Worn-out crankshaft or CVT?  By  bigmac (Read 11,312 times)

I'm guessing new rollers and belt will most likely take care of it. As I said in an earlier post, the noise is almost gone with the belt off so if it were crankshaft bearings, then it should still be just as noisy with or without the belt and if it was the clutch, then the noise should be completely gone since that doesn't move at all with the belt off.

I've ordered the parts. They should be here in about a week. We'll see what happens.

Figured I'd post an update on the situation.

I ordered and installed a new clutch assembly so now the whole transmission is definitely good to go. I also checked those three bolts that can come loose and rub against the clutch assembly but they were all set. The noise is still there though. I don't know how a noise that sounds so much like it's coming from the CVT isn't really coming from there.

I even took it on a short ride and can actually feel a difference in the performance of the CVT. The clutch pads grab onto the bell better and the acceleration feels better and smoother. As for the wheel turning at lower rpms than before, it was just the driveshaft moving a little from the clutch assembly rotating around it and not the clutch pads catching the bell. It stops turning if I place a figure against the tire.

Some of you might be wondering, "why would you suspect bad crankshaft bearings on an engine with only 6,000 miles?" Well, the reason why and I know many others have made this mistake, too, is that I followed the poorly translated owners manual and didn't correctly interpret the section about checking the oil level. The owners manual said, "do not wrist the dipstick". Apparently, that's their way of saying, "don't screw it in". So for awhile I was ridding around with too low of an oil level until I eventually found out the correct way to check it online.

I'm sure this ruined the oil seals on my cylinder head which is why I had to replace the head already but I likely have excessive wear on other parts as well. I took the camshaft out today and found the bearings on the side closest to the gear have some wiggle and I can feel vibration when I spin it by hand. I plan to order a new one and see if it fixes the noise problem.

I might your ancer
I have a 2008 Short wheel base engine it had 13 inch wheels on it it had 400 miles on it. It does not have any extra parts on it the motor has never been open up.no stator,no brakes I baught the scooter and the wire harness shorted out so I used the parts off it for my other scooter.
With my back I needed a longer frame.
I live in Middlefield Ohio 44062. 40 miles south east of Cleveland Ohio
If you can use it let me know.

Oh wow Middlefield. close to were grew up.
And I can't miss "The Great Geauga County Fair" in a week.

lhumpolick - I'm in Massachusetts. But if you would be interested then surely someone more close by to me could be, as well. I'm thinking of removing the engine and parting it out, then selling the rest of the scooter as an engine swap project bike.

onewheeldrive - The possibility that the slight movement I feel is actually from the flywheel moving on the shaft crossed my mind. I thought about taking it off but just can't bring myself to take any time to get the flywheel puller and spanner wrench out and do it. Which brings up the main problem I'm faced with, and that is I don't care. As chewbaca pointed out, the whole engine could be rebuilt or replaced fairly cheaply but after so many issues and bad experiences, I don't care anymore. I've lost my patience and no longer find fixing this thing enjoyable or worth while. It just feels like a waste of time, effort and money since a new problem is always bound to occur 100 or less miles down the road.

I've gone maybe three miles since the noise started and I haven't noticed it getting any worse. I don't really have a way to record the sound. Everyone seems to have phones that can record and upload videos these days but I have a $10 Tracfone I bought at Kmart about 10 years ago so I don't have such capabilities. However, I did search youtube for "gy6 noise" videos and found one that makes the same noise as mine. The audio doesn't seem too great, but listen closely at the 0:36 mark. You'll hear a noise suddenly appear then disappear at about 0:43. Mine is just like that, comes and goes every few seconds or so.


Oh, and by the way, I was too late on the order cancellation. My new starter clutch should be in the mailbox any day now. I'm so excited.
Edit: I actually got the mail about an hour after posting this and it was in there. I guess I'll have one more part to sell.

By any chance, did you try grabbing hold of the crank and seeing if you could feel movement in the bearings when you had that problem? I ask this because I did take the flywheel off today and couldn't feel movement anymore. Maybe it's possible the bearings are worn enough that they make noise but aren't noticeably loose when the shaft is pushed up, down and side-to-side.

I noticed my spark plug was oily so I thought maybe a piston ring was worn or broken and that's how oil was getting to it and maybe even the cause of the noise I hear. However, I took the top end apart today and didn't see anything wrong with the piston, its rings or the cylinder walls. Only thing I saw was some slight scuffing on the piston.

Maybe it's getting in there from a bad valve stem oil seal. I had that happen before. Is there a way to test it? Could I pure oil into the intake port and tilt the cylinder head and see if the oil leaks out around the seal? The head has about 4,000 miles on it. That's pretty crappy if it's seals are worn after only that many miles.

I have to admit, it's getting embarrassing now. Any of my friends and family who know about this scooter look at me like I'm one of those pathetic men in a terrible relationship who just won't get out and keeps trying to make it work when it obviously won't.

I think it's also getting harder for me because I have had a 2012 Yamaha Zuma 125 for about three years now and have had zero issues with it. I bought it used for $2,099. If someone invested the amount of time needed to keep a Chinese scooter running into a minimal wage job, he could easily make enough money to buy a Japanese scooter and never have to deal with crankshafts and cylinder heads wearing out with less than a few thousand miles. You could probably buy a non-Chinese scooter from the 1980's for the same or less than a brand new Chinese scooter and it would last many times longer than a new Chinese scooter.