This is one for Raptor owners. We have experienced problems with the engine backfiring which, in turn, blows the carbs off! This will completely ruin your day because it's not a simple, 5 minute job to put these suckers back on. The fix, according to Yamaha insiders, is to raise the idle to 1500 RPM, make sure the clamps that hold the carb boots are on as far toward the carb as possible and to make sure the clamp is not over-tightened. The reason you don't want to over-tighten the clamps, which seems contrary to what you might expect, is because when the clamps are too tight they cause the boot to pucker under the clamp. This makes an uneven seal against the carb, thus making the boot more susceptible to blowing off again. This is just a suggested fix. Give it a shot and let us know! Quoted from a article at Supertrax-Mag.com atv-mag.com