Bonneville America Forums Forums Technical Forums General Tech VIBRATION!!!

At about 2300 miles today my TBA developed a vibration. It starts at about 55 and progressively gets worse up to about 70. Over 75 it's pretty smooth again... only problem is the speed limit is 55. The vibration isn't something that will shake you off the bike... but you can really feel it in your seat and in your hands (especially your hands). I swear you cant hang on to the bike for ten minutes before your hands and arms go numb. Does anyone have any idea what the heck is going on?

Hi....I think you should check out your wheel bearings first. If it's not that..... Maybe you need to have your wheel balanced

Low air pressure in tires
wheel balance
Spoke alignment
Rear wheel alignment

Start there.
always check the most simple thing first!
It's rarely a big thing unless it "always did that"

I overtightened my chain which caused a subtle vibration to start around 50 mph. I slackened the chain a bit and the vibration went away.

Cody

I'll check the air pressure in the morning. How would you check the other items (disclosure, I'm a mechanical idiot)?

Ditto on the chain. Mine has developed a "surging" feeling as it has some spots tighter than others. My front wheel used to wiggle a bit too, until I got the venoms.

If I may be so bold....
Check the torque of all your major mounting bolts... the wheels, the frame, the engine.
If all ok, does it do it with the clutch disengaged? If not, there's something in the engine, drive train.
If so, it's in the wheels, tires, chain/sprockets, forks, swingarm, etc..

At different speeds, different harmonics are created. They are amplified by whatever "sings their song"....

I'm guessing since you have a BA you don't have a tach, but if you experience the same vibration when winding out in lower gears, have your carbs balanced. Triumphs like ours are susceptible to engine vibration in the 3000-4000 rpm range (right about 55-65 mph in top gear) when the carbs go out of synch. My SM had exactly the same problem which disappeared after I synched the carbs, and while I know the crank offset is different on the BA vs. the SM, the problem is the same.

That sounds like it could be it... how do you sync the carbs?

I use a TWINMAX balancer (www.rlmotorcycles.com) and a right angle screwdriver to turn the balance screw between the carbs. The instructions are in the factory manual. Once you do it a couple of times on these bikes, it only takes about 10 minutes.

Tony, I rode this afternoon... it does exactly that. You can feel the vibration when the revs get up near the top of the range in each gear. I'm going to call my dealer tomorrow and see if he has a carb balancer.

Update (this is long)... took the bike to the dealer today. They went over it with a fine tooth comb. Checked everything (spokes, wheels, chain, carb balance, re-torqued engine mounts, etc...). Tech rode it afterwards and said "I can't find anything wrong with it". Well, I paid my bill (why didn't they cover the diagnostic under warranty???) and rode the bike home... still does it. Hands, butt and arms completely numb after about 15 minutes. Still worse between 45 and 65 (its the absolute worst at 65). If you engage the clutch and release the throttle, it's smooth as silk. Engage the clutch and crank the throttle it starts vibrating again.

So, I took it to a acquaintance who is a respected custom builder and asked him to ride the bike then come back and tell me if he noticed anything. He takes off, stays gone awhile, comes back and say's "it starts vibrating at about 50 and gets pretty bad at about 65!". Then I tell him the story about it being checked out, etc... he said, I don't know what to tell you... it absolutely has a vibration. His advice was to run it for a couple of miles in third gear at 60 mph to try and burn out any carbon that may have built up during breakin. Now here is the really interesting part... in third gear at 60/65 it DOESN'T vibrate! Hit forth and fifth and it does! I am REALLY perplexed... could it be something in the transmission???

Hmmmmmmm interesting. Sometimes at low-ish RPMs if I crank the throttle, mine vibes some. Have to balanced the carbs lately?

Benny, they checked the balance and said it was "spot on perfect"... everything else the same. The only thing that was out of whack was the torque on the engine mounts (they were off about 4lbs) which they fixed. But still it vibrates. It feels like holding on to a weed trimmer when one string is shorter than the other. I have no idea what to do. I absolutely love the bike... but it has turned into an absolute monster to ride (comfortably).

So it only vibs at those speeds and in those gears... weird. Did the guy who test rode it get it up that fast? Maybe a vacuum leak somewherE? I dunno, thinkin outloud now...

I don't know if the tech did... I know my friend who rode it did.

I would do two things,
First, tell the stealer to refund your money since the bike is under warranty still. You should not have had to pay, especially if they fouind incorrectly torqued bolts.
Second, go to another dealer and have them check it out. It sound like something in the drive train is out of kilter still - chain/wheel alignment in rear, front wheel, bad front sprocket, bad chain, kink/stuck links in the chain?

Now, these bikes do vibrate a bit, but it's no worse than any other vertical twin I have ridden.

Another thing I rememeber, about 2 years ago, someone had theirs checked out and it turned out that the cams were actually installed incorrectly and were off by a tooth either in the intake or exhaust, sorry I don't rememeber.
This may not have anything to do with it, but I'm grasping at straws here without actually feeling it myself.

Good luck.
If you don't get any satisfaction, give Triumph in Newnan (T of North America) a shout, maybe they will intervene and get it sorted out.

Thanks Pat... will do.