got fuel, got spark, can hear it popping but no start

Yolandi

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so fitted one of the 2 stroke kits to my bike last week (completely stock set up) and the first night with some fiddling it did start and ran for hours, next day wouldnt start and been the same since, iv done all the usual checks and iv got fuel delivery, spark (NGK BP6L plug), at one point my magneto earth lead fell off but iv re soldered it on, also polished off the varnish on the back of the magneto for a better contact, one thing iv noticed is the spark is very dim, almost impossible to see in day light, iv gapped it down to .025
thinking about it it hasnt run since the earth lead came off and i resoldered it but when your pedaling you can hear and feel the fuel popping each time it fires but as soon as you pull the clutch in it dies instantly
iv ordered a new coil because it was cheap enough but it hasnt arrived yet also measures the magneto volts and its giving out a max of around 6v

i cant think of anything else to explore, help?
also have tried a small amount of e-z start but no difference
 
several months ago, there were some mags that measured 480ohms instead of the usual 350ohms - at that time some CDI units would burn out one leg of their rectifiers giving them very weak sparks at low revs - if your mag reads that high, you may need a new CDI

more likely is just a head gasket leak which is very common on these motors (look for oil seepage around head)
 
its hard to see seepage because i got the black coloured style but it is slightly wet on the fins around the gasket
iv checked the mag and cdi and they were both within range ohm wise
 
Have you pulled your head?
If so, did you re-install it with torque wrench?
I torque my 66cc heads down to 20#, 5# at a time in an X pattern.
 
on black motors, I use a paper towel wrapped around an old hacksaw blade to check for seepage around head - clean it well with towel then see if it returns after a few tries to start it
 
yes i pulled the head just to see if there was anything obvious inside, i turned the gasket 90 degrees when i refitted adn yes tightened down with a torque wrench, just pulled the exhaust and lots of black fuel poured out of it when i turned it upside down but it can be blown through easily, wondered if it was choked up and blocked
 
so fitted one of the 2 stroke kits to my bike last week (completely stock set up) and the first night with some fiddling it did start and ran for hours, next day wouldnt start and been the same since, iv done all the usual checks and iv got fuel delivery, spark (NGK BP6L plug), at one point my magneto earth lead fell off but iv re soldered it on, also polished off the varnish on the back of the magneto for a better contact, one thing iv noticed is the spark is very dim, almost impossible to see in day light, iv gapped it down to .025
thinking about it it hasnt run since the earth lead came off and i resoldered it but when your pedaling you can hear and feel the fuel popping each time it fires but as soon as you pull the clutch in it dies instantly
iv ordered a new coil because it was cheap enough but it hasnt arrived yet also measures the magneto volts and its giving out a max of around 6v

i cant think of anything else to explore, help?
also have tried a small amount of e-z start but no difference
Had the same crap. First day running great, second day wouldn't even start. Spark was really weak and I could barely feel it if I stuck my finger in the cap and pushed the bike. It was a bad CDI in my case.
 
sorry was peak voltage at 29 (so probably 30) on AC meter, had it on DC when i took the 6v reading

havnt really got the guts to stick my finger in the cap after working on some high voltage russian jeep engines XD
 
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