I recently purchased a 97 banshee, It is the most fun quad I have ridden, but it has a slight problem. The right cylincer pops. It has a slight backfire on the right cylinder. It is stock, stock pipes, everything is stock. I would really like to fix this problem. My father thinks that one of the ports is scratched allowing gas to blow by the cylinder and into the exhaust pipe, where it ignites and then creates the mild backfire. I checked the compression, and both cylinders appear to have similar pressures, and the plug color is a tannish color. Please respond, as I just have spent $3K on it and it is backfiring.

 

That is really good news on the results of your compression check! What were the readings?

Does it backfire when riding along at a steady pace or only when decelerating? How about when accelerating? How does it idle?

Quick synopsis is that at least one of the carbs is out of whack. Could be bad jetting, dirty jet, air leak, sticky float. More info will definitely help. How long have you had it? Did it ever run correctly?

Get back with some more info and I can promise you will definitely get some good responses to help you out.

 

Both cylinders read slightly over 100psi, I know that it should be around 130, but I think that the compression tester is slightly inaccurate. It idles fine, but it is when I give the throttle a pretty quick blip between maybe an eighth of throttle and a third of throttle when it "pops". It does not seem to do it as frequently when it is hot and is ridden for a longer period (30 minutes or more) but it still will pop occasionally. I have owned it for about a week, and when I test rode it, the quad did pop, but only once. I thought it would be a simple fix, but according to my father may be rather costly. I love the quad, and I plan on keeping it for a while if I can get it to run properly.

 

Both cylinders read slightly over 100psi, I know that it should be around 130, but I think that the compression tester is slightly inaccurate. It idles fine, but it is when I give the throttle a pretty quick blip between maybe an eighth of throttle and a third of throttle when it "pops". It does not seem to do it as frequently when it is hot and is ridden for a longer period (30 minutes or more) but it still will pop occasionally. I have owned it for about a week, and when I test rode it, the quad did pop, but only once. I thought it would be a simple fix, but according to my father may be rather costly. I love the quad, and I plan on keeping it for a while if I can get it to run properly.

 

There is an air screw on the bottom of the carbs on the quad. If you're sure it is the right carb that is popping, turn the air screw in(clockwise) on the left carb until it seats. Count how many turns it took until it stops. Now put it back where it was. Don't tighten it too much. Just turn the air screw in until it barely stops. Set the right carb to the same setting(number of turns).Hopefully this is the problem. If not we'll need more info on your quad. Stick with the forum until we get this figured out. Don't tear anything down just yet.

 

jprog7, I just noticed that you are from Derby. I moved from Shelton to Wyoming almost 3 years ago; man CT is a terrible place to find riding places. I used to ride near Beacon Falls and near the Stevenson Dam and some trails North of Oxford.

Anyway, if you are concerned with the cylinder being scored you could pull your pipes and use a flashlight and a dental mirror to look around in there. Most likely it is a jetting/air screw type problem but you are due for a rebuild anyway. I would say tear the carbs down and clean and inspect everything but do the air screws first like ridnwarrior said.

 

WyoDuner,

You are right about the riding spots here in Connecticut...There is none, at least no legal placed to ride anyway. Jprog7, where do you ride at? I usually go up to Cromwell/Rocky Hill or North Branford.

IronBear

 

Before you get nervous about a rebuild. Check the synchronization of the carbs. Sounds like one is a bit off. I would pull the carbs and give them a good cleaning. Check the jetting. If all is in spec and it still backfires...More likely than not you have a bad ring or maybe a scratch on a wall. The bike should run fine with over 100lbs in each cylinder.

Do not get all worked up about the money...since you do not know how hard the bike was ridden before you bought it...spend the ~$200 and get new pistons. At least you will have peace of mind that it is fresh to start with. You may luck out and need just rings and a slight hone.

Now that I think about it. It may be as simple as a cracked reed on the right side. That's cheaper yet. Take off the reed cages (intake) and check for a gap...there should be none. (if you question the gap...you may be able to flip the reeds to close it again.)