jaykup Posted July 10, 2008 Share Posted July 10, 2008 2003 Blackbird is just over 20,000 miles. I have only done oil changes, a new windscreen, lowered the foot pegs using a member on this forum's custom aluminum mounts, raised the handlebars using VFR handlebars, and put an aftermarket JT 18T front sprocket along with a new DID VZM2 chain, about 500-1000 miles on the new chain/sprocket config. I notice vibration in the foot pegs most of all, and its very noticeable now. Almost makes my feet fall asleep on longer rides. I noticed that it goes away completely when I pull in the clutch and just coast at any speed. If I'm in say 6th gear doing 45-60mph and give it 1/4 throttle or more it is VERY noticeable, getting worse as more throttle is applied. Even under normal acceleration its almost annoying. Anything over 3,000 RPM. I've had the bike since it had 6,000 miles on it, and I've never noticed it this bad before. In fact, I loved the smooth silky feel it had. Two things that may be related. Before/during this happened, I was stuck in traffic for about 30-60 minutes, shutting off the engine when I could. I think my temp reached 235-240 before I was able to get to an off-ramp. An hour or so after that I drove through ~3 feet of water (strong current) for about 1/8 mile (closed road due to flooding) which is stupid now that I think of it, but at the time, it was an amazing experience. The water was not so high that it got into the intake. The bike ran fine through it. Wasn't able to go more than 2-4 mph with out the tire breaking loose. Not that I wanted to go any faster. The vibration I think was slowly getting worse before this though. I use Mobile 1 MX4T Synthetic oil, changed every 5,000 miles or so. Any ideas? I don't think its sprocket/drive train related, because it goes away when the clutch is in. I also don't think it is the tires (BT-021) for the same reason. Quote Link to comment Share on other sites More sharing options...
BearXX Posted July 10, 2008 Share Posted July 10, 2008 I had the same problem when changing the front sprocket. The old had rubber dampening while the new one didn't. Quote Link to comment Share on other sites More sharing options...
beondwacko Posted July 10, 2008 Share Posted July 10, 2008 I had the same problem when changing the front sprocket. The old had rubber dampening while the new one didn't. I didn't have the vibration , but a whine without the rubberized sprocket. I wonder if his bike is generating a harmonic situation that translates into a vibration at a given pitch? Quote Link to comment Share on other sites More sharing options...
Hooplehead Posted July 10, 2008 Share Posted July 10, 2008 Check your chain slack. Quote Link to comment Share on other sites More sharing options...
Iceman_40 Posted July 10, 2008 Share Posted July 10, 2008 Check your chain slack. +1 along with checking for any tight spots. If you drove throw alot of water it may just need a good oiling. Quote Link to comment Share on other sites More sharing options...
CxBXR Posted July 11, 2008 Share Posted July 11, 2008 Check your chain slack. +1 along with checking for any tight spots. If you drove throw alot of water it may just need a good oiling. +2 most likely cause for foot peg vibration is chain/sprocket related Quote Link to comment Share on other sites More sharing options...
jaykup Posted July 11, 2008 Author Share Posted July 11, 2008 I don't think the chain/drive line is the problem. Let me give you an example of me driving when I notice it. I get the bike up to 60mph, in 6th gear. Just cruising I can feel vibration in the pegs, its worse than a normal BB, but not excessive. When i roll on the throttle, it gets worse, much worse. Seems like the more load I give it, the worse it gets. Here's the kicker. When I'm still doing 60mph, I can pull in the clutch to let the engine idle, and all the vibration goes away. With the clutch still in, I can rev the engine and hold it around 3-4k RPM and the same vibrations come back. This makes me believe that it has nothing to do with the chain/sprocket. So, what else could be causing the vibrations? Anything common with the birds? Quote Link to comment Share on other sites More sharing options...
Para045 Posted July 11, 2008 Share Posted July 11, 2008 I don't think the chain/drive line is the problem. Let me give you an example of me driving when I notice it. I get the bike up to 60mph, in 6th gear. Just cruising I can feel vibration in the pegs, its worse than a normal BB, but not excessive. When i roll on the throttle, it gets worse, much worse. Seems like the more load I give it, the worse it gets. Here's the kicker. When I'm still doing 60mph, I can pull in the clutch to let the engine idle, and all the vibration goes away. With the clutch still in, I can rev the engine and hold it around 3-4k RPM and the same vibrations come back. This makes me believe that it has nothing to do with the chain/sprocket. So, what else could be causing the vibrations? Anything common with the birds? I have had a similar vibration on my 98 now for quite a while and put it down to tight spots in my chain, it does go away to a degree when coasting but is really noticeable at ~3500-4500rpm More so in the LH foot peg as well and I also get some vibes up through the tank as well, never had it when I bought the bike, will be changing the chain and sprockets shortly so will see then :icon_think: If that makes no difference I will try the balancer adjustment Quote Link to comment Share on other sites More sharing options...
Fast Eddy Posted July 11, 2008 Share Posted July 11, 2008 Look up balance shaft adjustment. Quote Link to comment Share on other sites More sharing options...
Hooplehead Posted July 11, 2008 Share Posted July 11, 2008 Look up balance shaft adjustment. +1 on that too. Kind of a pita, but doesn't cost anything, and that's what really matters! I know you don't think it's the chain, but perhaps you could loosen it a tad just to see? I know when I overtightened mine a tad, the vibration was pretty bad under acceleration and also when I shifted my weight rearwards. It was so bad, that my suspension wasn't even working in the rear. I went really slowly and :icon_pray: my front seal didn't explode! I believe the chain tightens a little as the rear end sags? Doesn't the bike also sag a little when it is being rev'd? Soak that bad boy in lube, give it a little excess slack (keep it straight), adjust your balancers, and ride like the wind. Or sell it to my girl for $10 and then I can keep mine! I hear bicycles get great mileage and don't vibrate much. Quote Link to comment Share on other sites More sharing options...
jon haney Posted July 11, 2008 Share Posted July 11, 2008 Check your cush-drive and wheel bearings and the one in the rear sprocket carrier. Bad bearings tend to vibrate worse under load and then smooth out with no load. I don't think the problem is in your engine. It's highly unlikely anyway. Quote Link to comment Share on other sites More sharing options...
speedygeezer Posted July 12, 2008 Share Posted July 12, 2008 Have you tried revving the engine above the 3-4K rpm level where you feel the most vibrations? Do the vibes dissipate above 4K rpm? Balance shaft problems often cause vibrations in the tank and hand grips in addition to the footpegs, but it doesn't sound like that's the problem. Another thing that causes vibrations - in addition to a rattling sound in the engine - is a bad lifter. It will cause vibes from 3K to 5K rpms, peaking around 4500 r's. But, it, too, doesn't exactly fit your description. Have you checked all the fasteners for tightness? As others have suggested, the chain sounds like the most likely culprit. Quote Link to comment Share on other sites More sharing options...
slowrideCX Posted August 12, 2008 Share Posted August 12, 2008 Another thing that causes vibrations - in addition to a rattling sound in the engine - is a bad lifter. It will cause vibes from 3K to 5K rpms, peaking around 4500 r's. But, it, too, doesn't exactly fit your description. There aren't any lifters in the BB motor the cam rides right on the shim bucket which sits on the valve stem. A bad CCT will cause a rattling sound and a slight vibe from 3-4k rpm. I have a similar Vibe but it changes at 5k-6k rpm not bad but noticable. Everything is tight the chain is adjusted properly and well lubed I think it is coming from my front sprocket that doesn't have the rubber damper in it due to being an after market. I have heard of this before. The only thing that you said that is differant than mine is you said you can recreate that vibe with out the bike in gear/ moving mine is only when ander a load, not excelerating holding that rpm range, speed/gear does not matter only rpm. Quote Link to comment Share on other sites More sharing options...
airborneXX Posted August 12, 2008 Share Posted August 12, 2008 Another thing that causes vibrations - in addition to a rattling sound in the engine - is a bad lifter. It will cause vibes from 3K to 5K rpms, peaking around 4500 r's. But, it, too, doesn't exactly fit your description. There aren't any lifters in the BB motor the cam rides right on the shim bucket which sits on the valve stem. A bad CCT will cause a rattling sound and a slight vibe from 3-4k rpm. I have a similar Vibe but it changes at 5k-6k rpm not bad but noticable. Everything is tight the chain is adjusted properly and well lubed I think it is coming from my front sprocket that doesn't have the rubber damper in it due to being an after market. I have heard of this before. The only thing that you said that is differant than mine is you said you can recreate that vibe with out the bike in gear/ moving mine is only when ander a load, not excelerating holding that rpm range, speed/gear does not matter only rpm. He's referring to the Cam Chain Lifter which is the proper name for the CCT that we all replace.... dopey I had very similar vibes from the JT 18 tooth sprocket. When I pulled the sprocket it had a very odd loooking wear pattern forming so I put a stock sprocket in. Vibes gone. Also check chain tension. Stay to the loose end of spec. especially if you have shimmed the rear shock. Quote Link to comment Share on other sites More sharing options...
slowrideCX Posted August 12, 2008 Share Posted August 12, 2008 Another thing that causes vibrations - in addition to a rattling sound in the engine - is a bad lifter. It will cause vibes from 3K to 5K rpms, peaking around 4500 r's. But, it, too, doesn't exactly fit your description. There aren't any lifters in the BB motor the cam rides right on the shim bucket which sits on the valve stem. A bad CCT will cause a rattling sound and a slight vibe from 3-4k rpm. I have a similar Vibe but it changes at 5k-6k rpm not bad but noticable. Everything is tight the chain is adjusted properly and well lubed I think it is coming from my front sprocket that doesn't have the rubber damper in it due to being an after market. I have heard of this before. The only thing that you said that is differant than mine is you said you can recreate that vibe with out the bike in gear/ moving mine is only when ander a load, not excelerating holding that rpm range, speed/gear does not matter only rpm. He's referring to the Cam Chain Lifter which is the proper name for the CCT that we all replace.... dopey I had very similar vibes from the JT 18 tooth sprocket. When I pulled the sprocket it had a very odd loooking wear pattern forming so I put a stock sprocket in. Vibes gone. Also check chain tension. Stay to the loose end of spec. especially if you have shimmed the rear shock. :icon_doh: :icon_doh: :icon_doh: Quote Link to comment Share on other sites More sharing options...
Hobicus Posted August 13, 2008 Share Posted August 13, 2008 It's worth checking to see if there's been any movement of the exhaust manifold, and the rubber bushings that hold the collector to the foot peg. It's possible that the engine RPM vibration you're feeling in the footpeg is transfering via that route. Quote Link to comment Share on other sites More sharing options...
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