:27
Wobbly, are you there?
This one is for you, as I promised my lady a holiday and she promised to throw my laptop out the window if I don't stop answering forum questions.

ief
15th August 2012, 03:29
That is all ready covered in this thread... somewhere :)

one little snipped i could find for now:


Originally Posted by wobbly
Only Yamaha stuck with the wank flat roof scenario way after the use by date, and got their arses kicked for years in GP.

Till they finally bought a CNC controlled Jante machine from Czech, went square bore/stroke and using the 500 cylinders on the 250 easily won the champs in 2000 with Olivier Jaques.

The secondarys facing each other relatively flat will always collide, but the hooks rotate the flow under the boost as it exits the port ( easy to see with the tap water Jante trick),clearing out a big "dead" area
in front of the rear port.

All modern race engines have a nozzle restriction at the flange face, as big T ports and tripple Exhausts loose alot of velocity going into the header.
Rule of thumb is a 75% of the effective EX area at the flange.
Stepped oval duct into a round flange does work, but I have used a CNC oval to round transition in the spigot for years, as has Honda in A kit, and Aprilia factory engines, this works way better.

Here is a sim showing my new 400cc F3 engine, with and without the spigot nozzle.

The stinger nozzle effectively removes the stinger tube length from the equation - it was developed for Spencers NSR that had one stinger 150 long, the other was 450. The nozzle is around 2 to 3mm smaller than the tube stinger .

TZ350
15th August 2012, 03:37
A (partly) closed powervalve will spoil the exhaust pulse and exclude true 180°-resonance, so you will never get a decent torque value.

I have had a re read of your original post, thanks .....


The short answer is yes. But why is it that each time you people sit down for five minutes to write a question, I have to sit down for two hours to write an answer?:msn-wink:

When the exhaust port opens, a pressure pulse starts moving through the exhaust pipe. It is reflected at the end cone and it should be back at the cylinder just before the exhaust port closes.
Next a part of this reflected pulse bounces off the partly-closed exhaust port and a residual pulse starts moving down the exhaust pipe. This residual pulse too is reflected by the end cone and starts moving back to the cylinder. Ideally it will arrive at the exhaust port just when the port opens again. Then the cylinder pressure and the pressure of the residual pulse combine their energy and the resulting pulse will be stronger than the pulse from the previous cycle. And the combined pulse from the next cycle will be stronger still, and so on; we have achieved true resonance.

Some may argue that we want a low pressure in the exhaust pipe when the port opens because then the spent gases will experience less resistance while leaving the cylinder. But that is not true. Gas flow depends on a pressure difference ratio. But once that ratio reaches 2, the flow velocity will reach Mach 1, the speed of sound. Raising the pressure difference any further will not raise the flow velocity any further.
The cylinder pressure at exhaust opening can be as high as 7 bar and the pressure of the reflected pulse will be about 2 bar. Thus the pressure ratio is well above 2, so lowering the pressure in the exhaust duct outside the cylinder will not do any good to the flow.

What has the exhaust timing got to do with the 'true resonance' I mentioned above?
The initial pulse starts moving at Exhaust Opening and it has to be back at Exhaust Closing, or a little earlier. This pulse travels with the speed of sound and its journey up and down the exhaust pipe will take t seconds.
The residual pulse starts moving at Exhaust Closing and it has to be back at the next Exhaust Opening. This pulse also travels with the speed of sound and its journey up and down the exhaust pipe will also take t seconds.
So from EO to EC takes t seconds and from EC to EO also takes t seconds. In English: the exhaust port should be open just as long as it should be closed.
Assuming that the crankshaft rotates with a uniform speed, this means that the crank angle during which the exhaust is open must be equal to the crank angle during which the port is closed. So both angles must be 180°.

I developed this line of thought some 40 years ago, but when I first published it in 1978 (in the motorcycle magazine Moto73 of which I was the technical editor) everybody called me crazy. Some people still do, but I got used to it :p.

Above I made a couple of assumptions. The crankshaft does not rotate with a uniform speed, but at high revs the deviation is negligible. In case you really want to know, I did the math for the Aprilia RSA125. At a nominal rpm of 13,000 the minimum rotation speed is 12970 rpm @ 107° after TDC and the maximum value is 13031 rpm @ 356° aTDC. What's more significant: the deviation in crankshaft position from truly uniform rotation is always less than 1°. So that really is negligible.

Second assumption: both the initial pulse and the residual pulse move with the speed of sound. Not true: the pulse pressures in exhaust waves are so high that acoustics rules do not apply any more. We are dealing with gas dynamics here and the stronger a pulse, the faster it moves. Since the residual pulse is weaker than the initial pulse, they move at different speeds. But we will leave this aside for now.

Third assumption: the initial pulse starts moving as soon as the exhaust port starts opening. More or less true, but we are not interested in the first weak appearance of the pulse; we want to know when the pulse reaches its maximum amplitude. And that requires a certain amount of open exhaust port area. It turns out that for our desired theoretical exhaust timing of 180° we will need a geometrical exhaust timing of about 190°, depending on the shape of the port: does it open gradually or does it open over its full width all at once.
The obvious question will be: why has the Aprilia RSA125 a geometrical exhaust timing of about 200°? True, at 190° the maximum torque value would be higher, but the engine would not want to rev because the blowdown time.area would be too small.
The 200° are a compromise: a bit less torque and a bit more revs; as long as the torque decline is smaller than the rpm rise, we gain horsepower.


The tech term for what Frits is describing is Superposition of the Ex pulse.
This is easily described in a sim, where a residual pressure ratio is seen sitting at the Ex port when it is opening.
The "new " pulse is added to this residual, and a very large pressure ratio exits down the duct to the header.
The larger the initial ratio, the larger the amplitude of the wave in the diffuser - this creates a deeper depression around BDC, and it is this that initiates the biggest mass flow
from the transfers.
The lower Ex timings of 190 and below create larger residual pressure ratios,over a wider band, and thus these work with a good pipe design to use "resonance" to increase band width and also peak power.
Big problem though is this whole concept is at odds with maximising blowdown to allow good peak power and more importantly, overev power.

The sim shows RGV100 making serious power with the superposition pulse going down the duct - off the scale.

Re the trombone pipe results you did sims for TeeZee.
Look carefully when you say it seems to affect the top end "more ".
At 9000 the lowest reading is 13 Hp, the highest reading is 17 Hp, thats an increase of 4 Hp, thats 31% more power in the bottom end, that then allows the thing to rev to 17,000.
Seems a not bad result.

Re the powerjet temp result you mentioned.
The effect of the solenoid powerjet is as you described - this I only discovered recently with a datalogger that I could set the sample rate of the EGT high enough to read the temps quick enough - along
with some exposed junction probes.
I was testing a RS125 on the dyno and it was making NO power past 12500, looking at the data you could see the egt drop from 640 C to 580 in around 400 rpm.
After fixing the fact some idiot had left out the rpm plug in the loom, the solenoid now switched on at 12200, and the temp stabilised at 650 past 12500 and the thing than reved out to 13500 +.
So the powerjet switching isnt making the mixture "lean"as such, it is simply maintaining the correct mixture, and thus the temp in the pipe.

wobbly
15th August 2012, 07:56
Simple answer re the odd shape and reduced area of the Ex duct exit is that with a 3 port cylinder, the area of the main port is plenty big enough to support the gas flow
created by the power being made.
The big Aux additional area allows better Blowdown STA, but this area is only needed above TRO.
Thus having a huge duct simply drops the velocity, reducing the wave amplitude into the header.
The Aprilia shape promotes the flow from the Aux ports by keeping the extra horizontal area all the way into the pipe - thus helping blowdown flow and overev power..
Reducing the duct vol by having area reducing steps, keeps the velocity high and again promotes the flow regime in the side ports.
There may be a case to say that the steps reduce backflow from the pipe at low rpm when it is too short,but for sure there is no outflow disruption,and in any case tests showed that power went up as the duct became smaller.
I have exhaustively ( pun ) tested the vol/shape effects on a T port ( as has Mr H ) and an oval to round transition with no steps works better.
A factory A Kit has a very small 41 by 32 oval, with a CNC transition into a 41 header.

RAW
15th August 2012, 10:47
A big thanks guys, looks like I need to build me some new header spigots
anyone know which page has a pic of this oval to round transition, I'm getting very forgetfull and just don't have the time to re-read this forum at the current time

F5 Dave
15th August 2012, 11:00
And you think we do?:blink:


Try the advanced search for this thread & search say on Wobbly & CNC or something like that.

Haufen
15th August 2012, 11:00
A big thanks guys, looks like I need to build me some new header spigots
anyone know which page has a pic of this oval to round transition, I'm getting very forgetfull and just don't have the time to re-read this forum at the current time

here you go (http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1129955411#post1129955411) (did a thread search on "Only Yamaha stuck with the wank flat roof")

Wer there any suggestions on where to put the o2r transition and how long it should be, ideally? Like percentage numbers or something like that.

2T Institute
15th August 2012, 13:42
Wobbly, are you there?
This one is for you, as I promised my lady a holiday and she promised to throw my laptop out the window if I don't stop answering forum questions.

You forgot the simple bike pump analogy you gave me many moons ago Frits.

"The connector between the pump and tube has a very narrow, the tyre will have much higher pressure than the pump, the connector make a high velocity pulse that can over come the pressure in the tube to force some more air into the tube. If the connector had a large volume the pump would only vary the pressure in the connector and never open the valve"

Taken from my dodgy memory. Just another clever Jan Thiel trick.


Further with the aprilia RSW / RSA exhaust port, the exhaust stub fitted to the barrel is approximately 40mm long and roughly has an internal diameter of 43mm, the port shape within the barrel is not round leaving a large step upon the upper and lower surfaces, how,why what is going on here ? I'm aware this is common to several engines but I have never spent the time to ask myself as to what may be the reason for this, I can only imagine there must be a good reason for this but I'm unable to think of one .

RAW
15th August 2012, 15:20
here you go (http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1129955411#post1129955411) (did a thread search on "Only Yamaha stuck with the wank flat roof")

Wer there any suggestions on where to put the o2r transition and how long it should be, ideally? Like percentage numbers or something like that.

Cheers, appreciate the help,
So many things to contemplate now, spigots, trumpet pipes & there drive systems, oh well I suppose I won't get bored, just frustrated on how i may go about all of this new learnt performance advancement correctly

TZ350
15th August 2012, 16:31
... don't have the time to re-read this forum at the current time

You can also use Thread Tools then View Thread Images and sort them 70 to a page, thats a quicker way of re finding interesting stuff.

TZ350
15th August 2012, 18:17
268228 268223

I am taking another look at the plenum, tonight I Devcon puttied up the inside of the chamber so that any fuel dropout runs to a collection point and can be pumped away by the pulse pump. Hopefully this will get over the unstable fuel mixture issues with the puddling problem we had before.

At the moment the chamber is 1L and EngMod suggests 2L would be better so a bit of work to be done there. For anyone interested in the math, 2L makes the plenum 16 times the size of the engine.

wobbly
15th August 2012, 20:26
Exactly the reason that the so called pumping pressure the Yanks love is a complete and utter waste of time.
Unless you use the same guage for years and understand the numbers it tells you.
Spin the engine over and it pumps up 180 psi - change the dia or length of tube between the gauge and the plug hole and the number changes.
Accurate as hell eh - even how much lube on the bore will change the number.
Just lazy bastards that dont want to or dont know how to, do it properly, will think this is just fine.
16 :1 full stroke com is a calculated number - who gives a shit where the Ex port opens, the ratio is still the same.
If its the correct ratio to use with a specific port timing is another matter altogether.
Lets at least try and move ahead in the most accurate and repeatable way possible

TZ350
15th August 2012, 21:00
Exactly the reason that the so called pumping pressure the Yanks love is a complete and utter waste of time. Lets at least try and move ahead in the most accurate and repeatable way possible

Totaly True .....

But there is another use for knowing the pumping pressure .....

Having accurately cc'd the clearance volume and adjusted it to the design spec, measuring the actual pumping pressure hot with your trusty compression tester can be very useful when trying to diagnose a problem like I had at Taupo.

Where there was enough compression to feel good pulling the back wheel over but less than the original pumping pressure was or should be.

If I had recorded that and measured what I had at Taupo I would have known where the problem was. There are times when having a compression gauge and knowing what the original pumping pressure hot at cranking speed was can be very handy. Of course in the interests of repetability it pays to use the same gauge.

If you were not to lazy to have noted the original pressure, re checking it in times of trouble is as simple as checking for spark and fuel really and just as important.

When the engine refuses to play the game, if it was built properly and has been running well before, who cares what the designed clearance volume or com ratio was.

At the track, its all about Compression Pressure plus Fuel and a Spark at the right time, the three essentials and it pays to know all you can about each of them.

Bert
16th August 2012, 01:17
Totaly True .....

But there is another use for knowing the pumping pressure .....

Having accurately cc'd the clearance volume and adjusted it to the design spec, measuring the actual pumping pressure hot with your trusty compression tester can be very useful when trying to diagnose a problem like I had at Taupo.
.......
When the engine refuses to play the game, if it was built properly and has been running well before, who cares what the designed clearance volume or com ratio was.

At the track, its all about Compression Pressure plus Fuel and a Spark at the right time, the three essentials and it pays to know all you can about each of them.

Yip; that's why I test (same old meter; which I do check periodicity) it after rebuilds and write it on the inside of the frame or engrave it on the head. nothing worst than loosing your bit of paper in your toolbox on race day; when the pressure is on to sort it out....... I do agree with Wobs; but comp testing is another tool to help make diagnostics and if used correctly does help (just don't forget to measure the temp as well; I never understood why the testers didn't have a temp probe built in as well:angry:).

wobbly
16th August 2012, 08:05
Using the pumping pressure for diagnosis is fine.
Saying - its got 220psi, so is perfect for Avgas is bullshit.
I have seen a variation of 30 psi in 200 depending upon how wet the bore is.
Try varying the com up or down by 15%,thats instant blowup Vs a piece of shit.
Then factor in the issue of varying pressure depending upon the length/dia of hose between different gauges - a flawed test device of the first order.

TZ350
16th August 2012, 08:19
Saying - its got 220psi, so is perfect for Avgas is bullshit.

Do people say that? .... where? ... not here surely.

TZ350
16th August 2012, 10:03
A measuring tool is just a tool.

And one has to apply some intelligence in how you use it and what you infer from it.

268306


- a flawed test device of the first order.

There is no way of making the perfect measurement, every test and measurement device ever known to man is flawed in its own way. Its just a question of how useful the measurement that you can make with it is.


I have seen a variation of 30 psi in 200 depending upon how wet the bore is.

You can probably expect a "Hot" test to reflect the wetness (sealing) of a running motor.

On a four stroke, oil is added to a cylinder that is down on compression as an aid to determining if the compression leak is in the rings or valves, the oil helps seal worn rings. And that probably adds weight to the notion that more oil makes more power in a 2-Stroke.


Then factor in the issue of varying pressure depending upon the length/dia of hose between different gauges

268304

There is a valve in the spark plug adapter fitting so the length of the hose does not matter as the hoses internal pressure is pumped up. And after a few cranking cycles the pressure inside the hose approaches the peak cranking pressure inside the cylinder.

268302

The errors here are the accuracy of the gauge itself and the pressure required to open the valve.

268301

There is another valve here to release the pressure from the hose.

268303268305

The biggest problem I can see with making good measurements, is the difference in volume between the pressure gauges adaptor and the spark plug.

On a big V8 that might not be a significant problem but a 1/2" adaptor on a 50cc 2-stroke engine that uses a 3/4" reach plug like an RG50 now that would make a big change to the measured pumping pressure.

The first picture shows a gauge with different adaptors for this problem.


Try varying the com up or down by 15% ...

So ... yes on our little bikes using a pressure gauge for setting the com ratio would be a disaster.

CCing the assembled engine is the correct way to vary the com ratio, a compression tester is a diagnostic tool. Used properly it can give you some re assurance that everything is OK, and that you havn't made some gross mistake CCing the cylinder/head.

F5 Dave
16th August 2012, 10:03
I've had retarded conversations with people about using gauges for tuning, but they want to cling onto the measuring tool in their hand because they get numbers. Who cares if its wrong or right? There's Numbers!!

:facepalm:

for Giggles a few years ago having rebuilt my dirtbike I thought I'd do a before & after rebuild. Then I skimmed the head to correct crazy squish, got the compression ratio too high (as I'd expected) then took some out of the chamber till I was happy. - Obviously measured with a Burette

the Gauge numbers were all around 199, 198 etc near the end, but actually went up a number when I had measured that I'd taken metal enough to lower the compression about 2 full ratio numbers. Clearly the gauge was bollocks (despite being German) as a tuning tool & overly influenced by oil kicked out of the cases or whatever. To even measure wear over time (which was my only interest) might be distorted.

A leakdown test may (I've never used one except my low pressure - piston at bottom for case leak) be better for checking wear, but why not just pull the top & measure the ring? I spoke to a kart tuner the other day who was all into 'ring seal'. Seemed a bit elusive, I've only just measured ring gap & that seems consistent with power loss, but what do I know, maybe I'm missing something.

bucketracer
16th August 2012, 19:09
268315

Old style dropper Burette, we have several, the taps tend to get stuck if left and they are broken easily.

268314

An easier to use Burette for jobs like CC ing combustion chambers, ESE has one. TeeZee swears its the ultimate.

268316

Then there is the quick and dirty 3 - 5 - 10 CC plastic syringes which are pretty cheap from your local Chemist.

Then top it off with a compression test. :laugh:

Compression testers seem to generate as much emotion as discussing the right type of oil to use did.


I've had retarded conversations with people about using gauges for tuning, but they want to cling onto the measuring tool in their hand because they get numbers. Who cares if its wrong or right? There's Numbers!!

Yes, comfort in numbers, a bit like copying down all the digits from a calculator in the mistaken belief that makes the result more accurate.

husaberg
16th August 2012, 19:23
Compression testers seem to generate as much emotion as discussing the right type of oil to use did.


Tooo Right I am still in Therapy from that one myself.
But somehow i are starting to suspect my psychiatrist must fancy my Mum?
because he always goes on and on about banging her:innocent:
Gee what what Freud say about that? And whats up with this guys Cigar?
gee what would he say about that, Plus why do i like two strokes:eek5:
<img src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Sigmund_Freud_LIFE.jpg/200px-Sigmund_Freud_LIFE.jpg" width="140px"/>

SwePatrick
16th August 2012, 23:51
268228 268223

I am taking another look at the plenum, tonight I Devcon puttied up the inside of the chamber so that any fuel dropout runs to a collection point and can be pumped away by the pulse pump. Hopefully this will get over the unstable fuel mixture issues with the puddling problem we had before.

At the moment the chamber is 1L and EngMod suggests 2L would be better so a bit of work to be done there. For anyone interested in the math, 2L makes the plenum 16 times the size of the engine.

Cool.. but why not just build a pipe like rodeltrack from carb to inlet tract?
It lets almost all fuel that falls out to be sucked in into the engine, then you can tune the plenum pulse with different opening at top of the 'tube'.

it dampens out the pulses and letting the carb work with more even flow but still almost all fuel into engine.
More easily to tune.

Rgds
Patrick

RAW
17th August 2012, 00:29
This ones for Frits
On the pit lane forum you discussed the joining of the intakes upon a twin cylinder reed valve engine, the conection being between the 2 carbs and the reeds of each cylinder, how would this in your opinion function in a twin with rotary discs, would you explain the pros and cons of such a set up for each engine please

TZ350
17th August 2012, 07:16
... but why not just build a pipe like rodeltrack from carb to inlet tract? It lets almost all fuel that falls out to be sucked in into the engine, then you can tune the plenum pulse with different opening at top of the 'tube'. It dampens out the pulses and letting the carb work with more even flow but still almost all fuel into engine.

Hi Patrick sounds good but I don't understand what a "rodeltrack" is or looks like.

I guess its like an inlet tract from carb to crankcase inside the plenum with the top of the inlet tract cut open so it vents to the plenum but guides the fuel and oil into the engine.

Do you have a picture of what you mean?

husaberg
17th August 2012, 07:35
Maybe Trombone Exhaust? or Rod and Track in Google translate?

teriks
17th August 2012, 08:07
Rodel and bobsleigh use the same tracks/runs, see video below.
Looks like you can have fun even without two-strokes ;)


http://www.youtube.com/watch?v=ufRNTCeuDPg&feature=related

F5 Dave
17th August 2012, 10:00
This ones for Frits
On the pit lane forum you discussed the joining of the intakes upon a twin cylinder reed valve engine, the conection being between the 2 carbs and the reeds of each cylinder, how would this in your opinion function in a twin with rotary discs, would you explain the pros and cons of such a set up for each engine please

I think you'll find hes on holiday mate. These Europeans & thier smug opposite hemisphere climates. Oh well at least its not raining here today.

2T Institute
17th August 2012, 11:10
I think you'll find hes on holiday mate. These Europeans & thier smug opposite hemisphere climates. Oh well at least its not raining here today.

Maybe Vrouw Overmars carried out her threat ! (but we all get those threats don't we :yes:)

F5 Dave
17th August 2012, 11:19
Its the middle of summer. "Shall we go on holiday?" Doesn't sound like a threat, - sounds like a treat!


Probably going to be raining at the track sunday when I try my new engine. Dumb winter.
[sigh]

RAW
17th August 2012, 21:07
Maybe Vrouw Overmars carried out her threat ! (but we all get those threats don't we :yes:)

Yeh thats rite, good luck to him ( Frits & partner ) hope your enjoying yourself, I'm sure he is trying to sneak a peek at the forum world given half a chance

Just think of the hundreds of forum questions about the world he now has a chance to answer, this is the first time I don't wish to be in your shoes Frits

RAW
17th August 2012, 21:10
Maybe Vrouw Overmars carried out her threat ! (but we all get those threats don't we :yes:)

Yeh thats rite, good luck to him ( Frits & partner ) hope your enjoying yourself, I'm sure he is trying to sneak a peek at the forum world given half a chance

Just think of the hundreds of forum questions about the world he now has a chance to answer, this is the first time I don't wish to be in your shoes Frits.
:bleh::bleh::bleh:

Haufen
17th August 2012, 23:11
268383

She must have found his spare laptop, let's hope he is allright :chase:

Jokes aside, enjoy your holiday, Frits! :apint:

husaberg
17th August 2012, 23:22
Cool.. but why not just build a pipe like rodeltrack from carb to inlet tract?
It lets almost all fuel that falls out to be sucked in into the engine, then you can tune the plenum pulse with different opening at top of the 'tube'.

it dampens out the pulses and letting the carb work with more even flow but still almost all fuel into engine.
More easily to tune.

Rgds
Patrick

Is this what you mean by rodeltrack.... A spiral?
http://www.clker.com/cliparts/f/4/f/b/1194985749666213381stock-spiral.svg.med.pngor http://ereview.org/wp-content/uploads/2011/08/WaseemTouma_Internal-Formations-plenum-8-5.jpg
kind of Ricardo?
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=268396&d=1345203507&thumb=1&stc=1

I mentioned a while beck thet i guess the reason for dropping the Plenum original was the fuel dropout.
I said something like a balloon or bike tube to vary the volume here is a patent for something similar.
http://www.google.com/patents?id=TVyOAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

2T Institute
18th August 2012, 00:10
268383

She must have found his spare laptop, let's hope he is allright :chase:

Jokes aside, enjoy your holiday, Frits! :apint:

:lol: classic

dtenney
18th August 2012, 00:44
Mr. Bucket racer:

Where does one find the measuring device you showed us...that is really cool. I have broken a lot of burrette tips over the years! I tried to Google search for it but was not successful.

David