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Post by dejavu165 on Jul 14, 2018 15:34:59 GMT -5
I've got through everything I could think to get this gy6 150 scoot to start. Here's everything I've tried/checked so far -
Good spark New carb that I know works Good vacuum/good fuel flow to carb Checked and adjust the valves (they weren't bad to start with)
And it just cranks (new battery), doesn't even try to fire up. It act like it doesn't have spark. But the plug shines bright (also new plug) . I really dont know what else to try. Is there any chance its not getting spark once the plug is back in the engine? I test it laying against the valve cover so I know its ground properly. Kind of lost what to try next on this one.
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Post by 2stroked on Jul 14, 2018 15:44:15 GMT -5
You have a way to check the compression? How fast is the starter turning the motor? Have you tried to put a few drops of gas in the cylinder then put the plug in and quickly try to start it?
Final question. Have you checked to make absolute certain the tining is spot on?
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PirateLabs
Scoot Enthusiast
Posts: 296
Location: Bowling Green, KY
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Post by PirateLabs on Jul 14, 2018 15:47:25 GMT -5
You said good fuel flow to carb but...it is good fuel? Just to eliminate that as a possibility, I would drain off some of the gas from the fuel bowl drain into a clear container and look at it. If it looks cloudy or, has globules floating around in it that is water. Let the container sit for a bit to see if you get a layer to form. If it all looks fine...dump back into the tank. If it is cloudy or has globules in it...drain all of the fuel and replace with good gas. The ethanol in the fuel these days attracts water and 2 times I have received water in the gas from my local station. First time it made it run really bad and bog. 2nd time, it would not even fire up at all.
The only other thing I can think of is it may be getting spark, but at the wrong time? Sometimes the keyway on the crankshaft can shear partially and that can make the stator fire at the wrong time so, you have good spark, just not when you need it. This may not be likely but, it is also a possibility that fits your clues.
Bill
EDIT: I see that 2stroked has just posted above a minute before me and also asked about the timing.
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Post by tortoise2 on Jul 14, 2018 15:50:32 GMT -5
Also verify flywheel-crankshaft woodruff key has not sheared (altering timing). Insert a probe into the sparkplug hole and turn flywheel to position piston at top-dead-center . . then observe if flywheel T-mark is aligned with case indicator.
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Post by dejavu165 on Jul 14, 2018 18:39:31 GMT -5
Well I checked a few of your recommendations. Fuel is good, all new. The timing looks good. But then tested the compression and only read 30 psi.. So must be something else going on here. Any idea where to start there? Bad piston rings? There's only 1000 miles on the engine
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PirateLabs
Scoot Enthusiast
Posts: 296
Location: Bowling Green, KY
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Post by PirateLabs on Jul 14, 2018 20:37:11 GMT -5
Well I checked a few of your recommendations. Fuel is good, all new. The timing looks good. But then tested the compression and only read 30 psi.. So must be something else going on here. Any idea where to start there? Bad piston rings? There's only 1000 miles on the engine Not to sound like a broken record here but, if the timing has shifted, a valve could be partially open during the compression stroke and allowing air to escape. Or, you may have a stuck valve or sticking valve or a burned valve leaking. Probably not the rings with that low mileage even if the oil was never changed which, I am sure you have done several times. Bill PS Could also be a leaking head gasket. Check around where the head joins the cylinder and see if you see any signs of leakage.
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Post by dejavu165 on Jul 14, 2018 22:31:27 GMT -5
How can I check if the timing shifted? I lined up the T mark with the big hole in the cam shaft.
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Post by dejavu165 on Jul 14, 2018 22:32:15 GMT -5
Would I be able to tell if the valve was sticking if I watching them while cranking?
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Post by pinkscoot on Jul 15, 2018 15:05:49 GMT -5
Where did you get your compression tester from? HF gauges mostly only read 30PSI.
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Post by dejavu165 on Jul 15, 2018 20:11:49 GMT -5
HF gauges? I got it online somewhere, probably amazon. Ive used it a few times before with now problems.
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Post by dejavu165 on Jul 17, 2018 17:31:03 GMT -5
bumpy
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Post by 90GTVert on Jul 18, 2018 12:06:51 GMT -5
If it actually has on 30psi of cranking compression, it should be easy to turn over by hand. It should also spin fast when using the e-start with a good battery.
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Post by dejavu165 on Jul 22, 2018 21:32:43 GMT -5
Sorry for the delayed response. So ya it is pretty easy to crank and turns really fast with the e-start. So I desired to take a look at the valves and piston. Here's what they look like - To me they valves and the top of the piston look really chared.. What would be causing that? Is the exhaust valve sticking? How does that relate to very little compression? I didn't see any cracks or anything else wrong with the engine.
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Post by 90GTVert on Jul 24, 2018 8:24:17 GMT -5
Looks like carbon to me. Could possibly be some mild oil burning. Having it that far apart already and with 30psi, I'd look over the rest of the piston, rings, and cylinder. If in any doubt of their condition, a piston kit or ring pack is pretty cheap.
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Post by dejavu165 on Jul 24, 2018 19:03:51 GMT -5
Ok, Ill get that ordered up and installed. Then Ill let you know if fixes the no compression issue or even wants to start. Thanks for the suggestions!
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