Engine sprocket coming loose

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Jul 18, 2016
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#1
The sprocket on the 66cc grubee skyhawk engine I have keeps getting loose, if I tighten it and try to ride it then the sprocket gets too loose for the engine to turn over when I try to let out the clutch.

Any ideas on this one?
 


Street Ryderz

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#2
Are you sure that the clutch isn't slipping? The drive gear and every thing on the shaft ends have a woodriff key locking them in place on the shaft!So if your gear is spinning on the shaft pull it off and check for damaged key,keyway and gear itself!
 
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#3
Are you sure that the clutch isn't slipping? The drive gear and every thing on the shaft ends have a woodriff key locking them in place on the shaft!So if your gear is spinning on the shaft pull it off and check for damaged key,keyway and gear itself!
yea the smooth side on the bottom of the shaft that pushes the rod in was damaged, the corner was grinded smooth so I replaced it with a spare one from another 66cc engine I had. I thought that would fix it but now the sprocket gets loose it seems.
 
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#4
yea the smooth side on the bottom of the shaft that pushes the rod in was damaged, the corner was grinded smooth so I replaced it with a spare one from another 66cc engine I had. I thought that would fix it but now the sprocket gets loose it seems.
I

I have never worked on one personally but in my experience when you have something that's a drive with some sort of threat on it if it's on backwards or reverse if it's not put on correctly as you turn it it will become unthreaded

Example I had this fold up bikes from Yugoslavia yes Yugoslavia right around the same time that Ugo's (CARS) came out in the 90s and the pedals threaded backwards so when you would pedal down the street your pedal would fall off because you are uhthreading the pedal as you cranked along get it? I know it sounds strange but stranger things have happened just food for thought if not you can get a chuckle on how the yugo's built bikes that folded in half and the pedals came off as you cuddled because they were reverse threaded.
sorry if there's quite a few typos in here good luck and post what the problem was when you figure it out thanks
 

gary55

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#5
Like Street ryderz said The first time it loosened the woodruff key probably fell out. Now no matter how many times you re tighten it it will not hold unless you replace the key. If you can see the sprocket spinning while the shaft is stationary you need to pull it off to find the problem.
 
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#6
I tightened it again this morning and it seemed fine? engine turned over and i rode it for a good 10 minutes before the winter cold got to me, I will post updates if it happens again but for now im just gonna bring the socket and wrench with me in my tool bag in case it happens on the road.
 

Steve Best

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#7
Yer not listening. It needs the woodruff key, otherwise it is tearing up the shaft.
You will RUE THE DAY you did not heed the advice of those old men... (He, he, he...)

Steve
 
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