I'm fairly meticulous with my track bike so I'm a bit confused. I went over everything this winter to make sure that I would be ready for another great track season (suspension rebuild, new tires, ect.) At the track this past weekend, I noticed that anything over 90mph I get a serious vibration from the front end. At lower speeds the R1 feels nice and smooth, but trying to get up to speed and then on the binders from over a hundred will almost blur my vision from all the vibration. My first thought was a warped rotor, but they checked out fine. Second idea was that the front wheel wasn't balanced correctly, but it was spot on aswell. Could the new Pilot Power 2ct be a bad tire? Suggestions?
First check that the tire bead is seated evenly all the way around. Second, check for loose steering head bearings by sitting on the bike and rocking it front to back while holding the front brake on. If they are loose you can feel, and as severe as you describe, hear a clunk in the steering head. Third check the wheel bearings. A tire this bad is extremely unlikely unless it was damaged. For instance, run over by a fork lift in the warehouse.
Just out of curiosity, what do you guys use to check your rotors? Maybe I need to double check them with other methods.
You can check runout as is done here: http://www.geocities.com/sl_mille/runout.html I have also had to clean the buttons on previous bikes and if the buttons get seized, the rotor doesn't float and you get hot spots and warpage. Also, make sure your caliper pistons are fully retracting, sticky pistons have been known to warp rotors. John
Dial indicator normally .1mm is tolerable. Rotors usually only cause problems when the brakes are applied. I notice you did a "suspension rebuild", anything wrong here, such as improper assembly of the shim stack, damper, wrong oil level or no oil, ( I've seen it)missing bushing,missing parts, can cause vibrations. I've also seen 18mm ID bearings on a16mm axle and axle spacers that were MIA. Re-check all your work and that done by others.
It was a small re-build. Changed springs, new seals, and fresh oil. Oil level was checked and double checked. So I don't think that the forks would cause it, but Ive been wrong plenty of times before.
If it is the loose. Will tightening the steering head properly do the trick, or should I be inspecting the head bearings aswell?
Assuming they are greased, adjusting should be all that's needed. If they feel notchy after adjusting, then you'll need to replace them.
Did the tires sit all winter ? Or when were they first used I have never seen a defective Pilot Power .
How was the front wheel balance? Did the shop use a computer balancer? or did they use a static balancer? Because it happen to me A few yrs. ago I had a R1, first track day of the year I had new tires put on the bike I did the work my self at a local powersports shop with a computer tire balancer. At the track I could not go faster then 90 due to a vibration. The next day I took the tire back to the same tire balancer and the tire check out OK. but i noticed the tire was out of round. I called the manufacturer and complained. The manufacture said they would take back the tire but they wanted me to get the tire to a rep. the next weekend I took the tire to summit point raceway were the rep was and he put the wheel and tire on a static balancer and balance the tire. the next day we had a track day on the main course and i did my personal best lap time. So hope this is good info for you.
If you run out of things to check on the front, then start on the back. Motorcycles and less often cars have a way of transfering the vibration from the end that causes the problem to the opposite end. Think of all the times racers have felt a tire chunking on one wheel only to have it changed and discover it was the wrong wheel.
Agree with Desmo, vibrations are funny things, and so is transmissability. I would check both front and rear balance straight away and on a different machine. Curious, does your vibration frequency seem to increase with vehicle speed, i.e. tire rotation? Usually tire balance yields a first order vibration, meaning that the impulse is felt with every one revolution of the tire (again could be front or rear). If this is the case, it's a stronger case to devote the time to re-check the balance on another machine. Also, relative to bead seat... If that was the problem, that during the balance procedure your bead was not fully seated on the rim (assuming the balancer did it's job), then once you drove the bike and put some force and heat into the tire/wheel the bead would have seated. After that happens the balance would be off since the balancer did it's job when the rubber was in a different position on the wheel. Bottome line is, I would re-check the balance to be safe, it doesn't take much time and it's an easy cheap fix. Once you rule out the easy cheap stuff, then head for the big or more expensive ideas. Good luck!
By the way, the tire uniformity could be an issue, which would most likely also cause a first order vibration, i.e. felt with every one revolution of the tire/wheel assembly. Think of it like this, the tire is very similar to the spring in your shock, only it has a different spring rate (tires are a part of the suspension function right). if the tire has good uniformity then while it rotates it does not cause a force input to the forks. Now assume the tire has a very slight bulge in it. When this tire rotates, every time the bulged section comes into contact with the ground a force is input from the tire/wheel assy to the forks and could be felt by the rider at the bars. While a bulge is not a uniformity type defect (obviously that type of defect is an off center mass), it still creates a once per revolution forcing input from the tire as it rolls like a uniformity issue could. Uniformity is normally a defect found due to tire construction. My point for bringing this up is this... if the uniformity was bad, the balance could still be done properly and the vibration may still be felt by the rider. You can balance out off center mass, but if the springrate is the issue, not off center mass, you cannot balance out that type of defect. That being said, Michelin makes a darn good tire and their construction processes are very well controlled when compared to the competition so it's unlikely that you have this problem, but it could be. One quick way to tell, change nothing else, but swap the tire and rebalance the new one and take it for a ride. That's my 2 cents
Were you getting a head shake too and not just a vibration? At one time I had a front tire which required a single ¼ ounce weight to balance the front wheel and the mechanic put it on the outer edge of the wheel. I experienced severe head shake on the big end of the Pocono East's back straight and it got worse as the speed increased. After trying many things I finally noticed this in the afternoon and moved the weight to the wheel's center line and the head shake disappeared. I also had a true vibration from a front wheel which could not be removed by rebalancing. As the tire was past 75% I chose to discard it. Possibly an internal defect. This particular tire was a Dunlop 208GP and as the speed increases the Dunlop tires grow (this is documented that Dunops grow more than Pirelli and Michelin) and I thought that perhaps the cords were damaged and the tire was growing uneven and that was what was causing the vibration.
wpasicznyk, was that a stick on wheel weight used to balance your tire and when you moved to the center did you use the same weight or a new one?
It is vibration rather than head shake. I checked the steering head yesterday and set everything to spec. Took it out for a test ride and it's still acting up. I'm going to check and re-balance the front wheel this afternoon. Hopefully it's as simple as that.