yfz450r motor build need some advice

[Jake250ex]

got a '11 yfzr that was a basket case and Im going to rebuild the motor and race XC with it.

Got a oem crank, going to run a replated OEM cylinder and big nutz racing is building it all for me

but I want a little more power. I was going to go with a 12.5:1 JE piston and a 06 + yfz carb model intake cam. I dont want any reliability issues what so ever or it to run hot so if I gotta give up a few hp to not have any problems Id rather do that, I can get a better deal on OEM stuff anyway.

And if I do that will I need a programmer? Quad is stock motor wise other than a two bros full exhaust and 2 bros juice box

[Kovatch]

I would suggest getting an MSD or the PowerCommander 5 with Timing. These are the two most popular EFI programers out there which in turns gives you a lot of help/advice etc.

Look into an FCI intake with the air box, although you may want to stay with the stock intake tube/box because you may need to run a airbox lid for XC?? I run MX so it's a little different: no need for a lid. Have you thought about getting your head ported? Porting does not decrease reliability.

Once you have an exhaust, intake cam, intake tube/filter, piston, EFI controller, and what not take it to a shop and get it dyno tuned. It may seem like an ordeal, but a dyno tune can yield a few extra ponies for $100-200. This allows you to optimize the mods you have done to the bike.

I have the aforementioned mods less the FCI intake and I am very satisfied with the power.

Boring out the Throttle body will help a ton!