ESE's works engine tuner

[husaberg]

2 strokes on overrev with closed throttle as well as the engine being driven by a wheel and rider or a drum on a Dyno do not get any significant lubricating oil. 4t's survive this better a most have positive lubrication systems not reliant on a petrol mist.
Honda for the 2ts at least (but pretty sure XR and the like also) used to colour code roller cages the big end even own the commuter bikes like H100's offer many different specs std for selective fit ,after market not so much.....

Wobs way is obviously the preferred method
but different Honda ones used to be on one of the first few pages in the parts fiche.



Bell devotes a lot of space into how to build decent big ends and cranks in his book

[Wos]

2 strokes on overrev with closed throttle as well as the engine being driven by a wheel and rider or a drum on a Dyno do not get any significant lubricating oil. 4t's survive this better a most have positive lubrication systems not reliant on a petrol mist.
Honda for the 2ts at least (but pretty sure XR and the like also) used to colour code roller cages the big end even own the commuter bikes like H100's offer many different specs std for selective fit ,after market not so much.....

Wobs way is obviously the preferred method
but different Honda ones used to be on one of the first few pages in the parts fiche.



Bell devotes a lot of space into how to build decent big ends and cranks in his book

Cloed Throttle...

The more important is to have a well tuned idle jet/ airscrew to be not too lean there...

[koenich]

Re winning with Motul 800 - if thats the case then they are not pushing the mechanical/thermodynamic limits, but in every case they are leaving power on the table.

We are talking 8h endurance racing - depending on the year we had differences of ~15 °C ambient temperature from start of the race 11:00 am to noon. Even if the weather is supposed to be stable, I wouldn't jet on the edge as a part of risk mitigation to make it the full race disctance.

[Peter1962]

50cc big end pins are Ø15 or Ø16 mm; that is roughly equivalent to 22 mm for a 125cc engine. The RSA had a 24 mm big-end pin, which posed no problems; an RSA crankshaft survived a full season on the test bench. Wob, what is the big end pin diameter in the KZ engines?

What does fail on the 50cc engines, are poor-quality big end and small end cages and poor-quality axial thrust washers.

Frits, could forced lubrication of the big end, like Neil Hintz is doing on his 360 engine make a difference on the freetech 50cc engines concerning reliabilty ?

My mate emot.nl is concentrating on developing more reliable stuff for the Freetech racers. But I don't think they are going to rev to 20.000 rpm any time soon. Some things, like boundary layers, are not scalable which means the smaller the engine, the harder it becomes to create sufficient angle.area.

Most certainly not with the actual trend of using more reed valve engines, compared to some years ago, when a lot of the freetech engines were rotary valved. Strange evolution...