hey guys, my friends 2002 quadrunner is having some running issues, it runs fairly well for about 10 to 15 min max then starts backfireing and bogging down even at full power. happens like clock work. soon as it gets good and hot it starts messing up. when you stop, instead of ideling it shuts off and then it is a pain to restart, have to give wide open throttle and lots of ignition time "holding start button" and finaly it will very very slowly start to run, and it still back fires and bogs down. you have to leave it off for a good amount of time and let it cool way down befor it will run fairly well again.

he thinks carb problems but is not sure and a new carb is like 500$ wich is what he gave for the whole atv to start with. so natuarly he does not want to spend that kind of mony unless he is fairly sure its the carb. local small time repair shop messed him around for 4 months and didn't fix any thing. so im hopeing you guys will have some advice or suggestions.

Thanks in advance for any help.

 

My '99 Quadrunner was like that when I bought it. I bought it used from a dealer (never again) but it ran perfect during a test ride for about 5 minutes. Got it home, and it ran fine for about 5 or 10 minutes, then started losing power and dying. Hard to re-start, but ran fine whenever it was cool again.

The dealer said they'd look at it for free, they stand by their sales. (They have a "100 point certified used inspection") or something to that effect. Anyways, they found that their tech had over-filled the oil, rather severely.

On the suzuki, there is a sight glass in the side of the case, and the oil should be filled to the center of the glass. The tech had filled the oil until it started leaking out the fill hole. This would be proper on some small engines, but not on this model. They drained off half the oil, and it ran fine ever since, for the next 12 years. This didn't stop them for charging me $90 to fix their mistake, but what else would you expect from a dealer.

They said the oil was so full that the piston and crank were having to slosh though it on every stroke, but I never understood why it ran fine cold, but not hot, but after it was fixed it had noticably more power at any temp. This was my first quad and I didn't realize how much power was missing when the oil was over-filled.

I do get some backfires now and then though when letting off the throttle at high rpm. These have pretty much always been there since I bought it 12 years ago, but I never bothered with it.

 

thank you for replying, he is going to check that out. but if any one else has any suggestions please post. also he wanted me to ask if any one knows a good online store to buy a carbarator for it, all the new carbs he has found is like 500$. maybe that's normal but it seems a bit steep for a tiny atv carb. could he use a def carbarator that might be cheaper with out any major mods? the bike is in pretty bad shape and he does not want to spend to much on it.

 

probably what was happening with oil being overfilled is when it got warm and thinned out. It would get by the rings and start fowling out the plug. Probably not enough to totally mess up the plug but enough to make it run bad. I overfilled my 300 king but had no issues running.