I have a Polaris Magnum 325 I am trying to fix up for my neighbor. It will sit and idle great. Once your about 1/2 throtle it starts to bogg. The carb is spotless, cleaned with my ultra sonic cleaner and for good measure I soaked it with carb cleaner for 2 days. New All ***** carb kit installed, mixture at 2-1/2 turns out. New spark plug. Drained the fuel tank, fresh fuel. Even tryed running it from a remote fuel source omitting the fuel tank and fuel pump. Still boggs. It does have a new aftermarket foam air filter installed, wondering if it's too much restriction compared to the paper air filter. If I run it with the air box lid off it seems to run 100% better. I am going to check the compression and valve adjust next. Any help you can give me would be greatly appreciated.
Thanks
Mark

 

So try the paper filter see if that changes anything. Checking valves is a good next step. While your at it check your timing and your chain tensioner.

 

Compression was at 160 psi and the valves within spec. I don't have the stock paper air filter as it was thrown away.
Thanks