It is fun to dance but not at 70 mph

[MikeZ06Allen]

Ok last weekend I opted to replace both front and rear tires. The rear was pretty much shot so I decided to step the size down to help reduce the ride height a bit. I have a 28" inseam so the VR can get a little top heavy for me. Anyway I digress; I went with a Shinko 712 (100/90) up front and a Shinko 777 (130/90 6 ply) rear.

 

BTW, thanks to this great forum I was able to get both front and rear wheels off (kneeling). While the wheels were at the dealership getting tires mounted and balanced. I was able to completely service the rear diff and grease everything up. Man those splines were dry as a bone and rusty (explains the roaring noise). I also repalced the brake pads while I was there. Once I got the wheels back I replaced the seals and bearings in them too. All in all, not a bad way to spend the weekend if you ask me.

 

I have to say I am absolutely thrilled with the low speed handling however at anything above about 70 mph it seems the front starts to shimmy around a bit. I originally had too much air pressure all the way around so I dropped it 4 lbs in the front and 2 lbs in the rear. Bringing it to 36 front and 45 rear, even at that pressure I am still getting the shimmy motion (kinda like being buffeted by a strong crosswind) even when there is nothing around but me and superslab with no breeze. I have since dropped the rear shock pressure and made sure the front was as close to zero as I can get (progressive springs installed with heavier oil). I will see if that helps. If not I am totally puzzled.

[dingy]

I am fairly sure you set the preload on steering head bearings by manual.

 

That leaves a few other items.

 

Fork cross brace support (Condor has a nice upgrade)

 

Worn bushings in the forks.

 

Rear swing arm to frame bearing torque.

 

Gary

[Marcarl]

Try going 32 in the front and 38 in the rear, or maybe 40 in the rear.

Could also be steering head bearings,,,,, too loose is no good and too tight is downright nasty, but just below too tight is just right.

Also the procedure for mounting the rear wheel is important, loosen the 4 bolts hold the pumpkin on,,, just loose not off, install the rear wheel and snug the axle, then tighten the pumpkin and then torque the axle.

JMT

Carl

[abnormalwon]

Hey, may want to recheck your pressure. I had a set of shinkos on my v-strom and had issues with the rear which I had set at 40 or 42 (from the suzuki manual)psi. When I spoke with the Shinko rep about warranty he inquired about pressure and told me I was way high, that there was pressure limits posted on the tire (which were like 33 rear) and that I should use their recommendations. They still honored the war. and sent me a new tire but I reduced the pressure as they recommended and all has been well since. Shinko was the first manufacturer of MC tires that I know of to have pressure settings on the tire (like car's).

 

All the best,

 

Norm

[MiCarl]

Did you really go to a 100/90 on the front instead of a 130/90, or is that a typo?

 

If you really put a 100/90 on it's going to feel a lot less stable at speed. Not to mention the wheel is way too wide for the tire.

[MikeZ06Allen]

Hey, may want to recheck your pressure. I had a set of shinkos on my v-strom and had issues with the rear which I had set at 40 or 42 (from the suzuki manual)psi. When I spoke with the Shinko rep about warranty he inquired about pressure and told me I was way high, that there was pressure limits posted on the tire (which were like 33 rear) and that I should use their recommendations.

 

All the best,

 

Norm

 

Actually, the rear max pressure for this tire is 49 psi so I am well below the max pressure but I may lower it a bit more and see how it feels.

 

Also the procedure for mounting the rear wheel is important, loosen the 4 bolts hold the pumpkin on,,, just loose not off, install the rear wheel and snug the axle, then tighten the pumpkin and then torque the axle.

 

I was not aware of this procedure for torqueing down the rear. I will redo the tightening process to make sure I do not have anything binding.

[MikeZ06Allen]

Did you really go to a 100/90 on the front instead of a 130/90, or is that a typo?

 

If you really put a 100/90 on it's going to feel a lot less stable at speed. Not to mention the wheel is way too wide for the tire.

 

As I understand it the stock size is 120/90 so I figured stepping down to a 100 mm would not adversely affect the handling as it equated to about 3/4 of an inch in overall width at the tread, not the bead. As I mentioned, the handling is great except above 70 mph and I feel far more stable on the bike up to that point. I still have a perfectly good Metzler that I may put back on and go back to tippy toes.

 

Changing the rear shock pressure and rebound rate helped so I think I am heading in the right direction. I noticed some vibration in the handlebars this morning so I will probably check the steering head this weekend and take the wheel back to the dealership to check the balance. (And drool some more over the 2011 VMax:no-no-no: = wife)

[MiCarl]

You're correct, the stock size is 120/90. Typo on my part.

 

You're still going to find that the 100/90 is more inclined to follow any contour to the road. The wheel is going to be too wide for a 100 width tire which will make the profile flatter. Not sure what effects that will have for you.