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Post by kamchatka on Jan 29, 2014 22:38:35 GMT -6
Thanks, Alley
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Post by kamchatka on Jan 29, 2014 15:21:07 GMT -6
Hi chums, Wanted to put a new intake manifold o-ring on as part of ongoing rebuild; the old one doesn't look too great. More complicated than expected. The "GY6 complete gasket set" I bought on ebay has an o-ring ostensibly for this purpose. But as I try to show in the pictures, it doesn't match what I had before. Everything on the engine is stock. I can stuff it in the groove on the manifold but a whole lot of material is sticking out. Maybe this is intended? Does the o ring compress? Thinking back to school, remembering a 2000 page "handbook" about O-ring manufacture and installation, thinking these are some deceptively complicated little suckers. If not, any ideas for how to go about getting the right part? Have not been able to find anyone selling just the o-ring online. Attachments:
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Post by kamchatka on Jan 22, 2014 8:54:07 GMT -6
regarding carb: everything is stock
I assume carb size is inner diameter of outlet. Mine is 24.5mm
Main jet is 107
Pilot jet is 35
Have not yet put top end back together. May not get a chance to before having to leave town for work. Strongly considering new piston rings and valve oil seals. Even if they aren't defective, the cost is low and potential benefit is high. Will update as things develop.
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Post by kamchatka on Jan 20, 2014 12:04:52 GMT -6
Gotcha. It's much appreciated. Can you suggest a course of action based on where I'm at?
In brief: white smoke, wet fouled spark plug, engine dying below 3000RPM
justbuggin2 suggests new rings, hone cylinder, and new gaskets... do you concur?
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Post by kamchatka on Jan 20, 2014 5:37:50 GMT -6
Enthusiasm got the better of me and I tore into it already... I'll try to remember the hand test for gas spray in the future.
Smoke was definitely white. Not to contradict you alleyoop, I know from reading your other posts you've been in this game for awhile, but I was CONVINCED from reading manuals, forum threads, etc that BLUE was gas and WHITE was oil. How did I get that one mixed up... Spark plug was also looking pretty oily as I recall; apparently I cleaned it off between the time the problem arose and I posted about it.
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Post by kamchatka on Jan 19, 2014 11:59:34 GMT -6
Looked up cylinder honing. I Didn't even know that was a thing!
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Post by kamchatka on Jan 19, 2014 11:57:21 GMT -6
Thanks for replying
I don't know what honing the cylinder means...
Staggering rings is same as clocking right? Arranging gaps 120degs apart? I did that.
I replaced these gaskets:
-cylinder gasket (paper one)
-chain tensioner gasket
-exhaust gasket
I reused these gaskets:
-cylinder head gasket (metal one)
-valve cover O-ring
-carburetor O-ring
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Post by kamchatka on Jan 19, 2014 11:31:46 GMT -6
Hi chums, Sorry for creating a thread for what I'm sure is a common issue, but I've done my reading and still feel like I need to consult. Context: tore down the GY6 150 on my 2008 UM Matrix II up to the point of needing to split the crankcase, for practice and education. Put back together; no problems for first 60km of break-in. At that point, engine began to  white smoke and would not start without opening throttle/would not run under 3000RPM. Spark plug was quite wet. Air filter completely clean. Oil somewhat blacker than I would expect after a couple dozen miles of riding. I think oil is entering the combustion chamber via piston rings or the valve stem oil seals. A reasonable guess? I've got it apart once again. The piston rings look fine. The piston seems to fit in the cylinder OK. Goes up and down with some resistance. No scoring or scratches on the cylinder that I can see. No deformation obvious to my eye. I believe I should measure gap in the piston rings. Do I do this with: a) rings on the piston b) rings off the piston c) rings off the piston but fit inside the cylinder a combination of a), b), c)? Will a digital micrometer from an auto parts store be sufficient to take a measure? Anything else I can do to determine if this is the issue? I am still working on getting the valve springs off. I have no idea what I need to be looking for once I can actually see the oil seal. Will I need to take the valve guides out of the head to inspect them? Heat up the head and all that? Thanks |
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white smoke and would not start without opening throttle/would not run under 3000RPM. Spark plug was quite wet. Air filter completely clean. Oil somewhat blacker than I would expect after a couple dozen miles of riding.