I am still new to fixing quads and I have never really fixed them. However I moved to kansas and the shop here is backed up by 3 or 4 months. I just recently bought this quad and it is in really good shape however, The exhaust pops and backfires on deceleration which I can understand to be normal if it is a little to moderate popping. The popping gets better if I let go of the throttle slowly and will also pop when your high up in RPM and need to shift. It also pops more when it is colder out as well. The exhaust on it is a DG aftermarket exhaust as well. When I looked at the exhaust pipes the header pipe kind of moves around a little bit when I push and pull it. This can't be normal can it? if not where would I get a gasket for it as it's aftermarket. Also what should the Idle sound like on theses? to me it sounds way too high as we used to have quads as kids and at idle they would sound like they are just putting around.

 

The popping could be coming from the engine running too lean, and getting worse when it's cold is another indication of this, because cold weather leans the engine out more. I would start with replaceing the exhaust donut gasket, a factory gasket will work fine. If it doesn't have any airbox or air filter mods then you may be OK. If it does have airbox/airfilter, then you may need to jet it richer or put it back with the factory airfilter/airbox/airbox lid.