Recently went for a ride on my H1, purchased earlier this year. Put on approx. 55 mi. through some swamp and mud, nothing extreme. On the way home, bike started backfiring whenever I eased up on the throttle. Was going about 30mph, then ease up to go around a bend in the road, this is when it would backfire. Carb was checked, it was clean. There was no indication that water had seeped in. However, I found anti-freeze was down about a litre. Dealer suspects a problem with head gasket, is being replaced under warranty. My question; How would anti-freeze, if it was leaking in, cause a backfire? I do not pretend to be a small motor mechanic and perhaps someone out there may have had a similar problem. What was done to rectify problem? I have no reason not to trust my dealer as he has been good so far, but I am curious.

 

antifreeze and a head gasket probably wouldn't do anything for the backfire. These quad motor's carbs, being of the vacuum slide style are known for the backoff backfire. The motor goes real lean and you get the backfire. Try enriching the pilot jet a 1/4 to a 1/2 turn and see if that helps. I just ignore it on the 2 quad in the family as it doesn't hurt anything. It might even help keep carbon buildup out of the exhaust system.