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Discussion Starter #1
Hey guys, I finally have an issue I couldn't solve by searching, so I guess it's time to register :).

I recently mounted some S22's on my 2012 gsxr 600 and went for a ride with some friends. When I got back to my garage I was doing a quick check to see how the tires were scrubbing in and saw some weird pattern on the front.
Rear looks to be nice and even, but the left side of the front has almost a scalloped pattern whereas the right side looks to be pretty normal.
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The only symptoms I can think of is a slight vibration at about 75mph which, on our roads, may just be the road.
Leaning right felt fine, but leaning left felt a bit off, which at first I thought was just me getting used to the tires.
But after seeing that pattern I'm scratching my head.
Any help is greatly appreciated.

Z
 

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Discussion Starter #2
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Well after a day at work pondering the situation I got the bike out in day light and it's not as terrible as it looked last night.
The pattern I was seeing looks like the discoloration outside of the scrubbed in section. The scrub in looks pretty good actually.
I may have to tweak tire pressures a bit since it has the beginning of some track boogers from only a short bit of carving curves a little on the fast side.
Guess that's my warning to tone it back a little on the roads. I dont want to end up as a statistic..
This thing has been a whole new beast compared to the old Hondas I had.

If anyone sees anything out of the ordinary feel free the let me know though.

Z
 

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check your tire pressures after about 20 minutes of good railing, if you have a lazer temp record the temps as well..

many things can contribute to cupping, pressure, rebound, spring rate, defective compound..

have you sprung for your weight and set sags?

might want to remove wheels and check that balance again, make sure its nutted, you lined up the DOT with the STEM right? keep an eye on it, hopefully you can dial it out so yo get full wear out of them..
 

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Discussion Starter #6
I have not swapped the springs out, but have set the sag.
Front is at 1.25", rear at 1.375"
Rebound on forks is set fairly slow honestly to tone down the pogo. Compression set at the spec in the manual, don't recall the turns. Rear set to match the front compression and rebound.
Previous tires were PR3's, and these S22's are quite a bit softer feeling compound to me, so I guess it needs to be dialed in a bit better.
I am going to keep an eye on air pressures during the next ride and see what it's climbing to and planned on checking tire balance after the first couple of hundred miles to see how it shaped up. Riding normally the bike is super smooth, so I don't think balance is way off, but it may be off a little since I used my manual balancer.
I was leaning toward it looking like cupping, but it being on the left side only has me puzzled still. I'll be watching it to see if the pattern clears up under normal riding conditions also. That particular ride was a bit more aggressive than I would usually hit the twisties.

Thanks for the replies.

Z
 

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That looks like a rebound wave since the peaks are pointed against rotation direction, but I'd expect to see it on both sides. Reading tires from the street isn't the same as reading from track since you never see the same loads on the street. Maybe the tire just isn't perfect from the factory. Does it feel bouncy turning left?
 

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Discussion Starter #8
That looks like a rebound wave since the peaks are pointed against rotation direction, but I'd expect to see it on both sides. Reading tires from the street isn't the same as reading from track since you never see the same loads on the street. Maybe the tire just isn't perfect from the factory. Does it feel bouncy turning left?
No bouncy feeling anywhere.
The bike turns smooth, and once you get set in a curve it doesnt walk or wobble at all.
I did notice while spinning the wheel on stands yesterday that the rubber had a little runout as compared to the wheel. Not wobble, but runout on the axis of rotation.
It maybe just slightly out of round from the mold. Not a totally uncommon sight over the years.

The rebound thing has me curious though since I have not found any tips on what rebound causes aside from at the start or end of a tread block.
Would the wave be from too slow of rebound or too fast?
 

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Could be either. The wave just indicates oscillation.
 

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Discussion Starter #10
I made some adjustments and opened up rebound front and rear, and lightened the fork compression to get a little more movement from the front end.
After a ride over the local mountain twisties at a normal pace the wear area is scrubbed in normally. Those wave marks didn't look like they had freshened up any, so it may have been the forks "packing" like running too slow of rebound on a dirt bike through the whoops. I will keep an eye on the tire and if the pattern appears to come back I will update.

Thanks for the input guys, it got the wheels turning up stairs. Been a few years since I've tackled this kind of thing. 😉


Z
 
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