Author Topic: 1980 Honda CB 750 DOHC Firing Order???  (Read 13393 times)

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ElCheapo

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1980 Honda CB 750 DOHC Firing Order???
« on: May 06, 2006, 05:58:55 pm »
Ok I got this bike in and cleaned the carbs and I guess I never verified that customer installed the replacement coils correctly. When it came to me it was running on 2 cylinders. Because of the coils failing (cracked), it looks like the ignitors were seriously overheated to the point that the black sealant melted out the back and made a mess. All I can verify is that I have spark on two cylinders. I know one of the ignitors is dead as when I swap them I have spark in the opposite coil and not in the other. But none the less...

I NEED A FIRING ORDER -- HELP

Offline GroovieGhoulie

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Re: 1980 Honda CB 750 DOHC Firing Order???
« Reply #1 on: May 06, 2006, 06:20:04 pm »
I thought these puppies fired 1-2-4-3.  I know that the most common firing order for 4-cylinder engines in cars is 1-3-4-2, why Honda went the other way on that one, I dunno.

ElCheapo

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Re: 1980 Honda CB 750 DOHC Firing Order???
« Reply #2 on: May 06, 2006, 06:26:29 pm »
I thought these puppies fired 1-2-4-3.  I know that the most common firing order for 4-cylinder engines in cars is 1-3-4-2, why Honda went the other way on that one, I dunno.

What I am looking for in order is left coil is whatever cylinders and right is whatever

Offline crazypj

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Re: 1980 Honda CB 750 DOHC Firing Order???
« Reply #3 on: May 06, 2006, 09:52:10 pm »
 coil  (1-2) goes to cylinders 2-3. Coil 3-4 goes to cylinders 1-4, Two of the leads should be almost the same length and the other coil should have one long and one short lead, Short is no. one cyl. ( I'll check when I find the book.)
PJ
« Last Edit: May 06, 2006, 10:00:43 pm by crazypj »
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Offline ofreen

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Re: 1980 Honda CB 750 DOHC Firing Order???
« Reply #4 on: May 06, 2006, 11:48:57 pm »
Greg
'75 CB750F

"I would rather have questions I cannot answer than answers I cannot question." - Dr. Wei-Hock Soon

ElCheapo

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Re: 1980 Honda CB 750 DOHC Firing Order???
« Reply #5 on: May 07, 2006, 08:57:11 am »
Here's a link to the Honda manual -

http://cb1100f.net/modules.php?name=Forums&file=viewtopic&t=955

Here's a link to the specifications, has electrical and ignition info among other things -

http://www.cb1100f.net/Other/CB750FManual/Honda%201979%20thru%2083%20CB750%20Service%20Manual%20Chapter%2001%20General%20Information.pdf

This was of great help. Thanks for the help guys. With any luck and a different set of ignitors it will be running by monday morning.