I bought this quad for 900 dollars a couple weeks ago. It ran rough but after a quick carb rebuild and an oil change...it was smooth. Unfortunately I couldn't test drive it because of where i live so I just let it run for ten minutes or so and called it good.

Fast foward to today. My wife and I go to an ATV park and after about 15 minutes it shuts off. It only does it when she comes to a stop though. For the next 10-15 minutes it died about 4 times and then I said screw it....and towed it back.

After that it wouldn't start for the next six hours.

We get home and I try to start it and noticed the choke cable was screwed up on the carb and therefore it would stay about 1/4 way on the carb. That got it to stay running longer but it still insist on running pig rich.

After warming up good, you have to hold the throttle in as it chugs to life and then it runs great. If you let off the gas...it sputters out.

I know it's running rich. I can't get to the dern mixture screw on the bottom so I'm kinda SOL right now.

Anyway...here's a picture of the spark plug:
spark plug
Here's a picture of the carb it has...
carb

Can someone please help me. My wife would really enjoy riding her own quad and we don't want to go in debt to buy a new one.

Thanks,

Jason

 

Okay...I was able to tighten the mixture screw. It is ALL the way in and I moved the needle jet washer up one space which I read will help the overly rich condition.

It runs much better but if you let it sit at idle for about 20 minutes...it will die. and the plug will be black!

My only guess is the float?

I really need some expert experience here people.

Thanks...

 

If the float level is too high it should either flood out or run at high RPM instead of idling. Sounds like your air filter is very dirty,and it's not getting enough air. How good did you clean the carb, I soak mine overnight in gunk carb cleaner and then blow everything out good with 125 lb air pressure.

 

the filter is brand spanking new. I coated it in Suzuki 10W-40 like the instructions said. Was that a bad idea?

The small parts of the carb were soaked for a week in a carb cleaner bucket and the the main parts were put in boiling water/castrol parts cleaner fluid.

All the orifices were blown clean with compressed air and everything was bolted back up.

It was BARELY running before the rebuild and now it's 99% better.

As for the float...it doesn't flood out and it doesn't idle high...I can control the idle pretty good with the regular idle adjusting screw.

Anyway...I'm wondering if I should pull the carb but I don't see it being helpful. Perhaps dropping the needle jet one more position would help?

 

I think the oil is a little heavy for the filter, and you don't want it soaked. Try taking the filter off and see if it improves,this might cause it to rev higher. Other than that is the needle valve marked at all,any indentation on it and it needs replacing as well as the seat, this is critical . Then there is the choke,are you shure it goes all the way off.Take the float off and shake it to see if it is leaking gas into it.You need a guage to set the float correctly,on my lt160 I hold the carb upside down and measure the float hight from the body to the top of the float ball,but I have a different carb. I have a 1999 bigbear 350 4x4 also. It could be that someone before you got the bike rejetted the carb for more power and it;s too big a jet/ I have a question for you ,does your bigbear have a knocking sound when you give it gas in 1st or reverse, only when you barley give it gas,sounds like the counter weight in the centrifical clutch,I first thought it was a rod.

 

bearclaw - I think you solved it bro! When I put the oil on my new filter I pretty much saturated the whole thing. So I went and popped off the air filter box cover and VOILA..a puddle of nice new 10W-40 oil. The filter was dripping oil.

I suppose that when we took off yesterday on the trails, the oil was shaken around and got on the filter, clogging it up and not letting any air by. That's what my theory is right now.

As per the Big Bear - it does have a clunk to it. Especially when i shut it off. Sounds a big rod knock. I have no idea what it is but my Yamaha runs awesome.

Thanks again for the help.

The Suzuki is outside running right now and has been for the last 20 mins perfectly. If I don't report back...it's good to go.

l8r,

Jason