trex banshee Posted August 10, 2005 Report Share Posted August 10, 2005 ok there is something deffinatly wrong with my brothers shee. here recently it boggs really bad when trying to drag race you have to hold it wide open and dump the clutch for it to take off hard. you can still just ease out on the clutch to take off normal. then if you try to pin it in every gear and shift you know like you do when you race it pulls fine through the middle but when you get to the top it just missis like crazy(spits and sputters and sometimes backfires). now we haven't changed any jetting and it ran fine for about 3 weeks so it is not lean. i need to check the compression but haven't got a gauge yet. the low end and top end suck really bad. is it time for a top end? also what is the gap supposed to be between the flywheel and the pickup coil? Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted August 10, 2005 Report Share Posted August 10, 2005 What kind of setup is he running? Pipes, carbs, jets, air filters, etc? A dirty air filter or clogged outerwear could cause it to seem like it's misfiring on the top end simply because it's not getting adequate air flow. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted August 10, 2005 Author Report Share Posted August 10, 2005 he has fmf sst's with stock carbs and a k&n with the lid removed. his main jets are 270 with air screw 1.5 turns out. i don't know what the clip is on because the carb tops would not come off. lets see i think that is it... its got reed spacers and a cool head not sure of size of dome oh and a boost bottle. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted August 10, 2005 Author Report Share Posted August 10, 2005 ok i did a compression check both cylinders are at 120. it has a cool head but not sure what size domes. even if it had stock head probably time for rebuild isn't it. i think i fixed the top end misfire one of the plugs caps was almost screwed off. it doesn't miss on topend any more but the low end still sucks really bad it just acts like it has no power. Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted August 10, 2005 Report Share Posted August 10, 2005 ok i did a compression check both cylinders are at 120. it has a cool head but not sure what size domes. even if it had stock head probably time for rebuild isn't it. i think i fixed the top end misfire one of the plugs caps was almost screwed off. it doesn't miss on topend any more but the low end still sucks really bad it just acts like it has no power. 403137[/snapback] I'd say time for a rebuild!!! Stock compression (with the stock head) is supposed to be 120. With 21cc domes you would be around 140-150 psi so I can imagine with the cool head on there has to be at least 21cc domes in it. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted August 10, 2005 Author Report Share Posted August 10, 2005 i thought stock compression is 135 oh well it doesn't matter i think we are going to rebuild it. one more thing i thought of he went from running straight 91 to mix 91/111 could this result in a rich condition Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted August 10, 2005 Report Share Posted August 10, 2005 i thought stock compression is 135 oh well it doesn't matter i think we are going to rebuild it. one more thing i thought of he went from running straight 91 to mix 91/111 could this result in a rich condition 403151[/snapback] No sir, at sea level (or close to it) the stock compression is 120psi. I'm not 100% sure but I do not believe that going to a higher octane gas could cause a rich condition...If the bike is rich now and it wasn't a couple of weeks ago (when you jetted it) I would bet the farm that the richness you're experiencing is fuel that isn't getting burned due to low compression. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted August 10, 2005 Author Report Share Posted August 10, 2005 ok i that sounds right. i forgot about the different sea level effecting the compression. do you know by chance what my elevation is(Pleasant Hill Missouri) Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted August 10, 2005 Report Share Posted August 10, 2005 You are 909 feet above sea level. http://www.city-data.com/city/Pleasant-Hill-Missouri.html Quote Link to comment Share on other sites More sharing options...
trex banshee Posted August 10, 2005 Author Report Share Posted August 10, 2005 cool thanks man now i know for future preference. what size jets should be in that thing. all i know is it has 270 mains. it has sst's,k&n no lid,boost bottle,reed spacers, cool head Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted August 10, 2005 Report Share Posted August 10, 2005 Not 100% sure, every bike is different to some degree....but 270 mains does sound a little lean for having the air box lid removed. When I ran my Toomeys with no lid I had 290 mains. I think I'm right around 600 ft above sea level. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted August 10, 2005 Author Report Share Posted August 10, 2005 alright it is worth a shot Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted August 10, 2005 Report Share Posted August 10, 2005 Absolutely...I would be sure you've checked everything out before going the extra mile and doing a top end job. Have you checked the filter to see if it's dirty/clogged? I know it sounds too easy but it could definitely cause your bike to bog and would make it seem rich. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted August 10, 2005 Author Report Share Posted August 10, 2005 well i ran it with it off just in the grass and down the paved road it still seemed to bogg but that is when it was misfiring. so i fixed the plug and put the filter back on. the misfiring was fixed but not the bogg. i need to give it a thorough cleaning and i will get back with you. i forgot about a week ago the bottom stator bolt came out and the little waher got in between the flywheel and that black box (pick up coil) and it also bent the brackt so the box was further away from the flywheel than it is supposed to be i think i remember someone saying the air gap should be .018 is this right? but still we went riding at a rock quary on sunday and it ran fine so that shouldn't be a problem. the timing was at 3 advanced when we got it so we turned it up to 4 it ran fine but then when that bolt came out it chewed the firing spots on the flywheel up just a little. so i put the timing to 2 because of the chewed up spots. but this was all before sundays ride at the quary. so i will clean the filter and go from there. damn i just wrote a whole book. Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted August 10, 2005 Report Share Posted August 10, 2005 well i ran it with it off just in the grass and down the paved road it still seemed to bogg but that is when it was misfiring. so i fixed the plug and put the filter back on. the misfiring was fixed but not the bogg. i need to give it a thorough cleaning and i will get back with you. i forgot about a week ago the bottom stator bolt came out and the little waher got in between the flywheel and that black box (pick up coil) and it also bent the brackt so the box was further away from the flywheel than it is supposed to be i think i remember someone saying the air gap should be .018 is this right? but still we went riding at a rock quary on sunday and it ran fine so that shouldn't be a problem. the timing was at 3 advanced when we got it so we turned it up to 4 it ran fine but then when that bolt came out it chewed the firing spots on the flywheel up just a little. so i put the timing to 2 because of the chewed up spots. but this was all before sundays ride at the quary. so i will clean the filter and go from there. damn i just wrote a whole book. 403188[/snapback] Typically a bog means it's too lean...do you know what size pilot jet is in it? If I'm not mistaken, the SST's are more of a low/mid pipe (I may be totally wrong though ) and might like a fatter pilot jet. Does it seem to idle OK? Granted, your filter may be dirty causing some of the problem but if the pilot is too lean, it would definitely cause a low end bog, especially off idle Quote Link to comment Share on other sites More sharing options...
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