22 replies to this topic

[tbzep]

I spooned a new PP/PR2 combo on the bike a couple weeks ago and did a quick shakedown/scrub session. The combo worked great. Unfortunately, due to work, family, weather, etc. today was the first day I've had a chance to do some real riding.

I discovered a severe vibration/bouncing issue. It was minimal as I took off from a stop, increasing and maxing out around 30-40 mph, then subsiding again as speed increased. The vibration was so bad that it was uncomfortable to ride in town. Using the mirrors between 30-40 mph was impossible. I could lean over and see the tire bouncing as I went down main street. I didn't think I threw a weight because the vibration didn't resonate again at higher speeds. I got off and looked. Nope, the weights were still there. I then thought maybe balancing was the issue anyway and I just screwed up balancing it even though it's so simple a caveman could do it. Nope. I checked the balance when I got home and it was perfect, never stopping the same place twice.

I didn't notice the vibration when I did the scrub in session because I went from zero to wahoo! in about 3 seconds and never slowed down until I parked the bike. So what is the problem? The tire is out of round by nearly 1/8". I'm going to do some investigating. I'm going to check and see if the wheel is true. If it is, I'll break the beads and reseat them. I guess it's remotely possible that they aren't seated perfectly, but I don't see any sign of that just by looking. If it is still out of round after reseating, I guess I'll need to call JakeWilson.com and see what they will do. If it's the wheel, I guess I'll have to start looking for a new one.

[tbzep]

Update.

I checked the wheel and it is true. It is nice and round and it has no side to side wobble.

I broke the beads and spun the tire 180 degrees while I was at it because I had to use a ton of weight when I mounted it. I wish Michelin would mark their light spot like some of the other manufacturers. I lightly lubed the beads and seated them. It only took about 20 psi, so I aired it on up to 36 psi and spun it. It is now less than 1/16" out of round. I balanced the tire again and took it for a test run on several different sections of pavement to take the surface out of the equation. It still has some bounce between 30-40 mph, but it's not as bad. I can see stuff in the mirrors now. Anything above 45 mph is now silky smooth.

[gll429]

your may be straight and true.. but its out of balance
take it to a shop with an electric balancing machine..

[tbzep]

your may be straight and true.. but its out of balance
take it to a shop with an electric balancing machine..

I've mounted and balanced every tire I've ever run on my VFR's and never had a balance problem. I use a Marc Parnes balancer, which is sensitive enough to show the change made by a small piece of tape.

[hondalover]

I know it's rare, but I've expierenced the same thing. I do respect Greg's opinion, but in this case I think he is incorrect. I was lucky enough to have my expierence when I was a wrench at a dealership, and I had bought the tire through the dealership. Our supplier sent out a rep to observe the problem, and this was for a fairly inexpensive Bridgestone. I sure hope Jake Wilson takes care of this. And just FWIW, my wheel demensions were perfect, balance was perfect and performed on an electronic spin balancer.

[spud786]

_{Tire would have to be severely out of balance to show up at speeds under 50mph , and Ive never seen those Miches out of round like that. Actually those miches I've found are near perfect balance in comparison to say Metzeler, but if your seeing out of true, and its the tire and not the rim, that speaks for itself.}

[gll429]

the MP balancer is still a static balancer .. a dynamic one is ALWAYS better.
i have tried getting a wheel to balance equally on both.. and NEVER had any luck.

the fact is.. the wheel spins.. and the best kind of balancing will be dyna beads.. or a very similar product.
HDs ..as you know are VERY shaky motors.. the best balanced engines have a grove cut into the flywheel and a mercury
bladder epoxied in. it makes a MASSIVE difference.

[tbzep]

the MP balancer is still a static balancer .. a dynamic one is ALWAYS better.
i have tried getting a wheel to balance equally on both.. and NEVER had any luck.

the fact is.. the wheel spins.. and the best kind of balancing will be dyna beads.. or a very similar product.
HDs ..as you know are VERY shaky motors.. the best balanced engines have a grove cut into the flywheel and a mercury
bladder epoxied in. it makes a MASSIVE difference.

I've never seen a bike balanced any closer than 1/4 oz from a dealership. Static balancing can get that close quite easily.
I've already mentioned that I've never had a balancing issue before and I've done a bunch of them.

[gll429]

I've never seen a bike balanced any closer than 1/4 oz from a dealership. Static balancing can get that close quite easily.
I've already mentioned that I've never had a balancing issue before and I've done a bunch of them.

you are missing the point..
dynamic balance is more accurate even at 1/4 oz off.. due to the fact its measured on a SPINNING WHEEL!
i have seen static wheel PERFECTLY balanced.. then i put that wheel on a electric balancer.. it will show the wheel is out of balance! EVERY TIME!!!!!!!
and here is where it gets nuts.. ever have a perfect ride.. until you hit 95 mph?
you get a bit of head shake.. but if you keep on the gas the shake goes away.. say 102mph... but if you stay on the gas the shake may come back.. 134.. then vanishes at 141
just pulling numbers out of my head there.. as it has happened to me on a few bikes.

[tbzep]

I've never have had that happen on tires I've balanced.

Dynamic machines are better because they also balance off axis. That's fine for cars, but we put our weights at the center line. Most shops doing car tires don't bother adding weights to both the inside and outside of the wheels, so that advantage goes out the window.

I'm not arguing that the machine can't do a better job. I'm arguing that I've never, ever had this issue because static balancing has always been accurate enough to prevent it. My problem is an out of round tire. I was able to visually confirm before I even set up a rig to measure it. No amount of weight will solve that problem.

Edited by tbzep, 22 July 2012 - 11:57 PM.