Bonneville America Forums Forums Technical Forums General Tech Vibration

Hello everyone, fairly new to the site and have already learned so much about my bike, the info so graciously given here is invaluable.Now, here is my problem, i have an 06 America, started with mods, AI out, CA evap off, Brent's thumbscrews,18 tooth sprocket, snorkel removed and Thunderbike pipes.After i put the sprocket and the pipes on i noticed a vibration at about 40 mph in second gear, don't think it was there before. Balanced carbs, re adjusted chain but still there.Not a gut wrenching vibe more like a buzz through the bike, but annoying. Just ordered the freak and nology coils from Brent, don't know if that will help or not.Any info on this annoying problem would be greatly appreciated.

If it wasn't there before the mods then my best advice is to undo what you've done one step at a time until you identify the culprit.

you may find it is just the pipes.
some pipes resonate(vibrate) at different rpm's that
can cause a vibe through the entire bike.
go faster, it will stop.

If i can't find any problem, well,i guess i will just have to go faster, it does smooth out after 40.

Check your chain tension. I had my chain too tight and a vibration kicked in about 40 or 50 mph. You should have about an inch of deflection midway between sprockets.

Checked and re adjusted my chain again,should be right. Took out for a short spin and still a little vibe, i will keep messing with until i get it right or just ignore it and go faster.

Is this ONLY in second gear or more speed related, as in at 40mph in any gear and does it stop if you pull in the clutch?

Seems to be most noticeable when i am accelerating through second gear, it does seem to do this a little in each gear as it gets higher in rpm, but then smooths out. I will have to check it by pulling in the clutch and seeing if it still does it. Have to wait a couple of days, weather is turning for the worse, AHH, spring in Utah, 70 one day, snowing the next

Not sure if you found the cause of your vibrations but, for what it's worth, I had a problem with vibes between approx. 3200 and 3800 RPM, regardless of gear. My local Trumpet tech said that, to pass emissions, Triumph (and all vehicle manufacturers) have to lean the fuel mixture out at a certain rev range (less fuel=less emissions); the rev range they test at is between 3 and 4k. Your aftermarket pipes (I have TORs) accentuate this leaning out, causing more noticeable vibrations.

Go for a ride and you should see that the vibes are more apparent between 3 and 4k revs, rather than a set speed. (If not, then it needs investigating)

(Note: if you look at a dyno reading of any production vehicle engine, you'll notice a dip at approx. 3500 RPM. The idea of tuning/dyno-ing, etc is to reduce this dip as much as possible.

neill

The only vibrations I pick up are 'Good Vibrations'

Seriously folks - Of all the vertical twins I've riden ( this is the fourth) from 1972 to present, this is by far the smoothest.

Just installed a tach, and you're right,at about 3800-4000 rpm i get the vibe no matter what gear, not really bad but i know it is there, but i had a BMW 650 for a loaner one day and i will never complain about my bike vibrating again, i think this beemer was a little beat up though. I have purchased the FREAK and will install and re jet very soon, i will let you know what happens. Thanks for the reply

Today I did a long trip, and was thinking to this thread.
I also noticed some vibrations on transitions between 3400-3900 rpm.

It seems normal and something related to pipes and resonances.
It can change with different engine setup. But nothing serious.
Lot of us say they have this vibration so it seems something characteristic of this engine.

I have ridden more vertical twins than I can count.I own 20 personally and work on at least another 20 for people on a regular basis. Every one has a vibration to it. If it is a mild vibration you are probably just feeling the nature of the beast. If it is a bad vibration there are many possibilities ranging from tire wear or wheel true to carb sync. to internal problem. From what you describe I believe it to be the former , ie normal.