Hello, I am new here.

To start, I just got a 2003 700 Sportsman, Love it! But I have a problem!!!!!!!!!!

It was runs fine when cold, but when it warms up it runs like poo! It misses, backfires, no power... I put new air filter, plugs in it, but no change. I check the fluid in the rad, it was full. but to my suprise, it has alot of little bubbles in it when I have the rad cap off and the motor is running! The rad is clean, no mud. fan is new, and it is working. And the overheat light doesn't come on. And it does't seem to be leaking or using any fluid.
??????????????????

This message has been edited. Last edited by: Sujada,

The '03 models are Carbed. Not sure where you are at but sounds like carb adjustment is in order, maybe running too rich when you open throttle. Could be a wrong size jet. If you are here in the mountains, a smaller jet size is necessary to prevent over rich situations. Several others are better experienced in Carb's than I.

Sometimes the rubber wire caps on the spark plugs may tend to push the connector loose. I had to cut 1/4 inch off the bottom on the right side. That cured my problem.

It sounds like you may be describing 2 problems.
The bubbles in the radiator could indicate a blown head gasket; which may or may not cause it to run bad when it warms up.

The second problem "runs fine when cold, but when it warms up it runs like poo! It misses, backfires, no power... " could be a split in the intake boot. That is the rubber boot between the carb and the engine, and was a common problem in the early carbed 700's.

This message has been edited. Last edited by: Sujada,

I had an 02/700 and the split carb boot is a very likely suspect.....

You might want to check the adjustment on the throttle cable.

I would be willing to bet the rubber tubing that connects the carb to the engine is cracked. I had to replace mine because of a crack.

A compression test on each cylinder may tell if the head gasket is blown.

Thanks for all your input!
I have checked the boot for the carb to the engine,(its ok), I had started it lastnight it ran fine......even when it got warm????? But i did note the it is running alittle rich.
As for compression test, I will do this weekend.
Awesome idea "johnny mac" on the spark plug trim. I did not like how they went back on. I mean i heard the click on the plug, but did like how they were getting pushed back off....

Again thanks for the information everyone!
I will keep you informed..

Riding this weekend in the Michigan U.P.
Hope it dont brake down....lol

Still running like crap!
I am thinking Spark issue, Coil, stater, wiring...

Please recheck the rubber manifold between the head and carburator. You may need to take it off completely to verify.

Mine had a hairline crack which I fixed.

OK, will inspect rubber manifold tonight again.

When you pull it off. Look at the bottom closes to the carb and see if there is a crack, you may need to stretch it. If you find one, let me know and I'll tell you how to fix it vs. spending $50.

Most times you have to pull it off and flex it to see the crack. On the ATV it is almost impossible.

Think I recall some one saying spray with WD40 while quad is running it speeds up there is a leak.

quote:

Originally posted by Cob:
Think I recall some one saying spray with WD40 while quad is running it speeds up there is a leak.

That works troubleshooting lots of Carb/manifold problems; and as a starting fluid too.
Nothing special about wd40 - it's the PROPANE they use as a propellant. ;-)

OK, Pulled off intake manifold, checked it! no cracks! put it back on!

Was looking at the ETC, I had adjusted the distance between the contacts!
And my problem is GONE now!

Thanks for all your input on this problem!