No spark under compression????96XP

[Brprxt215]

Bought a project a couple weeks ago. No clue if it would run. Bought a battery and got it to start with a little ether. After it died out cranked it again and it ran off fuel from the tank for about 15 seconds. Have not got it to run again since then. When turning over it clunks then cranks fast like it should. Positive wire from battery to solenoid gets warm but positive from solenoid to starter does not. I replaced the solenoid yesterday. Re ran primer line so I know carbs are getting fuel. Test spark with a tester. Plugs out I get spark over a 3/8 gap. Put plugs in I get no spark at all. I tried a jumper ground from the coil to the block no difference. I tried a new coil no difference. I am stumped now. Could it be the cdi or mpem shorted out somehow randomly? Turns over fast enough to fire but just won’t. Any guidance would be appreciated. I’ve also tried two sets of new plugs gapped to .22 and trimmed plug wires back quarter inch.

 

[Dr Honda]

When you are testing for spark... are you grounding to the engine?

The no spark under pressure is kind of an "Old School" problem. It was caused by a weak coil... or plugs that decayed internally. But, I haven't really seen much of it in "Modern" times.

So... with my thoughts above... and knowing you tried another coil... maybe you have a poor ground to the engine block. Try adding a ground wire from the CDI/Coil, directly to the block. Also... put in a fresh set of plugs.

 

[Brprxt215]

Grounding plugs out yes. Tried a jumper ground from coil to block still same problem. I’m going to pull engine ground and make sure connection is solid. Also I’m going to load test battery today even though it’s new. I think whatever the clunk is before turning over is just too big of a draw on the battery. I’m also going to pull the starter and see if it’s oem and have it rebuilt if it is.