Yamaha CA50 Riva- No power/rpm's

[william]

First post here, hope you can help-
I recently bought a Yamaha CA50 Riva for twenty bucks at a yard sale. While the cylinder was at the local dealer getting bored (along with a new piston and rings), I went over the rest of the scooter with a fine toothed comb, including the carburator.

It was nice to finally get her started but she has no power under load. Once she's warmed up she idles fine and revs responsively as long as the rear tire is off the ground but when I try to ride it she'll only go about ten miles an hour. If I open the throttle wide open it just bogs down.

It's a 1984 with only 1700 miles on it and it's really not in too bad of shape, considering. It has a new battery, a clean carb, a new coil, and a new spark plug. I disconnected the auto lube hose to the carb, and plugged it off, (I think it failed on the previous owner and suspect that is why the cylinder was in such bad shape) and premixed the oil 32:1. The muffler appears to be clear of obstructions but drips oil. (Am I mixing too much oil?)

Why don't I have any power or rpm's? Thanks in advance...

[90GTVert]

Have you inspected and cleaned the CVT?

[william]

CVT? Central Velosity Terminal? Hehe. I don't know what a CVT is. I downloaded a service manual and it doesn't list a CVT. It does have a CDI though (I don't know what CDI stands for either). This is my first scooter ever so I'm not real knowlegeable about them, but maybe this will help...

The key switch has three positions. Off, start, and run. If I try to rev the scoot while the key is in the "start" position it just goes Blarrrraaaaaaaaaa. Even if the rear wheel is off the ground. I can't get it off of idle. When I turn the key to "run" it's better, but only by about 50%. I THINK the CDI has something to do with spark, as it feeds the ignition coil. Maybe is advances or limits the spark, like a governor or something? It doesn't spit or spatter or miss-fire or anything like that, it just won't go.

And, thanks for the welcome and reply.

[90GTVert]

CVT is the transmission system... continuously variable transmission. CDI is the ignition box, capacitor discharge ignition.

Here's a glossary I put together so you can check out a lot of the commonly used terms you'll hear here.
49ccscoot.proboards.com/index.cgi?board=basicstuff&action=display&thread=347

These may be of help with more info on what a CVT is and how to check it out...







I've never had a scoot with a start position on the key, but I would suggest leaving it at RUN once the scoot is started.

[william]

I have a new project. The CVT! I had the cover off and cleaned out all the belt goo from within, but didn't go any further. By watching the above half hour video I can see how that can be a possible solution to my problem. If that system is all gunked up and can't move freely that might limit things. Makes sence to me. You're a good mechanic sir! But I'm gonna use two hands for the repair!

[jmkjr72]

well first thing i would assume the belt is the orginal belt

and being almost 30 years old it is glazed and that is your issue right there

along with the clutch and contra springs being weak from age

so that is where i would start in the trans

[2strokd]

I know these are belt drive but do they even have a CVT, or is it a fixed ratio?

[william]

Well, I took it all apart today and there are definately issues that need to be addressed. The one thing that I'm not sure of is the Primary Sheave Assembly. Inside of it are 6 rollers and some of them have flat spots. Not real bad but flat spots nonetheless. I believe I'll replace them but there's the grease issue. Should the surface where the rollers ride on the housing have grease? The only place where there was grease was along the inside of the outside walls of the assembly, probably misplaced because of cyntrifical force? That would tell me that this assembly should be serviced periodically correct?

Anyway, I think I'll order some parts for the CVT along with a new belt because what I did to it today had no effect on performance, but I sure did learn a whole lot. I video'd the whole thing today. Maybe I'll do some editing tonight and post it. Maybe y'all will see something I missed or have some helpful hints for me.

I sure do appreciate the help I've gotten so far. Thank you all very much!
Bill

[jmkjr72]

some varatiors call for grease and others dont
i dont have a serrvice manual for a ca50 but try to find one and see what it calls for in the service manual

[jmkjr72]

its a vertical and without actauly seeing anything i would consider looking at stuff for the prebug zumas

[william]

Here's an initial look at what I found when I pulled the cover off. Keep in mind that I already had the cover off once before and cleaned out massive amounts of belt residue. I didn't want to spend more than I had to until I knew what I was in for but I'm almost at $500.00 so this has to be done now too. One way or another I'm gonna get 'er road-worthy! I'll put up another one on the Primary Sheave (with the rollers) and y'all can tell me what you think I should do- If you would be so kind... www.youtube.com/watch?v=xokPJB8ufLw

[jmkjr72]

that belt is toast way toast that is part of your probelm plus the rusty torque driver wont help when you add a new belt it will chew it up
and that is a style of varatior that gets grease
yes the clutch shoes look glazed over
and now that i saw the inside i do not think prebug parts will work

[william]

I'm pretty sure now that I know what the Variator? does now but I post this video just so you can see the inside of it and if it looks salvageable. I don't think I can just get those rollers but I'm not sure yet. I might have to buy the whole assembly. Oh boy!

I think I have a video of the cleaned-up torque driver plate. If I do I'll post that too and you can tell me if you think I can still use it. They're not even listing the clutch assenbly in the catalogue so I don't know if I can get parts for that either. I'll know tomorrow.
youtu.be/21UqPqXTTZk

I did have the Torque Driver video. Will this work? Again, I don't know if I can get a new one.
www.youtube.com/watch?v=_FY_8YMHU4g

[jmkjr72]

you will need to put all 6 of them on a scale that measures grams and get an average weight
it should be around 6.5 to 7.5 grams
then you need to measure the dia and the width
there are oem yamaha 50 so im going to guess the athey are 15x12mm
once you know what size and how many grams if its a fairly common size you can order them i doubt you will be able to get may parts from yamaha any more as most of the parts are discontinued for the 1984 ca50 at least thats what i get from cheapcycleparts.com

the grease goes in the tracks that the rollers go in

[90GTVert]

6.5 to 7.5 gram rollers? I'm used to Chinese 2Ts, but mine came with 4-5g stock. Is that something with the design of those engines/CVTs/gear ratios that they need all that weight or could that be part of the low revs if they're that heavy?