Hi all,Sorry for the long story but a bit of background may help someone realise what I could have done wrong. My question in short is lower down highlighted in bold. I have a background in automotive so didn't think small engines would be any more difficult.

So about 5 months ago I received a chinese made quad with a Zongshen 167fmm engine (250cc I believe) in not running condition. It's a electric start engine so no kick start. The elec start wouldn't turn over the engine so thankfully it is manual so bump start is possible. Later found out the starter clutch gave out.

I did a tear down of the engine and replaced the piston, piston rings, head/cylinder gaskets. I honed the cylinder and deemed it reasonable condition. Got a new wiring loom with cdi, regulator, starter solenoid, coil pack. I also bought a new carburetor as the old carby was shot.

While I was in there I found the starter clutch roller bearings had gave out so it would free spin when starter was engaged. In the interest of getting it going I decided to remove the starter clutch and just welded a 14mm socket to a spare bolt and used the drill to turn the engine over.

After putting it back together and filling with oil. It started (with the drill) and ran fine. Decided to do a compression test, running 125 psi everytime. Seems to be good so I rode it for about a week. Started everytime and ran fine everytime.

One day I was riding and it just cut out. I pushed it home did another tear down and found 1 of the hex key bolts from the magneto had worked itself loose (despite using red threadlocker) and chewed up the stator. This time I thought I would put a new starter clutch on for the convenience of having elec start. So 1 new stator, 1 new starter clutch and 1 new 12v 9AH battery later it's barely turning over. Figured it was the starter so replaced that too and it turns over no problem. Still not starting though. Did a compression test and it seems odd, 100psi. Nothing in the top end changed so it seems odd to me that it drops 25 psi out of nowhere. Note that the throttle was wide open. I did a leak down test and there was no leakage at all.

Pulled the spark plug and am now not getting spark. Pulled the wire coming into the coil pack and held it near a ground and saw it sparking there, although pretty faintly.

With the lower compression and lower spark is it possible that the engine isn't being spun fast enough by the starter? If so, is there a common fix or am I just missing something simple?

Any help would be appreciated and apologies again for the life story. Happy riding!

 

Do the help diagnose stator tests at the top of this section of the forum. Once you get a spark the engine should fire up with 100psi compression, any higher and the engine would be turning over slower on the starter anyway.

 

Hi, I have the same engine. I'm hoping to replace the piston rings (kit) if you wouldn't mind sharing link to were you got all of your parts from please.