You really need to check compression before throwing a bunch of parts at it. Having said that, a new plug is pretty cheap. New or not, they are sometimes bad from the start. While you are at it, I would start inspecting your wiring harness as well.

 

I will do that too

 

What should I look for when looking at the wiring harness

 

I would suspect if you had a wiring issue, you either wouldn't have spark at all, or might possibly blow the starter relay fuse. First I would check any grounds in the system. Even if they look good, I would clean these up so I knew they were making good contact. Then I would check connections for corrosion or dirt infiltration that may be hindering contact. This is a good time to place a little dielectric grease in your connections to keep them happy. You also can check the wires themselves for areas where the insulation is wearing away, kinks, pinches, etc.

A multimeter and good service manual/wiring schematic are essential for tracking down electrical issues if that is truly what you have. It may even be as simple as a bad plug wire.

 

Changed plug checked compression all good still not starting.

 

i was just looking at my cdi and there a wire missing from one of the holes i cant find a loose wire anywhere its been gone for a while because there was dirt in the hole. What should i do?

 

Here is a schematic of a 400ex electrical system.what wire is it?[IMG][/IMG]

 

https://blu184.mail.live.com/att/Get...UvanBlZw_3d_3d

 

believe its the green and white one.

 

NOT WHITE AND GREEN im not sure which one do you know?