2 stroke has spark and compression 70psi and fuel . Just won't fire up.. think its timing but there are no timing marks on flywheel or the crank case so can't assess if it's timing or not. It also has dc CDI and I assume the one wire from stator is trigger? Any help appreciated.

 

70psi is low, even for a two stroke. A dodge that often works with them is to squirt gas from a gas blowlamp up the air intake whilst turning the engine on the starter, use no choke and a clean, dry plug. You can use starting fluid, but that tends to wash oil from crank and bore, so not good for the engine. And yes, the wire from stator to CDI will be the trigger. Engine makers usually put the keyway for the flywheel at the top when the piston is at TDC, on "upright" engines, and the "lump" on the flywheel is going to be passing the trigger coil just before TDC.

 

Thx for your reply . Have tried quick start via the air inlet to carburetor still no go. Fly wheel has no bump on it .cheers

 

In addition there appears to be no external /intrnal trigger sensor. Will try an upload a photo.

 

That different coil indicates a magneto rather than a CDI. Some makers produce a sort of hybrid, Suzuki LT50s were more magneto than CDI. Anyway, if the flywheel keyways line up, the spark has to be at the right time. Clean the carb out, blowing jets and orifices out with compressed air. Check the oil seal on the crank at the other side, the one showing is OK, or the stator coils would have been covered in oil and dirt. If it has a reed valve, check that is working, make sure the exhaust isn't completely blocked. If all these are OK and it still won't fire up, take the cylinder off and check it for wear. If it and the piston are OK, treat it to new rings and cross hatch the bore. Check head and cylinder surfaces are flat. Rebuild, and try again.

 

thx merryman. You’ve given me a lot to work on. Is it difficult in checking the oil seal. I don't have a manual for this atv. Cheers

 

A blown seal leaks fuel/oil mix, so you can usually tell if it has been leaking if you strip far enough to see it. However I would do that carb clean and other checks first and see if it then fires up, if it looks like the other crank seal is hard to get to. It could just be a carb or exhaust, etc.

 

Still have this 2 stroke LEM atv which has spark and compression but wont fire. Have checked all above as per merryman.Can anyone tell me if the cdis for 2 strokes are configured differently to 4 strokes due to the timing. I understand this is definitely a 6 pin DC powered cdi. I cannot find a diagramm for 2 stroke cdi terminal positions with respect to 1through to 6.. I look forward to any help on this. Cheers

 

As you are getting a spark, it is unlikely to be ignition that is the problem. I guess that black coil could be a trigger coil but it looks a lot more like a magneto to me. What do all those 6 wires to CDI do? You could have two from stator coil, one live from ignition switch, one earth, one to ignition coil, and odd DC set ups do have a kill wire, even though turning off the live from ignition kills the spark on them. Initial spark timing is set by the trigger coil position, only advance/retard is set by the electronics in the CDI and won't be all that different on a two stroke. Some Minarelli 90 two stroke clones use DC CDIs, not sure if any of them are 6 wire though.

 

6 pin wiring: 2 wires Black both to ground, 1 red/black from stator (250 ohm assume this is trigger) ,1 red from key switch 12v ,1 to kill B/W and 1 red/grey to coil . Also if the black coil is not trigger then what triggers the cdi? Thanks for your help