Scooter SOMETIMES won't go into "neutral"

[mhost2]

A couple weeks ago, when stopped at a light (without holding the brakes), the scooter started thrusting. It was trying to move forward, but would only move like 1/4 inch and go back to where it was. It was doing this constantly. Hence the word thrusting. If I held the brakes so it couldn't move, the bike starts shaking. It shakes so much that my sideview mirrors are vibrating and the cars (in the mirror) get almost blurry.

For the rest of the ride, it does this every time I am stopped. When I come to a rolling stop, the bike doesn't ever disengage. Normally, if I coast to a stop (especially downhill) there is a noticeable point when the bike gets out of gear. On a downhill, the bike would actually speed up at this point. On a flat, I would now be going slow even to stop by just putting my foot down (no brake). But now, when this problem is happening, the bike just keeps rolling once it gets down to about 3-4 mph even on a flat.

If I put the bike on the stand without shutting it off, the back wheel is spinning really fast. I can apply the brake to stop it and it immediately starts going fast again when I let go of the brakes.

As the title of this post says, it only happens sometimes. Usually, when I first start driving after been off for a while, it's fine. And within 5 minutes of riding, it starts. Once it starts, it continues until I shut it off and park it for a while. At first it was also only doing it some days. But the last few days, it's been doing it every time I go out with it, but only after a few minutes.

My first thought is the idle screw needs to be adjusted on the carburetor, but why would it only happen sometimes and not all the time?

I doubt it's related, but there has been another issue for a few months now. Sometimes, when I start to move from a stop, there is a kind of bell like rubbing sound that lasts for a half second. It seems to do it every time I start moving from a stop for a few days. Then it stops and no noise for a week or two. Then it comes back and lasts a few days. It's hard for me to be sure and could just be a coincidence, but it might only start on rainy days.

I read that the clutch nut might be loose. I opened it up this past weekend and it seems very tight, so I don't think it's that.

Any thoughts on what I should look at or try?

Thanks.

[tortoise2]

Apr 18, 2018 12:00:12 GMT -5 mhost2 said:

thoughts on what I should look at

Potential clutch nut issue?

[pinkscoot]

That or a bad spring or 3.

[mhost2]

tortoise2 Like I said, I read that it might be loose (which it isn't). Do you mean a different issue other than being loose?

pinkscoot What springs are you talking about? Pinching the clutch required a fair bit of strength, but doable. I have no reference on how difficult it should be as that was my first.

[tortoise2]

Check if a rear gearbox bolt has backed out, and is contacting the clutch inner surface.

Also check for a deficient bearing.

[mrkswthwrth]

My fist thought is idle is too high. My engine revs at idle fluctuate a bit. Do you have a tach?

Otherwise id say a loose nut in the trans somewhere. But im no expert.

[pinkscoot]

Apr 18, 2018 12:59:04 GMT -5 mhost2 said:

tortoise2 Like I said, I read that it might be loose (which it isn't). Do you mean a different issue other than being loose?

pinkscoot What springs are you talking about? Pinching the clutch required a fair bit of strength, but doable. I have no reference on how difficult it should be as that was my first.

I'm talkig about the 3 springs that control the speed that the clutch opens. If they get weak or break they will allow the clutch to stay engaged. Here is the link to how to install new ones:

49ccscoot.proboards.com/thread/721

[GrumpyUnk]

I suggest removing the CVT cover, and the clutch 'bell', and inspecting the clutch shoes and springs. A dragging show will try to engage at low rpms, not effectively, but it will also diddle with the idle making it seem the engine is under load. If you wait long enough, you will likely have the clutch shoes all fall apart and be stranded alongside the road. I have yet to figure out the why of shoe breakage, but it seems they break close to the pivot shaft, and leave bits & pieces flopping around in the CVT case.
If you have the money, a complete replacement is the easiest thing to do.
tom

[mhost2]

Thanks for all the suggestions. I was going to look into it however my charging system has failed. So I have to prioritize fixing that first now. I did some testing last night and it looks like the stator is the culprit of this new problem.

[pinkscoot]

What tests did you do to determine it was the stator and not a bad regulator?

[GrumpyUnk]

FWIW, if you can get it to start and run, you can check the yellow and white wires from the stator for voltage. They both produce AC volts, increasing with rpm. If they are not producing voltage, then the wires or the stator are likely suspects.
tom

[mhost2]

I tested the resistance between the three wires coming from the stator. One pair had 0.8 ohm, but the other 2 pairs has about 125 ohm. From what I've read, that means bad stator.

[mhost2]

Installed the new stator and that fixed the charging problem and the headlights work now.

However, when reinstalling the clutch, I read that the torque should be around 30 ft lb. I hand tightened it at first (so it was on proper), then started to tighten with torque wrench. I didn't even reach 30 ft lb and the nut because loose. I tried removing it and it wouldn't. It would just spin and not back out. I had to cut the nut off. And now the threads on the driven pulley shaft are completely destroyed.

I believe to replace that shaft, I have to take the back wheel off and open the reduction case. Is that right? Is this a really difficult job? Am I right that there will be gear oil in there too?

[GrumpyUnk]

Yes. The wheel nut must come off, on the other side, the brake lever adjuster nut, the pin the adjuster bumps on, and the cable must be removed.
Remove the drain plug on the bottom, and catch the lube. It will be about 10ml, easily fit into a 1 cup measure or a small plastic pan. The bolts on the CVT side must be removed and then the case can be split.
The clutch drum & shoes must be removed from the input shaft. The shaft can the be removed from the bearing.
I would inspect all bearings while it is apart. They should all turn freely and have no 'rough spots' in their rotation. Take a look at the gear teeth also, looking for 'dents' in the teeth area where the gears mesh. The teeth can be worn a bit, but you don't want 'dented' teeth.
Use a plastic scraper or putty knife, or chisel if adventurous to remove the old gasket from both outer case cover and the engine assembly. You'll need a new gasket. There is a full-size image available on site if you want to make one from gasket paper(NAPA? Autozone? Advance? Kragen? O'Reilly? or Amazon/ebay), or you can use 'oaktag' from a file folder.
There are two 'ferrules' that will align the to case halves, don't forget them, don't lose them. I used 85W90 lube from Wally, and 120ml, a syringe w/o needle to squirt it into the hole after assembly. Fill until it starts to drool out the fill hole, sitting on the center stand.
Get a new torque wrench that works. The old one is/was an expensive lesson. The gear is available online or at a local shop. Prices range from $7-$12 for a reasonable cost.
There is a post on the site and a video about replacing the bearings, which is very explanatory.
tom

[mhost2]

I finally received the shaft last week and did the job this past weekend.

The gears fell out when I opened everything up. The shaft had to be hammered out and the new one hammered in. There is no gasket. And the local vespa service shop told me to just use thread locker like it was RTV. They also told me to put in 200ml of the oil.

Drove it around a bunch yesterday and today and so far, it seems to have fixed the problem of not going into neutral.

Thanks for all the help.