Hey all,

building a bitza:

1993 CB1000 Super Four (no forums for that so I hope u don’t mind!?)

1993 CBR1000f loom

1995 CBR1000f spark unit

fires up but only 3&4 cylinders get hot. Possibly a slight warming on cylinder 2. Cylinder 1 cold. Remove ht lead whilst running and it makes no difference.

stuff already checked

1) Plugs. New and all 4 do spark
2) coil wiring (left does 1&4, Right 2&3) and swapped the coils over to check
3) Pulse unit (single pulse not the old double version)
4) Earths seem all good
5) carbs rebuilt and all getting fuel
6) power to coil wires
7) compression test OK

welcome your advice on what else to check.

couple of possibles

1) Throttle position sensor is missing. Not ideal but would it cut just 1&2 cylinders
2) cam timing?
3) using a car battery to crank it. Plenty of power but of course not the standard fit
4) spark unit is a different year to the loom
5) Engine is 1994 japan model. Loom and spark unit are UK
6) black and white coil leads are live. Blue yellow and yellow blue wires are not live unplugged but go live when connected to the coils with just the ignition on but without the bike running. Normal?

any ideas greatly appreciated.

Chris.

 

When you say pulse unit is single pulse, are you saying it's not set up as a waste spark system? If so, that could be your issue. It's not firing 3 and 4 on the right stroke.

 

No sorry. I mean the pulse unit on the left of the engine crank has a single unit rather than the pre 89 twin version