78 CB 750-K

[Jeff Stock]

Hi,
My 750 was running great when one day I rode it about a mile and it shut down. After pushing it home I found it had no fire to the plugs. SInce the engine was hot I suspected coils gone bad. I ohmed them out like the manual said and they checked good. This bike's ignition has been converted to Martek Industries CDI unit. When I try and start it hot, no go, but when I turn the ignition key off I get a monentary spark on the plugs. So that shows me the field is being broken but by the switch??
So not sure how to trouble shoot that CDI system, they are over $200.00 and so are coils. I hate just taking a shot in the dark by changing parts since that can get very costly.
Any help would be greatly appreciated.
Jeff

[TOOLS1]

I would put a stock point type ignition (they are cheap) back in it, for testing. If it still does not start hot, then it is the coils. If the problem no longer exists, then put another electronic ignition in it.
TOOLS

[Re-run]

Do you still have the old points plate or was it converted before you got it?

If you get all your lights and everything powers up ok, I would rule out fuses.
I would check the battery though. Leave it off and check voltage, should be about 12.6 - 12.8.
Then turn on the key and check again. If it drops to under 12, the battery might not be holding enough charge anymore to allow proper coil saturation for ignition. You get some spark, but maybe not enough and when not running, the battery provides all the power for your coils. You may want to take your battery in to be tested too. If you don't know the age, it may be time for a replacement. 2-4 years seems to be the average life span for a battery in older bikes like this depending on care of battery and condition of charging system and quality of battery.

From there, you may be able to contact martek but I don't know if that is possible.

[Jeff Stock]

I wish I had the points, at least those you can trouble shoot.
I just checked my battery voltage and showing 11.7 volts with nothing on, with the key on its showing 11.0. So I guess i'll try charging it and see if I can bring it up to your recommendation. This battery  is only about 6 months old, but its a Wal-mart brand so you never know????

Thanks
jeff

[Jeff Stock]

Yes, good idea also. Those points plates are all over ebay and cheap. But I did find the battery voltage low so I'll start there and see where that leads me.

Thanks
Jeff

[Re-run]

Yeah, get it charged up and see what the voltage is. If it still does not get above 12.5, it may be a dud.
I used a walmart battery before and it kinda sucked for longevity.

If the voltage comes up, see if it starts. If it does, hook up the meter again and rev to 3k rpm and check voltage.
It should hit about 13.5 at least to 14 volts. If it hits 14.5, I would check the gaps on the voltage regulator as 14.5 is a bit high.

If voltage does not go up, you have a charging issue.

[Jeff Stock]

Well I have 12.6 volts in the battery but only getting 9.0 volts to the coils and no fire to the plugs again.
Starting to think there is a bad connection in a wire or intermittant broken wire.

[Re-run]

A 3+ drop is significant. trace the wiring to the ignition and see if it drops. Then check immediately after the martek. If the drop happens after the martek, I think it may be bad.

If you do need a new one, the pamco unit is a very good unit.