I recently purchased a 1988 Honda CBR 600 F J off ebay as spares or repair.

There was no spark at any of the cylinders when it arrived so I bought a Haynes Manual and started troubleshooting.

I have done all preliminary checks, state of wiring, connections, earth points, fuses etc. and checked all wires for continuity.

I used a multimeter and measured the impedance of the pulser coil, ignition coils and ht leads. all fell into spec as given by Haynes.

I have tested the cdi unit using a multimeter to test output voltages when the run switch is on/off. it appears to be working as it should.

I have replaced the ignition coils and the starter motor.

I now have a spark when there are no plugs in the bike, however as I start adding the plugs and creating compression, the spark gets weaker, until under full compression (all plugs in the head) there is no spark at all. I have bought a set of new plugs for the bike.

What can be the cause of this?

I have tried everything I have discovered through research and nothing seems to be solving the problem. Hopefully someone here can help..

 

Is the battery fully charged? The fact that there is compression is going to make the the starter work harder to crank it over. You need to have a fully charged battery for trouble shooting.

 

Hi, thanks for the reply.

Yes I am using a fully charged car battery at the moment so there is more than enough amps to power the circuit.

I did try with a fully charged battery off my dads honda, and the cranking was much slower.

Its nothing silly or obvious like that causing the problem, thats why I have resorted to the forums to try get some help.

 

I was told to NEVER jump a motorcycle battery with a Car battery, I have been told it will burn out the CDI ignition.

 

no you can jump a bike battery with a car battery as long as the car isn't turned on. my friend used to work at a bike repair shop and he told me to do that when i left it in park by accident instead of fork lock and drained the battery. started right up too, but do NOT turn on the car while jumping it