Shim needed?

[rd400pi]

Hey Penton People,
  I am putting 520 chain on my 74 250 HS.  I have reviewed all of the posts I could find about 530 to 520 conversion.  Lots of agreement about doing it but, only a passing mention about shimming the counter-shaft sprocket.  So what is the concensus?  Shim or not to shim?  That is indeed, the question!:D

  Mike "miles to go before I sleep" Husted
  Reunion ride or bust!

[DKWRACER]

Mike, in a humble opinion, the CS sprocket may already be OC...try a dry fit and see....
Adios!
Tom

[john durrill]

Mike,
 Check with Barry Higgins. He knows how wide the shim should be and how you should measure to be sure. Its something like 1 or 1.5 mm.
 Seems to me we used one of the  shim's that had teeth on the inside from the transmission  as our shim back when. Its been a long time
John D.

[rob w]

Mike,
 It occured to me, if you have a '74 with a full length side cover and an enclosed C.S. area. Then you probably don't have a "crank case protector" plate that I'm thinking of (late '74), there's the older style "curved" crank case protector.
 In that case you have more tolerance to play with. Like before, put the boss or raised shoulder on the sprocket to the inside, and have it shimmed out until just enough of the splined shaft is showing that you can get the lock washer on, and that the nut tightens.

Bob

[tomale]

Miles to go Mike,
I just went out to the shop to look at the CS sprockets. I looked at the stock one (530) and then the replacement(520). I would imagine that it would indeed make a difference who makes the spockets but at lest on mine, there was no need to shim it because the overall width of the sprocket is the same. the positioning of the teeth has been moved to accomadate the newer smaller width chain, thus keeping the chain in line with the rear sprocket. If I had put any shims behind the sprocket I would not have been able to get the lock washer on.  If the teeth in the lock washer does not mesh with the splines the washer will not do its job. ON some bikes it does not matter too much how wide the sprocket is but on the KTM it really does. To answer your question I got the sprocket from AL. B. I did my convertion last year and it has been holding up just fine. I am still running a (530) chain on the 400 but that is because I had a brand new (very expensive) rear srocket and figured I might as well us it because I would never get out of it what I had into it. I had ordered it and they messed up and sent it with 530 teeth. I had just gotten the 400 and figured that since It was going to need a new chain and sprockets I might as well keep it. besides having a heavier chain on the 400 is not as big of a liability. What do I need with even more power. You should see the looks I get when I ask for a non 0 ring 530 chain. They look at me funny and then say why would you want such a large chain. So I tell them it came that way stock. then I really get some funny looks. Come to find out the 530 chain is use mostly theses days on street bikes. Did you know you can get a 525 chain as well. I have a rear sprocket that size. NO idea what I am going to do with it.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
78' 400 MC5

[Mike OReilly]

With all due respect to "Rob W". what you are shooting for is to have the front sprocket line up with the rear sprocket (and of course first check you rear axle alignment). I used a straight edge (or a yard stick) to do this. And shim as necessary. I used shims that I picked up at the Ariens lawnmower dealer actually.
It's not rocket science, and as long as you're close, it will be fine.
Good luck at the ISDTRR. Watch for Bob on the MX tests, he's real fast once he's out of the woods.
Mike

[firstturn]

To add to what Mike and others have said this isn't high science.  Just get a yard stick and measure the rear axle from the piviot bolt(on both sides) and be sure everthing is "square".  In other words - rear axle is equal length on each side from the piviot bolt.  Then line up the rear sprocket with the front sprocket.  Then put shims in (the front sprocket)to make them line up.  Then you can start all over again with the chain on and put the proper adjustment for chain tension or lack there of depending on the bike.  I hope this makes sense.

Ron Carbaugh