Triumphrat

jkdjim · 02-20-2004, 06:43 PM

I just returned home from work on a nice day and while running my Trophy 3 on the highway I was cruising at 100mph for a few miles. I noticed vibration in the front handlebars and the backend began to wobble or porpoise. I get a similar porpoise wobble when going into a corner.

My Trophy 3 has less than 8k on it. The tire pressure was checked this morning, rear tire is brand new, front tire has less than 3k on it. Mechanic recently checked the suspension and made some adjustments for my weight.

Where should I look next for what might be causing the wobble? Or, is this how the Trophy handles at high speeds and in corners?

jimballard · 02-20-2004, 09:26 PM

O.K. Jim,
Assuming that the tires are a matched or compatible set, did anyone check the head bearings or better yet, re-adjust them? I don't trust the "shake the fork" method for play in the head bearings as I've seen it be wrong in the past. Did you spin the tires and check the tread to see if there's any "runout" in the tire? New doesn't always mean right. Are you carrying anything real heavy in the bags? That might throw the fore/aft balance out a little bit. Last guess; is there a tight spot in the chain that might give a "pulse" of sorts to the drivetrain? I'm kind of grabbing at straws, but I've seen some strange things over the years happen in both cars and bikes.

Hope this helps: Jim

jkdjim · 02-20-2004, 10:08 PM

Jim,

The tires are a matched set. I am not not quite sure i do it right at checking runout but there doesn't appear to be any under my view. How will I know for sure?

The Head Bearing is another issue, I don't think they checked that out when I had the suspension and tires checked out. Good idea....

The bike doesn't have luggage, although I do carry a small tank bag most of the time.

I'll have to check on the chain again too.....

Thanks Jim

jimballard · 02-21-2004, 05:48 PM

Hi Jim,
All I'd do to check the tires is to spin them with the bike on the center stand looking for any wavering or flat spots, "lumps" etc. in them. It's a good time to grab the wheel you're checking and shake it to check the wheel bearing as well. May as well see if there's any play (side to side) in the rear suspenion while you're at it. The mechanic probably did this as part of his work, but a double check never hurts. Double checking the weight setting on your suspensing wouldn't hurt either, just to be safe. As I said before, I'm doing a bit of guessing here; hope it helps.

Good Luck: Jim

relocatedfixer · 02-24-2004, 01:38 PM

I've been told it could be more than coincidence that you have just had a new tyre fitted. Check tyre pressures, could be you should have changed both tyres at the same time ?
R.F.

jkdjim · 02-25-2004, 10:58 PM

RF,

I thought about that too, but the bike felt the same way on the previous tire too. It just may be the different feel I have with the bike compared to my TT600. I don't think so, I think it isn't quite right.

Thanks...

02-26-2004, 12:47 PM

Nobody has mentioned the front wheel balance. I assumed that the vibration only started when you had a new rear tyre as RF did.
Most handlebar vibration is caused by wheel balance although Jim B may be correct about head bearings.

03-20-2004, 12:53 AM

The condition sounds like an alignment issue. As each wheels attempts to straighten itself on the intended path, it has to flex the chassis. The chassis then deflects back. The recent issue (I think) of MOTORCYCLIST has a column on setting the alignment in a home shop.

03-20-2004, 05:12 PM

I would agree with the alignment issue. Make sure that both the front and rear tires are in straight. It can also be frame flex but i doubt this is the issue. Might want to check fluid levels in the forks and preload on the springs if any. Check wheel balance as it will change with new tires and sometimes weights do come off. Of course the head bearings should be checked also. You don't mention your weight but regardless you might want to increase the preload in your rear shock. Wheel vibration or wobbles should be looked into immediately as they can be a serious safety issue.