ESE's works engine tuner

[Rick 52]

Hi there,

Attachment 297908

the results of the 8^th & final round of the 13/14 season of AMCC bucket racing from today are attached, Tim will be updating the website.

Congratulations to the winners:
F4 Rick Ford
F5 Tim Fraser
B grade Pete Leahy
C grade Helene Conway
Sidecars Rick & Henk

No Diproses this season, even though Nathanael did win the last 10 F4 races in a row… (out of 16 total)
I guess if I want to win anything I should stop falling off my mountain bike.
Regards,
David Diprose

Thanks to the ESE Team for your help and advice over the season, winning the Auckland championship is not easy and I am over the moon .

[peewee]

I have been working on a ZABEL 700 cc two-stroke single for sidecar-MX.

ive wondered about the zabel engines. is it one with the reeds in the crankcase and whats your thoughts on the engine as a whole from a engineering standpoint. does it look like it has alot of potential ? i thought about picking up a zabel if i see a used one for a decent price

[TZ350]

A butterfly in the header to switch between chambers would be worth looking at. Ages ago I drew something along these lines for Solex racing, with a rotating drum, switching between a short and a long header. I can't find the picture any more but it was not unlike the variable-length inlet system found nowadays on some Audis.

Audi variable-length inlet system.



http://www.autozine.org/technical_sc...e_exhaust.html

[Frits Overmars]

ive wondered about the zabel engines. is it one with the reeds in the crankcase and whats your thoughts on the engine as a whole from a engineering standpoint. does it look like it has alot of potential ? i thought about picking up a zabel if i see a used one for a decent price

Yes, it has case reeds. This version won quite a bit of world championship titles but from an engineering standpoint there are always unfulfilled wishes.
It's a short-stroke engine (100*89 mm) which is not favourable for a two-stroke, and the con rod might have been longer than the current 146 mm, but those mods would result in a larger engine, so all in all it ain't bad (as long as you don't have to kickstart it yourself.)

[husaberg]

Audi variable-length inlet system.



http://www.autozine.org/technical_sc...e_exhaust.html

Ages ago I posted one from a bike same idea only simpler........
it will take me ages to find it...........

http://www.kiwibiker.co.nz/forums/at...9&d=1341619864

3553 picures............

[speedpro]

Audi variable-length inlet system.



http://www.autozine.org/technical_sc...e_exhaust.html

Interesting - splayed intake valves

[WilDun]

.
It's a short-stroke engine (100*89 mm) which is not favourable for a two-stroke,

I notice that two stroke competition engines usually have a 'square' bore and stroke (as opposed to chainsaws etc. which are usually very much 'oversquare') and I'm sure that there must be a very good reason for that, - what is it?

[Drew]

I notice that two stroke competition engines usually have a 'square' bore and stroke (as opposed to chainsaws etc. which are usually very much 'oversquare') and I'm sure that there must be a very good reason for that, - what is it?

Am I correct in guessing it's because they sit at max revs/full song non stop. So the crank takes less of a hammering with a shorter stroke?


Hmmm. So if I went cvt on a bucket sidecar, this would be a handy thing to remember...provided my guess is right. Hello 13,000rpm 100cc twin cylinder two stroke.

[speedpro]

- what is it?

Lots of things. As usual there's compromises to be made. It's explained earlier in this thread somewhere.

[TZ350]

Hmmm. So if I went cvt on a bucket sidecar, this would be a handy, 13,000rpm 100cc twin cylinder two stroke.

There are rumors, so if you wan't to be the first, you may have to be quick ....

[wobbly]

In a competition engine square bore/stroke gives the best compromise between revability - dependant upon the stroke length,and the bore angle area available.
A short stroke bore with the same timings as a long stroke has less angle area available, and this limit on performance is not outweighed by the basic notion that rpm
makes power due simply to P= T*RPM/5252.
With less angle area available in a short stroke/big bore the torque cannot be held up sufficiently to use the rpm advantage.
Yamaha tried forever to use the 56 by 50.6 setup in GP racing and finally saw the light of 54 square dimensions, allowing Jaques to win the 250 title in around 2000
after years of hamstrung engines.

There is probably some merit in the idea that a short stroke saw engine can sit at peak rpm with less crank/rod loads, but I think most saws have been increased in size
over long periods, and the easy way for a factory is simply to bore it out.

[peewee]

In a competition engine square bore/stroke gives the best compromise between revability - dependant upon the stroke length,and the bore angle area available.
A short stroke bore with the same timings as a long stroke has less angle area available, and this limit on performance is not outweighed by the basic notion that rpm
makes power due simply to P= T*RPM/5252.
With less angle area available in a short stroke/big bore the torque cannot be held up sufficiently to use the rpm advantage.
Yamaha tried forever to use the 56 by 50.6 setup in GP racing and finally saw the light of 54 square dimensions, allowing Jaques to win the 250 title in around 2000
after years of hamstrung engines.

There is probably some merit in the idea that a short stroke saw engine can sit at peak rpm with less crank/rod loads, but I think most saws have been increased in size
over long periods, and the easy way for a factory is simply to bore it out.

ive been trying to understand angle area more. is it simply the amount of port area for every degree of crank rotation ? just for example can we say a short stroke engine has 1mm of port area for every 1 degree of crank rotaion and a long stroke engine might have 2mm of port area for every 1 degree of crank rotaion ? ive seen the term angle area used alot in books but never found a simplified explanation of what it is

[monkeyfumi]

Interesting - splayed intake valves

5V heads, 3 intake, 2 ex (just like Yamaha used to have)

[TerraRoot]

5 valve head i believe

edit, too slow

[husaberg]

So they have 5v heads 5 cylinder engines and buggered er up the Logo at bit.