Reviving this thread wondering where the best (cheapest) place to get OEM friction plates for a CT-1 is? I previously bought aftermarket plates, that cost less for a set of 5 than one OEM plate (as shown in post #13) and am tired of them slipping. Once they warm up they're mostly okay, but can still slip if I don't baby them. Is $100+ for an OEM set the only choice? BTW I already did replace the springs.

Tom maybe your local dealer will give you a better price my dealer is closed this week or I would check dealer cost for you 

That's a good idea, I'll do that. It's not a rush, but now that it's cold it's slipping more than usual, I might as well put some good plates in there.

I bought friction plates for by R5 and DS7 from Yamabits. Prices amazing and and quality seems good too that the overseas shipping seemed worth it, especially if you end up buying all the other "might as well get these too" bits. And shipping faster than Partzilla

yambits.co.uk/ct1b-clutch-friction-plate-kit-p-96401.html

Called the closest Yamaha dealer, $35 per disc! He has to order from Yamaha. Partzilla would be $123 shipped for 5. Makes my slippy $14 set not look that bad LOL! But I do want to put OEM in there. I'm in California BTW. 

Another question: I've been running Yamalube 20w/40 in the tranny because when I began restoring the bike it was the only one I could find that I was sure was good for wet clutches, and I wanted to stick with OEM lube. However, the manual states 10w/30. What are the rest of you using in similar bikes? Might be worth trying that first to see how these cheap plates work with a bit thinner oil. It's due for a change anyway.

In my opinion, aftermarket or not it still shouldn't slip unless there's a problem causing it.
Like those rubber rings left in place, or for some reason not enough spring tension although unlikely.
Or adjustment is to close to the zero clearance & the helical primary gears are moving the shaft sideways a fraction under power & reducing clearance to minus zero [i'm clutching at straws lol].
Or cable is binding [bin it & replace with a nice new free sliding one].
Actuator is dry & binding. Things like that!!, or add a washer under the springs.
Do plates stack up less than the standard thickness. Is each one thinner.

As I posted in this thread last year, the aftermarket plates measured 3.92mm when I installed them. I left the rubbers out, and am sure both the lower adjustment and lever are good, with the proper slack in both. Also the mechanism in the left side cover is lubed and working well. When it's fully warmed up, it's pretty good... I always planned to try 10w/30 oil, as the manual calls for, but have never found any I was sure was okay for a wet clutch. Even now, I can't find any 10w/30 online that says wet clutch for sure. Yamalube only seems to come in 20w/40 now. BTW the old springs were a bit under spec, but I put in new ones that measured above spec. If I could find some 10w/30 wet clutch oil to try, that would eliminate that possibility.

Hey, here's some!

www.amsoil.com/p/amsoil-10w-30-100-synth...CTQT-EA#pills-home_2

Im not up to date on whats going on without refreshing my memory but hope you get it sorted. My 50 year old clutch on my AT1 [now 175] slipped like crazy but came right after a good thrashing [had a boring video up here somewhere ages ago]. That surprised me but doubt my luck will last.
Just to show how good "a good clutch" is, [or how stupid i can be at times] i ran EP90 diff oil in my DT1 through its MX racing life after i broke third gear [big weak coarse tooth in "68-"69] so thought cushion it as much as i could with thick EP oil.
Was going to extremes i know but clutch never slipped although dragged a little on cold winter starts untill warm but never broke another gear.
Anyway--don't follw me--i'm lost lol.

Found this locally. I'll try it tomorrow, and see what happens.

www.oreillyauto.com/detail/c/lucas-oil-p...0-1-quart/luc0/10708