VIBRATION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Riolongo]

I've now had my FJ just a little over two weeks and so far I love it. The previous owner told me it was good to go, just ride it, no issues, etc. However, in that short period of time I've changed the rear brake pads and rebuilt caliper as pads were worn right down and the pistons were seized, but the bigger issue is the VIBRATION.
I've pressed out the engine mount sleeves, cleaned up and greased, no improvement, I've also tightened every bolt I can find, again no change. The vibration is so bad that I can't ride very long without my hands tingling, doesn't seem normal to me. The vibration is really noticeable if I put both hands on either side of the gas tank where the inside of my knees rest and also seems to resonate through the foot pegs. I've heard that synching the carbs may help, but I'm not sure that is necessary as the motor seems to run smooth and pull really strong.
Does anyone have any suggestions to track this vibration down?

Thanks,


Mike

[rlucas]

Sync the carbs anyway; it can make a big difference and it's dead easy to do. It won't make much of a difference in power, just in smoothness. If at all possible, buy/beg/borrow/steal a Morgan CarbTune - it's a pricey bit of kit but well worth the $$$. Superior to a mercury manometer and small enough to pack along to a Rally, where you can sync everyone else's carbs. Just ask Rayforth. 

Rossi

[andyb]

Check the valve lash, synch the carbs, check the chain slack/wear, check wheel bearings, check things that rotate.

Vibration is typically caused by excessive exclamation point usage.

[Riolongo]

Sync the carbs anyway; it can make a big difference and it's dead easy to do. It won't make much of a difference in power, just in smoothness. If at all possible, buy/beg/borrow/steal a Morgan CarbTune - it's a pricey bit of kit but well worth the $$$. Superior to a mercury manometer and small enough to pack along to a Rally, where you can sync everyone else's carbs. Just ask Rayforth. 

Rossi

I was speaking with a local guy and he told me that synching the carbs will only help at idle speed, if the vibration is all through the RPM range it will not make a difference. Personally I have no idea and am relying on the experience of this board's members, so can you tell me if that is the case or it does matter.

Thanks,

Mike

[SlowOldGuy]

Unless you're really honking on the throttle, you're typically riding with very little throttle plate opening.  Thus, synching the carbs is VERY important for a smooh response.   

Next time you're headed down the highway, pay attention to how much you're twisting the throttle.  Probably not more than 1/8th.

Then tell your "local expert" he's full of $hit.

DavidR.

[andyb]

Depends on how the carbs are synched, too.  If you synch them at idle, then yes you'll see the best gains there.

Personally I turn the idle up and try to get things smooth in that 3-4k range that you're generally using.

[Coronet]

 When I bought my FJ the previous owner told me upfornt that the bike vibrated bad up  to about 3600 rpm and then it became glass smooth, (I had to drive about 500 miles one way to meet the seller and get the bike). He was right, bad buzzing vibration at low rpm. I went ahead and bought the bike as it was in such great shape.
I did all the recomended stuff, adjust valves, clean and lube front motor mounts, clean and synch carbs, (several times). I tried synching both ways, at idle and at about 2000 to 2500 rpm. I personally think synching at a about 2500 works better but you may not have a super smooth idle. And altho this did make some of the vibration go away it still had more that I thought there should be.
Well several months went by and I was really getting tired of the low speed vib. Decided I really had to do something more to try and fix the problem. Ordered in four new siphon tubes for the cards (had read that the stock ones could wear in an oval shape and make it hard to get good fuel metering at low speed) got the new tubes in, pulled the carbs down and installed them, reinstalled the carbs and synched them at 2400 rpm.
The next day I took the bike out for a ride - what a huge difference, VIBERATION IS ALMOST NONEXISTENSC, bike runs super smooth, no buzzing in the bars, gas tank or fairing.
My bike has 28,000 miles on it and the tubes had enough ware on them to cause a problem.
Just something you might want to consider.
Mark H.

[Dan Filetti]

Wow, you learn something new every day.  I would not have guessed it was the siphon tubes -then again, I'm not 100% sure what a siphon tube is...

Glad it worked out for you.

Dan

[Riolongo]

Thanks to everyone for all the great tips, I haven't had a chance to do anything other than the engine mounts so far. I don't have access to a Morgan carb sync tool which looks to be the best tool for the job and I'm not overly comfortable doing the valves, so I may have to take it into a shop. The siphon tubes are one more thing I can have checked out, maybe by the end of the riding season I may discover the source. It would be nice if there were a few local FJ riders so that I would have a point of reference in respect to the vibration, but at this point it doesn't look like it.

Thanks again,

Mike

[racerman_27410]

Wow, you learn something new every day.  I would not have guessed it was the siphon tubes -then again, I'm not 100% sure what a siphon tube is...

Glad it worked out for you.

Dan

emulsion tubes

[andyb]

Needle jets.

[Dan Filetti]

emulsion tubes

Ah, Bach.

Thank you.

Dan