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Post by 733scooterguy on Dec 31, 2013 6:43:32 GMT -5
I have a Sunny 150cc and at 5000k the crankshaft bearings went bad. No big deal I dropped the motor and changed the crank. I also replaced the seals and the starter clutch and the chain tensioner. It ran perfect for 2 weeks it was so smooth and strong I thought i had done a really good job on it. While I was at idle all of sudden the engine started knocking bad. It only knocks at idle speed not under power. when I got home I started checking everything thinking something had come loose. The only thing I could find was the magnetic pickup on the stator was a little loose. I eventually blamed the rear clutch and replaced the clutch and the shaft. Still made the noise when in idle not when I rev up. I pulled the engine again and took the crank back out and returned it thinking it was bad and got a new one. I put the new one in again and it still made the exact same noise. I then pulled all the parts in the kick start and started it with no clutches or belt, still same sound. It almost sounds like a tinging sound as the crank turns around. I can't make it do it when I turn it by hand. When I was changing the crank I noticed there was a lot of slack in the oil pump chain. Could this be it? Very frustrated any advice as to what can make this vibration noise would be greatly appreciated. |
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Post by millsc on Dec 31, 2013 10:48:54 GMT -5
My cam chain tensioner wasn't tight and my scoot was making a clunking metal type noise at idle. The cam chain was loose and rattling did you reset the tensioner? Also check to see if your starter clutch is on tight.
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Post by 733scooterguy on Dec 31, 2013 13:17:33 GMT -5
I had just changed the tighter. I went ahead and checked it again. it works fine. would have to crack the case again to check starter clutch. I did make sure the castle nut was tight when I assembled it. The starter clutch is keyed and will only go on so far.
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Post by millsc on Dec 31, 2013 15:10:09 GMT -5
does it sound like this?
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Post by 733scooterguy on Dec 31, 2013 16:12:34 GMT -5
Yes, I tried changing the head it quieted down some. But it still there
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Post by 733scooterguy on Dec 31, 2013 16:17:13 GMT -5
Heres the video you can hear it.
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Post by millsc on Dec 31, 2013 16:37:48 GMT -5
Mine did it for 600 miles no I'll effects ran fine just went away one day.
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Post by 733scooterguy on Jan 1, 2014 7:01:26 GMT -5
This is one of those problems that is very hard to determine without very expensive measuring devices. The crank seized up so I believe the race in the case that hold the crank have gotten scratched and and no longer hold the bearings tight and they are slightly spinning causing vibration. Weird it would happen two weeks after rebuild and you would think that the compression from the case being screwed together would hold those bearings in the crank tight. I give up on this one.
I bought a new (used) motor yesterday and started to rebuild that one.
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