Ok so i burned a piston last summer and finnaly got arround to putting a new one in. The cylinder walls were unscathed so i didnt bore it over. (dont need to, dont do it right?) Well the thing is i advanced the timing and it starts on the first push of a button. Runs perfect accept when i ride full throttle for almost a quarter mile it bogs out....If i let off to about half throttle it comes back and the bog goes away. Untill i do it again. The longer i let it bog down the further back i have to let off the throttle to get power back. I checked all the fuel lines and the jets every thing checks out. It never did this before and the only thing i changed was the timing and that doesnt seem to be the problem in fact it helped quite a bit. Also the problem arrises when i spin out in one spot for like 3 secconds. It only happens in the upper rev range.

 

don't have enough fuel on the top end, adjust the fuel setting on the carb

 

It ran fine the way it is now, i havent changed the exhaust, fuel, intake, or any of that stuff the only thing different is the timing and that helped i am at a loss for what could be wrong

 

how do you go about adjusting the "fuel setting" on a carburater perhaps you mean jet it? because if you are refering to the air screw on the side that has nothing to do with full throttle now does it.

 

on thing to know is that the polaris set the timing avanced from the factory an modded 250 an 400 motor are retared 2 degrees so I would put the timimg back. Also did you hone the cyclender for the new right it you don't they will not seat well an can cause problems.

 

well the reason i advanced the timing was it was missing and wouldnt start very well, and after i did it was fine but ill take it back a lil bit and see if it fixes it