View Full Version : '11 CRF450 w/stage 2 yosh need help

duc slayer
05-27-2011, 11:24 AM
ok fellas here's the skinny, My bro has an '11 CRF450 with the Yoshimura stage 2 engine, stage 2head and cam. now the problem is that it start's like a frig'n dumptruck, bike runs great, but just doesn't wanna start. We/they have richend (sp?) it up from the bottom up to about 2000rpm and that helped a little but not much and Yosh has been NO help what so ever, just well it works fine with our bikes

so anybody have a clue of what to attempt/adjust so we can start it easier??

05-27-2011, 02:11 PM
imho it sounds like the ignition curve,may be too advanced at the bottom of the rev range or the plug heat, if the standard airbox has been replaced with individual filter(s) the original bellmouth(s)/velocity stack(s) may be needed to smooth out the induction gasses. Valve clearances may also be a bit tight. Fark me thats a bit of a list:blah: sorry

05-27-2011, 03:10 PM
That sounds like a real challenge. Because the new ones are EFI without battery-assist, I could imagine all sorts of issues. I would think though "stage 2" would have EFI mapping & ignition adjustment requirements that are well documented. It could be just a case where everything was shifted to the top of the powerband to such a degree that down low it can't get the fire burning.

RZ Rob

duc slayer
05-27-2011, 04:03 PM
it still has stock timing at the moment and valves have been checked after every ride (4 rides so far)