ESE's works engine tuner

[speedpro]

My MB sidecar engine had a Keihin 28mm carb, beautiful little carb. Every other engine has always had the old 32mm round slide Mikuni and even the same main jet.

[TZ350]

I am Feeling very depressed today. I have finally got a handle on Jennings Time-Area/Angle-Area chart and how to use it and its not looking good.

Gordon Jennings:- http://www.vintagesleds.com/library/...20Handbook.pdf down load it from here.

To use this chart you need to know the port open duration and the mean area of the port, which is roughly ¾ of the total port area.

Finding the “SPECIFIC ANGLE AREA” for the “DISC-ROTARY INTAKE” on my Suzuki GP125.

First, the inlet port is slightly bigger than the 24mm carb, port area = 5cm2.

Second divide 5cm2 by 125cc and get 0.04.

The inlet timing is, inlet opens 145 BTDC, closes 85 ATDC so the port open duration = 230 degrees.

Now 0.04 times 230 equals a “SPECIFIC ANGLE AREA” of 9.2.

A “SPECIFIC ANGLE AREA” of 9.2 just puts me into the 8,500 rpm region of the chart.

The only way to move to the 10,000rpm region is to increase the inlet timing and lose low-end torque or increase the size of the port but this is limited by the carb/port size relationship.

The 24mm carb limit has got my hands tied. A 28 would be good and a 32 just right.

This time-area.angle-area chart is a real easy way to figure if youve got enough port size and/or duration for the rpm you plan on using.
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[k14]

The only way to move to the 10,000rpm region is to increase the timing and lose low-end torque or increase the size of the port but this is limited by the carb/port size.

The 24mm carb limit has got my hands tied. A 28 would be good and a 32 just right.

Well I think the only answer is to buy an fxr...

[Sully60]

Well I think the only answer is to buy an fxr...

Wash your mouth out!
Not enough cylinders

[SS90]

I
A “SPECIFIC ANGLE AREA” of 9.2 just puts me into the 8,500 rpm region of the chart.

The only way to move to the 10,000rpm region is to increase the inlet timing and lose low-end torque or increase the size of the port but this is limited by the carb/port size relationship.

The 24mm carb limit has got my hands tied. A 28 would be good and a 32 just right.


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Just to play devils advocate...is it possible to simply fit a bigger carb and test on the dyno (just for comparison)

I guess that is just academic, but it would be interesting aye!

10,000 RPM really is where you want to aim (aim my opinion), given the fact that you have an unsuitable gear box, but (as you are more aware than anyone that dammned 24mm carb really limits you!

My experience tells me that such an engine is possible (previous graphs), but, like I said, 28MM carbs (and up) are required!

PERHAPS (just a suggestion) you could reconsider your current cylinder, and simply make the engine (with different exhaust port timing) for low down power (with an ignition and pipe design) that simply allows for alot of "overrev", giving you not only an easier bike to ride, but also an engine that will have (similar) power characteristics to an FXR150.... (maybe)

[Yow Ling]

Maybe start looking for a gp100 barrel

[k14]

Wash your mouth out!
Not enough cylinders

We don't want everyone finding out how awesome cb's are! Leaves no spare parts for us

[SS90]

Maybe start looking for a gp100 barrel

That is a bloody good idea!

Sorry Teezee, but that may well be worth consideration!

[TZ350]

Links to Tech Stuff.

Gordon Jennings:- http://www.vintagesleds.com/library/...20Handbook.pdf

An assortment of Gennings Articles:- http://www.edj.net/2stroke/jennings

Graham Bell:- http://www.kreidler.nl/artikelen/per...raham-bell.pdf

Yamaha SAE Paper on Porting:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

Rate of Fuel Burn:- http://www.factorypro.com/tech_tunin..._vs_power.html

Reading Plugs:- http://www.dragstuff.com/techarticle...ark-plugs.html

Engine formulas:- http://members.bellatlantic.net/~vze...es/engine1.htm

A Handy Coverter:- http://www.mr2ownersclub.com/converter.htm

Detonation:- http://www.factorypipe.com/t_deto.php

Dale Alexander. The Art Of Squishing Things Until They Make Power:-
http://www.aircooled-rd.com/default....ge=squish1.htm
http://www.aircooled-rd.com/default....ge=squish2.htm
http://www.aircooled-rd.com/default....ge=squish3.htm

A preview of Kevin Camerons book “Sportbike Performance Handbook”:-
http://books.google.co.nz/books?id=L...esult#PPA81,M1

TUNING VESPA'S THE NORRIE KERR WAY.....
http://www.scooterhelp.com/serial/tuning.books.html

Crankcase delivery ratios and inlet timing for rotary disk motors:-
http://www.edj.net/2stroke/jennings/delivery_ratio.pdf

The effects of crankcase volume on the delivery ratio:-
http://www.edj.net/2stroke/jennings/...ase_volume.pdf

Piston pin offset and what it means for extra power:-
http://www.motorcycleproject.com/mot...ws-offset.html

4-Stroke stuff but very interesting about porting and combustion.
http://www.gofastnews.com/board/technical-articles/

Terminolagy:- http://www.2-stroke-porting.com/terminology.htm

Modifying a Suzuki open chamber to a squish head:- http://www.ozebook.com/compendium/t5...organ/head.htm

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[TZ350]

Just to play devils advocate...is it possible to simply fit a bigger carb and test on the dyno (just for comparison)

The problem with that is the whole inlet tract and port have to be reworked to suit the larger carb as the area of the port window needs to be just a whisker bigger than the carb.

A complete 100cc engine is starting to look like a good idea.

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[SS90]

The problem with that is the whole inlet tract and port have to be reworked to suit the larger carb as the area of the port window needs to be just a whisker bigger than the carb.

A complete 100cc engine is starting to look like a good idea.

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Yea, while I feel for all your hard work (and Thomas's....) with what you have learned from the 125, to apply it to a 100 would be quite amazing (and you could water cool the head as well)...... In THEORY you should be able to make more peak power than an MB100 (but alas, you get "fingered" by that transmission again), so making the bike rideable (with port timings to to extract that power might be hard work (but certainly possible).

Don't give up though.....not everything about two stroke tuning can be found in a book written in the 70's......

[TZ350]

Well I think the only answer is to buy an fxr...

I would buy a XL100 first and supercharge it, then your FXR's would be in real trouble.

Supercharged Honda 50 http://www.elsberg-tuning.dk/the%20bikes.html

Superchargers.

The smog pump - cheap and plentiful. Used on automobile engines since late sixties.
The Aisin AMR300. From Subaru Kei- car - 660cc supercharged citycar.
The KF Max10- 25. American aftermarket blower.
The Hansen V12. Made especially for supercharging Kart- engines from 5- 20hp.

Thanks to TerraRoot for his post on the Blown FXR thread.

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[xwhatsit]

I would buy a XL100 first and supercharge it, then your FXR's would be in real trouble.

Supercharged Honda 50 http://www.elsberg-tuning.dk/the%20bikes.html

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I've seen that before. Very impressive -- same motor as in my little Honda C50, which tops out around 65kph. He says he hit 142kph. Stock cam!

[TZ350]

I've seen that before. Very impressive -- same motor as in my little Honda C50, which tops out around 65kph. He says he hit 142kph. Stock cam!

The way to get drive out of a supercharged 4-stroke is to use the stock or milder than stock cam. As you are blowing the air in and don't need all that super cammy stuff.

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[koba]

I would buy a XL100 first and supercharge it, then your FXR's would be in real trouble.

Apparently it has been done before...
As far as I understand (so I'm probably wrong!) one major problem with supercharging (With a positive displacement blower) small bikes is the clearances in a blower stay more or less the same regardless of size so the smaller the blower the greater the pumping loss % or somthing like that anyway...

I did a bit of research on the Aisin AMR300 and AMR500 as I was looking using one on my VW Beetle. I think a 100 would have a fair ammount of trouble spinning it!

I think (Just as an idea) if you really did want to play with such a thing the compressor side of a tiny turbo would probably be worth looking long and hard at.

A. Graham Bell also has a great book on forced induction tuning.

Edit: Ahh, I see the guy in that article cut his blower down!
Smart bastard!