no spark at all

so i havea 1983 xj650 midnight maxim us import i put the 80 uk 4k0 engine in and connected everything up now have no spark any clues or ideas need it fixed urgently as its my only mode of transport please help

 

Check simple things first like the fuses, battery power, loose connections, etc.

Have you tried the main 30 amp fuse?

 

sounds like a new guy fail but no because the whole thing ran before i put a new battery on it because it was easier ( new shape new fitting due to being chopped ) batterys got even more output than old one havent checked the fuse tbh i cant evan find the fuse box on this thing and ive stripped it bare and all connections were tight anyway as refitted them all it cranks over well but just wont spark what so ever so i thought coils tested the coils and no problems just i wont be in the garage till tuesday and im after peoples input of ideas so i can walk in with a big list and just tick it off as i go

 

my guess was the wires in the block connector were different but how will i know what wire goes to what pin as they made massive changes ( my original engine had an electric tacho ) this 4k0 motor has a cable tacho

 

Thought you solved this back in January? Anyway, since I replied to that thread I now have a service manual that has electrical diagrams on each version. The 4K0 and 83 TCI look to be totally different, so it looks like you will need a TCI for the 4K0 to solve your problem, which it looks like you are already in search of.

Not the best photo, but you can see that the pick-up coils actually attach to different pins on the two models - providing the service manual is correct. You should be able to compare the two pickup coil harnesses that you have and verify this.

 

so heres the big question , cut the block open an re-wire ? yay or a nay my friend and i assumed it was this problem but i bought a 1971 mgb gt sports car restoration so the bike went on the back burner but summerarriving in the uk and damn do i miss the growl of my custom exhausts

 

Can you post a picture of the two different pick-up coils (6 pin) connector that mates with the TCI for a comparison, or just say yes they match the color and orientation of the diagrams provided?

I am having a bit of a problem determining exactly which TCI should go with the 4K0 motor, maybe another member has this knowledge and you can widen your search for the correct one.

I am fairly sure that although you might get spark with a re-wire of the 4K0 harness to the 83 TCI appropriate pins, that the timing and advance curves are likely different between the two engines so not likely a good idea.

 

to be honest the 4k0 motor is heavily modified has bin bored up to 760cc race cam ported polished gas flowed etc an yeah ill do that tuesday

 

looked today connection ive bin fitting has 4 pins so thats the 4k0 pick up so the other looked correct so need to refit the other one and try again

 

Race cams.... Are you sure the motor isnt out of time?

 

Do you have a side stand switch and relay? If so, check.