Posted by : Konstantine Tuesday, July 16, 2013


This is an update of this post: 1986 Yamaha XC125 Riva - Variator Weights and CVT issues

So I took everything apart and found this: 


Notice the tear in the rubber: no good. Essentially, the primary sheave housing, which incorporates the weights I was hoping to replace, had burst at the seams. Taking it apart revealed that a few plastic sliders, which allow a plate to be pushed in and out by the weights inside the assembly, had burst into little pieces and torn the rubber seal. The seal is there because there is an unusually large amount of grease housed inside the sheave. Apparently, Yamaha is the only manufacturer that uses this type of 'wet' assembly, where all other manufacturers use a dry assembly.

Kahuna Powersports has recently decided to no longer be a Yamaha dealer, and so my neighbourhood parts supplier had suddenly become Snowcity Cycle Marine, which is much further away from me. Either way, I ordered my sliders from them, and the primary sheave cap was ordered from a kind gentleman (peteyb5) off of the Riva Riders forums. It was serendipitous, because we had been communicating regarding other parts, and he had listed off a few things that he had in stock, but I had no use for at the time. The light bulb went off in my head when I saw the torn sheave cap, and surely enough, he had mentioned that very part. He was kind of enough to sell and ship to me from the States at a considerable discount.

The grease that is packed into the sheave is something from Yamaha, known as Ultramatic grease. No one knows exactly what it is, but most people have good luck with other high-temp, waterproof greases. I opted for the Lucas X-tra Heavy Duty Grease, which met those requirements, for repacking.

I also received the Dayco 8231K belt, that I had measured out to be a particularly good fit my the Riva XC125 application.

I'm happy to say, that after receiving all the necessary parts, I've reassembled the scoot's variator with new weights, grease and cap, and then installed the new belt. The scooter is on its 350th kilometer right now with the new setup, and it's running great.

In all honesty, the top speed still isn't what it used to be, and I'll chock it up to engine wear at this point. When I have more leisure time on my hands (not to mention more disposable income), I'll keep the scoot alive by boring out the cylinder head and purchasing the OEM oversize piston and piston ring set. That'll liven everything up.

At this point, keeping the Riva alive has become a hobby on its own, and it's no longer about the necessity of transport. I want to keep her going, maybe to one day give it to my little sister.

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I was born in Poland, raised in Ukraine, identify myself as Russian and now reside in Canada. How's that for an identity crisis?

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