Zongshen CG250 hard to start past compression stroke

[alex71]

Hi all,
First off i hope i am in the right section for a CG engine, its been some years since i played with these sorts of engines. I think from my little searching the CG and GY are fairly similar ?


Anyway my engine is a Zongshen 167FMM water cooled 250cc pushrod.
It runs very well and will for hours if i can get it started.
It struggles on compression stroke, remove plug wire and turns over great.


I think our engines are close enough you might be able to help me.


I have replaced everything on this quad, new wiring loom, stator, pick up coil, CDI, carb, starter clutch upgraded starter cables.. and nothing has improved.


Im a mechanic but on cars so i am a little lost with the magic of what happens inside a CDI etc.

But i do know100% is my issue is ignition related, remove spark plug lead and it cranks fine.


I have another thread on this site where i explain all i have done, here https://www.chinariders.net/showthread.php?t=34627


So i am left wondering how i can retard my timing.
I have already moved the pickup coil counter clockwise as much as my engine case would allow, about 4-5mm and it has helped me get more regular starts but it still isnt right.


Do flywheels go bad??

Do different engine sizes have different flywheels?


I found a Ytube video of a guy, same engine as me and he had same issue of hard starting and burning out starter clutches because of the kick back.


He has cut 5mm off the front of the timing hump on the flywheel and welded it to the rear with great success, easy starts and runs better while riding with slightly retarded ignition timing.



but it seems a bit excessive to me as a mechanic to go welding on a flywheel, even if it is only two tack welds.... but if needs must, just wanting to find out if i can indeed get differently timed flywheels??


Thanks
Alex