Post by irocss85 on Oct 6, 2022 0:18:27 GMT -5
so Im an auto mechanic. but only cycle experience is my pit bikes. and now this GY6. I have learned alot along the way. here goes.,
bought a moped that was hard to crank. ran out of oil until the eng wouldnt run. so he thought. I did get it to run and it would start kinda easy run ok but clearly rod knock. after a min or two would seize up and quit. no cranking until it cooled. took apart and wristpin seized and piston/cyl wasted. decided to buy another engine to get goin quick. bought a brand new parts moped used by a shop for a donar since it was damaged.so it was missing the carb, cvt, hand controls, some other random parts. 150psi compression so I figured swap my parts onto this engine and good to go. nope.
remember all my external engine parts were ok since the motor would run. swapped on (did disassemble to clean out but it was clean) my carb, used my coil and cdi since it was still bolted to my moped but I have spares now. great spark. cranks over good with the starter, sounds like a good speed. it will not even attempt to sputter or start at all. just cranks like it doesnt have spark. tested the coil, swapped the coil anyways. tested the stator , reset the pickup coil gap .012" reset the valve lash just to make sure. .003, .004, .005 no difference in compression. by now the cyl oil was wiped and found it was down to around 120psi. added a few drops of oil and boom right back to 150. I know ideally its between 170 to 190 psi. used a bore scope to look down the cyl and its brand new obviously has never been run. walls look good. no rust or scratches. just nice cross hatch. took off the flywheel to visually inspect the stator and its good. bought a brand new carb and no change. tried to start on parts cleaner and still not even trying to start. so Im convinced its not fuel. I beleive 150psi should be plenty to run.
I did inspect for the woodruff key on the crank cause I thought maybe it was missing and the flywheel was off timing. no luck. Im starting to think maybe the cam or crank was machined incorrectly? or the timing chain skipped a tooth. but I'd assume that would lead directly to low cranking pressure.
also note there is no kickstand safety, and I tested the kill switch and it does kill spark when turned to stop position. good spark in run position. I have a good battery being piggybacked to a car battery and I believe it does have good cranking speed. I cant get the kick start to work right it'll crank a few kicks then come apart.
oh also swapped cdi box with the spare one. but remember my moped ran so it shouldnt be those parts. but Im way past assuming anything so I swapped them all any ways. carb is full i did prime the fuel lines. new fuel lines as well and intake.
most of this time trying to start w/o the air box but have tried with the airbox on.
I did remove the egr and cannister. plugged off the 1/2" line that went to the cannister and the little extra vac line on the intake.
what am i missing here?
desperate and depressed. riding weather is almost gone.
bought a moped that was hard to crank. ran out of oil until the eng wouldnt run. so he thought. I did get it to run and it would start kinda easy run ok but clearly rod knock. after a min or two would seize up and quit. no cranking until it cooled. took apart and wristpin seized and piston/cyl wasted. decided to buy another engine to get goin quick. bought a brand new parts moped used by a shop for a donar since it was damaged.so it was missing the carb, cvt, hand controls, some other random parts. 150psi compression so I figured swap my parts onto this engine and good to go. nope.
remember all my external engine parts were ok since the motor would run. swapped on (did disassemble to clean out but it was clean) my carb, used my coil and cdi since it was still bolted to my moped but I have spares now. great spark. cranks over good with the starter, sounds like a good speed. it will not even attempt to sputter or start at all. just cranks like it doesnt have spark. tested the coil, swapped the coil anyways. tested the stator , reset the pickup coil gap .012" reset the valve lash just to make sure. .003, .004, .005 no difference in compression. by now the cyl oil was wiped and found it was down to around 120psi. added a few drops of oil and boom right back to 150. I know ideally its between 170 to 190 psi. used a bore scope to look down the cyl and its brand new obviously has never been run. walls look good. no rust or scratches. just nice cross hatch. took off the flywheel to visually inspect the stator and its good. bought a brand new carb and no change. tried to start on parts cleaner and still not even trying to start. so Im convinced its not fuel. I beleive 150psi should be plenty to run.
I did inspect for the woodruff key on the crank cause I thought maybe it was missing and the flywheel was off timing. no luck. Im starting to think maybe the cam or crank was machined incorrectly? or the timing chain skipped a tooth. but I'd assume that would lead directly to low cranking pressure.
also note there is no kickstand safety, and I tested the kill switch and it does kill spark when turned to stop position. good spark in run position. I have a good battery being piggybacked to a car battery and I believe it does have good cranking speed. I cant get the kick start to work right it'll crank a few kicks then come apart.
oh also swapped cdi box with the spare one. but remember my moped ran so it shouldnt be those parts. but Im way past assuming anything so I swapped them all any ways. carb is full i did prime the fuel lines. new fuel lines as well and intake.
most of this time trying to start w/o the air box but have tried with the airbox on.
I did remove the egr and cannister. plugged off the 1/2" line that went to the cannister and the little extra vac line on the intake.
what am i missing here?
desperate and depressed. riding weather is almost gone.
