What could this be? Acting weird on startup.

[cheetah]

I noticed a few days ago when I start my quad up it doesn't want to warm up. It's 90 degrees outside and it takes about 15 minutes to warm up. When I start it it backfires very hard again and again. It does this when choked and when not choked. If you give it any throttle past barely tapping it, it smothers out and dies. This is very strange and something is definately off. It is not my jetting, my jetting has been fine for 8 months so it's not lean. Air filter is clean and it has just had an oil and filter change. I'm stumped and ideas?

[cheetah]

Oh yeah after about 15 minutes once it warms up, it runs like a top the rest of the day.:ermm:

one of your valves may not be seated properly....when you first start it up does it smell realy bad blow a lotta smoke, then once it warms up it stops...if thats the case then you gotta pop the head off and get the valves re-seated

[cheetah]

It doesn't smell at all and I'm not really noticing any smoke, maybe a little, but it's not pouring out the exhaust.

[cheetah]

bump

Any other thoughts?:ermm:

[TheX1992]

sounds like my old valve trauma to me.

[MOFO]

Also sounds like your jetting is off a bit maybe...

[300exlunatic]

needs to be jetted had same prob. once

[cheetah]

Well I'm not going to say it isn't, but I highly doubt it needs to be rejetted. It's run great on jetting for the last 8 months and that kinda thing just doesn't jump out of whack. I'm gonna guess it's my valves then, I will have to check them.

BTW, I just remembered I fouled a plug for the first time since I got it (been a little over a year). Would that have anything to do with it. We made sure it was gapped correctly and we cleaned everything out.

I guess I'll just check the valves.

[crazybuffalo]

its just smothering out? it might be the carb. i dont know alot of the stuff for the quads but ive got one on a car that screws up the same way.