Quick Jetting Question

[pmarinello]

I recently bought an 2000 Yamaha Blaster went to clean the carb out today and noticed that there is a 360 main jet installed. The only thing that the bike has is an fmf fatty exhaust w/ pro circuit 304 silencer and k&n filter with cover removed. I am in the new york/long island area and that jet seems way to big being that stock is 230.

I read the directions for the dynojet kit the previous owner used and it says to use the 360. What do you guys think. Oh yeah, I just had the engine completly rebuilt bottom and top, thats why i'm so curious I don't need any more problems, and I dont feel like spending anymore money. lol

 

[mr_3_0_5]

sounds big to me..

 

[darealblaster]

dynojet jet kit main jets numbers are different from genuine mikuni jets, for example, that 360 main jet of dynojet could be equal to a 280 genuine mikuni jet, you have to check how it runs and read the spark plug.

 

[super noober]

sounds big to me..

me too, try it and see what happens. you wont hurt anything being way too rich except a plug.

 

[pmarinello]

ok, it was running pretty good before the crank blew, probably just needs fine adjustment, I guess ill just use the same jets and replace the other parts with my rebuild kit.

 

[gonzo]

its kind of expensive but if you come across a number and letter drill index they are great for getting jet sizes close, a Mikuni jet is a flow rated number and the aftermarket jets from rocky mountain are chinese knock off's and may be no where close to original Mikuni, so if you have alot of mods buy original or keep a list that says what size ea. jet is, a Keihin is simple a 140 MJ is 1.40 mm hole