I finally went to go riding on a long ride yesterday. With all the mods it runs perfect for about 15-20min then she falls on her a$$. When it gets nice and hot it loses alot of power and wont pull hard up hills. I can let it cool for 5 min or just cruise around at a slow steady pace and the power is there untill I start to race and get it hot again. Is this a too lean or rich condition. I check the plug everytime this happens and it is brown so this is where im lost. Plug looks good but loses power when hot. Bubba, Modquad, anyone with ideas or know what the problem is.

 

Did you by any chance try a new plug.Did it sputter at all when you would get on the throttle?If it is too rich you will get more of a sputter.A too lean condition would be almost more of a backfire type of stalling.

 

maybe the coil is bad? happened on my brothers 125 ran mint until it got hot and you would only get half power or it would shut off. might be electrical problem or then again it could be the plug

 

I had this symptom with my scram and it's looking like it is in the driven clutch. Have you had the clutches rebuilt lately? Just another suggestion.

 

Clean your air filter and see if that helps.

 

The clutches were done last summer. One of the polaris techs said it could also be in the clutches. I am going to switch the spring and weights to the origional to see if it changes. When I turn it off and try to restart it wont start right away. It takes a few seconds and sometimes it will backfire. I think I have 2 seperate problems at the same time.

 

Just a couple of ideas. When you filled the cooling system, did you bleed the air via the bleed screw on the stock head? Also, there is a small "bleed hole just below the radiator cap (inside the neck) if this gets plugged with silica distilates (too richly mixed coolant) that can raise some problems. Take the time to check your jetting. 4 seperate runs. 1/4, 1/2, 3/4, and wide open throttle. Make sure to stabilize for at least 1/4 mile then use the elec kill switch while holding the steady throttle setting. Kinda a pain, but will tell you for sure where you're at. Also, I don't know if I mentioned it before, but always make sure to retorque the cylinder base bolts after a 400's initial good warm run.

 

Sorry modquad but its a 250 not the 400.

 

and 1 and 2 and 3 (I'm doing punishment push-ups for not reading correctly). Sorry. O.k. now that I'm on the right page, still do the suggestions, but omit the coolant comments. and 4, and 5.....

 

When it looses power unscrew the gas cap real fast, your vent hose could have a slow flowing kink in it.