ESE's works engine tuner

[jamathi]

please Jan, send your wife more money so she can stay longer and write that book you should have written all along

Writing a book is too much work for me, as I hate typing........
It would take me more than a year.
What I am doing here now is my limit!
And my wife returns sunday

[husaberg]

Writing a book is too much work for me, as I hate typing........
What I am doing here now is my limit!
And my wife returns sunday

You don't need to type Jan. It even speaks Dutch.
https://support.google.com/docs/answer/4492226?hl=en
https://zapier.com/blog/best-text-di...software/#docs

[JanBros]

Writing a book is too much work for me, as I hate typing........
It would take me more than a year.
What I am doing here now is my limit!
And my wife returns sunday

no problem Jan, it was more of a joke and any info no matter how small is very much apreciated

[Martin1981]

Sorry if this was asked already... Jan and Frits, what was the reason the 250ccm 2 cylinder gp engine had 2 crankshafts? the engine would have been much more simple if it had only 1 crankshaft. but you knew that back then of course and decided to make it a 2 crank engine nevertheless. why?

[Larry Wiechman]

Jan,
Can you explain your methods of testing with the flow bench? What factors were indicative of engine performance? Was any testing done using Jante's anemometric methods?

Please collaborate with a technical editor and write a book. There is a fellow called Frits that has a gift for putting concepts into words, maybe you've heard of him?

[jfn2]

Jamathi:
In the picture where someone is holding a exhaust flange there is a pipe attached to the flange. Was this an attempt to cool that flange?
Also keep the thoughts and insights flowing. Great information.

[Niels Abildgaard]

Sorry if this was asked already... Jan and Frits, what was the reason the 250ccm 2 cylinder gp engine had 2 crankshafts? the engine would have been much more simple if it had only 1 crankshaft. but you knew that back then of course and decided to make it a 2 crank engine nevertheless. why?

Try to see a picture of a Trabant crank with two rotary inlet discs.The Aprilia solution is very much narrower and has fewer parts.

[Frits Overmars]

Jan and Frits, what was the reason the 250ccm 2 cylinder gp engine had 2 crankshafts? the engine would have been much more simple if it had only 1 crankshaft. but you knew that back then of course and decided to make it a 2 crank engine nevertheless. why?

Martin, Jan was not responsible for the 250 cc Aprilia twin (and even less for the 500 twin, which he despised). The 250 cc engine originated when Rotax built a tandem-twin by putting a second crankshaft in front of their 125 cc single. In fact, you could build a 125 cc single using one 125-crankcase half and one 250-crankcase half.
Rotax decided to build a series of these engines for the 1981 GP season and we had the "pleasure" of receiving the first two specimen in the winter of 1980.
I worked on one of those and the other one went to Dolph van der Woude, who later went on to work for Aprilia and gained their first 250 cc GP-win in 1978.
After this, Aprilia decided that they wanted an engine with an 'own' appearance, upon which Dolph designed the 250 cc V-twin that we still know today as the RSW250.

Jan Thiel had already built his own 250 cc single-crank V-twin in 1985, when working for Garelli. The engine was a beauty: light, compact and powerful, but participating in two GP-classes (125 and 250 cc) proved to be too ambitious for the small factory.

[Frits Overmars]

Jan, please collaborate with a technical editor and write a book. There is a fellow called Frits that has a gift for putting concepts into words, maybe you've heard of him?

Jan and I go back more than 40 years, Larry. So yes, he may have heard of me . But thanks for the compliment.
We discussed writing a book, but friends with more commercial insight than us figured that it could only be profitable if we where to produce both an English and an Italian edition, plus we would have to take care of all the copyrights to photos and drawings that I hadn't made myself.
Jan had already achieved everything that one man can achieve, and I am lazy by nature, so nothing came of it. Instead we write a little on forums.
By the way, you should know that Albert Einstein distinguished four kinds of people:
dumb + lazy: harmless
dumb + diligent: disastrous
smart + diligent: not much better than dumb + diligent
smart + lazy: the only useful kind; those are the ones who seek efficient solutions.

[Peter1962]

Martin, Jan was not responsible for the 250 cc Aprilia twin (and even less for the 500 twin, which he despised). The 250 cc engine originated when Rotax built a tandem-twin by putting a second crankshaft in front of their 125 cc single. In fact, you could build a 125 cc single using one 125-crankcase half and one 250-crankcase half.
Rotax decided to build a series of these engines for the 1981 GP season and we had the "pleasure" of receiving the first two specimen in the winter of 1980.
I worked on one of those and the other one went to Dolph van der Woude, who later went on to work for Aprilia and gained their first 250 cc GP-win in 1978.
After this, Aprilia decided that they wanted an engine with an 'own' appearance, upon which Dolph designed the 250 cc V-twin that we still know today as the RSW250.

Jan Thiel had already built his own 250 cc single-crank V-twin in 1985, when working for Garelli. The engine was a beauty: light, compact and powerful, but participating in three GP-classes (50, 125 and 250 cc) proved to be too ambitious for the small factory.

I think that the last picture is the most important one : three good friends together , who have written motorcycle history each in their own way. Be it on a drawing board, at the dyno or on a track, for sure they were succesfull together. I have a lot of respect for that.

[Larry Wiechman]

Jan and I go back more than 40 years...

My point, exactly!

Who better to set the scene and tell the story?

[Niels Abildgaard]

Jan Thiel had already built his own 250 cc single-crank V-twin in 1985, when working for Garelli. The engine was a beauty: light, compact and powerful,

Does a picture of that Garelli V crankshaft exist and can we see it?

[Frits Overmars]

Does a picture of that Garelli V crankshaft exist and can we see it?

I could have done even better with the original Hoeckle-drawing of that crankshaft but I lent it to a friend who is building a 50 cc V-twin.

[guyhockley]

I could have done even better with the original Hoeckle-drawing of that crankshaft but I lent it to a friend who is building a 50 cc V-twin.

Was that Garelli the one with the washer/shim labyrinth seal that you posted earlier?

[Lightbulb]

Does anyone know how or what the velocities of the gases are inside the crank case and transfer passages at their peak velocities?
What is the approx velocity of air through a venturi is?
Is there an advantage to adding the fuel before it all gets to the venturi point or is the fuel best added after the venturi point ?
This is for engines that are not allowed direct fuel injection.
Thanks for any replies, Neil