ESE's works engine tuner

[mr bucketracer]

Thank you, very interesting.

Two last pistons on the right without cutaways.

Yes, maybe this works only with Boyesen ports and without them would be different story. Two years ago, tested many things on Ns 250 ( compression, squash, pipe, reed, ignition, airbox, fuel, carburetor, ....... around 3000km). All tests were with "holed" piston and engine reactions, sometimes better sometimes not. But when I buy new pistons ( without holes ), simply was too lazy to do them again. Effect felt immediately, specific hole around 6700 rpm disappeared and gas felt very linear, but power remained the same. Maybe at lower revs when pipe not do so much, without holes in piston, flow through main transfers ports increase, and when piston is at BDC intake inertial flow impacted to piston and lift up to boos ports and to Boyesen ports. But its only considerations.

Photo I made in 2001 Brno GP Carlos Checa YZR 500 engine. Last, factory bike, two stroke 500 season. Piston and crankcase

buy the looks of that picture ,they new more about 2 strokes than anyone here , thanks for the picture

[katinas]

katinas how does the lower rod and crank bearings get lube if theres no hole under the 20mm plate? maybe im missing something

Hi,

Before assembly pour oil in crankcase ( in both working and free crank spaces ) . This engine is 2 cylinder, but only for tests made special 1 cylinder crank with long axis trough second cylinder crank space for ignition. So it is 3 main bearings and center bearing without seal. Working cylinder generate pressure and air with oil flowing through this center bearing to free space of 2 cylinder. But this is only for tests and of course for proper work need to do much like 4 stroke with small reed for depression with hoses for air and oil.

[katinas]

buy the looks of that picture ,they new more about 2 strokes than anyone here , thanks for the picture

when I'm getting ready to do the same with with Norick Abe engine, mechanic cover the engine with a shirt

So far, I feel very bad when I remember what happened to him, such a great guy

[mr bucketracer]

when I'm getting ready to do the same with with Norick Abe engine, mechanic cover the engine with a shirt

So far, I feel very bad when I remember what happened to him, such a great guy

its a shock whats happen to alot of racers outside the sport )-:

[husaberg]

its a shock whats happen to alot of racers outside the sport )-:

Yip tragically Hailwood was just popping down the takeaways, to pick up fish and chips.
Juan Garriga, 90's GP 500 rider road bike crash.
Juan López Mella 90's GP 500 rider car crash
Ronnie Smith ex TT winner and PB tester scooter crash

[TZ350]

F5 Dave is right, having a dummy cutaway case is great for checking the position of the gears. It looks like I need to move the selector drum 1.5mm left to the drive side to get the sliding gears in the right place.

[breezy]

Sorry https://youtu.be/OnLMIMiXoR8

nice work.... finally we hear the engine sound... would you say the rpm level gained is purely down to the lower piston friction ? and nothing to do with sealing the crankcase from the cylinder?

[wobbly]

So just to educate all the people in here that obviously know very little about a 2T - please do tell what is in that shot of the Yamaha V4 500
that wasn't common knowledge to every engineer in pit lane at the time,let alone 17 years later.

[philou]

Yamaha love case stuffing

[Grumph]

[QUOTE=TZ350;1131029490

F5 Dave is right, having a dummy cutaway case is great for checking the position of the gears. It looks like I need to move the selector drum 1.5mm left to the drive side to get the sliding gears in the right place.[/QUOTE]

Not uncommon. On the Aermacchis, I set up the endfloat on the selector drum first, then mock up the box, one shaft at a time. Peering at it through the cylinder hole - obviously without the crank in...
But they're Italian - and you expect to have to do that shit.

[jonny quest]

So just to educate all the people in here that obviously know very little about a 2T - please do tell what is in that shot of the Yamaha V4 500
that wasn't common knowledge to every engineer in pit lane at the time,let alone 17 years later.

The tubes feeding the front transfers from crankcase? Or were they directing a mixture to underside of piston?

[WilDun]

Yip tragically Hailwood was just popping down the takeaways, to pick up fish and chips.
Juan Garriga, 90's GP 500 rider road bike crash.
Juan López Mella 90's GP 500 rider car crash
Ronnie Smith ex TT winner and PB tester scooter crash

Ron Grant from America (formerly from Britain) who came over here often to race at Wanganui, drowned I believe while water skiing.

Geoff Perry from Auckland (son of famous Kiwi rider the late Len Perry) a very promising rider, died in a plane crash near Tahiti on his way to America to ride a 750 triple for Suzuki.

Brian Scobie - well known rider from Hamilton and his wife died in a car crash in America.

[wobbly]

Well we have found one person that knows less than Yamaha did back then.
They arent " tubes " they are the heads of Ti capscrews that run down into the case each side of the main bearing saddles.
A common idea used in many engines.

[jonny quest]

I was sooooo close! Lol

[Grumph]

Well we have found one person that knows less than Yamaha did back then.
They arent " tubes " they are the heads of Ti capscrews that run down into the case each side of the main bearing saddles.
A common idea used in many engines.

Not sure if yamaha did it in their 2T's first but they certainly use it in their 4T's - makes their inline fours harder to work on than they need be.