[rdharper]

I've a friend with a 1999 300 FourTrax.

Has run great since new. Completely stock. No maintenance other than sparkplug and oil

Over the last few months it has developed this problem. Cold and choked it runs normally. After warmup, it lacks power and backfires.

Sounds to me its running lean, fuel is blocked somewhere?

He's completely hopeless at troubleshooting, and is asking for help.

Harder to sort out when its not your bike.

He has no FSM, which I've suggested he get. But the parts layout I can get from bikebandit.

Where to start?

Addendum: fuel flow is ok into the float chamber. Air Cleaner is good.

Also, this message is not in the right section... if the moderator sees this, feel free to move it... thanks.

 

[rdharper]

QUOTE ("rdharper":h0k3lb7a)

I've a friend with a 1999 300 FourTrax.

Has run great since new. Completely stock. No maintenance other than sparkplug and oil

Over the last few months it has developed this problem. Cold and choked it runs normally. After warmup, it lacks power and backfires.

Sounds to me its running lean, fuel is blocked somewhere?

He's completely hopeless at troubleshooting, and is asking for help.

Harder to sort out when its not your bike.

He has no FSM, which I've suggested he get. But the parts layout I can get from bikebandit.

Where to start?

Addendum: fuel flow is ok into the float chamber. Air Cleaner is good.

Also, this message is not in the right section... if the moderator sees this, feel free to move it... thanks.

Just to follow up on this earlier post. The problem is fixed. Turns out the fuel had distilled in the float bowel. Once cleaned, the quad is now working fine again.

I think his problem would have been avoided had he run gas with an additive (such as Techron), or if he'd added such separetly once and awhile. Its not as if the bike wasn't used once a week at least. Maybe he had some bad gas or wasn't careful during the adding of gas... dunno.