I just got a 2008 Polaris outlaw 525s everything is stock it has a 138 main jet in it now from the factory and I live in Salt Lake City and Elevation4226ft do I need to put a bigger main jet in it if I take off the air box lid I don't plan on putting on a slip on wright now and it back fires a little when letting off the thumb throttle I think it's coming from the head pipe connection thanks guys

 

Stock jetting is usually good from sea level to about 6000 ft or so. It's jetted in consideration that the air box and filter is installed,lid on sealed tight.. You just lean it out by removing the lid.I'd keep it on.Plus check exhaust manifold bolts to make sure they're tight.If loose the exhaust can suck cold air in and cause popping back also.

 

ok great and thanx for the info and on the slip on if I get a hmf performance and lid off what would be a good starting point with jets to start with where am at and thanx again

 

Plug chop with the stock jetting first.LEAVE the lid on.. A lot of times just installing a slip on doesn't require a jetting change. Again just plug chop and see what color the plug is and see if there is any hesitation or bog. Should be a light tan to medium brown color. If electrode is whitish color,jetting increase needed.Rule of thumb is 10% increase for starters over stock main jet.

 

ok great thanx

 

ok how about if I put a clamp on uni filter straight off the carb would I make any changes with the jets then or air fuel screw and how do I change my user name instead of my email thanks again for all your help

 

have another ? for ya if I put a clamp on uni filter straight off the carb would I have to change the jets or adjust the air and fuel screw at my location at Salt Lake City ut and Elevation is 4226ft and thanx for all your help

 

If you install an aftermarket air filter along with an exhaust change then more than likely jetting change will be needed. Just depends on how much freer flowing the filter is compared to oem filters. Air filter changes affect jetting more than just an exhaust system modifications in a lot of cases. Again just start with stock jetting and go from there.

 

ok great and I do really do thank you for all your help thanx again

 

thanx again