My 700 backfires when I let off gas or run the rpm's up like going down hill without giving gas when gas is applied then it does not do it is it the boot on carb or something else

 

check the boots tats what i would do first been a problem in the past with the boots cracking/clamps,etc. Might be a jetting issue a lil too lean. Let us know what you find!

 

If you have put an aftermarket pipe or breather on you may have to rejet the carb.

 

Check the throttle cable adjustment, if it's loose the etc will cause the backfire...

 

but if it does it everytime, i would say its in the carb.

 

Does your machine run better at 1/4 choke with no backfire?? My 03 did exactly the same thing. I checked boots, changed plugs, changed air filter, adjusted the throttle cable & still would get the backfire. It only did it when I ran the machine hard. After talking to a local Polaris dealer & a performance shop in town. This is what they told me. On the 700, Polaris had to really lean the machine out at idle to get it to pass EPA emissions standards. The engine is starved for fuel when you let off the gas, hence the backfire. I installed a Dynojet jet kit and problem solved. Even on the coldest days, I barley have to use the choke.

 

I have changed the boot tonight on the carb 57.00 sucks! did find split next to clamp on carb side have not had a chance to ride yet but will in morning let you know. Tell me about this dyno kit never messed with carb before is it easy and what kind of kit do I ask for does the dealer sell them or is it aftermarket? Let me know.

 

Dyno Jet kit U can find 'em on E-bay. Just rejetting carb not too bad. Usually do not have to do unless you have put aftermarket exhaust/air filter on. I bet the split boot was your problem.

 

My 2002 sportsman 700 did it evey time just like you said. It was my ehaust seal doghnut between the y-pipe and exahust pipe. Under $20.00 from polaris. Easy to change just pull off the 4 springs and remove the pipe and install the new one.

When you let off the throttle, the excess gas, and air that comes in the leaky gasket creates the backfire.

 

My 02 Sp 700 did/does this. Since I put the new 800 headers on it, I haven't heard a back fire yet.