Intermittent Cylinder Misfire

[08 Ridgeback]

Can anyone give me an idea of what this issue could be. Sounds like a valve problem? I’ve checked continuity in my plug wires and coil. All check out.
compression on the cylinders:
Front: 155 Cold
Rear: 174 Cold

 

[Mikeinjersey]

Carbed or EFI ?
Can't speak from experience but possibly a failing fuel injector.
Just guessing of course but spark plugs, coil and any of the related wires and connectors back to the ignition module and the EHC.. Also turn your lights out and look for arching from the spark plug leads. Spark plugs and coils can look like new and fail. Plugs are cheap and a good place to start. It sounds to me like one cylinder stops firing then starts. I'm thinking electrical failure not valves.

 

[Sven]

compression on the cylinders:
Front: 155 Cold
Rear: 174 Cold

Mike, it has an S&S. Catch the video again. Tonight's elimination round goes something like this:
Spark box: Motherboard fires off a trigger, my thinking it fires off thru the same path. It does not come on and off. Not it.
Sparkplug: Fires right back up when there is spark. Not it.
Pickup and cup: E-trigger is one long wound wire in and wire out is the pickup. If it drops one cylinder it drops the other. Not it.
Coil: See threaded studs out of the coil? That's one long ass wire in/wire out is part of the coil. If it drops one cylinder, etc. Not it.
Carb: Always ready to supply the demand once spark occurs. Not it.
Compression: Theory wise, yes it fires on either cylinder. Technically not it. But we are done riding it wise, meaning a 10% difference is all she wrote, or slow meets fast and the balance is not pleasant engine wise. If we [I cheated] do the math, you're 11.5502% is the breakout from 10. You're done. Rebuild time.

And with that said, I think we are down to the last jobber of the spark loop. No offense Mike, but catch again the troubletree and choose a root cause. Think of each jobber in the loop. Charging system has 3. Eliminate the jobber. It's usually one thing. Can't be the fuel if it comes back on needing spark showing fuel is not it, right?

Swap plug leads. If the other cylinder drops, it's the lead. No change, hard to guess it's compression. Or say if it runs fine no drop, can't be the leads. Back to 10% chance it is the big C LOL.

 

[08 Ridgeback]

Carbed or EFI ?
Can't speak from experience but possibly a failing fuel injector.
Just guessing of course but spark plugs, coil and any of the related wires and connectors back to the ignition module and the EHC.. Also turn your lights out and look for arching from the spark plug leads. Spark plugs and coils can look like new and fail. Plugs are cheap and a good place to start. It sounds to me like one cylinder stops firing then starts. I'm thinking electrical failure not valves.

Hey Mike... It's a carbed model. I just replaced the EHC about 18 months ago. Thanks for the info.

 

[08 Ridgeback]

Mike, it has an S&S. Catch the video again. Tonight's elimination round goes something like this:
Spark box: Motherboard fires off a trigger, my thinking it fires off thru the same path. It does not come on and off. Not it.
Sparkplug: Fires right back up when there is spark. Not it.
Pickup and cup: E-trigger is one long wound wire in and wire out is the pickup. If it drops one cylinder it drops the other. Not it.
Coil: See threaded studs out of the coil? That's one long ass wire in/wire out is part of the coil. If it drops one cylinder, etc. Not it.
Carb: Always ready to supply the demand once spark occurs. Not it.
Compression: Theory wise, yes it fires on either cylinder. Technically not it. But we are done riding it wise, meaning a 10% difference is all she wrote, or slow meets fast and the balance is not pleasant engine wise. If we [I cheated] do the math, you're 11.5502% is the breakout from 10. You're done. Rebuild time.

And with that said, I think we are down to the last jobber of the spark loop. No offense Mike, but catch again the troubletree and choose a root cause. Think of each jobber in the loop. Charging system has 3. Eliminate the jobber. It's usually one thing. Can't be the fuel if it comes back on needing spark showing fuel is not it, right?

Swap plug leads. If the other cylinder drops, it's the lead. No change, hard to guess it's compression. Or say if it runs fine no drop, can't be the leads. Back to 10% chance it is the big C LOL.

Thank you Sven!

 

[john sachs]

If you can, do a cylinder leak down test. That will tell you the health of the rear cylinder vs. front cylinder. If there's any valve leakage, you will hear it . Just keep your face away from the carb, if the air cleaner has been removed.
John

 

[08 Ridgeback]

If you can, do a cylinder leak down test. That will tell you the health of the rear cylinder vs. front cylinder. If there's any valve leakage, you will hear it . Just keep your face away from the carb, if the air cleaner has been removed.
John

Thanks so much John. I was hoping you would see this post. I will give it a shot.