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Post by dejavu165 on Jan 19, 2019 15:34:31 GMT -5
I replaced the top end/valves of a my GY6 150cc recently and when attempting to start it the first time it only really struggled. When it seemed to get some kind of ignition, a lot of white, oil smelling smoke would come out the exhaust. After triple checking the timing/valves I decided to open it back up. Where I saw a good deal of oil sitting in the cylinder (the exhaust header was pretty covered in oil too). The top end kit came with its own piston rings, which I didn't really double check the gap at the time but they seemed too be pretty open when I set them in the cylinder. Do you think the problem here is too small piston rings?? What else could it be? I put in 750 ml of oil.
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Post by dejavu165 on Jan 19, 2019 15:34:50 GMT -5
I can snap a pic of the gap if it helps too
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Post by ryan_ott on Jan 19, 2019 16:04:24 GMT -5
The oil in the cylinder may be from assembly/disassembly. If you get difficult, smokey starting after the initial start then I would dig in further. Ring gap, head gasket and valve seals would be my first checks.
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Post by gsx600racer on Jan 19, 2019 16:12:22 GMT -5
In this process, did you also remove/replace the valve guide seals ?
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Post by dejavu165 on Jan 19, 2019 17:58:48 GMT -5
In this process, did you also remove/replace the valve guide seals ? I actually replace the whole head. |
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Post by lilpinny on Jan 19, 2019 22:04:49 GMT -5
Snap pics.
You'll want to take it apart again and make sure your gaskets are on right... Cylinder and head. Recheck the chain tensioner assembly. Check the Piston when it's in the cylinder to make sure it's and the rings are good.
But pics would help.
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Post by dejavu165 on Jan 20, 2019 14:07:58 GMT -5
 Here's a pic showing the gap if that helps. I understand that closes up as the engine heats up. |
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Post by jackrides on Jan 20, 2019 14:34:26 GMT -5
Ring end gap should be less than .010" or .25mm. refer to 4 stroke engine tech index.
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Post by lilpinny on Jan 20, 2019 15:03:24 GMT -5
my rings are pretty darn close it not touching the cylinder. Feels like a rubber stopper moving through there.
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Post by dejavu165 on Jan 21, 2019 21:47:34 GMT -5
Ok. I've got new rings coming. Crazy these were too small seeing that they came with the top
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