Good clutch plates

I need a good set of friction plates for my at1 vintage race bike. I put a 175 reed cylinder on it that’s been ported and it runs really strong, I’ve been struggling to get the clutch slippage under control. I’ve put new eBay plates on it, added an extra metal plate, sandblasted all the metal plates to rough them up and shimmed the springs (which measured within specs) another .040”. I only have a problem when you really get on it, most of the time it’s ok. I see that vesrah-209 plates are recommended but can’t find them anywhere. The eBay plates were pretty cheap, around $30 so I’m not terribly surprised.

willlgord wrote: I only have a problem when you really get on it, most of the time it’s ok.

Maybe you're just not hooking up. Are you roosting the guy behind you when it slips?

Schu wrote:

willlgord wrote: I only have a problem when you really get on it, most of the time it’s ok.

Maybe you're just not hooking up. Are you roosting the guy behind you when it slips?

I thought of this too. A month or so ago I was on a ride, sort of felt like my clutch was slipping. Reality was the rear tire was 'floating' over the loam and spraying/roosting the guy behind me. Feels like the rear end is dancing; Full Tilt Boogie.

I use EBC clutch plates, they seem fine.

I use the Barnett Kevlar plates. Night & day from stock

I have had good luck with Barnett, too. I recommend Barnett springs, too because they have a higher spring rate than stock.

You can try using Yamaha 401-16321-00 friction plates if you get rid of the rubber rings underneath the frictions. That will give you more surface area with the steel clutch plates, which could help especially with stronger springs.

JayB wrote: You can try using Yamaha 401-16321-00 friction plates if you get rid of the rubber rings underneath the frictions. That will give you more surface area with the steel clutch plates, which could help especially with stronger springs.

I would caution against getting a later superseded number that the 401- number goes to!

Thanks for the suggestions, my clutch is definitely slipping.....not roosting! It’s time to get ready the bike ready for the 2021 race season, first race is in the middle of March. I’ve got a couple other things to sort out but nothing serious.

Here is a picture of the original Yamaha replacement part for an AT1, which has space for the rubber ring underneath:


Versus the 401-16321-00 which was used on early MX and YZ 125s, which has no room for the rubber ring:


Hopefully the difference in friction area is apparent.

The 537-16321-00 are still available from Yamaha. I bought a few and will report back if they fit in the 100,125 and 175s. Here are pictures: