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S4R bad vibes reloaded

854 Views 4 Replies 5 Participants Last post by  socalrob
OK, many of you have witnessed the little soap opera that is my Ducati experience. Now, down to the hard work of figuring this out.
I put my old seat back on, no difference. When I got back from my latest test ride, I just sat on the bike at idle. Clutch in, clutch out, still slight vibration at 1000 RPM idle speed. Rev it to 2000, then to 3000 RPM, and the whole bike shakes. Strong vibrations through pegs and tank. Crack the throttle and feel vibrations through any part of bike I have a hold on.
I had none of this shakey-shakey before. If I revved the engine in neutral, I got only that tinny, metallic noise, no vibration.
I justed talked to a Ducati aquaintance out east and described these symptoms. He said that these motors have perfect primary balance. His best guess would be to check if the alternator and primary gear/clutch assembly are on tight. He also advised me not to ride it until I find the culprit.
So any other suggestions will be heartily welcomed. I want my old bike back!
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Drain the oil, remove the side cover and check to see if the flywheel nut is working loose. There was a service bulletin on some bikes for this problem. It is a warranty issue, and the "fix" is to apply locktite and retorque. A better way to go if you do have this problem is to get the special nuts produced by Nichols Manufacturing (50$). They are available from Motowheels, and will solve the problem. Good Luck!
Since the engine was already disassembled, I highly doubt that a problem so common was overlooked. All the dealers know about that issue and I'm sure that nut was locktited.
This all seems to go back to a 6,000 mile service. I'd recheck all nuts and bolts for proper tightness, esp. the the motor mount bolts. I'd also recheck the timing belt tension and cam timing. Then make sure that the throttle bodies are sync'd properly.
This may be out of left field, but when BMW boxers (twins with FI throttle bodies, so not as diff as you think) have unbalanced throttle bodies and/or out of adjustment valves the common symptom is vibration, as the cylinders are producing different power levels therefore not in balance. I am thinking this as the problem showed up after the 6K service when I assume the valves were adjusted & the throttle bodies synched (They do that on Ducs don't they?).

There are BMW riders that do their own service as they go for perfect valve adjustment (not just within "parameters") and will synch the throttle bodies with a "twinmax" vacumn guage strapped down on their tanks for real world analysis, and they swear their bikes run smoother than when the dealers do a quicky job of it.
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