Yamaha TRX850 Enthusiasts Forum

Winners in WSB and BSB - took a long time for Yamaha to realise the potential of 270 cranks eh?

Hmmmm,the ones I saw racing at EF were not a match for the GSXR`s though.
Maybe they had not been `worked` on enough?
Although,yes,it makes sense regarding drive,less tyre degredation etc,and they sound great.

That really sounds great, but in Finlands national SB Yamahas aren't doing very well. Mika Kallio's brother Vesa Kallio is dominating here with KTM RC8R.

Yamaha has had the crank firing patent since the 70s, but never researched it to use it properly.

Here in Australian Superbike (ASBK) they are allowed to alter cam timing, but NOT duration or lift.. Mearly to get the timing a bit more spot on than what the factory provides. They regrind 2 cylinder cam profiles to 180deg of where they are, and alter the fuel / spark accordingly. Makes its MUCH more tractable. Not quite as lumpy as the 09 R1, but fairly close. This has been going on since early 07.
Just another way around the "rules" about what you can, and cannot do to an engine. Seems to work quite well.. Jamie Staffeur did quite well that season on a R1, think he even raced in the 600cc to much success.

Quan-Time wrote:Yamaha has had the crank firing patent since the 70s, but never researched it to use it properly.

Here in Australian Superbike (ASBK) they are allowed to alter cam timing, but NOT duration or lift.. Mearly to get the timing a bit more spot on than what the factory provides. They regrind 2 cylinder cam profiles to 180deg of where they are, and alter the fuel / spark accordingly. Makes its MUCH more tractable. Not quite as lumpy as the 09 R1, but fairly close. This has been going on since early 07.
Just another way around the "rules" about what you can, and cannot do to an engine. Seems to work quite well.. Jamie Staffeur did quite well that season on a R1, think he even raced in the 600cc to much success.

So two pots spark at the same time, effectively an 'inline 4' 180 degree twin? Virgin Yamaha did that a few years ago with their BSB R1s too.

http://www.f1network.net/main/s180/st70459.htm

The R1 cross-plane crank is getting great reviews; and its layout may well become the norm for in-line fours on bikes, and eventually even on cars. As with the TRX's 270 crank, the R1 now benefits from never having all its pistons stationary all at once.

But it is worth observing that the 120-degree crank that is now the Triumph trademark has always given this benefit, which is why Triumph triples have such nice engines.

Later Laverda Jota engines also adopted a 120-degree crank; but the early Jotas were "three-quarters of a four", with two pistons up and one piston down. I never saw the point of that crazy flat-plane design!