Sorry to hear about this because I bought the same springs and plates that you bought.  I haven't installed them yet, but will soon.

Schu, I'll let you know how it goes with the 10w/30. I've already drained the 20w/40, but need to get a new drain plug gasket tomorrow. To be honest, these 5-for-$14 friction plates have been okay overall for the 2,000+ miles I've put on them, but when it begins getting cold again during winter, it takes them a while to grab really well. Once the crankcase is good and warm, I hardly notice any slipping. BTW, I did not rough up the old steel plates when I installed the friction plates, which I should have.

Tom, I have aftermarket friction plates in a all my 175s and I don't have any problems with them slipping and my bikes certainly get used.
The CT3 I recently bought slips a little when cold, but that clutch was installed by the previous owner, so I don't know whether he gave the steel plates any attention, something I'll look at when I get a chance.
When I replaced my clutches I made sure the steel plates were flat and gave them a good going over with wet and dry to remove any rust etc.
Let's not make this an oil thread and I'm not in the US so info might not be that useful but I use Halfords (a UK autoparts store) 10w-40 4 stroke Motorcycle Part Synthetic Engine Oil. Key part of the description is "Engineered to give the correct characteristics for motorcycles with wet clutches".
Hope you get it sorted.

It's not likely the oil if for wet clutches.

On the oil weight, there was some sort of "mandate" years ago that oils for passenger cars and light duty trucks be "energy and resource conserving". A 10w30 oil is generally used in the "light duty vehicle" class.

It's not that they can't make a 10w30 oil that isn't "energy conserving" but it won't be given the SAE rating (i.e. SN, SM, etc.) that meets modern car specified requirements... and no decent shop is going to use oils that don't meet modern specs. So obviously that oil is now only marketable to specialty markets like motorcycles with wet clutches. Which makes them more expensive.

10w40 oils generally fall into the heavy duty truck class and don't have the same energy conserving "slippery additive" requirements that can allegedly make a clutch slip... at least yet. I'm pretty sure that's why many of the standard "wet clutch" rated oils (even Yamalube) are 10w40 and not 10w30... most modern cars and light trucks haven't specified a 10w40 in many decades so the oil company doesn't lose a big market share by not adding the slippery energy conserving additives.

Had an old farmer tell me about John Deere Hy-Gard as it does state for wet clutches also. Have been using it and seems to be working fine.


shop.deere.com/us/jdb2cstorefront/us/jdb...-(1-Gallon)/p/TY6354

Honda has 10w-30 JASO MA/MA2 oil for wet clutch’s 

It was the oil! It's fine now with Lucas 10w/30, designed for motorcycles with wet clutches. Of course, when cold it slipped a bit in 3rd when goosed, but after about 3 miles warming up, it was fine. Before, if I was running 40 MPH in 5th and goosed it, it would slip, but not now. I wish I'd found this oil earlier, but am VERY glad I don't need to spend the money and effort on rebuilding the clutch now. 

imgur.com/5O0GdOX

Has anyone else run ATF in their transmission? Since your clutch is questionable it might be worth trying. My experience with ATF in my road race bikes was highly successful, your results may vary.

I've heard of running ATF in 2 strokes trannys, and it probably does work better with a wet clutch, but provides less protection for gears. Mine is fine now with the Lucas 10w/30, so I'll leave well enough alone.

This is what I was using. Maybe just the slightly increased viscosity made the difference in this slipping more?

imgur.com/k2RiqZ9
imgur.com/0hx9yGy

BTW, when I began working on my CT-1 it had 360 miles on it. Just back from a ride, and it just landed at 2500.0. However, I've been neglecting to check the battery level, and after a stop during the ride it stalled when turning the lights on at idle. Knew right away the battery was low, and when I got home and checked, it was. Barely below the lower line, so no damage. Just a reminder...