Guest turbodohc20 Posted September 8, 2004 Report Share Posted September 8, 2004 Hello all, I'm new here an this will be my first post. I bought my 90 banshee a few days ago so I haven't ridden much. After I got it home and removed the spark arrestors and took it for a ride it was backfiring like crazy when I hit powerband. I checked the compression first and found only 50psi on both cyl. I've rebuilt the top end and broke the engine in (120 psi now) and still get the backfiring. Runs Great at low RPM but as soon as the powerband hits you get nothing but crackling and Very little power. As I said I've rebuilt the top end, installed new plugs, new reeds and cages and still have it. I put a timing light on it and at high RPM the timing goes crazy. Is it reading too much knock or something CDI related? I don't know what to do and This is my first quad pretty much so take it easy on me. thanks in advance, Rick Quote Link to comment Share on other sites More sharing options...
J.J. Posted September 8, 2004 Report Share Posted September 8, 2004 turbodohc20, welcome to the HQ, I'm sure you'll find all the info you need right here. Backfiring is usually (not always) caused by a lean condition, either too small a main jet or an airleak. Search for an airleak from the air filter to the engine. This could be where the filter connects to the airbox, the carb boots, the carb tops, the little black choke tube between the carbs, the intake boots, the crossover or balance tube (boost bottle if you have one) the reedcage gaskets etc. As for the jetting, can't say at this stage, we need as much info about your bike mods as possible to make an educated guess if the propblem is jetting related. Example: Type of exhaust system, airfilter, airbox with lid or without. Also try to give an estimate of your elevation. I wouldn't bother about the timing light for now. Let us know the above, and I'm sure someone will get you sorted! Quote Link to comment Share on other sites More sharing options...
Toomey Banshee Posted September 9, 2004 Report Share Posted September 9, 2004 Is it breaking upon acceleration? Or is it backfiring? If its breaking up, lower your needle a notch, as far as backfiring, check your plugs, sounds stupid but make sure the caps on top of the plugs are on tight. Quote Link to comment Share on other sites More sharing options...
2Smoker Posted September 9, 2004 Report Share Posted September 9, 2004 Check your choke or something. If my bike is warmed up and I put the choke on, it will do the same thing as youre describing. Is there alot of smoke coming out of the pipes? is your bike warmed up? What do you mean by removing the spark arrestors btw? pull the plugs and look at them if theyre wet and black it means theyre getting too much fuel. you're rich. anyways let us know, someone can help you out. oh and some advice on the new shee - buy a clymer manual. itll help alot!! trust me. Quote Link to comment Share on other sites More sharing options...
FasterTHENyou Posted September 9, 2004 Report Share Posted September 9, 2004 The previous owner could have cut the head. What carbs are you running, is it ported? Check the cylinder wall clearance. All these problems could/would lead to low compression. What bore is the motor, that could also be a problem As far as the backfiring it could be your ignition or it could be rich/lean. Lastly a fouled plug will run fine at an idle and cut out on the top end. Quote Link to comment Share on other sites More sharing options...
frocashmoney24 Posted September 9, 2004 Report Share Posted September 9, 2004 how do the plugs look? a white/light tan, or a chocolate color? thats gonna be the first step in determening wether its a lean condition causing it, do a plug test and get back to us, if u dont know what a plug test is , do a search on the site, its been gone over many times, if the plugs look good, check the timing, maybe he had it advanced to much for your mods. Quote Link to comment Share on other sites More sharing options...
Guest turbodohc20 Posted May 2, 2005 Report Share Posted May 2, 2005 how do the plugs look? a white/light tan, or a chocolate color? thats gonna be the first step in determening wether its a lean condition causing it, do a plug test and get back to us, if u dont know what a plug test is , do a search on the site, its been gone over many times, if the plugs look good, check the timing, maybe he had it advanced to much for your mods. 254526[/snapback] Sorry guys but I thought I would get an email when a reply was posted. I didn't realize i had received any replies. Anyhow I got the problem fixed it was the CDI unit. Thanks for all the help tho. Quote Link to comment Share on other sites More sharing options...
03bansheeLE Posted May 3, 2005 Report Share Posted May 3, 2005 Check your choke or something. If my bike is warmed up and I put the choke on, it will do the same thing as youre describing. Is there alot of smoke coming out of the pipes? is your bike warmed up? What do you mean by removing the spark arrestors btw? pull the plugs and look at them if theyre wet and black it means theyre getting too much fuel. you're rich. anyways let us know, someone can help you out. oh and some advice on the new shee - buy a clymer manual. itll help alot!! trust me. 254410[/snapback] he means that he removed the caps off the back of the stock silencers. Darren Quote Link to comment Share on other sites More sharing options...
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