well about 2 month ago i bought a 87 250x. the engine was pretty beat from some bad things happening with the timing chain so i didnt hear it run.....(paid 200 bucks) got it home tore it down found out what needed to be replaced, well today i finished it up and tried to start it......no start.....has fuel,compression and to me it seems like a weak spark. maybe im used to car ignition sytems witch has a nasty spark but this doesnt seem to have alot of guts behind it. all my grounds are good cdi is good, engine timing is spot on.

i tested the coil with my ohm meter and it reads 0.5 for resistence between the two poles, my repair manual says it needs to be 0.1-0.2....could that0.3 difference be causing my problem?

 

Weak spark could be a bad CDI or as simple as a plug. I actually had a good spark but the plug was bad and it wasn't sparking under compression. For a few bucks, I'd start by replacing the plug. Are you sure the timing is not 180 degrees off?

 

its a new plug, no my timing isn't 180 off. cdi is brand new, the guy i bought it off of replaced it thinking that was his problem. the spark im getting is white and i should be seeing a nice blue spark, which makes me think its my coil. plus the manual says if its not within the range in the specs then replace it. idk im gonna go out after work and dbl check grounds and the wire harness.

or it could just be that the coil is over 20 years old lol.

 

I think you can get a new coil for under $15 so it's worth a try.