Just bought 2005YZ250F. need help

[YZ250Fast]

i have not ridden dirtbikes since 2000 so this new fourstroke technology is all new to me. I have been breaking it in according to t he manual and what i notice is t hat when ur accelerating it backfires alot and seems hesitant and dead untill tyou get on the throttle.. i called the dealer and they said they put regular gas it it so i took it home drained it and put in premium. i rode yesterday and it deffinitly ran better but still backfires while accelerating and im just not sure exactly how its supposed to run and sound when bran new.

 

[Ol'89r]

what i notice is t hat when ur accelerating it backfires alot and seems hesitant and dead untill tyou get on the throttle.. .

YZ250Fast.

The fuel is not the problem. If the bike backfires on acceleration you probably have problems in the carb. Make sure the hot-start button/valve is closed all of the way and sealing properly. If the accelerator pump is not adjusted properly or there is water or dirt in the accelerator pump, the bike will hesitate on acceleration. Water or dirt in the jets can cause this condition. Also, tight valves will cause a miss or popping. An air leak in the exhaust system can cause a backfire but, this usually happens on deceleration. If it were mine, I would take it back to the Dealer.

Just my $ .02

 

[YZ250Fast]

its a bran new bike and has not experianced a crash or nud or sothing just dry grass. carb is deff clean.. is it just cause the bike needa to be broken in more?? what kind of bike do u have Ol'89r

 

[Ol'89r]

is it just cause the bike needa to be broken in more?? what kind of bike do u have Ol'89r

Water can get in the carb from washing the bike. If the little rubber boot on the accellerator pump rod is dislodged, water can get in there.

Has nothing to do with being broken in. You have a problem somewhere. If it is brand new, take it back to the Dealer.

My current ride is a CRF450. Also have a CR250, a couple of XR350's and a whole gaggle of old Triumphs.

Also, may I suggest that you use the spellCheck feature when posting. It would make your posts much easier to read.

Ol'89r

 

[YZ250Fast]

I agree. The spelling on that last one was poor. The bike was never even washed so it has not seen water yet also. its actually my friend's shop i bought it from so he said he will take it for a ride and tell me whats going on. Can rideing over bumps very fast make it appear to be backfireing from the rapid vibration?

 

[jmics19067]

I am inclined to agree with 89'r the possibilty of water in the carb is greater than your realizing.
water could have easily been introduced from the dealers gas can or yours and if the bike sat outside for any length of time even before it was uncrated condensation could be an issue.
It is also very possible that if the bike was assembled and ran then sat on the show room floor for any length of time some varnish may have built up in the carb.

basicly don't overlook it just because it is new, inspect it(or have your buddy do it since it is new) and eliminate the possibilty