Having a problem with the return on my CT. When I had the cover off to address
some clutch issues with it I noticed that the snap ring on the kicker mech. was
getting into the boss of the case. Looked online at the parts and it didn't show a 
shim to protect the case. Did a little digging and found the service manual does
show a shim in that area. Found a part number somewhere for the shim and 
installed it and when the case is tightened up the kick starter would not  return 
without a little help. Thinking the return spring may just be tired after 50 years,
I got a new one and installed it. Still no luck. Shim I have measures .96mm. I am
guessing I need one about .75mm to get the clearance I need. I was wondering if
someone on here might have an old microfiche for a 73 that would have the old
part number that I could research. Thanks, Dennis

Did you put a new oil seal on the case?

Yes. I don't think the drag on the shaft is the problem though.
If you loosen the case bolts the kicker will return ok. Shim I
have measures 0.98mm. I think if it was maybe 0.75-0.50mm
it would work.

Had the same issue with my 81 DT175, kick start not returning without a little help, was told to double stack the case gaskets, that did the trick.

This thought had entered my mind. I may end
up having the boss touched up a bit.

Only shim part number I can find is shown for the earlier models and is listed as 1mm thick.

McMaster-Carr probably has something if you go by dimensions? 20.2mm ID x 28mm OD x 1mm thick is what parts book in Tech Library shows. Might convert to inches and see as well.

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What I'm about to say may seem insignificant to some, but I was actually taught this in one of my mechanical class's at AMI (American Motorcycle Institute)

Most circlips, e-clips, (and washers as well ), are stamped out of sheets of metal, and will have both a rounded and sharp edge on them.

If something is going to be directly rubbing or turning against the clip, the rounded side should be installed facing that part . .  and, if something is going to be rubbing against both sides, an additional washer should be used on the sharp edge side of the clip. 

This is exactly the procedure you will find between gears in most transmissions.
It may be that all you need to do is turn the clip around. 

If the softer aluminum case shows abnormal wear and/or gouging, you can bet the sharp edge of the clip was facing the damaged area at some point in time.
 

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I looked at McMaster and could not find what I needed. (rare) So I ,ahem, adjusted the kick starter boss to accept the 1mm shim that I found. Working as it should now and the endplay in the shaft if pretty close to zero. That should also help keep the rear spring on the kicker gear from coming out of the groove, hopefully.

I agree with the post from Enduronut about clips and snap rings. Also found out when I was doing a lot of transmission work on fork lifts that the flat side of your clips need to go away from the gear thrust if there is any. Thanks guys for the help once again. Didn't notice 'til today that the rear wheel on the CT doesn't have any rim locks on it. One more thing I have learned. D