150cc Timing Chain Crankshaft Sprocket

rks · 04-16-2018, 08:48 AM

Just thinking out loud here.....you said, "Carb is new and clean, stator is new, coil and plug cap are new. Plug is new. Head gasket is new. Cylinder gasket is also new".....how about the pickup coil, it's gap, and it's wiring harness....also check the pins in the connecter.

Because you stated the enricher had no juice with engine running, and the ignition, like the enricher, is AC powered... I keep thinking your problem is electrical.

But then again, bogging at higher throttle settings is a classic sign of too much fuel/not enough air. The carb you put on it isn't one of the high performance, 26mm or larger, is it?

GrouchyOle'Man · 04-17-2018, 04:56 PM

Hello again Mr. rks Well sir, not a high performance carb. The pickup module came new with the stator. I air-gapped it at .010". The pins in the connector for it seem fine. It seems to produce a yellow spark, but it IS consistent tested outside the engine. I advanced the timing some yesterday (to where the T on the flywheel lines up even with the crankcase indicator). I had it set a mark or two BEFORE the T (to the left) on the flywheel previously. The intake valve was too tight though and it ran the same. The way the old chain lays on the cam sprocket tells me it may be quite worn. There are gaps and it does NOT completely seat on the sprocket. It has always been that way since I started working on it. I didn't wish to do a complete disassembly. I am considering installing a new chain (which may CURE the problem), as I have tried everything else.
I am NOW getting current to the enricher and I checked it on the scooter running before installing it. I have a new one and an older one. They both work. I also have the horn working now. Whether or not it is sufficiently charging I have yet to check. It was not before and I am on my second Rectifier/Regulator.
Since it was backfiring thru the muffler, I figured the timing must be retarded. The thing is CLOSE to where it needs to be but may never be able to achieve correct timing with a worn chain. The NEW chain tensioner looks like it is extended pretty much ALL the way out too. There is a very pronounced DIP IN the top part of the chain where the tensioner is pushing it down.
Does anyone KNOW on a GY6 150cc engine how much a NEW tensioner would extend with a used (good condition) or even a NEW chain? That would definitely clarify the chain condition. Parts on the chains do wear and they can be become elongated by a substantial amount.

04-17-2018, 04:56 PM	#2
GrouchyOle'Man Join Date: Sep 2017 Location: NE Central Florida Posts: 37	Hello again Mr. rks Well sir, not a high performance carb. The pickup module came new with the stator. I air-gapped it at .010". The pins in the connector for it seem fine. It seems to produce a yellow spark, but it IS consistent tested outside the engine. I advanced the timing some yesterday (to where the T on the flywheel lines up even with the crankcase indicator). I had it set a mark or two BEFORE the T (to the left) on the flywheel previously. The intake valve was too tight though and it ran the same. The way the old chain lays on the cam sprocket tells me it may be quite worn. There are gaps and it does NOT completely seat on the sprocket. It has always been that way since I started working on it. I didn't wish to do a complete disassembly. I am considering installing a new chain (which may CURE the problem), as I have tried everything else. I am NOW getting current to the enricher and I checked it on the scooter running before installing it. I have a new one and an older one. They both work. I also have the horn working now. Whether or not it is sufficiently charging I have yet to check. It was not before and I am on my second Rectifier/Regulator. Since it was backfiring thru the muffler, I figured the timing must be retarded. The thing is CLOSE to where it needs to be but may never be able to achieve correct timing with a worn chain. The NEW chain tensioner looks like it is extended pretty much ALL the way out too. There is a very pronounced DIP IN the top part of the chain where the tensioner is pushing it down. Does anyone KNOW on a GY6 150cc engine how much a NEW tensioner would extend with a used (good condition) or even a NEW chain? That would definitely clarify the chain condition. Parts on the chains do wear and they can be become elongated by a substantial amount.
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