Limited87 Posted June 4, 2008 Report Share Posted June 4, 2008 Hi guys, long time reader first time post. I have a 1996 banshee with a stock bottom end. The bike is original and has very low hours on it. I just recently put a set of fresh FTZ cylinders that are .20 over with Weisco pistons, coolhead with 19 cc domes(didnt want to put to much stress on the stock bottom end), 35mm Keihin carbs with FTZ carb mount filters. It has Toomey T5s, Vitos timing advance key and I have been running U2 VP 2 cycle race fuel thats rates at 101 octane. I am running upgraded clutch fibers with heavy duty springs and bead blasted steels. Heres the thing...the bike sound has changed and it has a vibration. When you crack the throttle at idle when it comes down just before going back to idle it vibrates and I didnt notice it when I first had it put it together but it may have been there but the sound of the bike has def changed. The clutch also seems to be giving up alot now where it wasnt on the first tank of gas. The cylinders were suposed to have made mid 80s horsepower with 16 cc domes on race fuel. I need opinions on this set up, the vibration, am I risking major damage with this crank not being welded? Could this be the issue with the sound changing?? Whats the limit on horsepower and a non welded crank? Any and all ideas/help is appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
Limited87 Posted June 5, 2008 Author Report Share Posted June 5, 2008 No info or opinions guys? Quote Link to comment Share on other sites More sharing options...
FireHead Posted June 5, 2008 Report Share Posted June 5, 2008 Hi guys, long time reader first time post. I have a 1996 banshee with a stock bottom end. The bike is original and has very low hours on it. I just recently put a set of fresh FTZ cylinders that are .20 over with Weisco pistons, coolhead with 19 cc domes(didnt want to put to much stress on the stock bottom end), 35mm Keihin carbs with FTZ carb mount filters. It has Toomey T5s, Vitos timing advance key and I have been running U2 VP 2 cycle race fuel thats rates at 101 octane. I am running upgraded clutch fibers with heavy duty springs and bead blasted steels. Heres the thing...the bike sound has changed and it has a vibration. When you crack the throttle at idle when it comes down just before going back to idle it vibrates and I didnt notice it when I first had it put it together but it may have been there but the sound of the bike has def changed. The clutch also seems to be giving up alot now where it wasnt on the first tank of gas. The cylinders were suposed to have made mid 80s horsepower with 16 cc domes on race fuel. I need opinions on this set up, the vibration, am I risking major damage with this crank not being welded? Could this be the issue with the sound changing?? Whats the limit on horsepower and a non welded crank? Any and all ideas/help is appreciated. Thanks I would do a compression test on both cylinders. I would be willing to be that one is quite different from the other. :geek: Quote Link to comment Share on other sites More sharing options...
Limited87 Posted June 11, 2008 Author Report Share Posted June 11, 2008 I would do a compression test on both cylinders. I would be willing to be that one is quite different from the other. :geek: I just did the compression test and was 160#s on both sides. Is this about right with 19cc domes with the pro design coolhead? Quote Link to comment Share on other sites More sharing options...
FireHead Posted June 11, 2008 Report Share Posted June 11, 2008 I just did the compression test and was 160#s on both sides. Is this about right with 19cc domes with the pro design coolhead? I think that is about right. The compression being even on both sides was the important part. :geek: Quote Link to comment Share on other sites More sharing options...
Limited87 Posted June 11, 2008 Author Report Share Posted June 11, 2008 I think that is about right. The compression being even on both sides was the important part. :geek: Great, whats the next thing to look at? Could that vibration just before the bike returns to idle be normal? Whats the limits of horsepower not having the crank welded? I dont beat this thing up big hills or even trail ride it. I basically just rip around the yard and make some drag runs on the road. Quote Link to comment Share on other sites More sharing options...
Bill Posted June 11, 2008 Report Share Posted June 11, 2008 I heard that once you start raising the compression it puts alot of stress on the crank. All the motor mounts tight? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted June 11, 2008 Report Share Posted June 11, 2008 I've seen stockers separate... Raising the compression only increases your chance. Does it vibrate all the time, in gear, with the clutch pulled in or let out...?? Does the vibration get worse as the RPMs raise... Here's a couple things to look for.. Out of balance or improperly seated flywheel (did you recently have it lightened, or do you have a timing advance degree key?) Stock cranks are splined, it's damn near impossible to put it out of phase. Normally..when it separates, it won't vibrate like you're talking about....it'll just lock up. Could be loose or worn gears or cushions on the clutch... Time to tear both side covers off and start inspecting. Quote Link to comment Share on other sites More sharing options...
Limited87 Posted June 11, 2008 Author Report Share Posted June 11, 2008 I've seen stockers separate...Raising the compression only increases your chance. Does it vibrate all the time, in gear, with the clutch pulled in or let out...?? Does the vibration get worse as the RPMs raise... Here's a couple things to look for.. Out of balance or improperly seated flywheel (did you recently have it lightened, or do you have a timing advance degree key?) Stock cranks are splined, it's damn near impossible to put it out of phase. Normally..when it separates, it won't vibrate like you're talking about....it'll just lock up. Could be loose or worn gears or cushions on the clutch... Time to tear both side covers off and start inspecting. Its great to know I havent done any damage to the crank or I would really see a problem. Maybe its just me but the bike has a diff sound than it had when it was first put together but maybe the rings are seating and changin it a bit. Yes, thats why I didnt want to run alot of compression. I figured with 19cc domes and a factory stock very low hour bottom end I would be ok. I dont have a problem running the U2 race gas as little as I ride it. The port job on these FTZ cylinders are really something as was told that the bike they came off of made 89 horse with 15 cc domes. The clutch is slipping very noticeable now only on its 4th gallon of gas. I knew it probably wouldnt hold the bike long and I havent done any mods to the fly wheel, only the clutch mods with the springs, bead blasted steels but that was WAY before this new cylinder/carb set up. The vibration ONLY occurs when you decell the engine a split second before it reurns to idle with the clutch pulled in or out it doesnt matter. If you rev it the motor is glass and lightning quick...its only on the decel just as it reutns to idle. This maybe basically normal and Im totally blowing things out of proportion but I didnt notice it when the new cylinders/pistons/carbs were first put on it but it may have been there but you guys have messed with these things way more than I have so I want your best opinions/ideas. Thanks for the help/replys guys! Quote Link to comment Share on other sites More sharing options...
dajogejr Posted June 11, 2008 Report Share Posted June 11, 2008 Rings seat in 5 minutes.. I'm not saying you haven't done any damage to the crank, separating it to the point of lockup would be considered damage IMO... 15cc domes? Unless that guy rode at 8000 feet above elevation, he was wasting his time with those small of domes. You might have shift forks starting to go.... Quote Link to comment Share on other sites More sharing options...
Limited87 Posted June 12, 2008 Author Report Share Posted June 12, 2008 Rings seat in 5 minutes.. I'm not saying you haven't done any damage to the crank, separating it to the point of lockup would be considered damage IMO... 15cc domes? Unless that guy rode at 8000 feet above elevation, he was wasting his time with those small of domes. You might have shift forks starting to go.... Im about 3 hours from you in NE Ohio. :-) Thats what I was told. So whats your opinion? Dont ride the bike anymore till I tear it down and put a new crank in it? Or throw a new race clutch from FAST and nice basket and see how it goes with the current set up? I just rode it and even the clutch giving up alot it still feels nasty as hell...lol Quote Link to comment Share on other sites More sharing options...
dajogejr Posted June 12, 2008 Report Share Posted June 12, 2008 It's gonna cost nothing to take the ignition side off, and 20 to 30 bucks to take the clutch side off (gasket, coolant and gear oil/ATF) to at least take the clutch apart...etc. and inspect it. I would at least go that far. If the crank was out of true, you'd feel it more so revving up....NOT only on the decel. YOu won't feel it if it's separating, unless it's real bad...and the same above applies, NORMALLY!! I would at least check out the easy stuff on either side of the motor! Quote Link to comment Share on other sites More sharing options...
blue02 Posted June 12, 2008 Report Share Posted June 12, 2008 I had a buddy whose shee would vibrate badly when letting off the throttle, pulled it down and cant say for sure as to whether or not the crank had twisted but the crank bearings were in bad shape. We ended up replacing the crank, no more vibration! Quote Link to comment Share on other sites More sharing options...
dajogejr Posted June 12, 2008 Report Share Posted June 12, 2008 That's a good point, normally they vibrate under load, but bearings could be bad... Quote Link to comment Share on other sites More sharing options...
Limited87 Posted June 12, 2008 Author Report Share Posted June 12, 2008 That's a good point, normally they vibrate under load, but bearings could be bad... I will inspect everything as you said and probably throw in a new clutch before I put it back together and see what we get with that. Thanks again guys for all your help and ideas. Quote Link to comment Share on other sites More sharing options...
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