My 1997 Heritage Softail Classic is firing intermittently on the rear cylinder. The bike only has 25,000 miles on it.
I can smell and see the unburnt fuel as it runs. I did a compression test on both cylinders and they were both 180. I noticed the rear plug was fouled with black.
I changed the plugs and sparkplug leads.
I was wondering if it may be a coil issue. Any other thoughts?
Quote from: SoftailDave on April 12, 2021, 01:59:47 PM
My 1997 Heritage Softail Classic is firing intermittently on the rear cylinder. The bike only has 25,000 miles on it.
I can smell and see the unburnt fuel as it runs. I did a compression test on both cylinders and they were both 180. I noticed the rear plug was fouled with black.
I changed the plugs and sparkplug leads.
I was wondering if it may be a coil issue. Any other thoughts?
Pickup in nosecone or coil or ignition module it could be any one of them or it could be something completely different.
Only way to know is to test the coil and look at the pickup and see if it one of those.
I just checked the coil with an ohm meter. Primary jumps around from 4.9 to 7 ohms. Secondary are 18,000.
My Harley service manual says resistances should be Primary 2.5 -3.1 ohms and Secondary 10,000 - 12,500 ohms.
Looks like my resistances are out of spec.
Would this cause misfire on 1 cylinder?
Is it a single of dual fire coil?
It is a Dyna 2000i-P programmable digital ignition with Dynatek DC6-5 coil. Single fire.
DC6-5 coil specs.
primary resistance 3 OHMS
secondary resistance 16.5k OHMS
It's actually two independent coils within the case.
Would an intake manifold leak or out of adjustment pushrod cause a misfire?
Switch the two trigger wires, the two negative wires. Then switch the spark plug wires. If it's the coil the other cylinder will misfire.
Quote from: SoftailDave on April 12, 2021, 04:57:09 PM
It is a Dyna 2000i-P programmable digital ignition with Dynatek DC6-5 coil. Single fire.
See that would have been good to know in the first post you made :wtf:
I had another coil in my parts bin so I put it in and changed the setting to dual fire. Rear cylinder still not firing regularly.
Nose cone ignition? When they fail it usually shows hp at the rear cylinder.
Try a new plug wire.
Sorry about not mentioning it had the Dynatech coil and was single fire. I thought it was just a stock Harley coil. I discovered later it had been changed when I went to change it to my spare stock coil.
Yes Dyna nose cone ignition. I replaced the sparkplug leads but still has the same problem.
Tahink I will replace the Dynatech coil back in the bike and change the setting back to Single fire. As recommended I will swap the two negatives on the coil and also swap plug wires. Am I correct in assuming if the problem is with the nose cone ignition the misfire should move to the front cylinder?
I am starting to think the issue may be my rear cylinder has a manifold leak. I have new intake and exhaust manifold gaskets in my spare parts. So over the next few day I will replace them. I am slower at these tasks than I used to be. 67 years old and bad arthritis in both hands. A couple of years ago I took off the two carb Edelbrock system and replaced the stock carb.Think I may have torqued up the front manifold then the back manifold rather than doing a balanced tightening of the front and back. While I am at it I may as well change the exhaust manifold and replace it as well.
Will let you know the results.
Well I replaced the two intake manifold seals, manifold to carburetor seal and rear exhaust seal. Still the same problem, front cylinder firing like a champ, rear fires intermittently.
Beginning to think the Dynatek nose cone ignition is the problem. Going to verify the timing is OK.
I'm wondering if it is timed to the wrong cylinder. Is this issue something that occurred after it was running fine? If so disregard my WAG. :teeth:
Quote from: SoftailDave on April 17, 2021, 01:26:29 PM
Well I replaced the two intake manifold seals, manifold to carburetor seal and rear exhaust seal. Still the same problem, front cylinder firing like a champ, rear fires intermittently.
Beginning to think the Dynatek nose cone ignition is the problem. Going to verify the timing is OK.
Check all the wiring coming from the nosecone to make sure it has not rubbed through anywhere and is grounding out.
Did you try swapping the spark plug wires and switch the trigger wires from Ign Module at the coil? If it is the coil, OR the module, that should move the problem to the front cylinder.
-JW
Thanks everyone!
I reset the timing top dead centre front cylinder compression stroke then adjusted the nose cone Dyna. No change.
Yes I did do the wire swap. No change.
Will check wiring today to see if it is grounding anywhere.
I am going to check the carb mixture. I haven't touched anything so I don't know why it would have changed. Also I would think if the mixture was off both cylinders would misfire.
Update
Screwed the mixture screw all the way in then backed it off 1 3/4 turns. Turned the mixture screw in, didn't start to stumble until I had turned it in 1 1/4 turns.
Think I may have to have a look inside the carb.
Checked ignition wires, no grounding issues.