Friend of mine is out at moose camp 30 miles from the nearest dirt road.

He's riding an '04 700 Polaris sportsman (carburated). He says the exhaust pipe is getting hot enough that it's turning red. Not sure what's wrong with is and I'm seeking advice. I'll be headed his way in a couple of days and I'd like to have an idea of what to check.

I posted over on the Polaris board but there is typically a bunch more traffic here and you guys are pretty smart in all kinds of areas other than a Cummins.

TIA

 

'Bout the only thing I can offer is it's running too lean. Maybe the jet can be adjusted? Maybe there's something on-line in general about carburater adjustment you could take with you.

 

Clogged fuel fliter, or a leak in the gasket that for the carb, clogged jet.

Edit, should mention agree with scott.

 

Me too! When I used to ride trials, the events in CO made us have to go with a smaller jet at higher altitudes. If we forgot to re-jet it, it would run really hot at the lower altitudes.
You may want to find out where he got his fuel.

I do not remember where I got the following info from, it was in my notes:
In a lean condition the engine will surge and sometimes ping under acceleration. The engine will also be "cold-blooded" (hard to start and keep running) but will run better when hot. The spark plug will look bone white or burned in extreme cases. The engine may spit back or sneeze through the carburetor once in awhile too.. If the engine is running rich the throttle response will be fuzzy and not too quick. The engine will burble, miss and blow black smoke. It will start easy but will run funny when fully warmed up. The plug will be dark, wet or fouled (possible all three!).

Ok so what do you do first to cure the problem? The very first thing is to check and adjust the float level. If it's off one way or another it can throw the jetting off too. Set the float to the specs and retest the running. The next item is to determine a rich or lean condition. Let's say the engine gets hot and doesn't pull well. This is a lean condition so the engine wants more fuel. Stick in at least a two size bigger main jet and try it again. If it's better but still not right go even bigger on the jet. and try it again. Bear in mind that drastic or sudden changes in jetting usually mean an air leak has developed somewhere in the engine. Find it and FIX IT! When the engine burbles on the top end come down one jet size at a time until it winds all the way down. Don't drop and more sizes! If the engine seems sluggish and lumpy or want to load up on the bottom end the mixture is TOO RICH. Adjusting the low speed mixture screw helps a little but doesn't cure the problem completely. What you need now is a new pilot jet. Go one size smaller and try the adjustment again. When the engine runs smooth with the adjustment screw about one and a half turns out from the seat you have it!

As a final thought let me remind you that jetting is a lot like life, if you have a choice it's always better to be a little rich!"

Sorry that was so long. If I can find out who I got that info from (a long time ago) I will repost with his (or her) name because it is good stuff.

I toasted a good Bultaco motor just because the bolts holding the carb down had loosened allowing air to enter the motor past the carb making it run really lean and super hot.
As was said by the other guys, I would look for an air leak, clogged fuel fliter or clogged jet first (after you check his fuel).

 

Awesome guys.
Thanks a bunch.

 

Every ATV Ive owned (6 in the last 10 years) has glowed red hot in the dark. Even the 3 fuel injected ones all glow red hot in the dark.

 

I would have thought timing would be the issue.

 

I have 1999 500 and a 2001 700 both will glow red if you ride it hard. It's the way they are. Just don't look.

 

jeesh, I just got done with my harley on this.....


hey marc, I will fix it for him if I can watch the moose hunt.....

 

What his altitude? Air density makes a huge difference on the carb' quads. I have to re-jet mine anytime I get above 8,000 ft. If not, the quad will get very hot and runs like garbage..

 

My buddy found a crack in the carb to engine adapter. That'll lean it out and really heat the exhaust pipe. I found one here in town and will be hauling it out to him tomorrow. Apparently it's a somewhat common problem. The local dealer sells one of the adapters every month on average.

 

Holy crap, I was partially right about something! Mark your calendars and bookmark this thread because it don't happen very often!

 

Even a blind squirrel finds a nut once in a while......

 

LoL!!! Happend to talk with my Dad today. He had an 04 or 05 that he kept parked at a friends in Fairbanks. He got to old to come up hunting anymore and sold it a couple of years ago. Anyway, he said it got a crack on that adapter. They used shoe goo to repair it.

 

Does the exhaust sound restricted? It probably has a spark arrestor that might need cleaning (they are normally inside the muffler where the tail pipe is bolted on)