150cc GY6 engine starter defeated by engine compression

blueboy5000 · 03-21-2017, 06:49 AM

Sounds like a sticking starter clutch. It's common, and is an internal engine part.

randscaping · 03-25-2017, 09:33 PM

Thanks, Blueboy5000. I will definitely research this engine component further and see what I need to do to make it stop sticking.

So I finally wrapped up slapping some new parts on the scooter and tinkering around with things.

New since last post:
-new starter solenoid
-new positive and negative wires off battery
-
-new CDI(ended up sticking with old CDI)

Result: Still the same engine behavior when attempting to crank. So I started pulling apart some of the sheathing that keeps the wiring bundled neatly. I found where the ground wires from the various components merge to one wire and capped it so the copper wiring was not exposed. Also finally installed the wires that came with the ignition coil I had in. Ran that green side directly back to the negative battery terminal by itself. Still no spark when running starter and holding spark plug gap to engine casing. So I inspected the black-with-red wire from CDI to the hot side of the ignition coil and found no shorts. I replaced new CDI with the old one and it produced spark immediately upon retrying.

Successful ending:

Upon observing a dependable spark, I immediately reassembled the parts and compartments I had open and placed the CDI and starter solenoid back on their mounts. For good measure I added some ether to the intake and hit the starter button. It started making its usual racket and not smoothly turning but I let it try for about 7 seconds before BOOM!

The ether (starting fluid) had finally ignited. So I sprayed some more in through a straw via one of the vacuum ports on the intake and tried cranking again. This continued for about 2 minutes before I finally achieved a started, running scooter.

Summary: I feel the issue of failure to start/crank that I reported was a result of a lack of rich intake air and a fault in the wiring of the scooter. Whether it was the ground only or the hot side coming off the CDI box I can't really tell.

What happens next: I really don't like the racket it makes that sounds like grinding gears when the starter is attempting to turn the engine over. So I will be looking further into this sticking starter clutch that blueboy5000 spoke of. I'll be keeping an eye on the oil since it makes sense that a properly oiled engine will be easier to turn (over). I did get to ride it a little bit today before I let it stall seeing if it would idle. Trying to restart it independently (no jumper cables/battery booster) seems like a lost cause as the battery dies before I get it running. So if I stall at a light I'm effectively stuck there to push my ride to the curb and begin CPR, so to speak.

Sorry I wrote enough to be an autobiography here. However, I did intend to include as much detail(or storytelling, depending on how you look at it) to try to help a reader who might need it. Blueboy5000, would you mind elaborating a bit on how the sticking clutch would cause my reported problem?

blueboy5000 · 03-27-2017, 07:18 AM

The starter clutch is an internal driven bendix-style gear/clutch. Kind of like a combination of a flywheel and a bicycle freewheel.

randscaping · 03-28-2017, 01:48 AM

So is that the mechanism that is above the rear axle on the left side in the long case that says "4 stroke"? (the belt inside this case spins it)

03-25-2017, 09:33 PM	#2
randscaping Join Date: Mar 2017 Location: Bedford, VA Posts: 6	Thanks, Blueboy5000. I will definitely research this engine component further and see what I need to do to make it stop sticking. So I finally wrapped up slapping some new parts on the scooter and tinkering around with things. New since last post: -new starter solenoid -new positive and negative wires off battery - -new CDI(ended up sticking with old CDI) Result: Still the same engine behavior when attempting to crank. So I started pulling apart some of the sheathing that keeps the wiring bundled neatly. I found where the ground wires from the various components merge to one wire and capped it so the copper wiring was not exposed. Also finally installed the wires that came with the ignition coil I had in. Ran that green side directly back to the negative battery terminal by itself. Still no spark when running starter and holding spark plug gap to engine casing. So I inspected the black-with-red wire from CDI to the hot side of the ignition coil and found no shorts. I replaced new CDI with the old one and it produced spark immediately upon retrying. Successful ending: Upon observing a dependable spark, I immediately reassembled the parts and compartments I had open and placed the CDI and starter solenoid back on their mounts. For good measure I added some ether to the intake and hit the starter button. It started making its usual racket and not smoothly turning but I let it try for about 7 seconds before BOOM! The ether (starting fluid) had finally ignited. So I sprayed some more in through a straw via one of the vacuum ports on the intake and tried cranking again. This continued for about 2 minutes before I finally achieved a started, running scooter. Summary: I feel the issue of failure to start/crank that I reported was a result of a lack of rich intake air and a fault in the wiring of the scooter. Whether it was the ground only or the hot side coming off the CDI box I can't really tell. What happens next: I really don't like the racket it makes that sounds like grinding gears when the starter is attempting to turn the engine over. So I will be looking further into this sticking starter clutch that blueboy5000 spoke of. I'll be keeping an eye on the oil since it makes sense that a properly oiled engine will be easier to turn (over). I did get to ride it a little bit today before I let it stall seeing if it would idle. Trying to restart it independently (no jumper cables/battery booster) seems like a lost cause as the battery dies before I get it running. So if I stall at a light I'm effectively stuck there to push my ride to the curb and begin CPR, so to speak. Sorry I wrote enough to be an autobiography here. However, I did intend to include as much detail(or storytelling, depending on how you look at it) to try to help a reader who might need it. Blueboy5000, would you mind elaborating a bit on how the sticking clutch would cause my reported problem?
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03-28-2017, 01:48 AM	#4
randscaping Join Date: Mar 2017 Location: Bedford, VA Posts: 6	So is that the mechanism that is above the rear axle on the left side in the long case that says "4 stroke"? (the belt inside this case spins it)
	0