All -   I had clutch slippage under load at higher RPM on 69 At to CT1 (top end) so went to install new clutch discs - has slipped since I had the bike and haven't put many miles on it (way more hours working on it than riding).  The existing discs had over 4mm of material but I though perhaps the  PO may have put the wrong oil in it so I'd just go ahead and swap them out.  Now I've gone form slipping at high RPM to total slippage - basically the clutch is not grabbing to make the bike go.  I backed the rod adjustment beside magneto way out and I can put it in gear without even pulling in the clutch and it goes nowhere.  

Before I took humpty apart again I thought I'd check with the experts to see if there is something simple that can  be done.  Note:  I did NOT soak the new clutch in oil prior to install - figured it would get plenty of a bath in the cases.

Thanks for your wisdom!

Slippage in NC

I doubt theres a simple answer & ya gonna have to go in 'i think'. Check the stacked height of the new plates if measure thinner & the same number of plates. Then look close when assembled to see if the pressure plate is running into the splined hub before compressing the plates. At the moment its about all i can think of. Cheers--or tears as the case is.
One more thought but not maybe not directly linked to the problem--keave those rubber plastic ring things out. Hang them on the wall.
On second thoughts--ok third thought--its pos the new fibers 'if aftermarket' don't have room underneath for the rings & if fitted they'll just hold it from compressing up althought might look like its trying to. Just guessing as i've never experienced that particular problem.

This bike has the rubber o ring type material under the discs. I've heard some folks say they should be removed but I left it as it was. Any thoughts on that would be appreciated as well in case I have to pull it apart again. Thanks.

sorry think were typing at same time. above should cover that cheers.

Did you measure the new discs?  The exact same shape discs are made in different thicknesses.  Later bikes had only 3mm thick discs but they look the same otherwise.

 

Just went thru that exact scenario with my CT1B. Ordered aftermarket friction plates that were listed to be correct for my bike but as MarkT had suspected, they were for the later 175s and were thinner than the 4mm spec for my bike. I could tell as soon as I finished assembling the clutch because the plates were loose in the basket even when the pressure plate was bolted together with the new springs. I shelved them for future use in my DT175C and coughed up some serious cash for yamaha plates. All is well.

Just a thought but did you change out the steel plates?

Thanks for the feedback. Woke up in the middle of the night thinking about this (these bike issues do that to me). I didn't measure the new clutch plates but I know they are thinner than the 4mm ones I removed (which I did measure) as I had to release tension on the clutch cable after bolting up all 5 plates (clutch handle probably took up 1/4 or more slack from cable). These were "cheap" ones I bought from amazon that were amazing marketed to fit about every early yamaha ever made:-) they did fit perfectly in the basket but clearly are thinner. I was thinking in the night the rubber o ring things may actually be thicker than the clutch plates and keeping them from biting as well. The existing metal plates barely looked worn, as did the springs and clutch plates - it's likely PO had this replaced when a CT1 crank was installed less than 200 miles ago. I found a 3/4 empty bottle of lawn mower oil in with the parts that came with the which I'm thinking may have ended up in the case..

So it looks like I'll be going back in. How about this?.. 1) remove o rings, bolt back up and see if plates are tight per Schu's experience. If tight will see if it's grabbing by trying to roll in gear before re-assembly, and/or 2) Clean possibly wrong oil from previous plates (they look good, over 4 mm thick), remove o rings, reinstall and see if engaging (they were working before, just slipping under load) in hopes that it was just the wrong oil. if neither works then I'll buy some new plates. Heck, it's only labor and sometimes 3d time is a charm:-/

Hope to get into it today or tomorrow and will report back.

Thanks for the assistance!!

Also make sure you install friction first and stack should end with a steel under the pressure plate.

(Parts diagram is wrong, engineering diagram in service manual is correct.)

What i'd do, being tight as a fishes a@#e, is Just go get another steel from the local wrecker & add it to any steel--say the middle one--& it'll probably bring the stacked height up to about safe to stop pressure plate running into the hub before 'compressing'--if that makes sense. Also as think Mark said--steel in last for pressure plate to bare on. Reason being the P-plate isn't splined so is taking the drive on the spring posts.
& as i & other have said--toss those rings out.
Just out of curiosity, measure the inside id of the new compared to old fibers to see if they allow for the rubber rings.