450R Breaking-up Top-End...

[Yamaha72]

My friend took his 450R out today and when he really got on it on the top end it would pop and sputter, hense break-up. Could this be caused by a clogged or dirty main jet or a fouling sparkplug?

[4fittyr]

could be that or not jeted right or he's hittin the rev limiter and needs to but atfermarket one gives u 11,000 rpm instead of 10,000

[Yamaha72]

Its not jetting as it has ran strong, and its definently not the rev-limiter

[ebtrx450r]

If it's an 06 you don't need to buy aftermarket. you just unhook one wire and you get an extra 1000 rpm's out of it.

[TOY_DOCTOR]

take the choke off

[Yamaha72]

take the choke off

If it's an 06 you don't need to buy aftermarket. you just unhook one wire and you get an extra 1000 rpm's out of it.

Its a 2005, and TOY_DOCTOR, the choke wasn't on....

[UncleRico]

"Could be the Fitzer Valve!

In that case, you'll need some 30 weight motor oil and some ball bearings.

It's all ball bearings now adays"



Ummm...are you saying that it's dropping out in 5th gear only?

Or is it sputtering at the top end of the power band in the lower gears as well?

[Fox17]

we had a 250x that did that cause the carb bowl was gunked up. we cleaned it out and it runs perfect now. it would sputter and stall when we got on it hard.

[svtbolt04]

Question is, do you run with the air box lid off, and do you run a K&N that hasnt been cleaned in a while.

Take the bowl off the carb and pull the main jet and blow it out. Then pull the remaining out one at a time and blow them out and replace them. I am willing to bet anything if it has the airbox lid off, the jets have very fine amount of sand in there. Doing what I said will fix it up.

Dont use a air hose because its too much power and you might shoot it out of your hands.