bounce?

[drlapo]

my 05 Thruxton has a problem.
I've checked other forums and found that Tigers, do it, BMWs do it, even KTMs do it
the front end has a slight but noticable "bounce"
it feels like the front tire is running over numerous small ripples. at night you can see the healight beam bouncing up and down. Handling is fine: no weaves etc. I've worn the peg feelers off.
here is what I have done: new tires, both wheels trued and balanced, front progressive springs, front RaceTech valves, Hagon rear shocks, adjusted + adjusted the steering stem bearings, lost weight, gained weight, cataract surgery
:T

 

[RumRunner]

Is your SAG set properly both front and rear? My Thruxton did this before I reset the SAG rates. My front was too soft (for my fat arse) and the rear too stiff. Resetting the SAG, and changing my fork oil (I'm running F3 front suspension with 5w Redline) it made a huge difference in the "bounce"

 

[drlapo]

i'll try that

 

[ratlab]

i think racetech setup is to stiff for frame. i have done everything you have and nothing worked either.i cut spacers and changed to a lighter weight fork oil 15 to 10 and it is getting better.i'm going to keep going in that direction.i think we want a little more rebound and less compression to keep front from hopping

 

[RumRunner]

i think racetech setup is to stiff for frame. i have done everything you have and nothing worked either.i cut spacers and changed to a lighter weight fork oil 15 to 10 and it is getting better.i'm going to keep going in that direction.i think we want a little more rebound and less compression to keep front from hopping

I may be having better results due to a few things vs. you:

1. I'm a fat ass, so the extra mass may actually help with how I have my bike set up. 240 + Gear
2. I'm running F3 internals so I which is probably better than what the emulator type setups are capable of.
3. I prefer my suspension extremely tight (even on the street)
4. I actually just made spacers that were another 5mm longer for my bike, but I'm running even lighter 5 weight (Redline) oil.

That brings me to a quick rant on fork oil as there's no consistent measurement between fork oil manufactures so comparisons suck.

5. I recently went to beads in my wheels which I believe helped over external balancing

I think there's something screwed in your bike as it's been goofed up from word go. Might be worth having a laser alignment done to see if the frame is square, or if you possibly have bad steering head bearings.

 

[ratlab]

steering head bearings are ok-i even pulled swingarm and made sure sure it was straight from pivot-frame i don't know.i have been dreading finding out it's not straight. i have to do something because i hardly ever ride it

 

[RumRunner]

Hard to say. I'm friends with a number of guys who race in the Thruxton Cup, and one was having a nasty high speed wobble, they checked the steering head bearings and then checked properly but changed them anyhow and that turnout out to be the issue. A friend of mine took his brand new (never been down) Bonnie over to have Computrack check the chassis and the head stock was out of line.

Out of curiosity with all of the issues you've had with your bike (I recall reading a bunch of the threads and posts) have you ever rode another Thruxton to see if it's the bike or possibly how you're interacting with the bike? I road a buddies R1 after getting off the 996 and I don't know if it was just that the bike didn't fit me the suspension or what but I could never get comfy on her.

 

[ratlab]

that would be ideal to try another thruxton-the dealers here are always sold out-it would would be great if anyone in the bay area would want to swap for a day.i am for sure more dialed in with sportbike style of riding.i have tried to smooth it out on the thruxton,but i am still very uncomfortable with the wiggling, wobbling and hopping. your suggestion of computrack is probably what i have to do. i am pretty good with set-up,but this is beyond me

 

[RumRunner]

Hopefully you can find someone out there that is willing to go for a ride with you and do a quick swap. If you were on this coast I'd let you jump on my Thruxton to see what you think.