a problem with my yfz

[yamaha20]

i bought a brand new 07 450 and i love it but sometimes when i hit the throttle real hard to like clear a jump or something it cuts out or kind of quits on me. has anybudy else have this problem ?any help or sugestions would be great thanks!!

[Ride1Rob]

It's the jetting. If you don't take the time to dial the jetting in it'll do this.

[yamaha20]

the bike is all stock though could the jetting be wrong from the factory?

[06YFZ450SE]

There jetted way to lean form the Factory. Buy a jet kit and take the lid off and baffle out.It will run alot better and make sure your jetting is right.It will run alot better with the jetting right. If you have a bog and want to get rid of it go buy a leak jet or get a boyesen acc pump cover. The cover help out with the bog with mine. If you now how to do the free cam mod Do it it help my topend.

[csr250r]

Possibly jetting but my guess its the carb get a boysen quick shot accelerator pump it lets in more fuel in the carb so you get less bogging. I know the FCR carbs have a bogging problem stock.

[yamaha20]

ok thanks guys i will try these thing and see what happens. thanks!

[Ride1Rob]

Originally posted by csr250r
Possibly jetting but my guess its the carb get a boysen quick shot accelerator pump it lets in more fuel in the carb so you get less bogging. I know the FCR carbs have a bogging problem stock.

Woudn't that be jetting if it's the carb not getting enough fuel :huh (lol). And it's not the carb having a bogging problem, moreso the carb not being properly jetted from the factory.

[guy310]

A stumble off the very bottom end, or off idle, is a characteristic of the FCR carb on any quad. It has an accelerator pump which squirts a little bit of gas into the stream when you hit the throttle. It can be corrected either way, pilot jet or different accelerator pump cover, but never will you fully get rid of that. Just something you have to get used to.

[yfzrider45]

I couldnt hit my throttle hard when it was idleing before i jetted the carb, better. Listen to Ride1Rob, he knows what he's talking about!!

[Ride1Rob]

Originally posted by guy310
A stumble off the very bottom end, or off idle, is a characteristic of the FCR carb on any quad. It has an accelerator pump which squirts a little bit of gas into the stream when you hit the throttle. It can be corrected either way, pilot jet or different accelerator pump cover, but never will you fully get rid of that. Just something you have to get used to.

Every FCR carb that has come through my garage has been corrected by proper jetting. And most times this is after motorwork has been done, but also after topend rebuilds and such. It can be corrected and that doesn't mean buying an accelerator pump and such. You just have to Know how to get rid of it.