ESE's works engine tuner [Archive] - Page 56

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mr bucketracer

5th March 2014, 07:22

was told by Chris Ozbourne that he has seen 600s losing up to 3 hp with wets .. think its the stick of he tire when releasing from the tire . i did run my 50 up on a wet but some how dont think it heated the tire up .....but .3 hp bugger have i time

WilDun

5th March 2014, 18:02

That's pretty solid, there'll be a bunch of fast 50s this year. .

I'm still way behind with what's happening and of course I don't know just when the Tokoroa race day is.(this weekend?)
Seems that there is 50cc racing on there, - wouldn't mind seeing that! - I have never seen 50cc racing here in NZ, maybe I'll be able to make it there, with a bit of luck.

Thanks,
Will.

Henk

5th March 2014, 18:15

Wil

Tokoroa is on this weekend. Sidecar GP Saturday, F4, F5 and Tokoroa cup on Sunday.

TZ350

5th March 2014, 18:40

Tokoroa Air Field and Go Kart club, last side road on the left, off the main road going south, its just on the southern edge of the industrial part of town.

Henk

5th March 2014, 18:54

Aim feild road. Turn right at the end and then follow the gravel to the end.

WilDun

5th March 2014, 20:39

Aim feild road. Turn right at the end and then follow the gravel to the end.

Thanks guys, I hope I will be able to find the time to go there.

chrisc

6th March 2014, 21:00

The following content you are about to see is classified and only recently has been released to select kiwibiker viewers for analysis. This is brought to you by experts in the field who braved much danger to bring you images from behind roller door lines.

This unidentified alloy structure has been said to contain variable moving technology which enhances power delivery beyond that of any normal two stroke infantry man.

http://christophercain.cc/b/d/esefiles/IMG_3097.jpg

A close up of the inner workings of the structure revels alien technology

http://christophercain.cc/b/d/esefiles/IMG_3098.jpg

Like crop circles in adjacent fields, this structure has yet to be deciphered by any human being

http://christophercain.cc/b/d/esefiles/IMG_3096.jpg

These two clearly suspect looking extra terrestrial beings were also identified possessing the previously unseen ability to both increase power AND decrease in their unidentified machines.

http://christophercain.cc/b/d/esefiles/IMG_3089.jpg

http://christophercain.cc/b/d/esefiles/IMG_3087.jpg

chrisc

7th March 2014, 07:20

Bert

7th March 2014, 08:51

Love your work gentlemen...

Some very nice out of the box thinking. Going to make one very nice sidecar engine:innocent:

Drew

7th March 2014, 09:33

Two watercooled scooter motors, twin crank tandem style driving on V belt might be the go for my sidecar I think. Unless I buy shares in Devcon to alter the cases for a single reed/24mm carb and reverse port the GT lump.

WilDun

7th March 2014, 10:04

This unidentified alloy structure has been said to contain variable moving technology which enhances power delivery beyond that of any normal two stroke infantry man.

[/IMG]

When you fitted the new front crankcase, how difficult was it to get the shaft centers the correct distance apart and properly aligned? - I'd be willing to bet it took a bit of very careful engineering!

Will.

TZ350

7th March 2014, 10:17

An interesting bit of chit chat about the big bore Aprilia RS's ....

http://www.apriliaforum.com/forums/archive/index.php/t-246083.html

190mech

7th March 2014, 13:30

Ive grafted a 2T motorcycle engine to a scooter CVT with some sucess,details here;
http://49ccscoot.proboards.com/thread/7119/snoopy-dragscooter-build

husaberg

7th March 2014, 19:16

I no nothing about these? but are they a CVT with chain? I see no Gear lever?

http://www.ebay.co.uk/itm/1992-JAWA-ECONOMY-MOPED-49CC-COMPLETE-2-STROKE-AIRCOOLED-ENGINE-GEARBOX-ASSEMBLY-/271417921918?ssPageName=ADME:B:FSEL:GB:1123

Maybe not oh well.
http://www.jawamoped.com/html/f_a_q_.html

F5 Dave

7th March 2014, 19:41

Yeah you can see the bull Steve spins. Hes off on tangents and has no friggn idea what he's on about. Takes people in though as he spins a good yarn. Calvin died not too long ago.

TZ350

8th March 2014, 06:58

When you fitted the new gearbox housing, how difficult was it to get the shaft centers the correct distance apart and properly aligned? - I'd be willing to bet it took a bit of very careful engineering! Will.

Getting the center distance is no problem as the idle gear position can be adjusted and shaft alignment is not that much of a problem either as a bit of gear noise wont be a problem, things don't have to be perfect.

294600294601

This is Chambers side car project and he has arranged things so that when the GP engine is at 12k the front CVT shaft is spinning at 7k which is about what we think is the std working rpm of the GY6150 motor that the CVT parts came from. Of course final tuning of the CVT can be done with springs and slider weights.

TZ350

8th March 2014, 07:26

NedKellys 50.

294603294606

10.8 purple line Ex opens 87 deg atdc duration 186 deg and original fat pipe.
11.0 green line Ex opens 87 deg atdc duration 186 deg and original fat pipe -30mm from the mid section.
11.0 red line is Ex opens 87 deg atdc duration 186 deg and Frits pipe.
12.0 blue line Ex opens 81 deg atdc duration 186 deg and Fritz pipe.

294602

11.0 red line is Ex opens 87 deg atdc duration 186 deg and Frits pipe.
12.0 blue line Ex opens 81 deg atdc duration 186 deg and Fritz pipe.

294604

The timing for the Frits pipe was supposed to be Ex opens 84 deg atdc for 192 deg duration but I over cooked it and wound up at 81 atdc and 198 duration. As is the transfers were correct at 115atdc duration 130 deg. I found this little cylinder quite hard to work with accuratly. I guess the smallest of errors are magnified when your working with such small dimesions and horse powers.

294605

This is the first one of these small aftermarket cylinders I have worked on. Its pleasing to see that they can be ported without the nicasil pealing off. The technique is to first carefully grind a champher across the top of the port, this leaves a neat champher in the nicasil and a guide for grinding the exhaust port too. But I found it very hard to be accurate. The problem was after setting the piston at the correct position I scribed a line across the top of the piston and the width of the scriber made the line to high.

Next time I will be more careful and and grind the champher in stages, and re check the cylinder on the engine with a degree wheel until the timing is right. Then use the champher as a guide for porting the exhaust port. The nicacil is very hard and I had to grind it with a dremmil but the alloy of this cylinder very soft, much softer than the Suzuki GP cylinders.

TZ350

8th March 2014, 07:35

Packing and of to Tokoroa now ..... see you guys there.

wobbly

8th March 2014, 08:24

The Fritz pipe is very short and is designed to use port resonance with the 192* duration, that is why it generates the big fat rounded power curve.
The pipe using 198 duration is then way too short and has no mid power at all.
Drop the cylinder to get the Ex at say 82.5 atdc and you will get a combination of the fat power band and the good overev of the high duration setup.
Depending upon the transfer layout you could then try reverse stagger on the rears, by grinding them back up, like an Aprilia.
But this will reduce the blowdown, and you will probably loose some peak.

TZ350

8th March 2014, 08:39

Thanks I will try that, hopefully the cylinder as is survives the GP.

Frits Overmars

8th March 2014, 08:48

The Fritz pipe is very short...Mr Wayne Wright, if you keep calling me Fritz instead of Frits, I shall feel obliged to come up with some funny name for you too. Problem is, you've already done that yourself :msn-wink: .

By the way, you are Wright about the fat power band and the good overrev.

TZ350

8th March 2014, 10:01

The Fritz pipe is very short and is designed to use port resonance with the 192* duration, that is why it generates the big fat rounded power curve.

you are Wright about the fat power band and the good overrev.

I understood that, and was absolutely what I was aiming for but my porting skill let me down. :(

Experience with this cylinder has improved my technique, next one should be better. :)

WilDun

8th March 2014, 10:12

Getting the center distance is no problem as the idle gear position can be adjusted and shaft alignment is not that much of a problem either as a bit of gear noise wont be a problem, things don't have to be perfect.

Thanks Robert, I see now how it is possible to adjust the tooth clearance, (sorry, I said gearbox housing when I meant crankcase) - it's still quite an engineering feat which takes some courage to try! good luck with the endeavours.

Unfortunately I won't be able to go to the racing at Tokoroa this year but may have a look at the racing closer to home.

I'm looking forward to getting more familiar with the sort of technical stuff I've been missing out on for years, I hope that I can catch up, but I feel that I may have left it about 10 years too late. - eg, I'd never even seen a dyno in operation till I checked out the clips on this forum.
Also I'm impressed with the cooperation on technical matters between you guys, although I'm sure that you all have some closely guarded secrets too!

Will.

wobbly

8th March 2014, 12:52

So very sorry Frits, I always try so hard not to get it wrong as I know its an issue.
By the way I do have another name version - my youngest son uses it - wAnus - and I probably have the same reaction to that, as you do to yours.

RAW

8th March 2014, 13:28

Wobbly, I haven't heard anything, ? How did things go at the Island in Feb

wobbly

8th March 2014, 14:20

The Frepin with Trevor onboard was easily the fastest in practice, doing 237Km into turn 1 and into the 40s straight off.
But I had found an issue with the Nova special gearset when I assembled it, the two sliding gears on the input shaft were way too loose.
Anyway it jumped out of 4th and 5th several times, but was better when I shut off the speedshifter.
In race morning warmup it lost 4th over Lukey, and then luckily on the slowest part of the track going down into Honda, it selected two gears due to a bent fork , locked the rear and high sided
the old guy on his head, gave him concussion and he wasnt allowed to race.
And yes the cluster has now gone back to England.
Hopefully that will be fixed at about the same time as Trevors neck.
Luckily as well the FIM has now changed the rules re getting insurance for over 70 year olds, and Trevor can go back again for another shot.

RAW

8th March 2014, 22:12

Shit so Trevor is ok now ? Not good at all, if you guys get back to the Island I will try to get down and say hello

Frits Overmars

9th March 2014, 05:53

So very sorry Frits, I always try so hard not to get it wrong as I know its an issue.Pull the other one, Wob, it's not an issue at all. I don't mind if somebody misspells my name on purpose; I just want to prevent people from thinking that it really should be spelled the german way, wit a z.

wobbly

9th March 2014, 09:10

Yea well the 3rd Reich wasnt that enamoured with two strokes so we should keep your name well away from that connection.

WilDun

9th March 2014, 21:18

Pull the other one, Wob, it's not an issue at all. I don't mind if somebody misspells my name on purpose; I just want to prevent people from thinking that it really should be spelled the german way, wit a z.

I also made the same mistake with a guy whose surname Guerts and I spelt it Geurtz on a message, - needless to say I never did that again!

wobbly

10th March 2014, 07:29

F5 Dave

10th March 2014, 07:46

Yeah, if you're over 30 they seem to think you should put a bag over your head and lie down waiting for the inevitable.

RAW

10th March 2014, 12:24

Frits Overmars

10th March 2014, 13:08

Wobbly & Frits,
Some time back of which I'm unable to find so far Frits presented a 102 pipe dyno graph showing the differences between Titanium, Stainless steel & Mild steel,
Wobbly you referred to the mild steel pipe would need to be 8% shorter to match the presented power curves ( some 64mm ) if this is based upon overall length, this seems a major reduction in length, I'm thinking I've recalled this incorrectly, would you both Frits & Wobbly educate us all on this pleaseYou can find that graph here: http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130670008#post1130670008. But it was from a 50 cc engine; nothing to do with a 102-pipe.
In that graph the stainless and Ti pipes produced maximum power at about 13150 rpm and the mild steel pipe at about 12750 rpm; 3% less.
In this particular case the acceleration time on the dyno was quite short. A longer acceleration time would have promoted heat build-up in the pipes; especially in the mild steel pipe that suffers most from heat loss to the outside world, so the required length difference would probably be less than 3%.

RAW

10th March 2014, 14:45

Thank you Frits

Grumph

10th March 2014, 16:35

Old Trevor at 70 is of course taking a long time to recover from what would be a simple bruise to a younger man.
But he is running into trouble with the medical system as the crash has reinjured an old damaged vertebrae he got in practice for
the 350GP he won in Malaysia around 30 years ago.
Because they say ACC wont pay to "fix" it, they wont do anything - wankers.
Hasnt improved "Grumpys " demeanour any as his sponsored Arai is a mess as well.

Yeah, getting a new helmet is tough on the pension...the bugger was hard enough to race against in the 70's. Good on him for still riding - i'm a little younger but have enough health issues to pretty well rule out anything serious.
Once they (ACC) see you as being outside the workforce, you're fucked as far as getting anything fixed goes. Some of us were hoping Cashman would retire to NZ and he would be a way through the system - but that won't happen now.

husaberg

10th March 2014, 20:45

Armstrong Crankcase mirrored for the Aussie...................

TZ350

10th March 2014, 22:16

Page 920... there is a lot of information here, you will need to follow the link trail back to the original post to see the pictures and full text.

Frits, many many thanks for a great article ( and the previous 300 odd posts)

I have learned more in the last year reading posts from you, Wobbly and others than I have in the previous 50 years of 'playing' with two strokes.

I do not have much to offer to the discussion (apart from more questions!) but some may find this useful. Rather than use the site search which usually fails, use Google so to search this site use an ordinary search phrase and after it add

site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz)

for example

Frits priceless site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz)
or
Frits pisa site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz)

the same will work for other sites with the appropriate site address

Mick

Thanks to Mick for his search tips, now its easy to find good stuff on this thread.

I have often wondered why no one has really gone into expansion chambers in a big way on this thread.....They have you just wernt looking. In fact your first rants were about how Thomases cousin stole the worlds best pipe design from your mate the pipe genius and that was why all Asians could not be trusted ever again

Pipe Talk ... there is plenty here for those who want to design and build their own pipes. Starting from the beginning I have been collecting the posts that talk about pipes to collate and edit them for myself.

There is heaps of it and pages 620 630 640 650 660 670 680 690 700 710 720 730 740 750 760 770 780 have un edited collections of raw material. There is absolutly lots of good information here that even the professional pipe builder would learn something from.

You just have to make the effort to read through it and if your clever, take notes on the way.

Page 780 ... Setting up an IgniTec DC-CDI-Race-2 ignition

Page 820 ... more Ignitec http://www.ebay.com/itm/Knock-gauge-for-detonation-sensor-klopfsensor-NEW-/181138934401 Rich these are the det sensor posts that I could find.

I have learned from Flettner, that a competition two stroke can be successfully fuel injected and that EFI can work very well on 2T's.

A lot of posts on this page are about Flettners EFI and video of dyno runs and field trials of the two EFI bikes.

EFI YZ250 in the Forrest

Page 800 ... Where I have got to with the EFI fuel injection system. You will have to click through to the original posts to see the attached pictures.

Page 890 ... a lot of posts about EFI and more about my EFI journey.

Page 900 ... Tonight's effort. The Beast is starting to snarl and it will pull away in top gear on the dyno from 3500rpm and WOT, try that with your carburetor. I am pretty excited about the Ecotrons fuel injection system as its starting to be very easy to work with.

I think this EFI business is going to work out OK.

This link leads to a thread started by Speedpro that is devoted to setting up the Ecotrons EFI system.

A guide to installing and using the Ecotrons electronic fuel injection ProCal tuning software based on the experiences of a complete newbee with no previous EFI experience.

http://i1290.photobucket.com/albums/b522/TZ350AB/Start%20ProCal/Bubbles-2_zpsb58f2623.jpg (http://s1290.photobucket.com/user/TZ350AB/media/Start%20ProCal/Bubbles-2_zpsb58f2623.jpg.html)

The Ecotrons fuel injection system is my first experience with EFI. Sure, I had seen fuel injectors and mass air flow meters before and had some idea of how they worked but I was really a total newbee to EFI when it comes to installing one and setting it up.

Hopefully all this will be a help to anyone else trying to get their head around the ProCal file and directory structure.

Page 810 ... Bucket Racing Video from Chrisc's thread http://vimeo.com/64253234

and Pictures of the bikes http://www.kiwibiker.co.nz/forums/showthread.php/153656-Chris-Bucket-photo-thread-Bandwidth-warning/page7 … Exhaust port dam.

Page 830 links ... Looking for the good stuff ... Plugging piston pins ... http://www.pit-lane.biz/t4140-2-stroke-how-plug-up-a-2-stroke-wristpin And another approach taken by Wob, if any one is doing the piston pin thing this may be worth a try too. … Then Wobs thoughts on cylinder heads and plug to piston crown distance.

Page 850 link list ....

Page 860 ... Great little explanation of how a two stroke works. http://www.atvriders.com/articles/twostroke.html

Page 880 has a lot of foundry pictures ...

Page 900 ... To find the good stuff. follow the link to see how to view all the images on the thread and their associated posts.

Before calibrating an engine, it is first useful to have some concept of what you are trying to control.

"Fuelling Theory ... Lets start with the theory then. We are concerned with spark ignition gasoline engines here. I am only going to cover gasoline, since Diesel is for trucks and diggers, and alcohol is for drinking and drag racing." http://195.159.109.134/vemsuk/forum/index.php/topic,97.0.html

Wobbly!

We have talked over how important the blowdown and it's size are, but what about the blowdown's intensity? If the aux exhaust ports are opening later as the main exhaust port, the peak of the pression is smaller, meanwhile the blowdown lasts longer. Of course the STA is always the same. Here is an example 'One Half'

In case of almost every race cylinder the aux exhaust ports are opening later, and this can be observed in systems with or whitout a power valve. In case of a T port the top edge radius is not 0, but pretty much bigger.

Is it important? Why don't we open the ports the widest possible? That way the ports could be positioned lower what would be optimal.

There are two factors in play with the tripple port setup.
You have drawn them correctly with 68% main port width, as this allows greater blowdown area to be gained via the aux ports.
Out at 72% that has proven to be approx the reliable max width, you loose some blowdown, and gain total area. ( not relevant at all ).
The problem is that even at 68% you cannot run a flat port roof with 8mm corner radi, as the ring life will be zero.

Secondly is that it has been proven in many dyno sessions that having all 3 ports open together looses power.
I can only explain this as a function of the fact that the effective duct length from the outer corners of the Aux is alot longer than that from the main port
mid point to the header.
Thus you get a smearing of the initial wave amplitude ( wider but lower intensity ) as it exits the cylinder into the duct during blowdown.
This reduces the effectiveness of the expansion phase, creating less depression around BDC, and less plugging efficiency as the piston closes the port.

It would appear that having a 68% main port opening first gives a good, high amplitude wave action in the pipe, then the Aux STA gets the blowdown pressure dropped as much as is possible prior to the Trans opening.

A few pages back was a drawing I did years ago of a T port with the outer edges higher than the mid point, thinking that this would ameliorate the duct length issue, but later
testing proved it didnt work well at all.
So by inferrence even lifting the Aux higher than the main wont fix this issue either in a 3 port.

Gigglebutton

11th March 2014, 14:30

Big thanks to Cully and Rob for your help with our bike. Could not have done it without you :)

husaberg

11th March 2014, 18:14

Pretty sure its KR3's
Plus allegedly a mid 90s YZR500 cylinder

husaberg

11th March 2014, 21:09

Other 90's yzr500 nYamaha bling

RomeuPT

12th March 2014, 14:05

You can find that graph here: http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130670008#post1130670008. But it was from a 50 cc engine; nothing to do with a 102-pipe.
In that graph the stainless and Ti pipes produced maximum power at about 13150 rpm and the mild steel pipe at about 12750 rpm; 3% less.
In this particular case the acceleration time on the dyno was quite short. A longer acceleration time would have promoted heat build-up in the pipes; especially in the mild steel pipe that suffers most from heat loss to the outside world, so the required length difference would probably be less than 3%.

less than 3% and 8%.. there is a big mismatch here :)

I have been making some SS pipes, always thinking if going right or wrong, but using about 5%

TZ350

15th March 2014, 15:25

I was out looking for a bit of info on frame design and handling and came across this gem about "the wobbles":-

294911

Burst oscillations occurring at high speed, and under firm acceleration, can be suppressed with a mechanical steering compensator. Burst instabilities in the subject racing motorcycle are the result of interactions between the wobble and weave modes under firm-acceleration at high speed. Under accelerating conditions, the wobble-mode frequency (of the subject motorcycle) decreases, while the weave mode frequency increases so that destabilizing interactions can occur. The design analysis is based on a time-separation principle, which assumes that bursting occurs on time scales over which speed variations can be neglected. Even under braking and acceleration conditions linear time-invariant models corresponding to constant-speed operation can be utilized in the design process. The influences of braking and acceleration are modeled using d’Alembert-type inertial forces that are applied at the mass centers of each of the model’s constituent bodies. The resulting steering compensator is a simple mechanical network that comprises a conventional steering damper in series with a linear spring. In control theoretic terms, this network is a mechanical lag compensator. A robust control framework was used to optimize the compensator design because it is necessary to address the inevitable uncertainties in the motorcycle model, as well as the nonlinearities that influence the machine’s local behavior as the vehicle ranges over its operating envelope.

http://appliedmechanics.asmedigitalcollection.asme.org/article.aspx?articleid=1662295

TZ350

16th March 2014, 10:12

A lot of the 2014 GP Videos are on Richbans thread.

There are so many GP threads why not make another one. Lets all try and put the footage and pics here. Here is the onboard from my bike. Some close and closer racing.

<iframe src="//www.youtube.com/embed/c1eMn5b4IhQ" allowfullscreen="" frameborder="0" height="315" width="560"></iframe>

Lots of Bucket Racing video from Team GPR http://www.youtube.com/playlist?list=UUg1Ze1muy87n3mkhOHMXVSg

I started a Flickr just for you sods. Jump on in, the water's fine.

Congrats to everyone who finished, and to those who walked away with shiny things.
I had a freaking ball! and my puney muscles are still sore http://www.kiwibiker.co.nz/forums/images/smilies/sobstory.gifhttp://www.kiwibiker.co.nz/forums/images/smilies/pumpiniron.gif

TOKOROA GP PHOTOS HERE: http://www.flickr.com/photos/120242274@N04/sets/72157642282552865/

http://farm4.staticflickr.com/3695/13121147415_f3f0c7fd25_c.jpg (http://www.flickr.com/photos/120242274@N04/13121147415/)
_MG_3088 (http://www.flickr.com/photos/120242274@N04/13121147415/) by sonscc (http://www.flickr.com/people/120242274@N04/), on Flickr

I'm totally happy for you all to save, share, print the photos on this thread and on my flickr. But please can you make a mention, provide a link etc where ever you use these. That'd be greatly appreciated. Enjoy!

F5 Dave

16th March 2014, 10:26

And despite the farty noises of the bikes in pic, the bike disappearing at the front is a 2stroke Derbi 80something.

WilDun

16th March 2014, 23:14

Didn't get to Tokoroa, would have liked to ..... maybe next year.

Good to see the fifties in action, as I said somewhere before, I have yet to see a 50cc race in NZ, looks like a lot of fun, but I guess a rider who is overweight wouldn't fare well in the acceleration stakes!
BTW, I used to ride an Italian 50cc ITOM sometime way back in the last century, (some hopefuls used to ride them at the first 50cc races at the IOM TT. - not much hope really!) - mine could manage 65 mph - guess that doesn't compare with the ones today, I also designed an expansion chamber by scaling it from a photo! - no "wobbly wisdom" in those days!

Thanks TZ 350 for taking the hard work from the browsing - makes things a lot easier.

Will.

F5 Dave

17th March 2014, 08:21

mr bucketracer

17th March 2014, 14:24

TZ350

17th March 2014, 16:37

the f4 is also a killer with power to weight . would be nice if everyone had lead weights on there bikes to suit the heavy weights lol :( .

I am all for it :yes: ... min 250kg Bike plus Rider in their kit and over 65's get a head start..... 294965

WilDun

17th March 2014, 17:16

I am all for it :yes: ... min 250kg Bike plus Rider in their kit and over 65's get a head start..... 294965
Now that's a good idea (not that i'll be able to benefit from it), especially the over 65 bit! that's what I say, a level playing field, also, I think the older guys should decide just where the lead weights should be added! - Why? well it keeps skullduggery to a minimum.
On the other hand, it wouldn't be much fun getting clouted by lumps of lead after someone had a high speed crash! Like the wild west, lead flying everywhere :eek5:

Will.

mr bucketracer

17th March 2014, 17:37

I am all for it :yes: ... min 250kg Bike plus Rider in their kit and over 65's get a head start..... 294965i would say 99% of riders+bike would be under 200kgs , so a 200kg mark would be the go (-: , yip 65 and over a 1 lap head start per 10 laps would be a fair go

TZ350

17th March 2014, 17:40

Having had a lot of fun on a borrowed F5 bike at Tokoroa I thought I would finish my own one off and get out there. Single exhaust port, so not expecting to much and if the carb is to steep I will swap to a pumper. But at least this one should have decent brakes, the one I rode at Tokoroa had virtually nothing and when it got hot there was an enormous hole in the mid range carburation. Made it very hard breaking down hill into the hair pin and then climbing back up the winding uphill bit to the front straight.

wobbly

18th March 2014, 06:47

Dont think the idea of an advantage for old guys would actually be fair at all.
Put the 70 yr old Discombe on a good bucket and he would lap most of the field starting from the back.

wobbly

18th March 2014, 06:50

That carb will for sure flood under brakes TeeZee, get a D slide downdraft off a RGV F3 or something.

F5 Dave

18th March 2014, 08:52

Cut the inlet off & start again. What looks good on the bench is too steep in the bike. Don't ask how I know.

Dowel the head, they move around too much and important with such little chamber. Don't try weld into the head. They get super soft & will warp like crazy unless you heat treat them.

mr bucketracer

18th March 2014, 11:05

a 28mm kr250 carb is the way to go

TZ350

18th March 2014, 11:38

a 28mm kr250 carb is the way to go

If anyone can sell me one, I would try it.

Plan B is to use a 24mm Tillotson pumper or get one of the carbs Yow Ling posted a picture of.

husaberg

18th March 2014, 12:53

If anyone can sell me one, I would try it.

Plan B is to use a 24mm Tillotson pumper or get one of the carbs Yow Ling posted a picture of.

The KR250 or the TZR250 both had the Down Draft 28 mm Mikuni.

WilDun

18th March 2014, 13:53

Dont think the idea of an advantage for old guys would actually be fair at all.
Put the 70 yr old Discombe on a good bucket and he would lap most of the field starting from the back.

So it is Trevor Discombe! - I remember he was NZ 350 champion ( on a Manx Norton) way back in 1966 when I first arrived in NZ, I nearly bought an old AJS 7R he was selling on behalf of someone but I thought the better of it as those bikes were being replaced by two strokes and I was always a 2 stroke fan. (ended up with a Suzuki)
I also remember him going for a skate just over the railway just before going through the graveyard at Wanganui, ending up in a heap, out cold! - I would say he had a sore head after that one.
Good on you Trevor for sticking at racing, do be careful though! :niceone:
Will.

F5 Dave

18th March 2014, 14:15

If anyone can sell me one, I would try it.

Plan B is to use a 24mm Tillotson pumper or get one of the carbs Yow Ling posted a picture of.

Can do better than that, Yow sent me a pair for giggles, I might still have them & could send them on. . .unless I gave them back. Were like 27mm Keihins from some flavour NSR. Sold my last 28 Downdrft mikuni to Tim I think.

Er hold on that is a downdraft Mikuni, only 15 or so degrees. Cut it off & start again but flatter & shorter.

husaberg

19th March 2014, 20:38

Can do better than that, Yow sent me a pair for giggles, I might still have them & could send them on. . .unless I gave them back. Were like 27mm Keihins from some flavour NSR. Sold my last 28 Downdrft mikuni to Tim I think.

Er hold on that is a downdraft Mikuni, only 15 or so degrees. Cut it off & start again but flatter & shorter.

Another idea the MVX250 had 24mm downdraft Keihins they were for a 80cc cylinder
They look like they could be bored out as well as a nice downdraft.Looks about 45 degrees.......

Try Drew or White Trash for some...........Alll the attachments are MVX250

Anyone know what the NS400R ones look like?
Latter I googled and they look like the NSR250 ones only 26mm
(links are all NS400R)
http://classicracereplicas.com/prod6.asp?ID=278&sub_cat=660&offset=60&prod_id=234&grpid=234&#prod_anchor
http://www.fastlineparts.com/media/catalog/product/cache/1/image/1600x/040ec09b1e35df139433887a97daa66f/d/s/dscn7828.jpg
http://www.fastlineparts.com/media/catalog/product/cache/1/image/1600x/040ec09b1e35df139433887a97daa66f/d/s/dscn7831.jpg
http://www.fastlineparts.com/media/catalog/product/cache/1/image/1600x/040ec09b1e35df139433887a97daa66f/d/s/dscn7825.jpg

wobbly

20th March 2014, 07:16

NSR400 carbs look the same, I have access to a bunch of those, will get one and see what size it is.

F5 Dave

20th March 2014, 08:38

husaberg

20th March 2014, 09:51

Oh yeah, when is Jared going to get the spark & pingas to finish that bike?

I have an MVX carb as well. Seems to measure 25mm. NSR ones at 27. I'd believe my expanding calipers and vernier before google. . . Not to say I wasn't shaky transferring the measurements, but I was pretty keen for the MVX to be 24mm to be legal for aircooled 125 at the time & I still couldn't convince myself they were.
MVX carb yours if you want it Rob.

I too would believe your calipers over Google too, Dave
But remember the GrandLord Satan the owners of Keihin, Measure the carbs in a way that they decide and i guess in the case of Keihins it is at the venturi.
I think there is about 4-6 different sizes for the NS-NSR250 carbs. Most i have seen are an oval like the XR200's.
I am begining to think they may all be based on only a couple of body sizes.The ns sites list them by they model numbers like TA09 etc
According to all the dyno stuff i have seen the NSR Keihins actually flow bloody well considering they are a STD production carb.
But they don't have the needle section and adjustability of the others......
I have a couple here (from Rob) off a NSR250 and they are about 32-34mm at the throat.

There is also another new downdraft Mikuni alailable in a lot of sizes based on what looks like a tmx you see them for pitbikes and so forth can't remember what they are called.(latter TDMR)
http://www.j-mart.biz/j-parts/images/takegawa/03-05-0041_2.jpg

F5 Dave

20th March 2014, 10:21

yeah those are probably ideal for my (super long term project) Stinger when I finally decide 'screw the misty-eyed std restoration idea' & tune the crap out of it instead:lol:.

Yow Ling

20th March 2014, 17:34

I tink MVX carbs are 20mm. Too big for your Stinger bucket 2 x 17 = 24mm equivalent

Now I have to go to shed to check

Strokerhaus

20th March 2014, 21:14

The theoretical MSV of 38M/Sec you are achieving will work OK, but for only 12200 rpm with 54.5 stroke the squish gap should be down at 0.6mm.
0.65 is useable in a normal 125 spinning to 14000 all day, but your piston is obviously heavyer.
The limiting factor should be that at the peak rpm used, the piston should be just shy of clipping the head.
Thus for the best squish action we end up with virtually zero clearance, so in effect the theoretical MSV becomes irrelevant.

What fuel are you using, race or avgas. I suspect the race fuel, if so, have you tried these MSV's with avgas. I did come across a bath tub combustion chamber on an Enfield GP5 of the late 60's, it had very sharp edges but a shallow almost triangular tapered section at the rear of the chamber. I was never certain of how good it was so never tried it, sounds like I have some more work to do.

Keep up the good work really interesting site.

F5 Dave

21st March 2014, 08:42

I tink MVX carbs are 20mm. Too big for your Stinger bucket 2 x 17 = 24mm equivalent

Now I have to go to shed to check

NahnahNah, the Stinger will never be a Bucket. . . .Actually one of them was an ill conceived bucket from down souf, - but its being combined with parts from Rusty the Stinker into a Roadbike as they are super kewl in a late 60s kinda way.

Yow Ling

21st March 2014, 14:00

NahnahNah, the Stinger will never be a Bucket. . . .Actually one of them was an ill conceived bucket from down souf, - but its being combined with parts from Rusty the Stinker into a Roadbike as they are super kewl in a late 60s kinda way.

Then use as many as you like , they are 21mm

wobbly

22nd March 2014, 09:56

The MSV numbers at 38m/sec work for FIM unleaded rocket fuel, as well as they do for AvGas.
Only a few class in USA allow real leaded racegas at 110 octane and over, so not really relevant anymore.
The numbers equate to something around 0.65 squish with around 45% width going to 14,000 + in a GP engine and these always go best when the piston
is on the verge of contact.

Strokerhaus

22nd March 2014, 10:50

husaberg

23rd March 2014, 14:16

2000 nsr500

husaberg

23rd March 2014, 16:09

One ones that were on Ebay

Grumph

23rd March 2014, 16:34

F5 Dave

23rd March 2014, 17:30

Shift drum is unlike anything I've seen before.

they do love their 26482 loom connectors.

husaberg

23rd March 2014, 18:13

Couple of oddities in the pic of barrel and pistons...those are big cutaways on the skirt sides...

And the cutback rear wall is pretty much exactly what I did on an RS125 at the customer's request...and it lost power.

6666666666666666666666666

Shift drum is unlike anything I've seen before.

they do love their 26482 loom connectors.

Grumph

24th March 2014, 06:10

Shift drum is unlike anything I've seen before.

And it appears to be cast too....If anyone has better resolution and can see tool marks, say so, but if it is cast it's pretty good work.

WilDun

24th March 2014, 08:30

And it appears to be cast too....If anyone has better resolution and can see tool marks, say so, but if it is cast it's pretty good work.

It's probably an investment casting, but the cam tracks will possibly be finish machined, too fuzzy to see.
However, producing the wax pattern itself would be quite a challenge!
Then again, I could be wrong.

husaberg

24th March 2014, 17:40

monkeyfumi

24th March 2014, 18:08

The discussion about the shift-drum reminded me of this video of the Redbull F1 factory
http://youtu.be/-t6cxIeCIjE

Gearbox stuff is from around 2:20 onwards, but the whole video is interesting, showing stuff like rapid prototyping, machining etc. Even the scale wind tunnel.
Thought some might enjoy it if they hadn't seen it.

As you were:)

Ocean1

24th March 2014, 21:44

It's probably an investment casting, but the cam tracks will possibly be finish machined, too fuzzy to see.
However, producing the wax pattern itself would be quite a challenge!
Then again, I could be wrong.

I think you're right, there looks to be no draught on the webs. Looks a bit delicate but obviously worked.

A decade ago I would have got the wax 3d printed, nowadays I guess you'd 3d print shells directly.

Forgi

25th March 2014, 00:04

Hello Wob!

I'd have a question if you don't mind!

What do you think why haven't become common the use of kart carburetors (tillotson, ibea, JHC etc.) among the gear class karts or scooters?
Rarely I can see a few attempts (http://www.tuningmatters.com/articles/how-to/50cc-scooter-tuning-guide/).

In the '90's we tired to use it in ICC class, and it worked very well, although we had to make notable modifications to make the carburetor able to carry enough gasoline.
Although in case of certain scooters (24mm and 50-90 cc) it would be enough, but they are not used.

These kart carburetors are quick and easy to set, but still everyone uses the ordinary carburetors. What is your opinion or experince?

Grumph

25th March 2014, 06:05

Best i can do.............
When you think about it normal shift drums are heavy.......
I seem to remember the 50 i posted having a different set up i had a gif on how it worked and i think (the Sachs) of the 70's had something different.
The brits used a camplate.......

Unless they've used something trick as material, I'd doubt if that's much lighter than the "normal" shift drum. Any gain would come from the lower rotational inertia as the main masses are closer to the centerline. IMO just another example of Honda doing something "just because we can"....

husaberg

25th March 2014, 07:29

Unless they've used something trick as material, I'd doubt if that's much lighter than the "normal" shift drum. Any gain would come from the lower rotational inertia as the main masses are closer to the centerline. IMO just another example of Honda doing something "just because we can"....

IMO Honda shift drums are generally bloody heavy, The MB one esp hefty, the NSR one pictured is very abbreviated it also is hollow ie light. The rotational inerta might help it change gear faster but i think it was a overall lightness exercise,Yes Honda often does stuff as a form of corporate Masturbation.

wobbly

25th March 2014, 13:54

The really good kart carbs with flat slides and 3 jets are very expensive, that is the main reason they are not used.
Only issue I have heard about ( not my experience though ) is that some have complained the pumper carbs must be backed off the throttle
too much to make the gearbox change gears.
I brought back from the World Kart Champs in Vegas a new Tillotson carb that was designed to be used as a replacement for the 34mm Dellorto used on Rotax Max.
It made better power everywhere, and was super easy to tune - but as I understand it Rotax said no to changing it - that carb was sold to me "cheap " by the chief engineer
from Tillotson in Ireland, it cost 500USD cash.
Thats going onto a lucky 100cc bucket engine soon.

WilDun

25th March 2014, 15:48

Unless they've used something trick as material, I'd doubt if that's much lighter than the "normal" shift drum. ....

In calling it "cast" I'm sure most of us are meaning good quality cast steel here, (as opposed to cast iron) - right?

Grumph

25th March 2014, 17:01

In calling it "cast" I'm sure most of us are meaning good quality cast steel here, (as opposed to cast iron) - right?

yes - and unlike husa apparently, I'm accustomed to seeing shift drums which are (a) hollow and (b) only solid where they have to be..
late jap road stuff is pretty good for minimum material use. Even the post classic stuff I see is at least as light as that Honda drum.

It would be possible to use something like hard anodised 7075 alloy on short use stuff. Ti doesn't like rubbing so rule that out. That leaves good old steel....

husaberg

25th March 2014, 17:09

yes - and unlike husa apparently, I'm accustomed to seeing shift drums which are (a) hollow and (b) only solid where they have to be..
late jap road stuff is pretty good for minimum material use. Even the post classic stuff I see is at least as light as that Honda drum.

It would be possible to use something like hard anodised 7075 alloy on short use stuff. Ti doesn't like rubbing so rule that out. That leaves good old steel....

Aye that remark resembles me.
I remember the story of TR750 with the mag and ti bits gearbox bits.
I did find this though while having a fosik.
Inside an AMA Superbike Suzuki engine.

http://www.mototuneusa.com/the_factory_superbike.htm

Honda F1 Car Shift drum should be the last pic
Honda RA106 Formula 1 Gear Selector Barrel (http://www.formula1-dictionary.net/gearbox.html)

Forgi

26th March 2014, 04:40

TZ350

26th March 2014, 22:12

So ive got some questions about Engmod2T... When modelling a reed cage that has an internal divider or stuffer before the reed petals, do you subtract the area of the divider from the area of entrance to the reed cage when calculating the 'diameter of the rubber block' (entered in the Inlet Port window)?

http://i553.photobucket.com/albums/jj373/dmcca/DSC08431.jpg

From an old thread in another forum but good info on modeling reed inlets in EngMod2T, link posted here so we don't loose track of some valuable reply's and info posted by Wobbly.

steamroller

27th March 2014, 21:12

mr bucketracer

28th March 2014, 11:41

tweak :facepalm:and I thought Seymour was billotlot maching a rs125 copy engine with a air cooled barrel:weep:

seymour14

28th March 2014, 13:13

and I thought Seymour was billotlot maching a rs125 copy engine with a air cooled barrel:weep:

Who said I was only machining one?

mr bucketracer

28th March 2014, 16:09

Who said I was only machining one?ok 3 then ha ha

Buckets4Me

29th March 2014, 15:03

why dont you just fit a red power band ?

http://www.planetash.net/gos/powerbands.html
:clap:

cotswold

29th March 2014, 16:07

why dont you just fit a red power band ?

http://www.planetash.net/gos/powerbands.html
:clap:

I just stole that, thanks

WilDun

29th March 2014, 20:48

why dont you just fit a red power band ?

http://www.planetash.net/gos/powerbands.html
:clap:

They sound great, where can I get one? - great article, might almost convince some people! eg:-
A long time ago, I bought a Suzuki RM80 aircooled mx bike for one of my kids, and the cow cocky I was buying it from insisted that it was really worth more than I was paying, because it had a powerband!

We had that bike for over two years and I think we were screwed because I never did find any powerband on it!

TZ350

30th March 2014, 15:15

Who knows how ""modern"" this thinking is but I found the description informative, especially the bit about expansion ratios in the diffuser.

http://karting.archive.netcopy.co.uk/article/early-march-1969/12/volume-tuned-exhausts

PART TWO
PRIMARY SYSTEM: The plumbing from the engine to the end of the megaphone helps the engine to pump air/fuel mixture. By breathing better, the engine has a good chance of producing more power. The low pressure created by the primary system is accomplished without the aid of the rest of the exhaust system. There are motorcycles and karts using just the lead-in pipe and the megaphone to good advantage. Unfortunately when used alone the bare megaphone is terribly noisy and also does not produce the broad torque range so essential to karting.

These primary systems can be tuned, however, to out-perform a machine using no exhaust system.
An understanding of how to tune a primary system for any two-stroke style of exhaust can best be developed by first examining an engine fitted with an unadorned straight pipe shown below. This lengthy explanation is worthwhile if you have not waded through it before.
When the exhaust gases flash into the pipe a high pressure disturbance is created which travels downstream towards the open end of the pipe at the speed of sound. This sonic pressure wave travels through the contents of the exhaust pipe. The important change that takes place occurs just as this positive pressure pulse leaves the pipe. A suction is created in the end of the tube which initiates the propogation of a negative wave back up the exhaust pipe toward the port. This wave, which is below atmospheric pressure, travels upstream through the particle flow with a relative velocity equal to the speed of sound. Here we have a strong low pressure wave returning back to the engine. This low pressure pulse could greatly aid the flow of exhaust from the cylinder if it were timed to arrive at the engine at just the proper instant.

Cut-and-dry methods used with an engine on a dyno indicate that this length is quite fussy for any given tuned rpm. The engine runs well at the tuned rpm, but does poorly 1,000 rpm either side of that speed. It turns out that a straight pipe without a megaphone returns a shortduration, high energy negative pressure pulse. A lowenergy, wide-duration wave would be better suited to the engine's needs. A straight pipe is worthless on a kart track, because of the rpm range it demands.
We can help the engine somewhat by adding a step to the end of our original straight section as shown below. It should help to extend the tuned rpm.

This pipe has two sudden changes of cross section at its open end and returns two negative pulses from the original 50 psi charge. Note that the timing of the first negative pulse is unchanged as it travels over the same round trip distance.
The second pulse which is reflected from the large diameter step must arrive up-stream at the port later. Its round trip distance is 2L. This has the favourable effect of extending the low pressure way duration, giving a better tuning effect.
If the steps were made very close together, a patient person would construct something resembling a diverging megaphone. Acoustically, the built-up pipe and the smooth megaphone produce the same effect—they return a series of overlapping negative pulses. The sum of these pulses produce a smooth wave which extends the useful tuned rpm range of the engine. Any high output exhaust system for the 2-stroke will have this megaphone.

The megaphone is a very essential part of the volume tuned exhaust system. A constant cross section primary system (no megaphone) was tried during the development programme. It resulted in a narrow tuned speed range and was also low on power—even though it exhausted into the volume chamber. The "S" shaped lead-in pipe of Figure No. 1 has a nottoo-constant diameter of 11 inches. I have no data concerning a different diameter. However, the length of this pipe (our length 1) is easily varied at the flex tube. A shorter length takes less time for our positive-wavecum-negative—wave to make a round trip. This change to a reduced length would be better therefore at a higher engine speed.
The diverging megaphone is eleven inches long and measures 70 surface to surface. By comparing the areas (not diameters) of each end of the megaphone we find a ratio of about four. Let me speculate for a minute on this number and its alleged influence on engine performance.
The energy contained in the reflected negative wave is taken from the original positive pulse as it moves downstream in the exhaust pipe. A slow tapering, long megaphone removes less energy from the positive pulse than a wide angled unit of equal length. The slow tapering megaphone with a total angle around returns a relatively weak negative wave, leaving considerable energy remaining in the positive wave as it leaves the megaphone. This should result in a strong back-stuffing wave when the positive pulse reflects off the closed end of the secondary chamber.

A wide angled megaphone in the 8° range uses more of the initial energy in producing a strong series of overlapping negative pulses. The energy left over for the positive back stuffing wave is therefore less than we had in the 4° diffuser.
The expansion ratio of the megaphone is a convenient means to compare this characteristic. Data taken from many two-stroke exhaust systems show that they use an expansion ratio which falls in the range of 3 to 7. In general, the observation is that engines with a narrow tuned range (and high peak power) use a low cone angle with an expansion ratio of 4.
A wide angle diffuser seems to be less sensitive to engine speed change, and retains its tuned range longer. This megaphone has a vigorous scavenging influence because of the strong negative wave it produces. Backstuffing, on the other hand, will be weaker as less energy is available to reflect off the closed end of the chamber. Timing of the long duration scavenging is also less critical than the shorter duration back-stuffing. It is therefore less sensitive to rpm change.

The Komet, PeriIla and Saetta expansion chambers have an expansion ratio of six. The McCulloch Volume tuned exhaust uses a lower ratio of four. An expansion ratio of six is quite large compared to the majority of racing exhaust systems being used today. For example:— 73cc Yamaha single — 1.90 inlet, 3.40 body; area ratio 3.20 250cc Suzuki twin — 1.50 inlet, 3.00 body; area ratio 4.00 344cc Greeves single — 1.75 inlet, 3.00 body; area ratio 2.94 250cc Yamaha twin — 1.45 inlet, 2.95 body; area ratio 4.10 250cc BuItaco single — 1.80 inlet, 3.31 body; area ratio 3.38 125cc Alpha twin — 1.25 inlet, 3,33 body; area ratio 7.32 100cc Komet single — 1.44 inlet, 3.57 body; area ratio 6.15 100cc PeriIla single — 1.44 inlet, 3.57 body; area ratio 6.15 Judging from just the information above, it appears that the "rpm-sensitive" motorcycles produce the best power with an expansion ratio of about four. Karting, with its broad torque band requirements, looks to favour a ratio of about six when the exhaust system is of the expansion chamber variety.

Judging from the broad torque band shown in Figure II, any change to the McC system would yield only a small improvement. Unless the reader is truly enthused about experimenting with the exhaust system, it is best to simply leave this parameter fixed.
Dyno testing shows that changes to the megaphone length affect performance only slightly. It is not as fussy as the critical inlet pipe length. The secret of tuning the exhaust's primary system lies in the length of the lead-in pipe. It controls the timing of the reflected wave, hence the tuned rpm. Long pipes require more round trip time and look the best at low engine speed. Figure II shows the power change caused by shortening the the lead-in-pipe on a McCulloch system. The data was obtained by a dynamometer test—the horsepower values have been purposely removed to indicate only the trend of the modification.

This curve points out the need for proper gearing. Engine speed must be kept above 6,000 rpm and below 9,500 rpm when using the stock 3 inch flex length. Removing the flex althogether requires a minimum speed of 7,000 rpm with a maximum above 10.000 rpm if you want to use the exhaust system to best advantage, Note that there is a good power band of 3,000 rpm. Many motorcycle systems are quite peaky with only 1,500 rpm leeway. The only variable in the test of Figure II was the effective internal length of the stainless flex tube. The plotted values are typical of those found in all tuned exhausts— the peak power at the maximum rpm must be sacrificed to obtain a broad torque range. Fast circuits such as Willow Springs Raceway, for example, keep the average rpm high, allowing a shorter lead-in than the 3-inch production length. Most manufacturers tune their systems for the "average track condition" leaving latitude for the fellow who tunes for the specific condition.

Figure III was included in this article just to show that the average exhaust temperature rises with engine speed. This increases the wave velocity in the exhaust system which tends to keep an accelerating engine in tune. The temperature rise, unfortunately, does not keep pace with the requirements imposed by the increased rpm. Hence, we must tune the system for the desired speed range. The temperature rises because the engine traps more of the mixture delivered because there is simply less time available for the air-fuel mixture to escape. This gives more efficient operation. Power drops because less mixture is delivered with increased speed above the tuned range—yet the temperature continues to climb because of the increased trapping efficiency.

Figure IV shows that the wave speed through exhaust gas is a function of the temperature (it is independent of the pressure). Note that the average speed will be in the 1,600' to 1,900 per second range.
The exhaust products move through the exhaust system at a much slower speed than the sonic waves— this velocity being around 300 fps. Hence there are two velocities in the pipe—we need to be concerned with only the high speed sonic waves which accomplish the tuning we are looking for. A sonic wave in the exhaust stream is analogous to a ripple moving upstream or downstream in a slowly moving channel of water. The wave can travel much faster than the average particle speed in the water channel.

Before we go on to the secondary systems let me restate the objective of the primary system. It must convert part of the positive energy, leaving the engine, into a delayed negative pressure wave. This wave, which can be thought of as a series of overlapping pulses, should arrive at the cylinder just before the transfer ports open. This low pressure area aids the scavenging of exhaust gas. It also should over-scavenge the cylinder, pulling some fresh charge into the exhaust pipe. The secondary system will complete this scavenging sequence.
SECONDARY SYSTEM:

A disassembled Volume Tuned Exhaust System without the cylindrical can is worthless. Dyno data shows that when the stock primary system is used alone, less power is produced than when the engine is exhausting directly to the atmosphere. This is contrary to what one expects from a lead-in-pipe and megaphone. Obviously, the secondary system changes the characteristics of the primary system. Any change, therefore, to the secondary system also influences the operation of the primary system. The secondary system of the Volume Tuned exhaust accomplishes the same thing as its counterpart on the expansion-chamber exhaust. As already mentioned, this portion of the exhaust system must send a positive pulse upstream toward the exhaust port to back-stuff the over-scavenged mixture into the cylinder.

The common expansion chamber does this by reflecting the original positive pulse off the semi-closed end of the chamber. Note that a closed end pipe reflects a positive pressure wave back to the source with the same positive pressure. A sign change does not occur. There is a well defined path for the wave because of the continuous nature of the chamber walls.
On the other hand, the volume tuned exhaust system has no organized path for this wave to follow until it gets back into the primary system. At first it was thought that the exhaust system relied only on the pressure buildup in the entire volume chamber to produce the back stuffing wave. This was the theory during the first months of exhaust system development which resulted in the volume tuned name for the system. However, if you measure the distance from the flat end of the can to the exhaust port, you will find the 28-inch length to be about the same as that found on an expansion-chamber tuned for the same rpm. This is an ideal surface to reflect a pressure wave. The positive wave could also reflect from the other end of the inlet end of the can or from the cylindrical chamber wall. The randomness in the volume chamber probably accounts for the silencing action.

What actually happens to produce the back-stuffing wave is somewhat of a mystery to me. We do know, however, that the factory set-up uses a can length of 11 inches. Decent power was produced during the development programme with shorter lengths of 10 and 8 inches, while shifting the peaking speed to a higher rpm. One fellow at a Willow Springs IKF enduro was using a homemade volume tuned exhaust system. The exhaust system looked similar to the McC layout except for the dimensions of the volume chamber which were altered —even though the volume remained unchanged. The modification was made because of a space problem in his "B-Bomb" powered F.K.E.
His dyno testing indicated a sizeable gain at the lowend, and also at the top-end. Unfortunately it had a flat spot in the mid-range that fell below the power produced by an exhaust stub, which has not tuning effect, This mid-range problem adds weight to the argument of maintaining a length in the 28 inch range from the exhaust port to the can end.

Just for the purpose of illustration for he back stuffing wave to arrive at the exhaust port just as the transfer ports close. Use a 9,000 rpm speed for the McC-91. The exhaust ports opens 82 before BDC, the transfer closes 61° after BDC; for a total required wave duration of 143 degrees of crankshaft rotation. A little arithmetic shows that it takes 0.00265 seconds for the engine to turn through this crank angle. In that short time, the wave must traverse up and back in a 28 inch system for a total earth length of 56 inches. The required wave velocity comes out to be 1760fps, indicating a reasonable average exhaust temperature of 875')F.
Getting on to the last item, number 5, we intuitively see that the pressure rise and average pressure in the volume chamber is also influenced by the area of the 5 inch long outlet pipe. A whole range of these diameters were experimentally tried on the dyno one at a time. From this data, power curves were plotted that slowly climb to a peak value and then fall off again. The quiet sounding small diameter pipes give a slight ( a very slight) increase in bottom end torque, while sacrificing mid-range and top-end power.

Excessively large diameters, in addition to poor power, result in a lot of noise. The 0.780 ID stock outlet is on the small side of the optimum power peak for a 100cc engine. Increasing this outlet would boost power a few percent in the 6,000 to 10,000 rpm range—but, as you might expect, this results in a discouraging increase in the noise level.
If the same experiment were tried on the larger B-class engines, the same trend would be observed. The specific change noticed would be that it takes a larger diameter pipe to reach the peak of the power curve. The 7.5 cubic inch McC-101, for instance, needs an outlet pipe diameter of just over an inch for best power and rpm.

If you want to experiment with this effect, weld on a 1-1/8 inch diameter outlet pipe in place of the present stub. Be sure to increase the hole in the exhaust system can to match the larger ID tube. The length of the pipe incidentally does not adversely influence power unless you get it excessively long (12in.). Some muffling is provided in the outlet pipe—so keep the length in the Sin. range. After the exhilarating effect of all that noise has worn you down, the exhaust system can be quietened by pinching the end of the tube down to reduce the area toward the stock dimension. Flatten the pipe until the area reduction begins to eat into your lap time. You will end up with an outlet area about the same as the stock set up. Make sure you leave the exhaust stub on the side wall. Less noise is created here when compared to a similar pipe on the flat end of the cylindrical can. The reason for this noise increase can be surmised by examining the pressure pulses in the volume chamber. When the initial positive wave reflects from the closed end of the can, the wall feels the effect from both pulses. The original wave and the reflected wave add, giving a greater pressure, hence a louder noise. The side of the can, on the other hand, does not lie directly in the path of the pressure pulse, resulting in a lower peak pressure.

If this hypothesis is correct, similar results can be expected by moving the tail pipe on the expansion-chamber type exhaust system to a a central location on the chamber wall. If you can not meet the silencing rules with your stock expansion chamber, this experiment is worth a try.
CONCLUSIONS: The purpose of the volume tuned exhaust system is to recover the energy remaining in the cylinder when the exhaust ports open—it must do this while maintaining a silencing effect. Both objectives are accomplished by controlling the resonant pressure waves in their primary and secondary systems. The right exhaust system re presents a good compromise between peak power, torque range, and noise. It can easily be re-tuned for a specific track requirement.
If you bother to try the tuning possibilities listed here, you would find that the biggest and the easiest gain in re-tuning can be made by altering only one dimension. This, the very important inlet pipe length. Most systems can be adjusted at the flex tube for varying track conditions. A change in the flex tube length alters the wave distance travelled in the primary system and also changes the total distance travelled by the back-stuffing wave. The flex tube length therefore has the ability to re-tune both the primary and the secondary system. If done with care, the results of your tuning will be a reduction in lap time and you will still have an exhaust system that is quieter than any production expansion chamber.

Exhaust System Design for the Karter In an effort to enable you to modify your present Expansion Chamber type exhaust system, or assist you in designing a more efficient exhaust system utilizing an expansion chamber, the following information is being printed to serve as a guideline.

IMPORTANT —Keep in mind that the following is not intended to be a suitable system for any particular engine, since that is dependent on several variables such as gearing used, fuel used, engine porting layout, type of track being used and entails considerable advance calculation. It offers a starting point only to design an effective system.
A properly designed exhaust system increases an engine's volumetric efficiency by complementing and raising the mean effective pressure, due to increased "breathing". The exhaust system offers what may achieve, the largest single increase of usable horsepower of any modification applicable to a two-stroke engine, however it remains a relatively dormant area of knowledge. Those willing to spend the time, study and effort to truly understand it are in a distinct minority.

The increase in power is achieved due to the action of what is commonly referred to as "pressure waves" in the expelled exhaust gases. By controlling the wave action, through exhaust system design, to correlate with and compliment port timings. A considerable power increase is possible. Since the wave action in a resonant chamber or expansion chamber is extremely complex. It is practical here, only to supply simple guidelines toward this end by offering what has been learned from experimental work, practical application and studies conducted on the subject.

The point in the RPM scale where maximum torque will be developed, depends on the distance from the exhaust ports' "inner edge" to the large end of the convergent cone, as well as the length and diameter of the system's outlet tip. The overall volume of the entire system also has an effect. A rough rule concerning this matter is that, "as the point where maximum torque is developed, rises on the RPM scale, the length and the volume of the expansion chamber decreases. But the outlet tip increases in length and reduces in diameter." This would mean then, that compared to an exhaust pipe designed primarily for use on a tight sprint track, an enduro tuned pipe would be relatively smaller, with a longer outlet tip of smaller diameter.

The megaphone (diverging cone) angle will lie between 6 degrees and 12 degrees, for a 100 c.c. engine. This cone should increase in diameter 1.4 to 1.8 times the engine bore diameter. It's length should be in the area of 8 to 10 times the bore diameter.
The second cone should reduce the diameter back down to .5 to .6 times the bore size in a length of 3 to 4 times bore diameter.
The outlet tip length will be 1 to 3 times bore diameter, dependent on RPM desires, and .2 to .3 times bore in diameter.
Diameter of the header pipe on engine will be determined by the exhaust port size and shape, but should fall within area of .6 to .7 of bore diameter.

Please remember that these figures are only a guide and final design will also be influenced by individual engine characteristics, as well as the type of track you will use it on.
Once you have designed a truly superior exhaust system, (within the current sound level requirements), and its efficiency increases, some engine modifications (in open" classes) which may be needed and will help even further, are "increasing size of high speed carburettor jet size and reduced exhaust port "lead time". These are both due directly to increased efficiency of your properly designed exhaust system.
VOL UME TUNED EXHAUSTS, written by DALE HERBRANDSON and reproduced by courtesy of XARTER NEWS

husaberg

30th March 2014, 15:18

Who knows how ""modern"" this thinking is but I found the description informative, especially the bit about expansion ratios.

I am guessing you went with the "white background forum option" Rob LOL
I can read it only by Highlighting the text with my cursor......

kel

30th March 2014, 16:39

http://www.planetash.net/gos/powerbands.html

'May result in tearing the arse out of the space time continuum' hahaha (sorry no emotive icons on app)

Buckets4Me

1st April 2014, 19:18

'May result in tearing the arse out of the space time continuum' hahaha (sorry no emotive icons on app)
295537 all the colours of the rainbow :facepalm:

TZ350

3rd April 2014, 18:40

Ok now that work is settling down to easy 12 hour days and the 50 is on track, I can get back to the EFI project again in my spare time.

295612

Started making a new injector manifold that points the small Ecotrons injectors across the transfer port windows, previously the outside pair had just fired straight into the B transfer ports and impinged on the back of the cylinder liner.

295613

I want some of those "Power Bands" and I am looking forward to completing the trial EFI project so then I can get onto the Suzuki GP125/RGV250 EFI air cooled cylinder conversion with TPS and Digital ignition. I am looking for mid 30's rwhp and a wide power spread from the RGV power valve, ATAC header, 50mm Trombone and variable stinger nozzle venture.

The rotary valve will be increased from 112mm to 126 and the crankcase volume increased as much as I dare. The EFI is so I can re visit the plenum as previously with a carb there was a lot of raw fuel sloshing around in the bottom of the plenum and this upset the fueling.

Also the Ball Valve inlet is 34mm diameter and with the Ball Valve inside the plenum the plenums 24mm inlet is less of a restriction than having the 24mm carburetor equivalent nozzle in the inlet tract itself. And as a plan B in case I can't get the plenum to run as well as I would like is a large boost bottle arrangement that will sit between the 24mm restricted Ball valve and the large rotary valve window.

295611

I see the biggest issue with the air cooled RGV250 cylinder will be getting the heat away from the underside of the exhaust port tract area. This is what we do with the GP125 cylinders and I have new and bigger ideas about what we can do to extract heat from the RGV cylinder in this area.

Sure, it will not be as good as having water cooling but then there are ideas about an H2O CVT unit based on the RG400 cylinder that could very well become the follow on project.

husaberg

6th April 2014, 10:18

Thought i had posted this (but looking back maybe not)............

lodgernz

7th April 2014, 11:08

I'm planning to make a 2T LC cylinder head using inserts. Any ideas on what alloy spec would be best, and where I might get billets thereof?
I found a place (Znoelli) selling 6061 T6 & T651 billets, would those be good composition/hardness/etc?
All suggestions & guidance welcomed...

Drew

7th April 2014, 18:35

So I'm putting the MVX bucket together again. It's getting a GT125 up it again for now. Mr Nabbs prolly gonna get his arse roped into the building thereof.

But I've got a wee gem of a question that some of you knowledgeable types might enlighten me on.

The MVX motor is a V3 with a terrible issue with fucking the rear slug. The things fire both front pots at the same time, then the rear (middle) 90 or 270 degrees later.

Anyhoo, can I get the crank pressed apart, replace the middle webbs and crank pin with a straight bar from the inner webbs of the front slugs...at the same time as having the front two timed to 180 degrees?

From there I chuck a pair of Honda scooter slugs and barrels. Boom, 100cc water cooled two stroke twin, with a great six speed box?

Flettner

7th April 2014, 18:35

6061 T6 is a good all round alloy for machining engine ( and autogyro ) parts.
I use 6061 T6 351 to make autogyro rotorheads amongst other things, good strength, good corrosion resistance, machines very well, accepts anodising well.

TZ350

7th April 2014, 19:53

can I get the crank pressed apart, replace the middle webbs and crank pin with a straight bar from the inner webbs of the front slugs...at the same time as having the front two timed to 180 degrees? Boom, 100cc water cooled two stroke twin, with a great six speed box?

Doubt anyone has done this with a MVX but definitely doable I imagine. A 100cc H2O motor with a sweet gearbox sounds like it would be worth the effort.

Bob Haldane had a TR250 development motor with one pot, the left side flywheels were replaced with a straight shaft, worked a treat. I used it to develop a methanol setup for a TQ midget he was sponsoring at the time. The TQ midget had to be air cooled and later they used TZ cylinders with large holes cut in the water jackets, with methanol they worked a treat like that too.

husaberg

7th April 2014, 20:05

Drew

7th April 2014, 20:23

Doubt anyone has done this with a MVX but definitely doable I imagine. A 100cc H2O motor with a sweet gearbox sounds like it would be worth the effort.

Bob Haldane had a TR250 development motor with one pot, the left side flywheels were replaced with a straight shaft, worked a treat. I used it to develop a methanol setup for a TQ midget he was sponsoring at the time. The TQ midget had to be air cooled and later they used TZ cylinders with large holes cut in the water jackets, with methanol they worked a treat like that too.I was just concearned that the pin replacing a pair of webbs might not stay located, and twist. But it shouldn't if I think about it, since the left side was always supplying drive from a long way away from the primary drive cog.

Mmmmmkay, looks like I need to go and save a buggered MVX lump from a trip to the scrappy.

From memory the MVX250 has the same gearbox and ratios as a VT250F and i think a CBR250r
they are good close ratiosFirst is very tall, then nice short steps right through the box. I dunno why this didn't occur to me before now. P'raps the GT will remain on the shelf...or move to someone elses.

husaberg

7th April 2014, 20:32

I was just concearned that the pin replacing a pair of webbs might not stay located, and twist. But it shouldn't if I think about it, since the left side was always supplying drive from a long way away from the primary drive cog.

Mmmmmkay, looks like I need to go and save a buggered MVX lump from a trip to the scrappy.

First is very tall, then nice short steps right through the box. I dunno why this didn't occur to me before now. P'raps the GT will remain on the shelf...or move to someone elses.

I see a fly in your ointment drew the MVX has a 48mm stroke...
Maybe a Aircooled 125.........

Drew

7th April 2014, 21:31

I see a fly in your ointment drew the MVX has a 48mm stroke...
Maybe a Aircooled 125.........

The extent of work in this crank, replacing the webbs with Beat items won't be the end of the world.

speedpro

7th April 2014, 21:53

lodgernz

7th April 2014, 22:26

Drew

8th April 2014, 06:24

You might as well fuel inject it as well. You double up what Rob has. You'll need the 250 chassis to fit the wiring in. Good thing is the 250 alternator will supply the needed ergs.

I can see it now - watercooled 100cc twin, 15000rpm, fuel injected with 2 injectors/cylinder(minimum).I can't tell if you're being serious.

I would be using the 250 chassis, it's just had a VFR750 fork conversion and is getting a CBR600 swingarm and suspension. To allow for proper sized wheels.

I've chopped off all of the standard engine mounts unfortunately, so might have to hunt down another roller. Luckily, not too many MVXes were written off. They tended to blow up before anyone made it to the twisty roads.

Size of the thing is my only concern really. They're a wide bit of kit!

mr bucketracer

8th April 2014, 07:09

I can't tell if you're being serious.

I would be using the 250 chassis, it's just had a VFR750 fork conversion and is getting a CBR600 swingarm and suspension. To allow for proper sized wheels.

I've chopped off all of the standard engine mounts unfortunately, so might have to hunt down another roller. Luckily, not too many MVXes were written off. They tended to blow up before anyone made it to the twisty roads.

Size of the thing is my only concern really. They're a wide bit of kit!don't even go there , it will never get done .. i have 2 of them engines and would never do it in a million years

wobbly

8th April 2014, 07:58

I have a friend that rides his MVX every day - so if you guys get bored thinking of ways to ruin one, then remember there are a few people
out there that need the parts for a runner.

Flettner

8th April 2014, 08:46

Thanks Flettner, sounds perfect. Where do you get your billets?

I get my alloy from Nalco, good people to deal with.

Drew

8th April 2014, 10:27

I have a friend that rides his MVX every day - so if you guys get bored thinking of ways to ruin one, then remember there are a few people
out there that need the parts for a runner.

My brother has a runner also. Chap over Coro way from you has about enough bits to make five of them.

Gigglebutton

8th April 2014, 17:26

Thanks Flettner, sounds perfect. Where do you get your billets?

Try Nalco, Wakefield Metals and Special Steels. Ritchy at Trimac in Penrose has off cuts he sells.

lodgernz

8th April 2014, 17:50

Try Nalco, Wakefield Metals and Special Steels. Ritchy at Trimac in Penrose has off cuts he sells.

Thanks Gigglebutton. I'm in Wellington, so has to be mail order. Nalco are assisting me with my enquiries at the mo...:rolleyes:

TZ350

8th April 2014, 18:57

For something different.

Anne has a F4 Honda 125T she races at Mt Wellington and a girlfriend challenged her to a drag race at Meremere this weekend.

295958

Not sure the friend expected her to front with a 1200 Harley, but why bring a knife to a gun fight.

A bit of time spent on the dyno sorting out which gears to use and the best one to start off in.

<iframe width="420" height="315" src="//www.youtube.com/embed/U1Rz_ohsnFM" frameborder="0" allowfullscreen=""></iframe>

295957

Just out of interest, a comparison of my 2T (the Beast - blue line) with the Harley.

Drew

8th April 2014, 20:30

I think you had the final drive ratio entered incorrectly. It's a seriously wanked skirtster that'll pull 200k's, and sixty ponies suggests otherwise.

TZ350

8th April 2014, 22:35

I think you had the final drive ratio entered incorrectly. It's a seriously wanked skirtster that'll pull 200k's, and sixty ponies suggests otherwise.

Hmmm yes I see what you mean, but no head wind on the dyno to hold the bike back so the Harley just keeps spinning the drum until the rev's top out, in real life it would have to fight a head wind too.

Drew

9th April 2014, 06:22

Hmmm yes I see what you mean, but no head wind on the dyno to hold the bike back so the Harley just keeps spinning the drum until the rev's top out, in real life it would have to fight a head wind too.I would have thught it would be bouncing off the limiter before 125mph still.

Smooth curve though.

F5 Dave

9th April 2014, 09:21

Its pretty good for a stationary pump, i thought they didn't get much more than mid 50s, but that was a while ago, not that progression has probably been more than glacial. Back int he Dyno-tech days Chris was doing a few, but the word got around that his dyno read low & Scooter-centre got one that read closer to the 'proper' numbers so everyone was happier. Chris also had an unfortunate habit of testing things, like removing the Gen-ewe-swine Raped Budgie(TM) parts like the Thunder jet etc that they'd just laid out money for & gaining power. Clearly didn't know what he was doing:pinch:.

Yow Ling

9th April 2014, 19:40

Thanks Gigglebutton. I'm in Wellington, so has to be mail order. Nalco are assisting me with my enquiries at the mo...:rolleyes:

Another good place is little metals in Chch, they will sell exactly the size you want , only stock ally, brass and zinc

they supply plenty of cnc places

lodgernz

9th April 2014, 21:50

Another good place is little metals in Chch, they will sell exactly the size you want , only stock ally, brass and zinc

they supply plenty of cnc places

Thanks Yow Ling, I'll keep them in mind

speedpro

9th April 2014, 22:12

Chris also had an unfortunate habit of testing things, like removing the Gen-ewe-swine Raped Budgie(TM) parts like the Thunder jet etc that they'd just laid out money for & gaining power. Clearly didn't know what he was doing:pinch:.

I remember a conversation with Chris about a Thunder Jet on some huge flash carb some dweeb spent loads of cash on. He couldn't get the fuelling right and in desperation in the end disconnected the jet and away it went. We also had a bit of a giggle over one costly hotrod Harley that made 80hp on the dyno. When it was taken off we rolled a ZZR600(stock) on to the dyno and it made more or less the same power.

Bruce Anstey used to eat all the choc biscuits there as well.

F5 Dave

10th April 2014, 09:36

And not talk.

Last time I saw Chris was a rather messy night when he was back in wgtn quite some while back, then a few months before at Philip Island (also rather messy) when he was with Padgetts looking after Jay Vincent or someone like. Wonder where he is now?

TZ350

11th April 2014, 19:06

Making some progress with the new fuel injection manifold.

296058

The injectors are angled so they squirt more horizontally across the transfer port.

296068

The small (bottom left) injector from the Ecotrons Small Engine EFI kit for two strokes has had the clips on its top cut back so the fuel barb can be swiveled in different directions.

296056 296057

I will cut back all the injectors like that to make them easier to fit into the tight space behind the cylinder.

296103

All of the injectors are in place and I found these neat little clips and hose connectors at the local hose shop for plumbing it all up.

296102

Lots of copper of course and in the cardboard box is a new four channel temperature data logger so we will be able to get some hard data on how hot the Beast actually gets.

Hopefully get back to the dyno next week.

koba

14th April 2014, 21:42

I've been pissing about with an AX100.

Yeah, I know they are crap...

Still, I've done some basic stuff:

Smashed a bit of the baffling out of the exhaust, stopped it pinking on long full throttle runs.
Slightly longer header, mainly for moving the exhaust for better ground clearance, also took out most of the step as it transitions from header to diffuser.
Cleaned up the terrible porting, still not perfect but far better. Clean up of Exhaust was worth almost 1 hp.
Pissed around with jetting to get it running better.

So the next thing I did was to take the standard quiescent head and cut it down to a squish head.

It went from around 8:1 to around 12.8:1 in the process.
0.8mm squish clearance, close to 50% Squish area and a real old school shape, the squish band opens up quite a bit towards the centre and it has a radius into the main combustion chamber.

I've gone this old-school was as I expect it will work better with the standard (Shit) ignition.

So, now it's pinking once it's got some heat into it, generally (as expected) only when heavily loaded.

I'm going to back the timing off until this stops.

So My Question for the experts:

Is this going to loose power over less compression/more advance?
Testing to find the best balance would be nice but I'm going to have to plug some guesses in to this too.
EDIT: Is it just that the burn time is reduced requiring less advance?

koba

14th April 2014, 21:49

Hopefully get back to the dyno next week.

:corn::corn::corn:

TZ350

14th April 2014, 22:18

...the burn time is reduced requiring less advance?

Sounds very very possible, often on the dyno we found backing off the "track tuned" ignition setting produced more power. Bikes were often presented, over advanced and over rich to compensate. Backing of both gave more power and a wider spread too.

wobbly

15th April 2014, 08:57

Depends entirely on the fuel.
At 12:1 and detoing means you cant be running AvGas and you should be, in small bores 16:1 is just fine.
The close squish clearance and 50% area are OK, but having a taper and a radius in effect means the squish is doing Jack Shit, in reality this will cause deto, not suppress it.
Easy fix is to change the fuel, but keep in mind that unleaded loves advance and hates com - and max power is gained when rich.
Avgas loves com and doesnt need much advance for max power - but works best run lean, but either way you have a compromised setup that can never make good power.

koba

15th April 2014, 22:23

Cheers.
I'll let you know where I end up.

No luck getting the timing backed of as an interim step tonight. Try again tomorrow.
I suspect I'll end up with lower compression and more aggro squish.
I currently think that too aggro with a shit simple ignition isn't so good but I'd like to prove/disprove this with some testing If the stars align

Also, should have mentioned that I'm commuting on this pile of poop, that makes AV too much of a mission.

speedpro

15th April 2014, 22:33

TZ350

16th April 2014, 16:12

:corn::corn::corn:

Three F5 50's just queue jumped me for time on the dyno ......

koba

16th April 2014, 19:05

My good motor has the squish area and then a radius into the chamber. I bought a fancy programmable ignition only to find it wanted the same ignition timing at all revs. I understand that an edge between squish and chamber would necessitate backing the timing off at higher revs due to faster flame propagation with the increased turbulence at those higher revs. Since you are running points and can't back timing off with revs the curve would seem to be the way to go. You're building the engine to suit the ignition's limitations.

Doesn't seem to be points, think it may have a modern sensor but otherwise the same architecture and certainly the same ignition crapness.
I've seen this before, I think, with my MB100 - although the pipe design may also play a part.
I'm considering an old style chamber on that as an interim step before getting the ingitech going on it, I desperately need over rev to give more spread and the latest, very aggressive cut took it away. Currently on an old CR80 Ignition.

koba

16th April 2014, 19:06

Three F5 50's just queue jumped me for time on the dyno ......

That takes me up to a dozen packs of pop-corn!

Worthy Cause!

chrisc

16th April 2014, 23:41

Found this in Bert's links
(http://www.kiwibiker.co.nz/forums/group.php?do=discuss&discussionid=1489)

GRP125 made into a 170 and home built EFI. Made 29hp, not extensively ported/tuned.
Unfortunately a lot of the earlier image links are dead but I think it was a carb replacement type injection rather than a transfer port injection type.
Have a look, I haven't trolled the thread much yet but man there are some idiots on that forum.

http://www.125ccsportsbikes.com/forums/index.php?showtopic=63480&st=320

2T Institute

17th April 2014, 13:00

F5 Dave

17th April 2014, 15:50

you mean the forum. I used to frequent the Derbi 50 one years back. but not for long when I realised who was posting

tonyed

17th April 2014, 18:11

Yea maybe a bit like Beck poking his tongue out at Clapton, a respectfully intellectual exercise .

But in a dissimilar vein here is some pervage for the boys,this isnt on track, its on the rubbish tin - and yes I know the floor needs sweeping.
Pre 82 Classic Frepin copy frame I have FEA corrected with TZ400 and S model fairing Billy is hoovering up now.
Coming together for Philip Island next January.
Late model Yamaha blue - tank/fairing will be a bit like Roberts colours.

I have the original Peter Pinion Frepin. It has a couple of extra tubes in it at the rear engine mount and between the top frame tubes. It houses a TZ350 G spec motor with G forks, ARE front wheel and a SMAC at the back (could not afford Campags).
I gather Peter bought the frame, swinging arm and tank back to England to have them copied, left them at a frame builder and never surfaced again. It has been round the houses a bit since then and at the Stafford Classic Bike show a couple of years back I talked to a previous owner who found the frame etc at the frame builders and bought it, not knowing anything about its' history. Built it as a 250 and raced it as a Yamaha in the TT. He said then he fitted a 350 engine and did the frame mods as the rear engine mount broke.

Murray DeLacey has one and some replicas.

Also a NZ contact was going to email me some photos of his but never did.

It always draws attention at shows and will be at Stafford again next weekend (26/27th April)

2T Institute

19th April 2014, 12:04

you mean the forum. I used to frequent the Derbi 50 one years back. but not for long when I realised who was posting

Yes no amount of experience or logic is equal to a cut n paste of the internet

TZ350

23rd April 2014, 06:46

... cut n paste..

296421

"Cut n Paste" ... replica of a 2T concept originally posted by Frits .... :D

how can we prevent a scavenging column from toppling over to the exhaust side like the leaning tower of Pisa? Not by pushing against its basis, but by pushing higher up.

Follow the link to read the whole story and see the original pictures.

wobbly

23rd April 2014, 14:55

Does anyone know if Pinion is still with us.
One of the frames I have came from Fred McLeans estate I believe, but I have never had any info re Peter.

Grumph

23rd April 2014, 17:56

Does anyone know if Pinion is still with us.
One of the frames I have came from Fred McLeans estate I believe, but I have never had any info re Peter.

My impression is that Fred was based in ChCh around that period - i may be wrong. I'll ask a couple of oldies i know not on here who may have some info on PP. At least one had a Frepin - and i've got the tank.

TZ350

23rd April 2014, 20:35

Unlike finicky carburetors, with fuel injection there is not the over enriching problems you get when the inlet stream bounces back and forth several times in the inlet tract. Passing the carbs needle jet several times and picking up fuel on each pass. With EFI I don't have to be so conservative with the rotary valve timing and can experiment a little.

296434

I have cut the top valve to have the same area but with a soft opening and closing effect.

296436 296432 296435

Soft Opening - Fully Open and Soft Closing.

With the inlet opening at the bottom of the port first I am hoping to encourage the flow to adhere to the port floor, that way I think there will be a greater total flow through the port.

Opening at the inlet port floor first is an idea that Jan Thiel talked about, I hope I can make it work for me. Looking at the Aprilia pictures it looks like Jan offset the RV a little sideways in relation to the inlet port and that way he was able to cut the RV so it opened from the bottom first much more neatly than I can manage with the GP.

And soft closing at the top because I think the bulk of any blow back will follow the inlet port floor. And having the valve close the bottom first will block it.

296433

Looking into the inlet tract you can see how the boost bottle directly feeds the inlet port as the RV starts to open it.

296437

All the fuel injectors, hoses and plugs fit, thank goodness... :sweatdrop ... I was a bit worried.

Anyway I have no real idea if any of this will work but I guess the dyno will tell us soon enough.

:scratch: now to figure out all the wiring.

wobbly

24th April 2014, 09:53

As I understand it Pinion and McLean did the Begg F5000 cars and the Frepin was a sideline.
But I would like to nail down the history and chat to the horses mouth if possible.
Even the butchered frame I have that had a 500 in it is mirky in that I have also heard the motor was a 700, but again - who rode it
and who did the crap job of fitting it together.

wobbly

24th April 2014, 10:08

TeeZee, I spent days on the dyno at ZipKarts running a Rotax tandem 250 trying all the ideas we had seen with various rotary valve opening/closing scenarios.
I tried convex and concave opening and closing edges, singly and tandem curves in all manner of combinations - initially all with the same timings of 140/88 but
later when getting no results I tried curved edges with less and then more timing as well..
Several ideas changed the full power egt and this was re jetted for, but none of the weird shapes made any more power, many made less.
Then years later, Ii read that Jan had said somewhere when asked about the RV shapes being used on the leading edge only of the Aprilia
that the angled shape had nothing to do with power, but helped ameliorate the rapid wear on the case that was caused by the unsupported
valve being pushed against the open port area by the inrushing column of air.
This may have changed later, but I sure could not find any hidden horses but ruined a heap of perfectly good discs.

F5 Dave

24th April 2014, 11:11

Thus stimulating the Austrian economy and promoting world peace, so not a total loss.

TZ350

24th April 2014, 16:12

I sure could not find any hidden horses but ruined a heap of perfectly good discs.

:doh:

Thanks for the heads up, I had to give it a go but will only try this one then maybe re fit the original one and save face by calling it a back to back test....

Ii read that Jan had said somewhere when asked about the RV shapes being used on the leading edge only of the Aprilia
that the angled shape had nothing to do with power, but helped ameliorate the rapid wear on the case that was caused by the unsupported
valve being pushed against the open port area by the inrushing column of air.

Makes sense.

wax

24th April 2014, 17:36

chrisc

24th April 2014, 18:19

I thought I had read that same info re the soft opening Rob. What you say wobbly makes a whole lot of sense though. I wonder if others have had the same experiences re the shapes.

Drew

24th April 2014, 19:09

Unrelated question. Do two strokes drink enough oil, to pump it in through the crank and run shell bearings?

Henk

24th April 2014, 19:12

Haven't seen a two stroke on shell bearings. Doesn't mean it hasn't been done.

Drew

24th April 2014, 19:18

Haven't seen a two stroke on shell bearings. Doesn't mean it hasn't been done.The biggest downside would have to be the volume I would have thought.

Unless the fickle bitch that is a two stroke tune and the narrow spread of power, means that there's no point in making one rev that high of course.

Was just a musing of course, I figure that if one could get a GT125 to rev past 15,000RPM it could have oodles of power extracted from it and still run a silly little 17mm carb per slug...But although I've read this thread, there's a lot I'm sure I didn't retain/understand.

pete376403

24th April 2014, 19:21

Drew

24th April 2014, 19:27

Not that you're ever likely to see one in a bucket, but, uniflow two stroke (eg GM) diesels run plain bearing cranks with high pressure lubrication. They also have cams, pushrods, poppet valves in the cylinder head and are still a two stroke.You forgot to mention forced induction. Can't even start one of those bad boys without pressure in the inlet tract.

They don't breath/burn the crank lubricant either, so it's not really relative to my question.

husaberg

24th April 2014, 20:35

Haven't seen a two stroke on shell bearings. Doesn't mean it hasn't been done.

Villiers used to run plain bushes.......not saying it was clever though:laugh:

WilDun

24th April 2014, 23:54

Villiers used to run plain bushes.......not saying it was clever though:laugh:

Yeah, so did British Seagull (outboards), Iron Horse (johnson outboards and lawnmower engines) and various others (including model aircraft engines). - The secret? 1 pint of oil to 1 gallon of petrol (think that's 8:1) and massive clouds of smoke!!

However, having said that, there have been many successful two stroke diesels with overhead valves and blowers which didn't use the crankcase as a pump, so really the same bottom ends as the four strokes.

Also, I remember one attempt at using overhead valves on an Italian two stroke kart engine - the overhead camshaft ran at half crank speed and the valves opened alternately (to prevent 'valve float' which would have happened if they opened at every crank revolution). I still think it used crankcase compression though, so no plain bearings.
Needless to say it didn't last long! - I haven't found it on the net.so far.

Trouble is, when you start adding all these things, then the weight, the complexity and the price also go up!
Let's just stick to the good old "simple" two stroke I say. Only problems it's got are pollution, exhausts bigger than the motor, high fuel consumption and it pisses off the Harley boys - nothing to worry about really! :laugh:

WilDun

25th April 2014, 00:57

On the other hand, here's one for you four stroke boys, (and this has been successfully done on YS model aircraft four stroke engines), why not get "free" supercharging from having a crankcase charged four stroke? ie using a needle roller crank and a petroil mixture.
The piston will produce crankcase compression on each revolution of course, so on a single, every other stroke the charge will be stored in a small chamber in the head near the inlet valve and released when the inlet valve opens to accept the charge on the next stroke - really a four stroke top end on a two stroke bottom end.

I might also add that a on four stroke twin either boxer or parallel, (ie with 360 deg crank on a parallel twin, or a 180 deg crank on a boxer), whatever, but with both pistons hitting TDC at the same time and alternate firing), the necessity for a "storage chamber would disappear! - where have all those CB 125T bikes gone??
Maybe FLETTNER would be interested.
It actually does work, but of course for bucket racing it might be banned I dunno! - could just give you four stroke boys a fighting chance though! :msn-wink:

Gotta get to bed, I might be hallucinating, then again I might not! :weird:

mr bucketracer

25th April 2014, 02:42

WilDun

25th April 2014, 08:27

after thinking of the idea 20 or so years ago i found a speedway guy had done it to his engine. sounded like it did not work to good but may not of done it propery.. i dont think it would be aloud anyway been a form of supercharging

Yeah, I thought that might be the case, but as we all know these things need a lot of hard work and fine tuning. It can work of course and it would be interesting to try but in this life we are restricted by rules wherever we turn. In saying that.
Buckets are a great outlet for experimentation but in order to keep things cheap and available to all, we have to have some rules I guess!
All just food for thought of course............How about an 'experimental and developmental only' class?? :wacko:

Ocean1

25th April 2014, 09:20

The piston will produce crankcase compression on each revolution of course, so on a single, every other stroke the charge will be stored in a small chamber in the head near the inlet valve and released when the inlet valve opens to accept the charge on the next stroke

Every stroke: Reeds at the base of the transfer ports.

. i dont think it would be aloud anyway been a form of supercharging

Which begs the question, why should 2 strokes be allowed the very same method?

WilDun

25th April 2014, 10:00

Every stroke: Reeds at the base of the transfer ports.

Which begs the question, why should 2 strokes be allowed the very same method?

We are talking four strokes here of course and having to store the charge for one revolution (in the case of a single, - twin is different) - two strokes don't have to store it although I guess they do exactly that in the exhaust chamber!
Would like to stay and talk but my wife is getting impatient with me as we are heading off! :rolleyes:

richban

25th April 2014, 10:05

So Rob. Check out the frame. Look familiar? Yep its the one you had in your lockup. A good use for it I think.

So its been slow going for a we while due to actually having to do work but it is now ready for its first Shake down on the track.

This is the first 2 stroke I have built from split cases up. And it will not be the last. New Nitron rear shock on its way and also just a bit of mucking around to fit the Honda RS250 forks I have for it. But as it sits I have the correct weight springs and the front has been completely rebuild and working very well.

The ignitech is on and running but needs fine tuning. That will come when my connectors turn up to hook in the TPS and power Jets from the 38's

Also pipes. At the moment they are the tyga 250 pipes. They are a temp option but look rather nice and give good midrange but not so hot on the peak.

296475296476296477296478

Ocean1

25th April 2014, 10:09

We are talking four strokes here of course and having to store the charge for one revolution (in the case of a single, - twin is different) - two strokes don't have to store it although I guess they do exactly that in the exhaust chamber!
Would like to stay and talk but my wife is getting impatient with me as we are heading off! :rolleyes:

Subtle difference, yes. Although if 2 strokes didn't store compressed gas why do they need reed/rotary valves?

I suspect the largest issue with case-charged 4 strokes might be keeping the valve closed, you'd need damned near double the spring pressure.

chrisc

25th April 2014, 10:25

Subtle difference, yes. Although if 2 strokes didn't store compressed gas why do they need reed/rotary valves?

I hate to argue semantics because it's hardly worth doing but a disk valve allows asymmetric inlet timing, and they both ensure that the charge is pushed through the transfers rather than out the inlet. A two stroke doesn't need a reed valve or a disk valve to operate (piston port) but allows better control of the charge. Obviously there is compression taking place here but I thought I'd point that out as an answer to your rhetorical question.

chrisc

25th April 2014, 10:29

So Rob. Check out the frame. Look familiar? Yep its the one you had in your lockup. A good use for it I think.

Sorry I haven't been following. NSR250 frame right? With the 250 engine out to 300? Looks good!

pete376403

25th April 2014, 10:52

after thinking of the idea 20 or so years ago i found a speedway guy had done it to his engine. sounded like it did not work to good but may not of done it propery.. i dont think it would be aloud anyway been a form of supercharging

Not supercharging, but positive crankcase ventilation for pollution control. So green it should earn carbon credits!

richban

25th April 2014, 11:50

Sorry I haven't been following. NSR250 frame right? With the 250 engine out to 300? Looks good!

Yep NSR MC21 with 150sp Barrels. Case ported copy of Honda F3 cases and nice tidy of the stock barrels. Its fun to ride I tell yah.

Ocean1

25th April 2014, 12:03

I hate to argue semantics because it's hardly worth doing but a disk valve allows asymmetric inlet timing, and they both ensure that the charge is pushed through the transfers rather than out the inlet. A two stroke doesn't need a reed valve or a disk valve to operate (piston port) but allows better control of the charge. Obviously there is compression taking place here but I thought I'd point that out as an answer to your rhetorical question.

Just as a 4 stroke doesn't NEED crankcase transfer pressurisation.

Not really batting for either side, but it's interesting how convoluted the rules would have to get in order maintain some balance between the fleet if manufacturers offered anything other than 2T or 4T, there's a large number of alternatives outside the biking world that are neither one nor the other and have many of the advantages of both.

But that's what development classes should be about, exploring the chinks in the rules to some advantage, there's enough classes where it's all about the rider, fuck all where the techies get to play.

Bert

25th April 2014, 16:21

So its been slow going for a we while due to actually having to do work but it is now ready for its first Shake down on the track.

This is the first 2 stroke I have built from split cases up. And it will not be the last. New Nitron rear shock on its way and also just a bit of mucking around to fit the Honda RS250 forks I have for it. But as it sits I have the correct weight springs and the front has been completely rebuild and working very well.

The ignitech is on and running but needs fine tuning. That will come when my connectors turn up to hook in the TPS and power Jets from the 38's

Also pipes. At the moment they are the tyga 250 pipes. They are a temp option but look rather nice and give good midrange but not so hot on the peak.

296475296476296477296478

Looking bloody good Rich.

So how many hours has it taken you to do all the F3 porting and build it up.
First time I've seen mx 38s on a NSR, they must have taken some fitting. Custom parts??

I'm assuming this is a SpeedJunkie partnership / race team. These bikes are going to make superlite/F3 very interesting this year.

mr bucketracer

25th April 2014, 17:41

Looking bloody good Rich.

So how many hours has it taken you to do all the F3 porting and build it up.
First time I've seen mx 38s on a NSR, they must have taken some fitting. Custom parts??

I'm assuming this is a SpeedJunkie partnership / race team. These bikes are going to make superlite/F3 very interesting this year.at least we will see them not like the other one meeting wonders

richban

25th April 2014, 18:21

So how many hours has it taken you to do all the F3 porting and build it up.
First time I've seen mx 38s on a NSR, they must have taken some fitting. Custom parts??

Hours. Not sure. At one stage it was all off the hours. But it has been heaps of fun.

Yep late model YZ250 carbs. And some very nice work from sketchy, sorted them out. We were lucky and had some Honda RS250 inlets to copy and (improve on).

I would still like to machine a nice bell mouth onto them but that can wait.

Yes. I think after they prove themselves on the track others will follow for sure.

Bert

25th April 2014, 19:05

Hours. Not sure. At one stage it was all off the hours. But it has been heaps of fun.

Yep late model YZ250 carbs. And some very nice work from sketchy, sorted them out. We were lucky and had some Honda RS250 inlets to copy and (improve on).

I would still like to machine a nice bell mouth onto them but that can wait.
Yes. I think after they prove themselves on the track others will follow for sure.

Great work Rich (and Sketchy's work looks great in the flesh).
Only feels like yesterday when the idea was floated.

It really has not taken that long to get them sorted and on track, very impressive; and I'm sure others will follow.

TZ350

25th April 2014, 19:34

So Rob. Check out the frame. So its been slow going for a we while due to actually having to do work but it is now ready for its first Shake down on the track.

296475296476296477296478

Rich, it looks stunning.

296499

koba

25th April 2014, 21:19

300 naked_Rich.jpg is getting me horny on a Friday night.

Something is wrong here!

koba

25th April 2014, 21:45

Drew, Why?

If the crank is poo wouldn't it be easier improving that within the bounds of a conventional 2 stroke crank?

Forgi

25th April 2014, 22:31

Frits Overmars

26th April 2014, 00:10

@TeeZee: If you just have been testing different types of rotary disc valves, then would it be a huge request to make a dyno test on a 88/88 rotary disc valve? I'm eager to know exactly what is the difference between the power of a symetric piston controlled inlet port and a rotary disc valve if each and every other pharameters are the same.They will probably not all be the same, Forgi. A rotary disc usually opens much quicker (= in fewer crank degrees) than a piston port.

jasonu

26th April 2014, 12:14

Rich, it looks stunning.

296499

Looks great. I hope it runs as good as it looks.
Where did the pipes come from.

TZ350

26th April 2014, 12:28

@TeeZee: If you just have been testing different types of rotary disc valves, then would it be a huge request to make a dyno test on a 88/88 rotary disc valve?

Hi Forgi, I agree, it would be interesting but its not very relevant to my project and its hard for me to do. The std inlet timing for my Suzuki 125 engine is 145/55 so 88 closing is easy, I would only need to cut the leading edge of the disk and it is what I routinely do to get the inlet duration I want. But 88 opening means adding material to the trailing edge, and that would necessitate making new disks.

Bert

26th April 2014, 12:57

So Rob. Check out the frame..........

Also pipes. At the moment they are the tyga 250 pipes. They are a temp option but look rather nice and give good midrange but not so hot on the peak.

Looks great. I hope it runs as good as it looks.
Where did the pipes come from.

TYGA NSR250 pipes.
Latest model given they are not hydroformed.

richban

26th April 2014, 13:20

On the 300. It has a funny little issue while warming up. Starts really well runs great on warm up then just stops. Start again and the repeat. Then 3rd go and it's fine. Could it be to much advance? 32 deg. It stops from quite hi rpm. 5 6k maybe.

Neal

26th April 2014, 14:25

Well done on getting the bike running Rich ! You must be using the ignitech to run the powerjet carbs ?

richban

26th April 2014, 15:09

Well done on getting the bike running Rich ! You must be using the ignitech to run the powerjet carbs ?

Hi Neal.

No power jets yet. Just waiting on connectors. I could just choc bock them but they are off with no connection so we will see how it goes like that.

When you bringing your one to NZ?

TZ350

26th April 2014, 16:40

Page 930 ....

I am going to start by using a AMR-300 Supercharger to develop the bike/motor. Then as time allows I will continue on with the development of the small centrifugal supercharger. Kyle managed to find a supplier of the small superchargers here

http://www.kemotorsport.com/

It was $280AUD including shipping for a good condition second hand or an extra $100 for a new one.

http://www.barikit.com/index.php?option=com_virtuemart&page=shop.browse&category_id=257&Itemid=8&lang=en
May be useful to some of you. Found what I wanted here.

this was posted a while back
http://www.underdogsracing.com/fospipe/
frits has also posted a pic of his 50pipe that has won the last 5 euro championships or something i have it somewhere.

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=276973&d=1358853762

Tim, right now you may be more interested in ' All that you wanted to know about the Aprilia RS50'. Here are some numbers to play around with. Exhaust pipes don't come any simpler than this, but don't let that fool you; this pipe was good for eight championships. Just don't show it to the Poms; year after year they keep trying to beat those Dutch 50 cc bikes :D.
About the step in the exhaust duct: if there is a step and you remove it, you lose power. I think the main reason is that in removing the step you increase the duct volume. The Malossi cylinder I experimented with has no step at all, but as you can see in the pipe drawing, the exhaust duct is quite narrow. That works.

https://www.facebook.com/pages/The-Balance-Of-Power/249827285189711

A page about suspension set up

Here's a valuable link:

Parts diagrams and numbers (http://www.battle.co.jp/partslist/index.htm)

Parts listings and diagrams for the following:

-----HONDA--HRC-----
Data Logger
Detonation Counter
DREAM50
NSR50
NSRmini
MH80
NSF100
RS125R
NSF250R
RS250R
CBR250R
NSR250
CRF250/X
CRF450
CB400SF
RVF400R
CBR600F/F4i
CBR600RR
CBR954RR
CBR1000RR

-----YAMAHA----SUGO KIT-----

TZ125
TZ250
YZF R-6
YZF R-1

They are an oddball unknown in the universe i think i posted the size on the Help NF4 page Scott knows anyway.

Oh well its not there but we discussed it somewhere i think the od has to be changed on a common one.......
Googlle,,,says.......

http://2stroker.createforumhosting.com/nf4-steering-head-bearings-t6176.html

here's he parts list the bearing sizes for pretty much anything are on the Sudco site.
I have posted and made a sheadsheet somewhere........

Click on the arrow after Husaberg below and it will take you to the sheadsheets

I will add this here as a few people don't know how to access this information.
Upper: 22.5 x 41 x 12.5
Lower: 24 x 41 x 12.5
Honda MB-5-50 (82)
Honda MR-50/K1 (74-75)
Honda MT50Z, MTX50
Honda NSF50F (90)
Honda Z50A/K3-K5/RH/RJ, Z50A (71-76)
Honda Z50R (79-87), Z50RD (86)
Honda CR60R (83)
Honda ATC70/K1 (73-74), ATC70 (78-85)
Honda CL70/K1-K3 (69-73)
Honda CT70/K1-K4 (69-76), CT70H/HK1 (70-73), CT70 (76-82)
Honda SL70/K1 (71-73)
Honda XL70 (74-76)
Honda XL75 (77-79)
Honda XR75 (73-7Cool
Honda MB80, MBX80RFD/RSD
Honda MTX80/C
Honda XL80S (80-85)
Honda XR80 (79-84), XR80RF-R (86-9Cool
Honda ATC90 (75-85)
Honda CS90
Honda CT90 (68-79)
Honda SL90 (69)
Honda ST90K1-K4
Honda CB/CL100/K1-K3 (76-7Cool
Honda SL100/K1-K3 (70-73)
Honda XL100/K1 (74-75), XL100/S (76-85)
Honda XR100RP-R (85-9Cool
Honda ATC110 (79-85)
Honda CT110 (80-86)
Honda XL110/S (76-85)
Honda ATC125M (84-87)
Honda CB125/S (76-85), CB125T/J (78-81), CB125TT (90)
Honda CG125
Honda CM125T/J (82-85)
Honda CR125M/M1 (74-7Cool
Honda CT125 (77), CT125H/J/K (87-89)
Honda MBX125
Honda MT125 (74-76), MT125R/RII (77-7Cool
Honda SL125/K1/K2
Honda TL125/K1/K2/S (73-76)
Honda XL125K-3 (78-79), XL125S (79-85)
Honda MR175K (75-77)
Honda ATC185/S (80-83)
Honda CM185C (7Cool, CM185T (78-79)
Honda XL185S (79-83), XL185SH/SJ/SK
Honda XR185 (79)
Honda ATC200 (79-83), ATC200E Big Red (82-84), ATC200S (84-85)
Honda CM200T (80-82)
Honda XR200 (80-83)
Honda CB250N (Late Models)
Honda CBX250F (85)
Honda CM250C (82-86), CM250T (80-82), CMX250C/CD (85-87)

Upper:30 x 55 x 17
Lower: 30 x 55 x 17
Suzuki GSXR600 (97-00)
Suzuki GSXR750 (96-03)
Suzuki TL1000R (98-00)
Suzuki TL1000S (97-01)
Suzuki GSXR1300R (99-00)
Yamaha YZFR6 (99-01)
Yamaha YZF-R1 (99-00)

Upper: 25 x 47 x 15
Lower: 30 x 55 x 17
Honda CB750KZ/FZ
Honda CB900FZ
Honda CBX/Z
Honda GL1000 (77-79), GL1000K3/Z
Kawasaki KX125 (82-91)
Kawasaki KDX200 (83-9Cool
Kawasaki KX250A5-A7(79-81), KX250B1/C1/C2/D1/D2/E1/F1/G1/H1/H2 (82-91)
Kawasaki KXT250A1/A2/B1/B2 (84-87)
Kawasaki KDX420B1 (81)
Kawasaki KX420A1/A2 (80-81)
Kawasaki KDX450A1 (82)
Kawasaki EX500B1-B4 (88-91)
Kawasaki KX500A1/A2 (83-86) B1/B2 (85-86), C1/D1 (87-8Cool, E1-E3/E4/E5 (89-93)
Kawasaki ZG1200B1-B12 Voyager (87-9Cool
Suzuki DR125SER/SES/SET/SEV (94-97)
Suzuki RM125J
Suzuki PE/RS175T-E (80-84)
Suzuki DR200SET/SEV/ SEW (96-9Cool
Suzuki DR250 (90-91), DR250S L/M/N/P/R /SES (90-95)
Suzuki GN250Z/D/F (82-85), GN250Z-ER (81-95)
Suzuki GSX250F M/N/P/R (91-94)
Suzuki PE250T/X (80-81)
Suzuki RG250G/FG (85)
Suzuki RGV250K (88-89), RGV250M/N/P/R (91-94)
Suzuki RM250J (8Cool
Suzuki RS250T/X (80-81)
Suzuki DR350 (90-9Cool
Suzuki DR350S L-HR (90-94)
Suzuki DR350SL/SM/SN/ SP/SER/SES/SET/SEV/SEW (90-9Cool
Suzuki DR400T (80) DR400ST
Suzuki GN400 (80), GN400T/TX/TZ (80-82)
Suzuki GSF400M (91-93), GS400 Bandit (91-93)
Suzuki GSX400EE/SE/EF/SF (85), GSX400ET/ST/EX/ SX/X
Suzuki GSXR400F
Suzuki PE400T/X (80-81)
Suzuki GS450E T/X/Z/D (80-83)
Suzuki GS450G Z/D/F(82-85), GS450L (80-8Cool
Suzuki GS450TX/TXZ/TXD/TZ (81-83)
Suzuki DR500X/Z/D (81-83)
Suzuki DR/PE500T/X (80-81)
Suzuki GS500E/EK/EV (89-00), GS500L (80-83)
Suzuki RG500G
Suzuki SP500X/Z (81-82)
Suzuki GS550E (83), GS550EF (85), GS550ESE/ESF (84-86), GS550ESG (86)
Suzuki GS550ET (80), GS550L (80-83), GS550LF/LG (85-86), GS550MZ (82), GS550TX (81)
Suzuki GSF600 (1996-00)
Suzuki GSX600FJ-FW (88-01)
Suzuki GSXR600WN/WP (92-93)
Suzuki RF600R (P/R) (93-94), RF600RR/RS /RT (94-96)
Suzuki DR650RE R/UR (94)
Suzuki DR650SN/SP (92-93)
Suzuki GS650D/XD (83), GS650EX/EZ (81-82), GS650GL (81-83), GS650 GX/GZ/ GD (81-83), GS650 MD (83)
Suzuki LS650F/P/G/J/K, LS650PS/PT/PV/PW Savage (95-01)
Suzuki NX85D (83)
Suzuki SV650 (99-00)
Suzuki GS700EF/ESF (85)
Suzuki GV700GLF (85)
Suzuki VS700 (86-87)
Suzuki DR750S/SU/J/K
Suzuki GS750ED/ESD (83), GS750ET/EX/EZ (80-82),GS750LT/LX (80-81), GS750SD (83), GS750TZ/TD (82-83)
Suzuki GSX750EF/F (85), GSX750ES D/E (83-84), GSX750F(89-92), GSX750FK-FT (89-96), GSX750S S/D (83)
Suzuki GSXR750 (86-95), GSXR750W N/P/R
Suzuki 750T/X (81-82)
Suzuki VS750G (88-91)
Suzuki VS800GLN-GLT Intruder (92-01)
Suzuki VX800L/M/N/P (90-94)
Suzuki VZ800V/W Marauder (97-01)
Suzuki GS850G/GL (79-83)
Suzuki RF900RR/RS/RT/ RV (94-97)
Suzuki GS1000C/EC/HC/N (78-79), GS1000ET (80), GS1000G/GL (80-81), GS1000L N (79)
Suzuki GS1000LN/SN/ST (79-80), GS1000SZ (82), GS1000T/HT/ ET (80)
Suzuki GS1100E (80-83), GS1100G/GL(82-83), GS1100GK (82-84), GS1100LT (80), GS1100SD (83)
Suzuki GSX1100E/ES/EF, GSX1100E T/X (80-81)
Suzuki GSX1100EE/ESF/EFF/EF/ESF/EFF (84), GSX1100F (90-93)
Suzuki GSX1100FJ-FP (88-93), GSX1100G M/N/P/R (91-94)
Suzuki GSX1100LT/ST (80), GSX1100 LN/SN (79), GSX1100S Z/D (82-83)
Suzuki GSXR1100 (90-93), GSXR1100F (88-92), GSXR1100G-M (86-91), GSXR1100WP/WR/ WS/WT/WV (93-9Cool
Suzuki GS1150EF/EG (85-86), GS1150ES3/ESE/ ESF (83-85)
Suzuki GSX1150E (83-86)
Suzuki GSF1200SV/SAV (97-01)
Suzuki GV1200GLF/GLG (85-86)
Suzuki GV1400G (86-89)
Suzuki VS1400 (87-01)
Suzuki VS1400GL H/R (87-01)
Suzuki VL1500 (98-01)
Yamaha BW80S/T/U/A (86-90)
Yamaha YZ100J/K (82-83)
Yamaha YZ125D-S (77-86)
Yamaha IT175D-K (77-83)
Yamaha IT200L/N/S (84-86)
Yamaha IT250D/E/F/G/H/J/K (77-83)
Yamaha TZ250F/G/H/J (79-82)
Yamaha TZR250R
Yamaha XT250L/LC (84)
Yamaha YZ250D-T (77-87)
Yamaha TT350S/T (86-87)
Yamaha XT350N/NC-K/KC (85-9Cool
Yamaha IT400D/E/F (77-79),
Yamaha FZR400 (88-90)
Yamaha YZ400D/E/F (77-79)
Yamaha IT425G (80)
Yamaha IT465H/J (81-82), YZ465G/H (80-81)
Yamaha IT490K/L (83-84), YZ490J-A (82-90)
Yamaha RZ500N (85)
Yamaha XT550J/K (82-83)
Yamaha FZR600 (89-99)
Yamaha TT600L/N/S/T/U (83-8Cool
Yamaha XT600L/LC-G/GC (84-95)
Yamaha YZF600 (95-00)
Yamaha XV650 (98-01)
Yamaha FZ700T/TC (87), FZX700S/T/TC (86-87)
Yamaha XJ700N/NC/S/SC/XN/XS/XSC (85-86)
Yamaha XV700 Virago (84-87)
Yamaha FZ750N/S/SC (85-86), FZ750U/UC (8Cool
Yamaha FZR750RT/RU (87-8Cool, FZR750R (90), FZX750 (87-89)
Yamaha XS750 ALL (77-79)
Yamaha XTZ750 (93)
Yamaha XV750 Virago (88-97)
Yamaha YZF750 (94-9Cool
Yamaha XS850 ALL (80-81)
Yamaha TDM850 (92-93)
Yamaha XJ900RK (83), XJ900FN (85)
Yamaha FZR1000 (87-91), FZR1000 EXUP (83-95)
Yamaha XV1000 Virago (84-85)
Yamaha FJ1100 (84-85)
Yamaha XJ1100J (82)
Yamaha XS1100ALL (78-81)
Yamaha XV1100 Virago (86-97)
Yamaha FJ1200 (86-91)
Yamaha VMX1200 V-Max (85-97)
Yamaha XVZ1200 Venture (83-85)
Yamaha XVZ1300 Venture (86-93)
Yamaha XVZ13 Royal Star

Upper: 25 x 48 x 16
Lower: 27 x 48 x 14
Suzuki RM125A/B/C (75-7Cool
Suzuki PE175C/N (78-79)
Suzuki GS250FW (85)
Suzuki GSX250T/ET (80)
Suzuki GT250A/B (76-77)
Suzuki PE250C/N (78-79)
Suzuki RM250A/B/C/C2
Suzuki TM250K/L/M (73-75)
Suzuki TS250 (70-79)
Suzuki GS300LF/LZ/LD (82-85)
Suzuki RM370A/B/C (76-77)
Suzuki SP370 (78-79)
Suzuki GT380K-B (73-77)
Suzuki GS400B/C/EC (77-7Cool
Suzuki RM400C (7Cool
Suzuki SP400T (80)
Suzuki TM/TS400 (73-77)
Suzuki GS425N/EN (79)
Suzuki GT500A/B (76-77)
Suzuki RE-Rotary (75-76)
Suzuki GS550B/C/EC (77-79)
Suzuki GT550J-B (72-75)
Suzuki GS750B/C/EC/N (77-79), GS750D C/N (78-79), GS750EN/ LN/LT (79-80)
Suzuki GT750 (72-77)

Upper: 25 x 48 x 13
Lower: 30 x 48 x 13
Suzuki RM100N/T/X (79-81)
Suzuki RM125N/T (79-80)
Suzuki RM250N/T (79-80)
Suzuki RM400N/T (79-80)
Yamaha L5T/L5TA-100 (69-70)
Yamaha RD125B/C (75-76)
Yamaha RD125LC
Yamaha TA125 (Roadrace)
Yamaha TD2/TD2B125 (70-71)
Yamaha TR2/TR2B125 (70-71)
Yamaha TZ125G (Roadrace) (80)
Yamaha YB125E/F
Yamaha RD200A/B/C (74-76)
Yamaha YTM200N/ERN (84)
Yamaha YTM225DRN/DRS (85-86)
Yamaha YTM225DXL/DXN (84-85)
Yamaha FZR250
Yamaha RD250 /LC (73-82)
Yamaha RD250YPVS (83-84)
Yamaha SR250G/H/J/TH (80-82)
Yamaha SRX250N (85), SRX250T/TC (87)
Yamaha TD3/TR3-250 (Roadrace) (72)
Yamaha TZ250 (73), TZ250C/D/E (76-7Cool
Yamaha TZR250 (87-91)
Yamaha XS250
Yamaha XV250U-W (88-89), XV250A/AC (90), XV250G/GC/H/HC/J/JC (95-99)
Yamaha R5/B/C (70-72),RD350 (73-79), RD350LC (80-82)
Yamaha RD350YPVS (83-84), RZ350L/N/NC (84-85)
Yamaha TZ350C/D/E (74-7Cool
Yamaha XS360C/D/2D (76-77)
Yamaha RD400A/B/C/D (76-79)
Yamaha XJ400 (80-85)
Yamaha XS400E/F/2E/2F (77-79), XS400G/H/J/K (80-83), XS400RJ/RK (82-83), XS400SG/SH (80-82)
Yamaha XV500 (83) XV535 (87-99)
Yamaha XV535 (91-94), XV535H/N (89-90), XV535SE (8Cool, XV535T/TC/U/A/ AC/EC/F/FC/G/GC/ SFC/SG/SGC/SH/SHC/SJ/SJC (87-97)
Yamaha XJ550H/J/K/RH/RJ/RK (81-83)
Yamaha FJ600L/LC/N/NC (84-85)
Yamaha XJ600 (92-9Cool
Yamaha YX600 (86-90)

Upper: 25 x 43 x 11
Lower: 30 x 48 x 12
Yamaha DT50B, DT50MX, DT50U/W/A (88-90)
Yamaha RD50MX (82), RX50K/L/MK (83-84)
Yamaha YSR50T-E (87-93)
Yamaha YZ50G (80)
Yamaha JT1/JT2/JT2MX (71-72)
Yamaha RD60/A/B (73-75)
Yamaha YZ60H/J/KM (81-83)
Yamaha DT80LC H/J/K (81-83), DT80MX
Yamaha GT80A-G (74-80), GT1/GTMX80 (73), GTMXA/MXB/MXC 80 (77-79), MX80G/H/J (80-82)
Yamaha RD80LC/MX(82)
Yamaha TY80A/B Trials (74-75)
Yamaha YZ80A-K (74-83)
Yamaha HT1/HT1B/HT1BM90 (70-71)
Yamaha AG100B
Yamaha DT100A-K (74-83)
Yamaha LT2/LT2M/LT2MX/LT3100 (72-73)
Yamaha MX100A/B (74-75)
Yamaha MX100F/H/J/K (79-83)
Yamaha RS100B/C (75-76)
Yamaha RT100A (90)
Yamaha YZ100C/D/E/F/G/H (76-81)
Yamaha AT1/AT1B/AT1C/ AT1E/AT1M/AT1MBAT1MX/AT2/AT2M/AT2MX/AT3/ 125 All (69-73)
Yamaha DT125 All (74-81), DT125LC (82)
Yamaha IT125G/H (80-81)
Yamaha MX125A/B/C (74-76)
Yamaha XT125J/K/KC (82-83)
Yamaha YT125N (85)
Yamaha YZ125A/B/C/X (74-76)
Yamaha AG175B
Yamaha CT1/CT2/CT3 175 All (69-73)
Yamaha DT175A-H (74-81)
Yamaha MX175A/B (74-75)
Yamaha MX175G/H/J (79-81)
Yamaha TY175B/C (75-76)
Yamaha YT175J/K Atv(82-83)
Yamaha YZ175C (76)
Yamaha SR185H/J (81-82)
Yamaha AG200
Yamaha BW200N/S/ES/ET/ EU (85-8Cool
Yamaha TW200 (87-92)
Yamaha TYM200EX/EL (83-84)
Yamaha XT200J/K/KC (82-83)
Yamaha YTM200K/EK (83), YTM200K/L (83-84)
Yamaha YTM225DXK (83)
Yamaha DT1/DT1B/DT1CMX/DT1MX/DT1S/ DT1C/DT1E/DT2/ DT2MX/DT250A-F/DT3 250 (68-79)
Yamaha MX250A/B (73-75)
Yamaha TT/XT250G/H/J (80-82)
Yamaha TY250A/C/D (74-77)
Yamaha XT250G/H/J/K/KC (80-83)
Yamaha XT250W (89)
Yamaha YZ250A/B/C (74-87)
Yamaha DT360A/B (74-75),
Yamaha MX360/A (73-74)
Yamaha RT1/RT1B/RTM/RT1MX360 (70-71)
Yamaha RT2/RT3/RT2MX360 (72-73)
Yamaha YZ360A/B (74-75)
Yamaha DT400B/C/D/E (75-7Cool
Yamaha IT400C (76)
Yamaha MX400B/C (75-76)
Yamaha YZ400B/C (75-76)
Yamaha SC500/A (73-74)
Yamaha SR500E/F/G/H (78-81)
Yamaha TT/XT500C-H (76-81)

Upper: 25 x 47 x 15
Lower: 28 x 52 x 16.5
Kawasaki KL250D2-D8 (85-91), KLR250 (-9Cool
Kawasaki ZX400K1/K2/K3
Kawasaki EN450A1-A7 (85-91), EN450N
Kawasaki EN500A1-A6 (90-96), EN500C1/C2 Vulcan Ltd (96-97)
Kawasaki GPZ550H1
Kawasaki KZ550F1/F2/M1 (83-84), KZ550H1/H2 (82-83)
Kawasaki Z550G6, Z550M1 Ltd (83)
Kawasaki ZR550B1-B5 (90-94)
Kawasaki ZX550A1/A2 (84-85)
Kawasaki GPX600R
Kawasaki KL600A1/B1/B3 (84-86)
Kawasaki ZX600 Ninja (85-97)
Kawasaki KLR650/B2 Tengai (89)
Kawasaki KL650A1-A11/B2/ KLR (87-97)
Kawasaki KZ700A1 (84)
Kawasaki ZN700A1/A2 (84-85)
Kawasaki GP750R, GPZ750R/R1
Kawasaki KZ750F1, KZ750L3 (83)
Kawasaki KZ750N1/N2 (82-83), KZ750R1 (82)
Kawasaki VN750A2 (86)
Kawasaki ZR750C1-C4 (91-94), ZR750 Zephyr
Kawasaki ZX750A1-A3/E1/E2/ F1-F4/H1/H2
Kawasaki GPZ900R
Kawasaki ZL900A1/A2 (85-86)
Kawasaki ZX900A1-A3 (84-86)
Kawasaki KZ1000J1-J3/K1/K2/ M1/M2 (81-82), KZ1000P1-P17 (82-9Cool, KZ1000R1/R2 (82-83)
Kawasaki Z1000K1 LTD (82)
Kawasaki ZG1000A1-A9 (86-94)
Kawasaki ZL1000A1 (87)
Kawasaki ZX1000A1/A2 (86-87), ZX1000B1-B3 (88-90)
Kawasaki GPZ1100A/S, B/S (81-82)
Kawasaki KZ1100A1-A3 (81-83), KZ1100B1/B2 (81-82), KZ1100D1/D2 (82-83), KZ1100L1 (83)
Kawasaki Z1100J/J2/Z
Kawasaki ZN1100B1/B2 (84-85)
Kawasaki ZR1100A1/A2 (92-93)
Kawasaki ZX1100A1-A2 (83-84)
Kawasaki VN15SE
Kawasaki VN1500A1-A9 (87-95)
Kawasaki VN1500B1-B5 (87-91)
Kawasaki VN1500A10/A11/C3/C4/D1/D2 (96-97)

Upper: 26 x 48.5 x 15.2
Lower: 30 x 50 x 14.4
Honda C250N (79)
Honda CB250 (Early Models)
Honda CB250RS (80-84)
Honda CBX250RS
Honda CM250T Rebel (82-84)
Honda GB250F/F2
Honda MVX250 (83-84)
Honda VT250F (83-86), VTR250 (8Cool
Honda CB350F/F1 (73-74), CB350G (73), CB350/ K2-K4 (69-72)
Honda SL350 /K2/K3 (69-73)
Honda CB360 (74-76), CB360GT (76), CB360T (74-77)
Honda CJ360T (76-77), CL360 (74-75)
Honda CB400A (74-75), CB400F (75-77), CB400TI/TII (78-79), CB400T (80-81)
Honda CBX400F
Honda CM400A/C/E/T (79-81)
Honda GB400
Honda CB450/K1-K7 (65-74), CB450T (82), CB450SC (82-86)
Honda CL450 /K2-K6 (68-74)
Honda CM450A/C/E (82-83)
Honda CB500/K1/K2 (71-73), CB500T (75-76)
Honda CX500 C/D (78-81)
Honda FT500 Ascot (82-83)
Honda GB500F/F2
Honda GL500/I (81-82)
Honda VT500 Ascot (83-84), VT500ED, VT500C/FT (83-84)
Honda CB550K/K1 (74-7Cool, CB550F (75-77), CB550SC (83)
Honda CBX550F (82-83)
Honda CB650 (79-82), CB650C (80-81), CB650SC (82-85), CBX650ED/SCD
Honda CX650C (83), CX650ED
Honda GL650/I (83)
Honda VT700C (84-85)
Honda CB750K (69-7Cool, CB750A (76-7Cool, CB750F (75-7Cool
Honda VFR750C (83)
Honda VT750C (83)
Honda GL1000 (75-76)
Honda GL1000L (76)

Upper: 30 x 48 x 14
Lower: 30 x 48 x 14
Kawasaki KH250A5 (76)
Kawasaki KZ250A
Kawasaki EX350B1 (83)
Kawasaki KZ350A1/A2/B1 (81-82), KZ350B2/B3 (87-8Cool
Kawasaki KH400A3-A5 (76-7Cool
Kawasaki KZ400A1/A2 (77-7Cool, KZ400B1/B2/C1 (78-79)
Kawasaki KZ400D/D3/D4 (74-77), KZ400H1 (79), KZ400S/S2/S3 (75-77)
Kawasaki ZX400D1-D5 (80-83)
Kawasaki KZ440A1-A4/D1-D5 (80-83), KZ440B1/B2 (80-81)
Kawasaki H1 500 C/D/E/F (69-75), KH 500A8 (76)
Kawasaki KZ500 (69-73)
Kawasaki H2 750 A/B/C (72-75)

Upper: 30 x 48 x 14
Lower: 30 x 52 x 17
Kawasaki EL250B2/B3 (88-89), EL250E1/E2 (91-92), EL250D4/D5 (93-94)
Kawasaki EX250E/E2/F2-F4 (86-90), EX250 F6/F7/F8/F9,F10/ F11 Ninja250R (92-97), EX250 H1-H5 (90-94)
Kawasaki ZX400H1/H2, ZXR400R
Kawasaki EX500A1-A7 (87-93), EX500D1-D4 (94-97)
Kawasaki KZ550A1-A4/C1-C4 (80-83), KZ550D1 (81)
Kawasaki KZ650B1-B3/C1-C4/D1/D2/E1/F1/H/ H1-H3
Kawasaki KZ750B1-B4 (76-79), KZ750E1-E3 (80-82)
Kawasaki KZ750G1 (80), KZ750H1-H4(80-83), KZ750K1/K2 (83-84), KZ750M1 (82), KZ750T
Kawasaki KZ900A4/B1 (76)
Kawasaki Z1 900A/B (73-75)
Kawasaki Z1R Series (78-80)
Kawasaki KZ1000A1-A4/B1-B4 (77-80), KZ1000D1 (7Cool, KZ1000D3/G1 (80)

Upper: 25 x 48 x 15.2
Lower: 30 x 48 x 15
Yamaha FZR400R
Yamaha SXR400
Yamaha SX500B/C/D/E (75-7Cool, TX500/A (73-74)
Yamaha XS550RK/RJ (82-83), XZ550RK/RJ (82-83)
Yamaha FZ600 (86-8Cool
Yamaha SRX600S/SC (86), SRX600T
Yamaha TX650/A (73-74)
Yamaha XJ650G/H//J/K (80-83), XJ650LH (81), XJ650LJ/LK/RJ (82-83)
Yamaha XS6501/1B/XS2 (70-72), XS650B-H/2F (75-81), XS650SE-SH (78-81), XS650SJ/SK (82-83)
Yamaha TX750 (73-74)
Yamaha XJ750J/K/MK/RH/RJ/RK (81-83)
Yamaha XV750H/J/K/MK (81-83), XV750SE (82)
Yamaha XV920J/K/MK (82-83), XV920RH/RJ (81-83)
Yamaha XV1000K/L Virago (83-84)

Upper: 26 x 47 x 15
Lower: 30 x 55 x 17
Honda NSR250R/F
Honda VTR250 (89-91)
Honda CBR400R (87)
Honda CBR400 R/R
Honda NS400RF/RG (85-86)
Honda VFR400ZG/RG
Honda CMX450C (86-87)
Honda CX500TC (82)
Honda VF500C (84-85), VF500F (84-86), VF500FE/FIIE/FF
Honda VT500C (85-86)
Honda CBR600 (89-90)
Honda CBR600F (87-90), CBR600 FM-FR (91-97), CBR600H
Honda VT600CJ (87), VT600C N-R (92-94)
Honda VT600C/CD Shadow VLX (88-97
Honda CX650T (83)
Honda NT650 (88-89)
Honda NT650J Revere
Honda CB700SC (84-86)
Honda VF700C (84-87)
Honda VF700F/S (84-85)
Honda VFR700F/F2
Honda CB750C/F/K (80-82)
Honda CB750F N-S (92-95)
Honda CB750FA/FB/FC/ F2C
Honda CB750SC (84-85)
Honda CBX750FE/F2F (84-86)
Honda VF750C (82-83)(8Cool
Honda VF750CC/CD/CE/SC/SD
Honda VF750F (83-84)
Honda VF750 F D/E/F (83-85)
Honda VF750FD
Honda VF750S (82-83)
Honda VFR750 (90-93)
Honda VFR750F/F2 (82-87), VFR750F L-S (90-95)
Honda VFR750FG/FH/FJ/FK/ FL
Honda VT800 (88-89)
Honda VT800C Shadow(8Cool
Honda PC800 Pacific Coast (89-9Cool
Honda CB900C (80-82), CB900F A/B/2B/C/2C (80-82), CB900FS(94)
Honda CBR900RR (93-9Cool
Honda CB1000C (83), CB1000F S (95)
Honda CBR1000 (87-93)
Honda CBR1000F (87-8Cool(90-96)
Honda CBX B/C (81-82)
Honda VF1000F (84-85), VF1000FE/FF/F2F, VF1000R (85-86)
Honda GL1100 (80-83), GL1100C/AC/DC/IC, GL1100D2D/AD/A/IA/DA, GL1100RB/RC/D/ID/DD
Honda VF1100C (83-86), VF1100S (84-85)
Honda VT1100C (85-89), VT1100C R-S (94-95)
Honda GL1200 (84-87)
Honda GL1500 (88-91)
Honda GL1500 AP-AR (93-94)
Honda VTX1800C (02)

Upper: 26 x 47 x 15
Lower: 26 x 47 x 15
Honda CR80RL-RR (90-94 )
Honda CR125R (82-89)
Honda NX125 (88-90)
Honda XL200R (83-84)
Honda XR200R (81-87), XR200RE/RF/RG/RH/RJ
Honda ATC250R (83-86)
Honda CR250R (82-89), CR250RE/RF/RG/RH/RJ/RK
Honda XL250R (82-87), XL250R E/F (84-85), XL250R J/K/L (88-90)
Honda XR250RE/RF/RG/RH/RJ/RK, XR250R N-R (92-94)
Honda XL/XR350R (83-85)
Honda XR350RD/RE/RF/RG/RH/RJ/RK
Honda XR400R (97-9Cool
Honda CR450R (81)
Honda CR480R (82-83)
Honda CR500R (84-89)
Honda XL500R (82)
Honda XR500R (81-84)
Honda XL600R (83-87), XL600RC/RF (85)
Honda XL600RD/LD/RE/RF/RG/V-VH(Transalp)
Honda XR600R (85-89), XR600RH/RJ/RK
Honda CB750F/K/L (79)
Honda CBX1000 (79)

TZ350

26th April 2014, 17:00

Starts really well runs great on warm up then just stops. Start again and the repeat. It stops from quite hi rpm. 5 6k maybe.

This may not be the answer but these are four possible power supply traps that will cause the Ignitec to turn itself off.

Trap (1) The Ignitec draws about 0.3A at idle and progressively more up to maybe 1.5-2.5A as the rpm increases. The Ignitec will turn off if the current draw pulls the battery voltage down to 8Volts.

If your running total loss and the battery is getting a bit low, and your just cruising then the Ignitec will miss fire but if your caning it, it will cut right out.

296543 The right way to check a battery is to put it under load.

The right way to check a motorcycle size batteries health is to put something like a 25-35W bulb across it and measure the voltage between the battery terminals while the battery is powering the light. A good battery will still show 12.0V a dud one much less.

296542 This is the wrong way to check a battery because it can give misleading results.

Trap (2) Another possibility is a battery with internally broken connections. I have had problems with those yellow batteries and also those black sealed jel ones. I think the vibration breaks the connections between the plates. If the break is still touching it will allow you to measure 12.6V across the battery terminals but its not a good enough connection to pass the current required by the Ignitec. Once again a 25-35W bulb is your friend here.

Trap (3) If you have a generator and capacitor system, then the voltage regulator could be cutting out when the current draw gets to high, I think you will need at least a 50W rectifier/regulator unit for a twin 2T.

Trap (4) Yet another possibility is your generator charging system is providing more than 18V peak.

296541

16V DC as measured by a volt meter can easily have 2-3V ripple on top that the Volt meter cant see. The Volt meter cant see the peak Voltage because the 2-3V ripple is effectively AC, but the Ignitec sees it.

2-3V ripple can easily happen if you have a high voltage generator that cant produce enough current or the capacitor is a bit under size. The Ignitec turns itself of when it sees 18V or more.

296540

If you have a ripple issue the Ignitec turns itself of lots of times in quick succession and as the rpm drops to the point the generator/rectifier/regulator/capacitor can maintain a steady voltage the Ignitec will come on and stay on until the current (Amps) load increases to the point you get ripple again.

296539

Ripple ... if Blue is Voltage and Red is Amps you can see how the voltage required to get enough current can easily exceed 18V.

Under 8 Volts or over 18 Volts the Ignitec protects itself by turning off.

richban

26th April 2014, 18:59

Much Thanks Rob.

I think it could be an old dodgy reg/rectifier. I have another so will give that a go tomorrow at the track.

speedpro

26th April 2014, 20:29

Depending on the charging system it may be capable of delivering a lot more current than you are using. With the usual motorcycle permanent magnet type of alternator that output is generated regardless of whether the motorcycle needs it or not. If it is not needed the reg/rec dumps it to ground and can get hot in the process. My FZR reg/rec got too hot to touch even though it was bolted to an alloy plate. Now I have the ALM lambda sensor drawing a bit of current it "seems" to be a bit cooler. If your voltage is not being regulated well it may be a matter of providing a bit more load.

TZ350

26th April 2014, 20:52

Depending on the charging system it may be capable of delivering a lot more current than you are using. If it is not needed the reg/rec dumps it to ground and can get hot in the process.

Now that is Trap (5) of electrical trickery things that could be wrong.

bucketracer

26th April 2014, 21:45

TZ350

26th April 2014, 22:56

296551

http://www.treehugger.com/cars/7-electric-motorcycles-you-must-see-including-1-that-does-0-60-mph-in-097-seconds.html

296552

Electrical trickery ..... is there no end to this clever electrical stuff.

I have just checked out that site and found a link to this. Ok so its not buckets but it is a motorcycle and seriously clever.

296553

Eva Håkansson is a hardcore “EV geek” with a green heart and passion for power and speed.
She is the owner, builder and driver of the record-holding electric streamliner motorcycle “KillaJoule” and part of the KillaCycle racing team. Married to Bill “Mr. KillaCycle” Dube’.
Eva is a Mechanical Engineer (M.Sc) and PhD student at University of Denver.

http://killacycleracing.com/about-us/eva-hakansson/

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KillaJoule is the world’s fastest electric sidecar motorcycle with a top speed of 216 mph (348 km/h) so far.
Builder, owner and driver is Eva Håkansson.
KillaJoule is really eco-activism in disguise. The only purpose of this 19 ft., 400 HP, sleek, sexy motorcycle is to show that eco-friendly doesn’t mean slow and boring.

And then there is the 8 second drag bike.

http://media.killacycleracing.com/2013/06/KillaCycle_Woodburn_no_color_for_slider.jpg

You will have to go and have a poke around the sight if you wan't to know more.

http://killacycleracing.com/about-us/eva-hakansson/ (http://killacycleracing.com/about-us/eva-hakansson/)

Neal

27th April 2014, 00:41

When you bringing your one to NZ?

Mine is half in SA and half in Oz , I need to pull finger and get motivated again .
I was battling with rich jetting in the higher gears with my powerjet carbs , it would pull clean in the lower gears but in 5 and 6th it would be too rich

Bert

27th April 2014, 07:19

Mine is half in SA and half in Oz , I need to pull finger and get motivated again .
I was battling with rich jetting in the higher gears with my powerjet carbs , it would pull clean in the lower gears but in 5 and 6th it would be too rich

Hi Neal.
I think wobbly made a comment earlier in this thread about moving the powerjet tube higher up the slide (I.e. Bending it upwards). And also some discussion around using the gear position sensor to better control the opening interval of the powerjet. Primarily achieving better over rev...

Hopefully he re-post further info on both points as I suspect it is going to be critical to the success of the 300.

husaberg

27th April 2014, 09:04

not sure if this will work...................

When using a simple powerjet nozzle the tip position matters in that no flow will occur until the slide is well past the exit hole, and there is sufficient airflow
to drag fuel up the feed tube above the bowl level.
With the aftermarket add ons and the ones as used by Lectron you can shorten the dump tube so that the flow will only occur at high slide openings,as well as high air flow.
These also have a built in "lag "control in that it takes time for the fuel to rise up the tube and dump out the exit into the air stream.
With a solenoid controlled setup all this is pretty much irrelevant as the flow can only occur when the solenoid is not powered up, and this
is TPS as well as rpm dependant inside the ECU program..
The carbs as used on the MX bikes has the dump tube very low in the bore as they added and subtracted fuel at low slide positions in those bikes.
For a race engine I bend the tube up to around 1/2 bore, as this is where the exit is on the Kehin SPJ carb for RS125/RS250 Honda.
And the general setting is the solenoid is powered up ie no flow below 4000 and 60% TPS and is powered up again at around 12400 to lean off the mixture and increase revon.
This causes a problem with Ignitechs that are used with only a capacitor, as at startup the solenoid is powered up, dragging all the voltage out of the ECU, so I convert the ECU output
to a 3 step truth table, and have the setting such that below 1500rpm the solenoid isnt powered.

Aha, I see. I think I got it now, Frits.
If the powerjet is positioned in the middle of the venturi or at a lower point, that will affect how much it will flow, correct?

I remember both Lectron and Mikuni aftermarket PJ kits' instructions, saying that the end tip of the pj should be around the middle of the carb.
Yet the Keihin PJ of the carbs for the mx250 models is down low! Position would also affect which fraction of the flow becomes more rich or not, or that doesn't matter??

255006

254941

Made an adjustable PJ out of a model aero engine carb needle jet for controlling the PJ. Now to get one of those solenoids the Husaburg posted to shut off the PJ for a bit of extra over rev.

Made some progress with the shorter inlet tract and expect to get the lower mid range back again with a bit of fiddling with the carburation.

Just a little bit more and the single exhaust port engine with the RS pipe will be very close to EngMod2T's predicted power output.

254940 125cc rotary valve with a 24mm carb and air cooled.

Measured 31 rwhp (estimated 34 crank hp) on the dyno tonight, red line is last night before the inlet tract was shortened and the jetting/ignition adjusted.

I have ordered one of Wobblys special kitset "A" Kit Pipes for a Suzuki GP125 ..... so hopefully 1 or 2 more hp and a wider spread of power. Then there is the ATAC idea for better low end.

Nope. It is drawn by the dynamic pressure at the fuel exit points in the carburetter. And that pressure depends on the mean air flow velocity along those exits.
Air flow velocity is at its highest in the center of the narrowest part of the inlet tract, so the location of the fuel exit will make a difference. And by mean air flow I mean (air flow into the engine + backflow)/2.
You see, more than enough variables; more than enough differences between the exit points of the fuel flow through the main jet and the flow through the power jet.

Re the tiny bleed hole in the TZ powerjet tube - I always thought that this was a good idea to emulsify the fuel as it exited the dropper.
But years ago i did some wet tests on the flowbench with a VCR video camera ( pretty trick shit stuff back then ).
The Mikuni was a horror scene when played back slo mo,with huge "gobbs" of fuel exiting the main and powerjet.
We then stuck on a Lectron - wow, lovely fine mist of fuel from the back of the flat needle face - and it flowed 12% more air - size for size with a venturi 2mm smaller behind the slide.

Next is the current state of TeeZees GP125, here is the latest dyno curve digitised with 16% added to simulate crank power.
Then there is the sim with an actual RS early model pipe.
Then there is the new pipe of my design.
Of most interest is that in this case the sim is giving slightly too much crank power - but the shape and peak point are all but perfect.
I would be confident now that any change in the sim, would be reflected in reality on the dyno.
In my experience the later Dynojets like a twin roller 168 with Eddy current load control to slow the acceleration rate down ,seem to read around 5 to 10% lower
so this would put the sim and the dyno reading very close, as the shape is spot on now.

You have to be very carefull with the switch point and the run time on the dyno.
The switch point is dead critical to 100rpm,so i always set it too high initially and make sure that the dyno is loading the acceleration rate to be as close to that on track as you can.
This gives the pipe time to heat up and affect the power over the top, as it would in reality.
On a RS250 dropping the switch point from 12800 ( std) to 12400 gives easily another 800 rpm of virtually no power drop past peak.
On the track,if the rider can feel the switch point ( it feels like hooking another gear)the jet is too big,when its right it should be seamless and just keep reving out.
Leaded fuel is the opposite to unleaded, in that as leaded likes to run lean - you can only use a small powerjet and thus only switch off a small amount.
A leaded engine works best with around 35 to 38 PJ, the unleaded fuel can switch a 60, in Keihin numbering, as the crap fuel makes best power at peak when quite rich..

And something that I scraped from the net.........

""The solenoid control on TZ type powerjets really just shuts off fuel flow to the powerjets right at the top of the rev range to lean the mixture off to increase the over-rev once you are past peak power.

I don't have the solenoids plugged in currently though as I find they work well enough for my current needs with the powerjets simply responding to venturi vacuum pressure in pretty much the same way as the oem 3MA powerjets work.""

233787233788

And here is a picture of the carbs and what I can make out, a dyno graph without, and with the power jet solenoids shutting off (red line) and extending the over rev.

So it looks like you can use an electric power jet like a standard one and when the carburation is sorted, try switching it of by activating the solenoid at or just after peak power and see what happens with the over rev.

The FPE superkart engine that won the NZ road title at Manfield a few weeks ago makes 92 RWHp on the Dynojet 168 I use.
Still not quite as good as the RS250 setup we did that won at Laguna Superkart Worlds a couple of years ago.

The powerjet carb is controlled by the Ignitech with a combination of throttle position and rpm in a "truth table".
In general the solenoid is activated with 12V ( no fuel flowing) below 4000 rpm and 75% throttle on the TPS.
Above 75% and around 12400 rpm it is activated again to lean off the fuel curve over the top of the pipe.
Looks like you will be able to reverse the fuel exit, blocking off the hole on the throttle bore side, and take off fuel from the outside bung, thru a needle jet and into the top of the venturi next to the slide.

Recently I got myself (Ebay) a 38mm carb with Throttle PS and Electric PJ from a motor crosser.

Wobbly told me that on those the PJ nozzel is to low and starts to flow to soon for a road racer and the MX ones are hard to tune.

230481

I couldn't afford to buy a good second hand TZ or RS unit. So I figure that moving the discharge nozzel.

230483

And adding an adjustable jet from a large model aero engine could be worth a try.

230482

On the dyno I have seen how a leaner mixture rev's on further and how richining it up for best power the over rev drops off.

I think that as the rpm goes up the mixture strength on an ordanery carb at max rpm goes over rich.

And at the moment I think the idea is that the PV is shutoff after peak power to get back to the correct mixture and by retarding the ignition at the same time extend the over rev, but I am sure there is more to it.

I would love to know more about how this type of carb should be used and/or setup.

The modern take on powerjets is to turn them off after peak power to extend the rev range. This assumes that you are happy for your engine to rev that much further past peak power & on many buckets perhaps this is not so good unless you have uprated the crank assembly. The jet will start to flow, depending on its position. Some don't seem to work well without an airbox if they aren't very prominant, or perhaps if the suction isn't so much (putting big carb on a smaller cylinder). In some cases they are best blocked off presumably if the air jet doesn't match very well & is tending to increasing richening with airflow as it is.

With all the talk about wanting to utilize only a couple of gear changes per lap, I would have thought that the solenoid powerjet was a gift from heaven.
A late model well tuned RS125 will rev to around 12400 if the PJ is disabled,turn the PJ function back on and it will go to 13800+.
Its so simple and you retain exactly the same lower rev power,but with easily another 1000rpm to work with you have the choice of adding teeth on the back, getting better acceleration from torque multiplication, or keeping the same gears - but increasing the terminal speed.
And from the dyno curves I have seen, most of the 100 buckets with short stroke lengths, arent even beginning to stress the bottom ends - with less peak rpm than the 54.5mm stroke 125 bikes or karts that will easily run to 13000 all day.

Some more RSA125 development info from Jan Thiel

"No pressure transducers were ever used in our engine development.
And time/aerea was never calculated.
The port timings remained practically the same during 15 years!
What we did was trying different angles and radiuses, mainly on
the transfer ducts. I think we tried 40 different types of transfer ducts
that did not chanche the time/aerea. It was all about in which direction
the charge entered the cilinder and how the tranfer streams influenced upon
each other! Also about 200 different exhaust pipes were tried. After 2004
nothing much was changed but we improved with different power jet and
ignition mapping. It seemed nearly impossible to improve the transfer ducts
any more. The exhaust ducts were CNC machined, using different programs,
mainly to reduce exhaust duct volume. Also about 100 head designs were tried"

Didnt calculate time area? Im guessing that means the time area requirement hasnt changed any in the last 15+ years.
So there you go its all about the transfer ducts, now where have I heard that before?
Check out the attached photos, I guess the idea of thinning the transfer duct bridge has gone out the window, and the exhaust duct hows that for a crazy shape

231454
231455
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Recently I got myself (Ebay) a 38mm carb with Throttle PS and Electric PJ from a motor crosser.

Wobbly told me that on those the PJ nozzel is to low and starts to flow to soon for a road racer and the MX ones are hard to tune.

230481

I couldn't afford to buy a good second hand TZ or RS unit. So I figure that moving the discharge nozzel.

230483

And adding an adjustable jet from a large model aero engine could be worth a try.

230482

On the dyno I have seen how a leaner mixture rev's on further and how richining it up for best power the over rev drops off.

I think that as the rpm goes up the mixture strength on an ordanery carb at max rpm goes over rich.

And at the moment I think the idea is that the PV is shutoff after peak power to get back to the correct mixture and by retarding the ignition at the same time extend the over rev, but I am sure there is more to it.

I would love to know more about how this type of carb should be used and/or setup.

Ok now we have a stepper motor controled power jet........

The 'high compression brickwall' is no longer as hard as it used to be. With leaded fuel the compression ratio was 19,5; nowadays it is about 15. The 'brickwall' arose from the high expansion ratio (which is identical to the compression ratio). The higher this ratio, the more the burnt gases in the cylinder cool down before they enter the exhaust, thus lowering the resonance frequency of the exhaust system.
Riders complained that the engine would not rev, especially not in the lower gears, where the revs rose so quickly that the rising wall temperature of the exhaust pipes could not keep up with them. So you had cold exhaust gas and cold pipes.

The problem was to a large extent solved when the solenoid-controlled on/off-power jets were replaced with stepper motor-controlled jets that could continuously adjust mixture strenght, allowing the engine to rev more freely.

229455

This is it. The stepper motor itself originates from a Fiat Uno where it regulates the idling rpm

Regarding the Aprilia RSW/RSA125 single, Jan Thiel told me that in seven years of testing the racing department had not been able to establish which was best: low or high inertia. I would choose low.....

Frits Overmars

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.

I have looked into the "overangled" issue that creates a problem when using the electronic powerjet carbs.
Its worth plenty of horsepower to keep the intake dead straight, and I am building a KTM250 for a open class kart at present.
I have bored the 38 to 40.5 and mounted it on a straight rubber manifold.
This sits the carb too steep, in that the siphon hole for the powerjet circuit in the side of the bowl is only just "underwater" when sitting static.
Get some serious G forces working and this will be sucking air.
It looks easy enough to Araldite a small external tube running forward to the front of the bowl that has plenty of fuel height above it at all times.
Or maybe drill a hole thru at an angle forwards, and press a small brass tube into this to collect fuel from the front side of the bowl.
I will pic this when I have done it.

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.

I have looked into the "overangled" issue that creates a problem when using the electronic powerjet carbs.
Its worth plenty of horsepower to keep the intake dead straight, and I am building a KTM250 for a open class kart at present.
I have bored the 38 to 40.5 and mounted it on a straight rubber manifold.
This sits the carb too steep, in that the siphon hole for the powerjet circuit in the side of the bowl is only just "underwater" when sitting static.
Get some serious G forces working and this will be sucking air.
It looks easy enough to Araldite a small external tube running forward to the front of the bowl that has plenty of fuel height above it at all times.
Or maybe drill a hole thru at an angle forwards, and press a small brass tube into this to collect fuel from the front side of the bowl.
I will pic this when I have done it.

Real transfer ports ..........[/QUOTE]

servo for PV

OK, here is some info on how to utilise the servo option on the Ignitech.
The servo has 5 wires, two are 12V +/- and the other 3 are the servo feedback positioning pot.
Always wire the two functions on separate plugs.Once you have the servo connected to the blade or whatever, disconnect the servo motor power plug.
Then on the screen you will have a readout for the servo position, as mV or as a % if using the RACE box.
I have never used the % option so here is how to program the mV setup.Drive the servo to the travel limit ( in, or down or whatever) by gripping the servo wheel with vise grips.
Cycle it back and forth a few times to get an accurate position that takes up any small slack in the cables.Note down the "servo measured" value on the screen.Then wind the servo around to the opposite limit, note this value down.
Then in the servo screen you can enter the two values of fully up, and fully down, with an rpm span between them.
Use a few of the extra points in between, so you can, if needed, force a non linear movement with rpm ie not a straight line.
Hit program, turn off the ECU,turn it on again, and it will cycle up and down,as it has been programmed.
You can check the up and down positions and compare the "servo measured" to the "servo desired" on screen, in real time.
The hysteresis should be set usually at around 100mV, less will speed up the response, but go too low and the servo will "hunt" around the values programed.
The RZ servos are all getting old and shagged - the newer R1 servo is mechanically very similar but uses a special molded in plug - I have the right ones to match.
The R6 and ZXR ones are not as well made, the shaft isnt supported at both ends properly.
Here is a sample wiring setup and a PV curve, set to start opening at 7200 and full open at 9000, with about 1V of span between.
You could use this to rotate a spool like an RZ, a blade like a flat PV or even the 1/2 throttle plate if you wanted to.

With 'theoretical cycles' you mean the Carnot diagram 8)? Yes, it would be nice to have a really fast combustion; then you could ignite later and the heat losses would be smaller. But there is a big gap between theory and practice.
In a 125 cc race engine the spark-plug sparks at about 14° BTDC @ 13000 rpm. Then combustion starts really slow: after the spark another 10° go by before you can detect the first signs of combustion. Then combustion continues for a little over 40° (this is at full throttle; with less cylinder filling, combustion is a lot slower).
According to a knowledge (e) KTM have a system where via data logging at the end of the straight as additional fuel is injected, with closed gas so, in order to lubricate the piston extra.
Because each lap can be different is the start / finish line, the point from which time is set.
That seems accommodation, at the end of the straight is the most critical point for a lockup!
With the throttle closes the piston cooling off, immediately!
And then they also have high speed by downshifting too early.

Is it useful to slow down combustion on some operating phases? Yes and no. I will try to explain this in a little physics lesson.
No matter which way the piston is moving, as long as there is combustion, the pressure in the cylinder keeps rising. Only after combustion is finished the expansion of the burnt gas can begin.
Slow combustion means that the piston is already well on its way down before expansion can begin; it means less expansion for the burnt gas in the cylinder before the exhaust ports open.
Less expansion means less cooling down of the gas in the cylinder: it is still hotter when it enters the expansion chamber. In hotter gas the speed of sound is higher and that means a higher resonance frequency for the cylinder-pipe system, so it works better at high rpms.

But how do you slow the combustion speed down? Less squish? Mixture too rich? You do not want to do that...
Fortunately there is a simpler solution. We do not slow combustion down; we just start it later: we retard the ignition timing. As far as the exhaust gas temperature in the expansion chamber is concerned, the effect is the same: the engine runs better at high revs.
That is the reason for programmable ignition systems.
Below the power band the ignition advance can be more than 30° so that there is a whole lot of expansion; the burnt gas contains hardly any energy when it enters the exhaust pipe, so the exhaust pulses that arrive at the wrong moments at low rpm, are weak and will not disturb the scavenging too much.
At the rpm of maximum torque the ignition advance is about 14° (careful, a litte too much advance here and you get detonation), and at maximum revs the advance can be 10° or less (Honda even went to 3° after TDC ).

Dellorto's have been gracing Rotax engines first , with the bore size growing to 39.5mm on the VHSB body, then after Aprilia took over the engine production the VHSD appeared with a 41mm bore then the first generation S-DAS (stepper motor driven power jet) then the pulsed power jet and the latest VHSG 42mm with the APX electronics .
Unsure if other carbs were tried but never seen an Aprilia RSA/RSW without one. I'm not sure but I think it was more down to Dellorto working closely with Aprilia and a pinch of nationalistic pride. No doubt they work very well and if it aint broke.....................

An area of differentiation seems to be in bellmouth designs which each team seems to have their own idea on what the form should be.
To give you an idea of the main jet / power jet ratio: typical RSA-values are main 220, power 120. That means the flow area of the power jet is about (120/220)^2 = 0.3 times the flow area of the main jet. And don't shut the power jet until well past the rpm of maximum power or you will risk a maximum seizure.

The 'high compression brickwall' is no longer as hard as it used to be. With leaded fuel the compression ratio was 19,5; nowadays it is about 15. The 'brickwall' arose from the high expansion ratio (which is identical to the compression ratio). The higher this ratio, the more the burnt gases in the cylinder cool down before they enter the exhaust, thus lowering the resonance frequency of the exhaust system.
Riders complained that the engine would not rev, especially not in the lower gears, where the revs rose so quickly that the rising wall temperature of the exhaust pipes could not keep up with them. So you had cold exhaust gas and cold pipes.
The problem was to a large extent solved when the solenoid-controlled on/off-power jets were replaced with stepper motor-controlled jets that could continuously adjust mixture strenght, allowing the engine to rev more freely.

• Aha, I see. I think I got it now, Frits.
If the powerjet is positioned in the middle of the venturi or at a lower point, that will affect how much it will flow, correct?

I remember both Lectron and Mikuni aftermarket PJ kits' instructions, saying that the end tip of the pj should be around the middle of the carb.
Yet the Keihin PJ of the carbs for the mx250 models is down low! Position would also affect which fraction of the flow becomes more rich or not, or that doesn't matter??

When using a simple powerjet nozzle the tip position matters in that no flow will occur until the slide is well past the exit hole, and there is sufficient airflow
to drag fuel up the feed tube above the bowl level.
With the aftermarket add ons and the ones as used by Lectron you can shorten the dump tube so that the flow will only occur at high slide openings,as well as high air flow.
These also have a built in "lag "control in that it takes time for the fuel to rise up the tube and dump out the exit into the air stream.
With a solenoid controlled setup all this is pretty much irrelevant as the flow can only occur when the solenoid is not powered up, and this
is TPS as well as rpm dependant inside the ECU program..
The carbs as used on the MX bikes has the dump tube very low in the bore as they added and subtracted fuel at low slide positions in those bikes.
For a race engine I bend the tube up to around 1/2 bore, as this is where the exit is on the Kehin SPJ carb for RS125/RS250 Honda.
And the general setting is the solenoid is powered up ie no flow below 4000 and 60% TPS and is powered up again at around 12400 to lean off the mixture and increase revon.
This causes a problem with Ignitechs that are used with only a capacitor, as at startup the solenoid is powered up, dragging all the voltage out of the ECU, so I convert the ECU output
to a 3 step truth table, and have the setting such that below 1500rpm the solenoid isnt powered.

twotempi

27th April 2014, 13:19

So what class would a 300hp electric bucket run in ??

F5 ??
:niceone:

TZ350

27th April 2014, 14:30

So what class would a 300hp electric bucket run in ?? :niceone:

Same Class as Doc's car, as seen here at EastWood Ravine.

296565

if you make a time machine these people are probably worth knowing http://thelegalgeeks.com/blog/?p=4691

<iframe width="560" height="315" src="//www.youtube.com/embed/8ktMe0xclxA" frameborder="0" allowfullscreen=""></iframe>

Grumph

27th April 2014, 17:23

So what class would a 300hp electric bucket run in ??

F5 ??
:niceone:

You've got the knowledge/qualifications to work out an energy equivalence formula, J. Base it on a fixed race length, same energy allowance for electric and fossil fuels. Then put a remit forward for a new "fiddlers formula' class.....may even get accepted as a green initiative.

WilDun

27th April 2014, 17:56

Subtle difference, yes. Although if 2 strokes didn't store compressed gas why do they need reed/rotary valves?

I suspect the largest issue with case-charged 4 strokes might be keeping the valve closed, you'd need damned near double the spring pressure.

Back home again, I haven't read the other posts yet, - yes I agree about the spring pressure - but there's always desmo!
Will have to think about the rotary valves bit etc.- however, it worked phenomenally well on the model engines.

richban

27th April 2014, 20:12

Now that is Trap (5) of electrical trickery things that could be wrong.

Faulty Reg. Good as gold with new one on.

First outing on track today. Not to bad. Improved the turning as the day went on. Went around in circles a bit with jetting. It never really felt great. No more tack tuning. Time for the dyno. One thing is for sure I need to step up my game. I was slow.

Good fun though.

WilDun

28th April 2014, 08:49

You've got the knowledge/qualifications to work out an energy equivalence formula, J. Base it on a fixed race length, same energy allowance for electric and fossil fuels. Then put a remit forward for a new "fiddlers formula' class.....may even get accepted as a green initiative.

"Fiddler's Formula" sounds great! and if you are into electric machines, Bunnings might sponsor it as their sales of power tool battery packs would soar right off the scale! :yes:

jonny quest

29th April 2014, 12:24

Couple of oddities in the pic of barrel and pistons...those are big cutaways on the skirt sides...

And the cutback rear wall is pretty much exactly what I did on an RS125 at the customer's request...and it lost power.

Are you talking about the B transfer ducts. .. or the Reed cage inlet being very wide entering crankcase?

Grumph

29th April 2014, 12:31

Are you talking about the B transfer ducts. .. or the Reed cage inlet being very wide entering crankcase?

The piston side cutaways looked unusually big to me - but what do I know...

The rear cylinder wall is usually much more prominent - to the point where a customer thought there was more flow to be gained by cutting it back like the pic in question...he was wrong as it turned out.

chrisc

29th April 2014, 14:23

The piston side cutaways looked unusually big to me - but what do I know...

The rear cylinder wall is usually much more prominent - to the point where a customer thought there was more flow to be gained by cutting it back like the pic in question...he was wrong as it turned out.

Rear cylinder wall in red, as I understand it. Could you offer a potential interpretation as to why this did not offer any gains? It surely would have affected crank case volume to some extent.

I have another question if I may. In yellow, the entry to the transfer ports protrudes into the casings. I have seen these (and admittedly done so myself) cut these down to be flush with the face of the cylinder floor. My initial thoughts are extending these would extend the length of the transfer ports which would need to be considering in the overall tune of the engine. Do you have any thoughts or recommendations in keeping these or cutting them down?

296648

Grumph

29th April 2014, 16:27

i don't know enough about these subtleties to advance an opinion worth snot....

People like Frits or Wob with enormous dyno time behind them may have some ideas, I'd only embarass myself.

husaberg

29th April 2014, 16:59

pictures.................

http://www.geocities.jp/noda_keni/h/00nsr500/00nsr500.htm

http://www.geocities.jp/noda_keni/h/00nsr500/00nsr-9.jpghttp://www.geocities.jp/noda_keni/h/00nsr500/00nsr-8.jpghttp://www.geocities.jp/noda_keni/h/00nsr500/00nsr-17.jpghttp://www.geocities.jp/noda_keni/h/00nsr500/00nsr-10.jpg

wobbly

29th April 2014, 19:15

Answers are easy to "get " when you know the effects of the mods.
Cutting away the rear tang support at the base of the cylinder means that the flow thru the reeds then smashes directly onto a flat surface - the piston.
This may seem counter intuitive, in that most people think ( wrong ) that when the piston rises it creates a depression that opens the reeds and it is this that causes inflow into
the case.
The rising piston may make a piston port lawnmower operate, but the vast majority of bulk flow in a race 2T is caused by the pipes diffuser depression, around BDC - when the piston is very much in the way.
This negative pressure ratio at the Ex port is then communicated to the reeds via the transfer ducts , creating flow when the piston is at BDC - exactly opposite to the theoretical scenario.
Secondly - many , in fact most modern engines have the same sharp edge scenario as is shown in the pic of the Honda transfer entry, at the bore.
But be aware - Mr Thiel is no idiot, and the Aprilia ( and all my engines ) have a LARGE ball nose radius where the duct meets the bore edge.
This is one of the ideas that last weekend won the National Kart title for KZ2 - 125 against the very best World Cup winning engines tuned at enormous expense in Europe by
a French dude called Savard.
We kicked arse - making the pass for the lead by simply having more power down the shute, and better chassis setup to drive away on better tyres.
Transfer duct length is a very tricky area, in that most times when you shorten this, in effect you are reducing the duct volume, AND reducing the area ratio between entry and exit.
This I believe has more effect than the actual "tuned" duct length has.

chrisc

29th April 2014, 19:30

Answers are easy to "get " when you know the effects of the mods.
Cutting away the rear tang support at the base of the cylinder means that the flow thru the reeds then smashes directly onto a flat surface - the piston.
This may seem counter intuitive, in that most people think ( wrong ) that when the piston rises it creates a depression that opens the reeds and it is this that causes inflow into the case.

The rising piston may make a piston port lawnmower operate, but the vast majority of bulk flow in a race 2T is caused by the pipes diffuser depression, around BDC - when the piston is very much in the way.
This negative pressure ratio at the Ex port is then communicated to the reeds via the transfer ducts , creating flow when the piston is at BDC - exactly opposite to the theoretical scenario.
Secondly - many , in fact most modern engines have the same sharp edge scenario as is shown in the pic of the Honda transfer entry, at the bore.
But be aware - Mr Thiel is no idiot, and the Aprilia ( and all my engines ) have a LARGE ball nose radius where the duct meets the bore edge.
This is one of the ideas that last weekend won the National Kart title for KZ2 - 125 against the very best World Cup winning engines tuned at enormous expense in Europe by a French dude called Savard.
We kicked arse - making the pass for the lead by simply having more power down the shute, and better chassis setup to drive away on better tyres.
Transfer duct length is a very tricky area, in that most times when you shorten this, in effect you are reducing the duct volume, AND reducing the area ratio between entry and exit.
This I believe has more effect than the actual "tuned" duct length has.

Congrats Wobbly!
I do remember reading about the radius on the bore edge and was going to comment on it not being on this NSR cylinder. I'm glad you did, and I'm glad you emphasised LARGE because I had no idea just how much of a radius it required.
Time to read up on duct volume and ratios. I know I saw some good content in this thread somewhere :scratch:

koba

29th April 2014, 19:53

...last weekend won the National Kart title for KZ2 - 125 against the very best World Cup winning engines tuned at enormous expense in Europe...

:2thumbsup:2thumbsup

Forgi

30th April 2014, 07:53

They will probably not all be the same, Forgi. A rotary disc usually opens much quicker (= in fewer crank degrees) than a piston port.

You are right Frits, I just couldn't realize this fact. Of course it would be better than a piston controlled port at the same size. But I'm sure the test would give a good guideline how much the power and the powerband can be affected by the fact that the rotary disc opens earlier with 50-60 degrees and that's why the time area could be duble.

Before I have read a Kreidler test in which the piston controlled valve had been transformed to a rotary disc valve. In that case with the same exhaust the power increased +15% and with a modified exhaust increased +40%.

wobbly

30th April 2014, 08:06

Forgi

30th April 2014, 08:06

Hi Forgi, I agree, it would be interesting but its not very relevant to my project and its hard for me to do. The std inlet timing for my Suzuki 125 engine is 145/55 so 88 closing is easy, I would only need to cut the leading edge of the disk and it is what I routinely do to get the inlet duration I want. But 88 opening means adding material to the trailing edge, and that would necessitate making new disks.

Hello Teezee. Of course I understand, no problem :)

RomeuPT

30th April 2014, 13:31

The other small point I thought of later was that the drop down rear piston support tang,if shaped well also helps to deflect the reed flow sideways
toward the transfer duct entry area, and not allow most of it to migrate straight forward and hide under the piston.
I should temper my comments about reed flow at BDC somewhat in that when you watch the tip lift and case depression curves in EngMod
you see that the case going negative and the inlet going positive, if tuned correctly opens the reeds very quickly and soon after BDC,thus initiating
flow into the case when the piston is still hanging around " in the way ".
But again I emphasise it isnt the rising piston that creates the inflow in a race engine.

Many Thanks for this great share of knowlegde.

So, as fuel passes inside the open reed cage there should not meet a very big case entry or the flow velocity is lowered too much, then the fuel should go in the easier path to sit under transfer ducts. Is this right?

Concluding, we can't make a divisor for fuel to avoid getting much under the piston because of big and small end bearings lubrification!?

Many Thanks

Grumph

30th April 2014, 13:44

The other small point I thought of later was that the drop down rear piston support tang,if shaped well also helps to deflect the reed flow sideways
toward the transfer duct entry area, and not allow most of it to migrate straight forward and hide under the piston.
I should temper my comments about reed flow at BDC somewhat in that when you watch the tip lift and case depression curves in EngMod
you see that the case going negative and the inlet going positive, if tuned correctly opens the reeds very quickly and soon after BDC,thus initiating
flow into the case when the piston is still hanging around " in the way ".
But again I emphasise it isnt the rising piston that creates the inflow in a race engine.

So then, how important are holes in the rear of the piston skirt ? Do you place more importance on a strong signal from inlet port opening with a solid skirt - or use a very strong signal from the pipe to get as much mixture as possible into the cases via a 360 degree opening using a ported piston ?

this is assuming a non case reed motor....I ask because i like the 360 deg opening but it's necessary to "life" ported pistons to avoid a messy disaster....

wobbly

30th April 2014, 15:55

The amount of inlet flow capability varies from motor to motor with cylinder reed setups..
But I know for example in the RZ400 I had to make the Boyesen ports in the CPI cylinder twice as big and then use a Blaster type piston full of big holes
to get sufficient inlet STA to support over 100 Crank Hp.
That engine ended up making 96 RWHP and held up over 90 at 12,000 so when pushing the limits on a cylinder reed you have to use everything available.
Here is a pic of the Blaster pistons in 66mm bore, next to stock Blaster and RZ ,I had Wossner make them for the RZ and the TZ400.
Been reliable to over 500Km hard racing so far.

wobbly

30th April 2014, 16:12

Re the reed flow - yes keeping the reed box duct volume small helps keep the velocity high and in all late model engines you can see
the progressively smaller entry volume being redesigned year by year.
I have thought about making a pair of curved vertical guides in the reed box that would direct the flow from the outer reed petals ( in a 6 petal reed )
toward the transfer duct entries.
The centre petals then dumping flow onto the big end slot for lube - not had a suitable project yet to try this..

jonny quest

2nd May 2014, 17:54

So what are your thoughts on making the cases as wide as possible on a case Reed motor? This NSR500 has the case Reed width almost as wide as the transfer ducts in the cases.

I have a cr125 that I'm doing and debating on how wide I should make the case Reed width entering the crankcase, and ultimately into the transfer ducts in crankcase

jonny quest

3rd May 2014, 03:59

Another quick question, has anyone tried adding transfer ports under the exhaust port?

Vertical slots cut in the cylinder wall, that just cracked open at BDC.

I believe this would help piston crown cooling immensely.

F5 Dave

3rd May 2014, 08:54

Read back a few hundred pages, it's been touched on.

wobbly

3rd May 2014, 09:16

From what I have seen by various factories the development seems to have been toward reducing the area/volume in front of the reed tips as much as possible - at the expense of what you would think was a "good " flow
regime.
But along with that the Italians are lifting the duct floor higher and higher with it sloping upward and transitioning into the flywheel covers, just leaving a slot for lube.
This has also coincided with angling the carb upward, removing any bend in the inlet tract.
That has also given festerers like me endless fun with reed configurations - no longer do we need to bias the flow with differing stiffness and or backups on the top/bottom to
counteract the manifold bends deleterious effect on flow.

jonny quest

3rd May 2014, 10:42

Read back a few hundred pages, it's been touched on.

The exhaust transfers?

husaberg

3rd May 2014, 11:39

The exhaust transfers?

Yip think it was on pitlane as well.......

TZ350

3rd May 2014, 12:19

Another quick question, has anyone tried adding transfer ports under the exhaust port?

Yes and No ... tried an exhaust port dam, seemed to work OK, as for the transfers under the exhaust port itself, good idea but from memory Frits reported that Jan Theil had tried it without success.

Is this what TeeZee is up to and Jan was talking about, raising the exhaust port floor and maybe fitting an extra transfer there too?

I would be very interested in the roof angle of the 6th transfer port thats under exhaust.

To make the raised floor work as part of an overall plan that was seen all the way thru by Jan at Aprilia, the area reduction at the port should be extended all the
way to the flange.
Making this oval, and reducing the duct volume all the way to the exit then works with the 75% area guideline for T or tripple port duct exit geometry.

The glued and screwed in port floor dam held up OK and the dyno results were better.

You work too hard, TeeZee. Leave out step 1 and step 3 and you'll end up with a clean bin and 37.7 rwhp
:D

Yes, high temp epoxy to seal the plate. I fastened the plate in with screws, the epoxy was mostly for sealing around the sides and under the plate.The dyno results were posted here.

I remembered that Jan and Frits had talked about experiments where raising the exhaust port floor made more power by reducing short circuiting.

And by reducing the exhaust duct volume and to help guide the washed-through mixture back over the piston edge into the cylinder. Lenghten it up to the flange face and make a smooth transition, like Wobbly advised.

Tdc211 its encouraging to hear you have got good results with your 5mm dam, and Romeu its hard to measure mine with the cylinder off but it looks like the dam is about 6mm or so above the piston and still 5mm or so below the top of the transfers.

Well at least its good to know I am on the right track but I sure would like to know if this is the limit or if I can take it closer to the top of the transfers.

292539

After 40 liters of fuel and hours on the dyno the exhaust port dam and Belzona epoxy are still there.

F5 Dave

3rd May 2014, 13:10

Oh, maybe it was pitlane I saw it on.

jonny quest

3rd May 2014, 17:41

Thank you for digging up those quotes. I'm familiar with raising exhaust floor. Been doing that for years. .. glad to see I wasn't alone. I came across it when I tried a different piston that had a shorter skirt. It opened up ex port at tdc. When I went back to other piston I found some power I didn't have before. Just dumb luck on my part ;)

Hopefully Frits will see this and comment on the ex transfer. .. what it did when it was tried.

TZ350

4th May 2014, 19:40

Rob
I have uploaded the results to Mylaps: http://www.mylaps.com/en/events/1012834)
I have also updated the link on the Bucket News section of the AMCC website.
And congratulations to Nathanael on his brilliant lap times at the weekend, in both F4 and F5.
Tim

296763

Great Day at Mt Wellington. Out on the 50 and had lots of fun. The bike ran really well, but I got slower as the day went on. My best time was 35.8, the winning bike (number 58) and rider were just a shade over 31's. That is faster than I have ever been around there, even on my 125.

Some of the other F5 bikes.

mr bucketracer

4th May 2014, 20:05

went out to brian thomas work shop today , i saw a 50cc Kreidler he had build ....yummmy! here is a link to some stuff he has built

http://www.themotart-journal.com/2011/11/brian-thomas-collection.html

husaberg

4th May 2014, 21:16

mr bucketracer

4th May 2014, 21:57

Was Brian Thomas the one that did the demo 250 Manx........yes and a desmo bucket racer

Frits Overmars

4th May 2014, 22:29

No two-strokes anymore, but you may want to watch the Spanish MotoGP just the same: http://cricfree.tv/bt-sport-2.php

richban

5th May 2014, 07:41

No two-strokes anymore, but you may want to watch the Spanish MotoGP just the same: http://cricfree.tv/bt-sport-2.php

A few 2 strokes on track yesterday. Both the 300 Honda's were out and what do you know a Wobbly RZ400. Not much in it with the fast 300 but still the RZ had the legs. My bike is maybe 15hp down but the rider still needs work. The F3 field was really good. Some cool bikes out and more to come from what I here.

It is really like stepping onto a 80hp bucket. Well a heavy and does not turn as good 80hp bucket. But does do wheelies and power slides.:crazy:

Drew

5th May 2014, 09:24

Was it Rob on the Wobbly thing? Big South African dude, top guy.

jonny quest

5th May 2014, 10:40

Muciek

5th May 2014, 11:36

There was one guy in Czech republic who tuned a moped engine to get he's degree at university and he done this kind of tests, here are the results Blue line piston angle same as head angle and red line domed piston and straight angle head and 2nd picture modified piston to get same angle as head.
296786296787

wobbly

5th May 2014, 11:47

Rob on his RZ400 has finally got to tune it and was able to keep it under 1200* all day - a first.
His bike is way heavy compared to Andys or the 300s as it has stock wheels etc, but very trick RT suspension.
The needles in the Smartcarbs are still not "right" as Rob has resorted to sanding the things to change the Jets as such.
Now he has control of the temps we can start looking at getting it back to 1250* where it makes alot more power.

Ocean1

5th May 2014, 11:51

Most us cut the squish angle of our heads on the lathe. With a domed piston which is a radius... the squish angle is slightly mismatched being a straight angle.

Any performance benefit to CNC the head squish to match piston dome?

You don't need CNC gear. Just organise an adjustable tie-rod with standard rod-ends mounted between the tailstock and the cross slide.

Adjust the length to match the piston dome radius, lock the tailstock and engage the cross slide feed. Done.

wobbly

5th May 2014, 11:56

The squish following the piston shape by using CNC is even more important if you are pushing the limits with around 50% SAR and very tight clearance.
This also works together with the sharp edge into the bowl, and I suspect that if the tests shown were done with all this in mind the difference in performance would have been even greater.

richban

5th May 2014, 12:20

R
His bike is way heavy compared to Andys or the 300s as it has stock wheels etc, but very trick RT suspension.

Yeah they get really Heavy with the amount of Fuel you need for 10 laps. Mine is no feather weight. Stock wheels and all. About 120kg. Then add 7 litres of gas. Then add me. 100hp would be nice actually.

jonny quest

5th May 2014, 17:09

I'm waiting on some parts... won't be able to test for a few weeks. .. but for those still dyno ing right now. .. here's something to try.

About 5mm from end of squish pad, close to bowl... on squish pad.... machine a groove about .015" thick and deep.

This acts like a "trip" zone to help with turbulence. .. along the same lines as the sharp edge leading into bowl.

Bert

5th May 2014, 18:13

Yeah they get really Heavy with the amount of Fuel you need for 10 laps. Mine is no feather weight. Stock wheels and all. About 120kg. Then add 7 litres of gas. Then add me. 100hp would be nice actually.

You (and Speedjunkie); did bloody well all things considered.
Given where you started on Saturday afternoon (with your bucket producing more power)...:cool:

It was a great turn out of two strokers overall with a number of 250s down the pack.
I have to congratulate VMCC for there 90s carb class, it seems to be a great formula.

wobbly

5th May 2014, 18:48

Slots in the squish band = no free lunch = more unburned end gasses = less power = waste of time.
Been there done that.

jonny quest

5th May 2014, 19:41

It works on the 4strokes.

I use to build 2 stroke exhausts for a living. I was put out of business by the 4 strokes in the MX market. ... I may get whipped for saying this here... but glad I did. Business has quadrupled because of all the extra moving parts.

I taught myself how to make cone pipes. ... spent the last year teaching myself cam design. It's a lot easier grinding a cam than cutting, hammering out a pipe. (Labor wise)

But I bought myself a fun little 2 stroke to play around with again. A newer CR125. Having fun playing. ... and it really is amazing how that technology applies to both.

jonny quest

5th May 2014, 19:50

See if this works. .. Some of my work

http://img.photobucket.com/albums/v250/williamsmotowerx/P1010004.jpg

mr bucketracer

6th May 2014, 19:12

TZ350

6th May 2014, 20:42

296833

Something I have just seen on the net. Valves dimpled on the head like a golf ball for better air flow over there surface, so clever I don't know why it had not been done before.

Haufen

6th May 2014, 21:15

296833

Something I have just seen on the net. Valves dimpled on the head like a golf ball for better air flow over there surface, so clever I don't know why it had not been done before.

Maybe because valves, unlike golf balls, rotate with a far lesser speed (if at all) and thus the effect does not work?

fixer

6th May 2014, 21:57

My beloved Aprilia RS50 acquired a new Doppler Vortex 50cc kit recently. I bought it because I liked the look of the wide bridged exhaust port and the wide and (I believe) nicely-angled transfer ports. It's advertised as a road kit so it (as I have discovered) has relatively mild port timing. There's a video showing the inside of the kit here: https://www.youtube.com/watch?v=mUeeycpkpc8.

The standard Aprilia top end with some exhaust port mods made a bit over 11hp on the ESE dyno. So we put her back on the dyno and, lo and behold, with the Doppler kit she was making just under 10hp with a dip in the power band the size of the Grand Canyon.

But ... we took advantage of the large number of exhaust pipes to be found in the ESE workshop to see if a different pipe might conjure up another pony or two.

So the Conti pipe (which had been largely responsible for an earlier increase from 5hp to 8hp) came off and another pipe went on. Still a large dip in the power band, but substantially more power. Back up to just over 11hp. This pipe was a bit large and only fitted a couple of mm into the barrel. So we shaved a bit off the OD so it would fit in better. It was probably about 10-12mm shorter when properly fitted, and was a disaster. Back down to just over 10hp. What??

Okay ... so we tried a different pipe. The result was MUCH better. Nearly 12hp with a much nicer looking power curve.

And then for the hell of it, we tried the original Conti pipe with a shorter adaptor between the pipe and the barrel (probably by about 12-15mm). Based on our previous experience of a longer pipe being better, I bet that this shorter adaptor would make things worse. WRONG!!! There was still a chunky dip in the power band, but it was back up to nearly 12hp.

The moral of the story ... the proof is in the dyno! Below centre is a photo of the 5 dyno charts. You can see the range of different results obtained from 3 different pipes, with two of them tried twice each with shorter or longer adaptors. The maximum power varies by around 20 percent, but 4 out of 5 have a similar dip. One doesn't. This is very promising.

The photo on the left illustrates the huge difference that just having a 10mm or so longer adaptor between the pipe and the barrel can make. The photo second from right shows the two adaptors.

So on went the degree wheel (see photo on right), and some considered measurements were taken (see photo second from left), with the result being that we're going to raise the barrel a bit with a spacer, machine the head to fit it into the top of the cylinder, tweak the squish band and stick her back on the dyno. More exhaust port duration is apparently what is required here.

Two-strokes and dynos ... a match made in, well, if not Heaven, then at least Wonderland.

Tim