Yamaha Zuma 50 having trouble accelerating from start By ssleeping (Read 6,321 times)

[ssleeping]

So I recently bought an 09 Yamaha Zuma two stroke with 5k miles on it. I am having an issue when I open the throttle it revs up for a bit then eventually starts moving. Before that its just crawling then it seems it grabs. Sounds like a slipping clutch but the seller told me that it is the nature of centrifugal clutches; any insight?

[Alleyoop]

First the Seller is full of it they will tell you anything to sell it.

From what you are saying something is slipping in the CVT, it could be the belt, weights and or clutch. So First thing is take the CVT cover off and start it up if you can with the Cover off and check out the Variator, Clutch and the Belt and see how they are working as you give it throttle. If you are not familiar with this take a video of the CVT as you give it throttle so we can see how the parts are working.
Alleyoop

[ssleeping]

Perfect, thanks for the reply; I had a hunch the seller was either full of it or very unfamiliar. I am mechanically inclined but this is my first time looking at a 50cc motor. I will take it off and give it a look; if I'm unclear I'll make a video. Thansks again

[Alleyoop]

Great if your mechanically inclined you will not have any problems. Don't hesistate to ask questions if your not clear about something, that is how people learn by asking questions and getting their hands dirty.
Alleyoop

[cyborg]

Alley is on it and correct in saying the seller is full of sh!t,,,,,, at 5000 miles it'll probably need a belt a clutch and variator weights,,,,then she'll run like new,,,,stick with Alley he'll set you on the correct path

[ssleeping]

Sounds good, I'll open it tomorrow. Also, if it helps it shudders at idle and eventually dies. When sitting at street-lights the headlights and dash lights are very dim until I start moving.

[Alleyoop]

Needs a little TLC, need to adjust your carbs AIR TO FUEL MIXTURE and here is a procedure you can follow.
The Idle may be set to low is why it shudders and dies at idle. Idle should be anywhere from 1500-1800 rpms.
Alleyoop

scooterdoc.proboards.com/thread/7678/2ts-carb-tuning

[ssleeping]

Anyone got an tips on how to remove the top screw on the CVT? There is a bracket that obstructs the screwdriver from making 90 degree contact with it.

[jct842]

Read the zuma service manual. It's in the library section.

[ssleeping]

Finally got around to getting the CVT off, I'm not sure what is going on so I took a video. Thanks

Link:

[Alleyoop]

Hard to see if the Variator belt was climbing up and the belt was down in the CLUTCH pulley. But it is
either you weights are all worn out and are very light and require a lot of rpms to move the variator out and pull the belt down in the clutch pulley OR the clutch pads are worn woen so much that it takes a lot of force to grab the bell.

So Take the Variator off and check the weights if they have really big flat spots that may be all you need new weights. If they DO NOT HAVE really big flat spots then it is your clutch pads.
Alleyoop

[ssleeping]

Awesome thanks, any tips on how to get the nut off the variator?

[Alleyoop]

Most of use an IMPACT WRENCH you will also need it for the clutch nut. But you can maybe hold the Variator with something like this:
Alleyoop

[ssleeping]

I finally got the the clutch and variator off. The material on the clutch looks good and there are no flat spots on the rollers? Any ideas?

[Alleyoop]

Sure looks like the PADS are not being thrown out at a lower rpm, the clutch may have a stronger clutch springs that require higher rpms for it to grab the bell. I bet this has been going on since you bought it. The previous owner may have put stronger clutch springs in. So take the clutch out and see what color the springs are on each pad are.
Alleyoop