Just bought an R got an issue

[bansheemorphine]

I just picked up an 04 450r yesterday it has a sparks head and cam. It also has a +3mm crank, 13.5:1 piston full yosh exhaust no airbox lid and crf flywheel and wiring harness. The motor was just built and only has had about 2 tanks of fuel through it.

I took it out today and it works awsome except when i hold it to the bar it seems to cut out and almost die untill i let off then works fine. I am assuming that it is the main jet not being large enough and it is starving for fuel when wide open do you guys agree or do you have any other imput?

[Black R/T]

from what you describe id have to say yes.

[REPOMAN]

another possible reason is a dirty air filter. mine also did that when i took the air lid off without proper jetting

[miles Machine]

if its like a false rev limiter, ur prolly running to rich. check your plug

[BlaineKaiser450]

check the plug to see if its lean/rich and check your air filter

[Project300EX]

Originally posted by miles Machine
if its like a false rev limiter, ur prolly running to rich. check your plug

I'm with him. If it pops on decelleration it's lean, but in my experience you sound rich on the main jet.

[bansheemorphine]

there is no pop on decel and my filter is clean so it must be rich on the main eh