98 Polaris Magnum 425 loses power after 10 minutes

[Dan Ellsweig]

Greetings
I have a 98 Polaris Magnum 425. Runs GREAT for 10 minutes then starts to load up (sounds rich) and looses power. Final;ly just stalls out on idle. If it sits 20 minutes will run again.

replaced fuel, added fuel treatment (seafoam), Replaced plug (carbon fouled), plug wires, air and fuel filter, checked all fuel and vac hoses, REPLACED carb with new. Still no good. Just ordered a coil, not sure if that will help
Note: both the new and old carb only had the idel adjuster screw - cant find the jet adjustments or air/fuel mix screws so I cannot say how they are set.

Looking for ideas short of spending big $$ on Polaris service

HELP?????

Thanks

Dan

[WILYUMS]

Just a thought check your fuel cap. Because it runs good to start it sounds like the cap might not be venting. I maybe way off but I've ran into this before. Mine wasn't actually the cap but the vent hose attached to it. Hope that it helps you. Also welcome!

[Frank Angerano]

Check your regulator/rectifier and see if it gets hot when the atv starts to act up.  Could be as simple as that. Its cheap enough to replace.    

[JacobSlabach]

is this a 2 stroke model or is it a 4 stroke?  if 4, try checking compression and also the fuel cap like @WILYUMS mentioned.  other than that, you seemed to have covered all the bases.

could also be electrical like @Frank Angerano mentioned..

but i always start by Checking things rather than focusing on what seems to be the issue and replacing that part.

[Dan Ellsweig]

same problem with or without fuel cap, rectifier is not hot

Changed the oil as someone in another felt fuel vapor in oil could be culptir - still no good

Also noticed that I am only getting half throttle - if that

[Frank Angerano]

What do you mean half throttle ? 
Pull the spark plug and see what color it is and put a new one in while ur at it. 
if its super black it's obviously running rich and it could be the rev limiter.   98 goes back a little ways so I'm not sure but look on the throttle control on the handlebars  and see if there are wires going into it.