Shock body tolerance variance? 06 KX 250F

[MXTex]

We're working on a couple of 06 KX250F's for a local Pro. One is his practice bike while the other is his race machine. Anyway, one of the shock bodys clearly has a smaller inner diameter. I've swiched pistons and seal heads and the shock body is definitely the differing factor. The deal is the resistance to movement created by this difference is significant, in a bad way. I mean you can barely stroke the shaft through the body without gritting your teeth. Additionally, the tight shock requires much less spring preload to meet numbers than the other shock.

So with all this said, is this a normal occurence? I would think that Showa manufacturing tolerances were better than this. With it being this tight, there's no way this shock can operate correctly. I'm wondering if a different seal band can be put on the piston or if this is going to have to be solved with the shock body as the focus. Perhaps removing and re-applying the inner coating?

Any feedback would be appreciated.

 

[blackjack]

Have you measured the inside bore with a set of mics to determine whether one or the other is smaller? There is a fair bit of slop between the piston and the bore normally but you would have to measure both to see what the clearance is. Its possilbe that one bore is out of round or tapered due to machining but you'll have to measure it to find out. If that's the case a new shock body is in order.

 

[bclapham]

i was told that they deliberately set the kxf shock up on the tight side to make the piston seal better.

 

[MRW]

Sometimes the o-ring under the piston band wears/flattens out causing less drag and possible leakage/blow-by during shock operation. I saw it on an old RT video in my gold valve days. :cool: