ESE's works engine tuner

[Condyn]

Question for Frits Overmars or anyone else who knows what I am referring to.
Several years ago I recall reading a text written by Frits about finding the optimal ignition timing. If memory serves, he talked about adjusting the timing for each rpm before combining them to create the best curve. I cannot find this text anymore and I would like to read it again.

[JanBros]

I have it in german, any good for you ?

[Condyn]

I am solo lingual but I could try translating it, so yes I am interested. Thanks

[wobbly]

Anyone here in NZ got a M30 x 1.5 female puller I could use to yank off the flywheel of the EngMod competition KR150.
Only need it for the 30 seconds it takes - can send straight back.

[Wos]

Frits ignition curves paper you can download in german here

https://oil-club.de/wcf/index.php?at...urven-132-pdf/

But Frits?
Wasnt a Englisch version available somewhere?

Thanks!

Wolfgang

[Wos]

Frits Englisch Version 😉

https://www.zweitaktforum.de/wbb/att...nce-curve-pdf/

[Condyn]

Thanks for tracking that down!

[ken seeber]

Gedday all,

The theme of this post is to get rid of those old fashioned expansion chambers with a straight header, and add some incredibly bulky packaging and an unknown, but complex crank coupling and swap these for something that mightn’t offer any advantages at all. Are you ready?

OK, recently on Rimar Motors FB page, where he shared the design and mfg of his 587v2 engine (Incredibly good stuff. See https://www.facebook.com/rimarmotors) that utilizes 2 * KTM 300 cylinders, someone asked him could he do a 3 cyl version. His immediate response was to say no, because of the bulk of the exhausts.

This reminded me of a time, 100 years ago at Orbital Eng Co, we first started testing a 3 cyl Suzuki DT85 1.2 litre outboard engine. We had no useful idea for the exhaust (expansion chambers were not a consideration) and various systems were made with separate headers etc. all worked at some point, but overall useless. Then we just created a simple chamber or plenum close to the 3 exhaust port outlets (similar to all multi cylinder outboards) and immediately got a nice high and flat power curve. This then, with time for emissions reasons, was changed to accept a catalyst brick forming the back face of the plenum.

Obviously in such an arrangement with an inline crank, there is an asymmetry in terms of communication lengths between cylinders. Unacceptable to any OCD type.

So, let’s arrange 3 cylinders symmetrically abut a common axis, with the exh outlet face facing the axis, ie inwards. With some form of a common plenum connecting the 3 exhausts, this could lead upwards via a single header pipe.



How it would fit anywhere? Fletto, where are you???

[F5 Dave]

Well that and a petrol tank for a 900 2 stroke would defeat the whole purpose.

The only 2 strokes I've been regularly riding recently are 300 enduros. On the dirt they have ample power in all the right places.

[Vannik]

Gedday all,

This reminded me of a time, 100 years ago at Orbital Eng Co, we first started testing a 3 cyl Suzuki DT85 1.2 litre outboard engine. We had no useful idea for the exhaust (expansion chambers were not a consideration) and various systems were made with separate headers etc. all worked at some point, but overall useless. Then we just created a simple chamber or plenum close to the 3 exhaust port outlets (similar to all multi cylinder outboards) and immediately got a nice high and flat power curve. This then, with time for emissions reasons, was changed to accept a catalyst brick forming the back face of the plenum.

Obviously in such an arrangement with an inline crank, there is an asymmetry in terms of communication lengths between cylinders. Unacceptable to any OCD type.

Ken, you are talking about the one long path vs the two short paths.

[ken seeber]

[QUOTE=Vannik;1131232270]Ken, you are talking about the one long path vs the two short paths.

Yes Neels, that's exactly the arrangement. Whether "actual equal lengths" in this situation would make any difference is unknown to me. One guy (Bromlech?) over here, shortly after GT750s came out, made a 3 into 1 system. I have no idea if they were any better performance wise , they had very long primaries, but they sounded so sweet.


F5 Dave, we're not talking about chook chasers here....

See you all next year...

[rgvbaz]

Strike are made for iron liners most KTM are made for coated.
Strike which is a family business based in AUS will make pistons with custom pined rings in any oversize not .25 of a mm if you use KTM you are stuck with 3 fitting pistons abc . Strike do hone to size pistons.
http://www.strikeproducts.com.au/pistons.asp
http://www.strikeproducts.com.au/pricelist.asp

piston dimenions KT100s
https://cdn.revolutionise.com.au/sit...avzy51kppz.pdf

or custom applications for AIDKA and Speedway racing applications Custom options include: High Ring Rotated Anti Rotation Pin for reeds and rotaries Dykes rings Sizes are made to order Rings to suit are dependant on application

PSS001 - Piston KT100S Smooth Finish Smooth piston skirt finish To suit Yamaha KT100S and ARC SPEC100 for AKA racing applications Size increments 0.05mm between Æ52.0 and Æ52.75 then 0.01 increments above Æ52.75mm Ring to suit is p/n PRS001 These are aus pasos S001 Piston KT100S Std $83.00 PS002 Piston KT100S >Ø53.00* $83.00 PS003 Piston KT100S >Ø53.75* $83.00 PS004 Piston KT100S Special** POA PSS001 Piston KT100S Std Smooth $91.50 *Not legal for AKA sanctioned events **Custom options: Indexed A/R Pin Location to any angle PRS001 P/Ring KT100S Std $21.50 PRS002 P/Ring KT100S Big Bore 53.5, 55.25, 55.5 $36.00 C001 Circlips Ø14*Ø1.0 x 50 off $45.00 PB001 Pin Bearing Thompson $18.00 PP001 Piston Pin Ø14*Ø8.9*40.4 $7.50 PP002 Piston Pin Ø14*Ø10*40.5 (Light) 7.50

Cheers mate 😃

[Storbeck]

[QUOTE=ken seeber;1131232286]

Ken, you are talking about the one long path vs the two short paths.

Yes Neels, that's exactly the arrangement. Whether "actual equal lengths" in this situation would make any difference is unknown to me. One guy (Bromlech?) over here, shortly after GT750s came out, made a 3 into 1 system. I have no idea if they were any better performance wise , they had very long primaries, but they sounded so sweet.


F5 Dave, we're not talking about chook chasers here....

See you all next year...

How about if you take your online three cylinder and tip the middle cylinder backwards until the exhaust port flanges of the tipped back middle cylinder and the outer two cylinders from roughly an equilateral triangle? That may allow the other cylinders to be moved in a bit of possibly allow them more room for transfer ports to loop out and around.

Maybe that leaves the "headers" still too long or gives problems with balance and firing order or some such. Could add a balance shaft and still be way more simple the previous arrangement.

[ken seeber]

[QUOTE=Storbeck;1131232289]

How about if you take your online three cylinder and tip the middle cylinder backwards until the exhaust port flanges of the tipped back middle cylinder and the outer two cylinders from roughly an equilateral triangle? That may allow the other cylinders to be moved in a bit of possibly allow them more room for transfer ports to loop out and around.

Maybe that leaves the "headers" still too long or gives problems with balance and firing order or some such. Could add a balance shaft and still be way more simple the previous arrangement.

Storebeck, thnx for the input. Did think along similar lines, but the primary passages would be quite different in length, similar to Neel's pic. So, without being totally pedantic about symmetry, one could rotate the outer cylinders (see A1 & A2) such that the exh axis was aimed to the central plane of cyl B, with "near" symmetry in terms of passage lengths and angles.

One would have to do a sweetheart deal with a piston mfgr to create blank full skirt pistons and then, say on a 3 axis, make the corresponding cut outs to match the transfers. Would also be issues with the piston pin bores.



However, the main question remains: Would a single common & low volume plenum work with such very short primary lengths?

[husaberg]

Suff

Hi Ken can you do a speil the Special 52-53mm KT100S Strike pistons in custom sizes and finishes and pinning rings or special Windows for RGVbaz.