mclark408 Posted February 10, 2009 Report Share Posted February 10, 2009 Alright guys. I just bought this banshee a few months ago. It bogs as soon as you punch it. Runs fine at idle and all the way through until you floor it. Looked as if it was rich. Was running 280 jets in the main. The wierd thing is it ran fine for about 15 minutes when I bought it. Has fmf pipe and an unifilter and a milled head. Tried running with the lid on and off. First I went to 300 jets just to see what it did. Got worse. I dropped jet sizes and am now down to 240 jet which I know is too low. Still bogs just as bad so I dont think its fuel anymore.Changed plugs several times and to me they still look rich. I dont think its burning it good. It does bang a little but bogs bad. I just did a compression check and one is 155 and the other is 135. Does it need a new top end or should I start looking at firing issues? Quote Link to comment Share on other sites More sharing options...
shogs Posted February 10, 2009 Report Share Posted February 10, 2009 Did you go from 280-300-240? That seems like too big of a drop. Make sure its not from 1/4 - 3/4 because that would be the needle. I'd try to do a 260 on the mains and see how that does. Mine did the same thing with cracked intake boots. Check for any kind of leaks or cracks when your around the carbs. Good luck. For the topend someone else can chime in on that. 135 seems low compared to 155 though. Quote Link to comment Share on other sites More sharing options...
magz Posted February 10, 2009 Report Share Posted February 10, 2009 Did you go from 280-300-240? That seems like too big of a drop. Make sure its not from 1/4 - 3/4 because that would be the needle. I'd try to do a 260 on the mains and see how that does. Mine did the same thing with cracked intake boots. Check for any kind of leaks or cracks when your around the carbs. Good luck. For the topend someone else can chime in on that. 135 seems low compared to 155 though. top end rebuild is generally required when theres a 10psi difference between the two. or 10 psi drop from original psi pressure for optimal use. so id say atleast pull the juggs, take them to a good builder and have him spec them and the pistons, and see if you can scoot away with just a hone and re-ring the pistons, i was able to rering mine after i noticed a loss in compression, i had 140 on each side and then after 3 rides went down to 130 so i took my juggs off and meased my ring end gap and noticed it was way larger then it needed to be but everything else was still perfectly in spec. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted February 10, 2009 Report Share Posted February 10, 2009 20 psi is a big difference, meaning new topend, usually. did you hold the throttle wide open, and kick like 15 times, untill the needle stops moving? also, check the reeds. Quote Link to comment Share on other sites More sharing options...
CBAIER1206 Posted February 10, 2009 Report Share Posted February 10, 2009 I had a 20psi difference between my cylinders about 6 mos ago after a dune trip come to find out the base gasket was leaking on one side. So I rebuilt it with new rings and made sure to use 1211 gasket sealer on every gasket and re-checked...they were both reading dead on after that. Even though they were 20 psi off, my bike still ran strong..I just happened to check compression for the hell of it and found the problem. So I guess what I'm getting at is that you do need to address the difference in compression but I don't believe that is making your bike bog at WOT unless it's an airleak. What temp does your bike run at? If I were a betting man, I would say you have a leak somewhere causing one of your banks to run lean and hot hence crappy at WOT. DO a leak down test and make sure it holds 6psi of air for 6 minutes and if it doesn't then spray around the gaskets with soapy water and look for bubbles, you will find your leak. If you don't have a tester, you can make one from parts at a local ace hardware for about 20 bucks. If you do a search on here, somebody did a write up on how to build one. By the way, with stock cylinders, aftermarket pipes and filter...you should be running between a 280-320 main. Hope this helps....good luck! Quote Link to comment Share on other sites More sharing options...
vulvafan537240 Posted February 11, 2009 Report Share Posted February 11, 2009 i would say that youre rich. did you do a WOT plug check when you said the plugs looked rich at 240 mains? 240 shouldnt be rich with your mods. like shogs said, i think 260's would prolly be good, but id start at 280 and work your way down. 300ish would be close if you had no airbox. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted February 11, 2009 Report Share Posted February 11, 2009 fo shitz and giggles, you may want to look into your coil, stator, and grounds too. even with the difference, it should be able to burn every bit of 300's above 115psi, with your mods. also, have the chambers measured in the head. if it was "milled" on a belt planer, rather than cut on a mill, the cut will be tapered tward the leading edge when placedd on the machine. this could cause the head to have different size chambers Quote Link to comment Share on other sites More sharing options...
Damnit Bob Posted February 11, 2009 Report Share Posted February 11, 2009 I had a similar problem with mine, and i went crazy with dif jetting combos, needle positions, air screw adjustments.. and nothing. Finally swapped the CDI box with my buddy's and bingo! just had super weak spark, just enough to burn at idle and min throttle. I would also suggest checking your spark strength. Quote Link to comment Share on other sites More sharing options...
fasstbanshee Posted February 12, 2009 Report Share Posted February 12, 2009 i had a similair problem with mine at one time and it turned out to be a made coil/wires. also very common, is if you have messed around with your wiring harness and moved it around check for a broken wire. this has happened to me it melted because i was in a rush and didn't route it well it burnt up against the exhaust, and look around any rubbing point. good luck Quote Link to comment Share on other sites More sharing options...
mclark408 Posted February 13, 2009 Author Report Share Posted February 13, 2009 i had a similair problem with mine at one time and it turned out to be a made coil/wires. also very common, is if you have messed around with your wiring harness and moved it around check for a broken wire. this has happened to me it melted because i was in a rush and didn't route it well it burnt up against the exhaust, and look around any rubbing point. good luck FINALLY! It was the coil. Swapped it out with my buddies and it worked fine. Going to order a new one. Thanks for all the info guys. Quote Link to comment Share on other sites More sharing options...
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