ESE's works engine tuner

[senso]

It has some big cooling fins in the crankcases, the metal piece that goes through the pick-up looks strange to me.

[wobbly]

The metal trigger plate is a copy of the Honda, it uses a long and short " lobe " for some reason to do with the PGM system ECU.
But this is easy to get to fire with an Ignitech.

[richban]

The metal trigger plate is a copy of the Honda, it uses a long and short " lobe " for some reason to do with the PGM system ECU.
But this is easy to get to fire with an Ignitech.

With the ignitech can you put in a minus value in the base advance setting?

[wobbly]

Nope, this in effect means the trigger is too close to TDC, but if you need more advance to get the timing lines spot on, then add some timing in the channel
trim boxes down the bottom of the ignition curve page.
You can use these to check each cylinders timing when under load on the dyno, means you can correct for crank wind up and also a crank that hasnt been assembled in phase correctly.
Doing this means you know for sure both cylinders are actually firing when the curve says it should.

[lodgernz]

So there you have it - the A Kit pipe is shit in comparison to that layout.
You have a 2 stage header with the optimum angles of 3.5 and 5.5 * ( even better than Aprilias Tubo designs that to my knowledge never had a 2 stage )
with a 3 stage diffuser,the steepest in the middle with approx equal angled 1st and 3rd stages - all good.
The tapered belly section can be tapered either way, depending upon the engines response to the diffuser action and how much overev it is capable of ( or needed ) via a steep rear cone.
The only element that I have found to work better is the relationships in the header.
In your design the end of the first header is at around 75% = 200/268,but as in the empirical design guides for the whole pipe of 33% header 66% diffuser, the same applies to the header lengths.
End the first 3.5* cone at around 66%, so you would then have two equal headers of 91.5mm ie 60+25+91.5 = 176.5/268 = 66%, thus the second header at 5.5* is 91.5/268 = 34%.

Wobbly, I'm still reeling from your above statement about header angles. Are 3.5* and 5.5* really optimum for headers?
That's just so much steeper than anything I've ever read anywhere, and makes the small end of the first diffuser so big that there isn't much more diameter left for the diffusers before reaching the optimum belly diam. Am I missing something? (Apart from brainpower, youth, good looks, hair, etc)

[wobbly]

Anything you have read is based in early 20th century experience and has no relevance to anything that can be achieved nowdays.
The angles quoted are assumed to be used on a high performance /race engine, not a Frances Barnett or some such shitter.
The first pipes started showing up with two stage headers with steeper angles way back in the early days of the Rotax 250 and were designed
by someone with the initials of VSK ( sounds Dutch as hell - Frits probably knows him ) I have been told, as these designs were published year on year as bigger numbers but always with VSK in front.
Those angles also assume that the engine can use effectively steep diffuser angles as well, this means that the transfers and ducts are reasonably well designed.
When you connect shit transfers to a fat pipe with steep angles, you get way more depression around BDC than the transfer streams can resist.
They loose directional coherence - they abandon the loop ,do a U turn and disappear out the header - overscavenging is the term coined by Erv Kanemoto when trying to get fat pipes on a TZ750.
Apart from having no physical room on the bike he found that on his single cylinder mule, anything over around 108mm lost power.
Nowdays we can scavenge a 125 cylinder effectively with a 134mm belly,something just not possible without very good loop control within the bore.

[2T Institute]

Your unknown engine is an ADM (built by Charlie AufDerMauer), a Swiss clone of the Aprilia RSA125 engine, in Honda RS125 frame.
In your pictures a Honda RS250 cylinder was fitted. Here are some more pics of that engine, this time with a proper ADM cylinder.

It's cousin EGA 125 (disc valve conversion to ADM NF4 cases) now resides on the southern hemisphere

Did that RSA copy ever race Frits?

[Kickaha]

Your unknown engine is an ADM (built by Charlie AufDerMauer)

I take it he built the ADM 500/4 sidecar motors? Did he work at Krauser when they were doing the same?

[husaberg]

I take it he built the ADM 500/4 sidecar motors? Did he work at Krauser when they were doing the same?

I think ADM did a V3 as well?

Your unknown engine is an ADM (built by Charlie AufDerMauer), a Swiss clone of the Aprilia RSA125 engine, in Honda RS125 frame.
In your pictures a Honda RS250 cylinder was fitted. Here are some more pics of that engine, this time with a proper ADM cylinder.

oh Frits thanks for solving the puzzle over what it was........
I have a feeling adm used to make cases for nf4 rs125 Hondas so they could run cassette gearboxes.......

[Kickaha]

I think ADM did a V3 as well?

They did a 500 triple with outside cylinders reversed
http://www.adm-racing.ch/index.html

[husaberg]

They did a 500 triple with outside cylinders reversed
http://www.adm-racing.ch/index.html

Here is below a couple of not so well known 3 cylinder 2 strokes.
No Honda's here. A ADM and not your normal Laverda triple either 1985
.

right you are ............

[lodgernz]

Anything you have read is based in early 20th century experience and has no relevance to anything that can be achieved nowdays.
The angles quoted are assumed to be used on a high performance /race engine, not a Frances Barnett or some such shitter.
The first pipes started showing up with two stage headers with steeper angles way back in the early days of the Rotax 250 and were designed
by someone with the initials of VSK ( sounds Dutch as hell - Frits probably knows him ) I have been told, as these designs were published year on year as bigger numbers but always with VSK in front.
Those angles also assume that the engine can use effectively steep diffuser angles as well, this means that the transfers and ducts are reasonably well designed.
When you connect shit transfers to a fat pipe with steep angles, you get way more depression around BDC than the transfer streams can resist.
They loose directional coherence - they abandon the loop ,do a U turn and disappear out the header - overscavenging is the term coined by Erv Kanemoto when trying to get fat pipes on a TZ750.
Apart from having no physical room on the bike he found that on his single cylinder mule, anything over around 108mm lost power.
Nowdays we can scavenge a 125 cylinder effectively with a 134mm belly,something just not possible without very good loop control within the bore.

Thanks Wobbly, fascinating. I guess I never thought about two stage headers since none of the published RSA125 pipes used them. I'd be interested to hear Frits' thoughts on them.

[wobbly]

Well the EngMod sim is right on the money with regard to the Aprilia RSA model.
And using a 2 stage header on that pipe modified to keep the same diffuser angles - but changed to a single rear cone, it makes between
0.5 to 1.5 Hp more in varying places - never less than the baseline sim.
This I fully believe, but unless we can get our hands on a RSA to do a back to back we will never know.

[Muciek]

On Pitlane there was talk about that, pipe was someone else design (Witveen?) and Mr Thiel was designing engine around that pipe...

[Frits Overmars]

...The first pipes started showing up with two stage headers with steeper angles way back in the early days of the Rotax 250 and were designed by someone with the initials of VSK (sounds Dutch as hell - Frits probably knows him) I have been told, as these designs were published year on year as bigger numbers but always with VSK in front.

I don't think VSK stems from somebody's initials; VSK has always the pre-designation of Rotax two-stroke expansion pipe drawings. This was already the case when I first got involved with Rotax engines, in 1978. I don't remember the VSK-number of the 1978 works pipe (I've got it at home in Holland somewhere) but I do remember the maximum diameter: 100 mm. Being a young smart-ass, I did some calculations of my own and according to those, that diameter should be 128 mm. Ridiculous of course, but I built it anyway. It was a missile. It took Honda all the way until 1992 before they brought out their first fat pipe (on the RS125 B-kit). And Aprilia did it in 1995 when Jan Thiel went there and carried my Rumi pipe.