Chain Rubbing crankcase problems.

[grtsctt]

Also posted in Long Term Chain Care.

I second the question posed by member SLEEZ concerning case scoring due to tight 520 o-ring chain clearance at countershaft sprocket.

SLEEZ states,
"I'm also due for a new chain, definitely an O or X ring. Did any of you have to get a spacer for the front sprocket to prevent the chain from rubbing the case?

I ask this clearance/spacer question also as i bought a junk K500 with sotck Countershaft 14 tooth sprocket that had o-ring 520 chain that ripped into case above sprocket from 10 oclock to 2 oclock respectively.

I think you must run a 15 tooth sprocket if you go with a 520 o-ring chain on K500 to avoid case-chain interference/rubbing??
Does anybody have rubbing marks?please advise

I wish to run same o-ring type chain on my 94KX250--Do I need to use a spacer or a 15 tooth sprocket to avoid interference??
Please advise--

PS I dont think there is room for spacer as no play in C sprocket, but only option is to mill sprocket or flip it if it is offcenter type.
Please answer SLEEZ and My Question and advise.
Thanks

[redlined_KX500]

I had exact problem on my K5 until I replaced spacer/o-ring.  Rubbed case slightly on top half as well.  I used enough JB weld to smooth surface and check every other ride now. 

I also just put a new spacer in periodically cause they're much cheaper than cases.

1 yr later still no new marks on case

[KXcam22]

If you look in my gallery you will see some pics of a mod.  I found a shim to go on the back and cut the same amount from the front so the sprocket would fit.  Not a mod for everyone but very successful. Cam.

[grtsctt]

Question for Redlined-Kx and CAM
What spacer?
What size c-sproket/how many tooth sprocket were you using?
Where did you get spacer/how thick?
You must have done what cam/KXCAM22 did as this is only way.
Will my O-ring rub if I use a 15 tooth sprocket??
Cam, did you have to mill off some of your sprocket in same amount as spacer?
Cam,Where did you find spacer, and how thick?

I will look at Cams galery for his fix, but i don't know if I will have a problem yet.

Thanks,
Scott

[redlined_KX500]

I use both 14 and 15 on countershaft.

Spacer and O-ring directly behind sprocket. Buy a good dental pick to get o-ring out.

In my case the spacer was worn and oring was damaged from grit/sand.

Cam's fix is great and will fix any related problems regardless of CS size..

[KXcam22]

My original spacer was a drilled out (to 1") thin washer about 0.080 thick.  Today I picked up a spacer for my new CRF450 to do the same thing.  It is called a VB100 valve spring shim (chev 350 I think). They are available in 0.015", 0.030" and 0.060"and measure 0.954" ID.  It fits the KX500 nicely.  I got a used 0.060" one for free from a local car engine rebuild/machine shop (he had a big box of them).  On the KX500 you will need to get a matching 0.060" pocket cut in the front face of the sprocket so you can install the circlip that holds the sprocket on the shaft. That is what I did. Hope this helps. Cam.

[Hillclimb#42]

I use a 14 and a 15 with no rubbing. I replaced the spacer and o-ring also. It is behind the sprocket. I did get damage from previous owner running a 12, for some reason. I always run 520 o-ring chains. Are you sure damage is not from stuff getting wrapped around sprocket? My guess is the spacer, since that is its main job.
 Is it possible that you have like one link that the rivots are sticking thru too far possibly done during chain breaking steps?

[grtsctt]

Thanks bros.
i have no rubbing as i have not run it yet with new o ring chain yet.
What is this o ring behind the sprocket you are talking about?
The bike does not come with a spacer or o-ring.
I understand Cam, and this is what i will do if it rubs, but I do not understand what o-ring the rest of you are talking about---you do not need and o ring if you are also using a spacer??
Unless you mean steel o ring? which is a spacer, then you mean 2 spacers.
JT sprockets says some sprockets are made offset, so you can flip them over to space the chain away from motor.
If you explain o ring and it works in conjunction with metal spacer, where do you get o ring and what is it made of (why do you use rubber o-ring for spacer), and where do you get spacer, and what is it made of/rubber?, and i assume you mill sprocket like in Cams nice pic??
I guess after one ride i will remove chain to see if it rubbing or not, but I suspect the 15 tooth will keep it off case.
thanks

[KXcam22]

grtsct,
   Behind the CS sprocket is a spacer that extends into the seal and hits the bearing behind the seal.  It provides the sealing surface rather than the surface of the Counter shaft.  To prevent oil from leaking out on the inside of the spacer (since it hits the bearing) there is a thin o-ring that sits between the face of the spacer and the face of the bearing.  After taking off the CS sprocket, yYou can pull the spacer out and then the thin oring.  If in doubt, look at an online microfiche.  Hope this helps. Cam.

[blueoval]

Cam, you mention using a valve spring shim and in your gallery you used a 316SS washer and then cut the CS the appropriate amount.  I need to do this mod or something else because the 520 O ring chain with 14 CS is rubbing the case - not much, but I don't want to have anxiety about this situation when it can be fixed.  Since some time has passed since the previous posts I am wondering what kind of conclusion(s) you have reached regarding which of all the fixes you would do?  Any and all input would be greatly appreciated.    Thanks in advance.    B.O.

[Polar-Bus]

I have a Regina ORN gold chain, and I do notice a very slight about of rubbing on the case. I think a lot of the rubbing circumstances revolve around the link plate thickness of different chains. My Regina ORN is one beastie of a chain !