OK fellas I just installed a jet kit and exhaust system on my 2006 Kodiak 450. Now after only a few trips....15 hours approx.......I am fouling out spark plugs! I'm also getting a lot of backfire when I come from high speeds and slow down. It normally doesn't backfire when I start riding, but after riding for a couple hours it backfires like crazy on my way home. I haven't done any modifications to my air intake. Do you think this could be the problem?

 

take the carb back apart. it might be that the piece that holds the needle stationary wasn't installed or incorrectly. plus check to make sure you tightened the clamps on both ends of the carb.

 

I didn't install the jet kit. The dealership installed it for me when I had the exhaust system put on. When I'm riding it runs great. Good acceleration and my top speed it a little higher. Just when I let off the gas and let the engine slow me down it backfires like crazy.

 

it still sounds like installation problems on your jet kit. call the dealer.

 

mine backfired stock.....but not anymore with a jet kit [img]i/expressions/face-icon-small-confused.gif[/img]

 

Really? It never does it when trail riding or anything and seems to run perfect. ONLY on my way home from trail riding......I have to drive on the road for about 10 min to get to the trails. On the way to the trails it doesn't backfire but on the way home it does. Only when I slow down from about 50 mph.

 

Mine also backfired when I bought it new. It continued to do it until I installed a Twin Air filter and new FMF pipe. I think the backfiring comes from a rich condition, which would also cause the plug to foul. Unburnt fuel in the exhaust. There are different jets that can be installed in some jet kits, sounds like the jet is too large, or aout of adjustment. Mine didn't need to be rejetted after the install of the new parts.

 

do you have a pic of the camo fender covers?

 

I don't have a pic of the camo skins, but I will try to take a pic tomorrow at the firehouse while I am working. I found them on EBAY for like $30 used. They fit pretty tight, I think they were off a 2004, with a little bit different body style, but they still work.

 

Sonic, you may have a few problems going on. fouling plugs is usually a good sign of a rich condition, but backfiring on decel is a lean condition. Since you paid for the atv to be jetted, I would try taking it back and see if they will get it straight for you. A reputable shop should do it cheaply or free as long as it hasn't been more than a few months since they jetted it. Barring that, go through all the intake and exhaust connections from the airbox through to the muffler and make sure everything is tightened properly. Check for any small cracks or leaks also. I am thinking you may have a very small leak somewhere that expands to become a problem when you run for an extended period of time and really heat it up. It is possible they jetted the carb to rich and that is covering the other problem until you are headed for home. Yamaha uses a crush gasket where the exhaust mates to the manifold. It is a $6.00 part that should have been replaced with the new exhaust. Is it listed on the invoice? If they just reused the old one, that MIGHT be your problem.

Then again I could just be full of it.