Only firing one cylinder 04 pitbull

Badazz

Member
I am completely stumped. The rear cylinder won't fire. I have put on a new coil, new ignition module, new plugs, new wires, compression is 140 on the rear 135 on the front. Anyone have any ideas here cause I don't know what else to try?
 

Sven

Well-Known Member
Have you physically witnessed spark at the plug? Say yes, because I'm assuming you do have spark? Compression seems low, especially needing a compression loss trigger to start it. Wouldn't need those pop off's at the head to start 140 pee yes I said if spark, it's comp. Can't be the carb if it fires the other cylinder. Only think left if fuel and spark is the kinetic to build heat.

Find the working number for comp. Say it gives a range of numbers [for argue sake] of between 186 - 225 psi. 185 means breakout, thus the rebuild/out of running spec/limit of performance... think.
 

Mikeinjersey

Well-Known Member
You should get a spark plug tester to confirm that is your issue. On a duel fire system if the front cylinder is firing but not the rear, swap the wires and plugs to see if the problem moves. You need fuel, ignition (timing) and compression for a cylinder to fire. Your getting fuel so Ignition and compression are left.
Did you have the problem before you installed all the new parts??
 

Badazz

Member
Have you physically witnessed spark at the plug? Say yes, because I'm assuming you do have spark? Compression seems low, especially needing a compression loss trigger to start it. Wouldn't need those pop off's at the head to start 140 pee yes I said if spark, it's comp. Can't be the carb if it fires the other cylinder. Only think left if fuel and spark is the kinetic to build heat.

Find the working number for comp. Say it gives a range of numbers [for argue sake] of between 186 - 225 psi. 185 means breakout, thus the rebuild/out of running spec/limit of performance... think.
Have you physically witnessed spark at the plug? Say yes, because I'm assuming you do have spark? Compression seems low, especially needing a compression loss trigger to start it. Wouldn't need those pop off's at the head to start 140 pee yes I said if spark, it's comp. Can't be the carb if it fires the other cylinder. Only think left if fuel and spark is the kinetic to build heat.

Find the working number for comp. Say it gives a range of numbers [for argue sake] of between 186 - 225 psi. 185 means breakout, thus the rebuild/out of running spec/limit of performance... think.
Yes it has spark
 

Badazz

Member
You should get a spark plug tester to confirm that is your issue. On a duel fire system if the front cylinder is firing but not the rear, swap the wires and plugs to see if the problem moves. You need fuel, ignition (timing) and compression for a cylinder to fire. Your getting fuel so Ignition and compression are left.
Did you have the problem before you installed all the new parts??
Yes it was why I got the new stuff
 

Badazz

Member
Have you physically witnessed spark at the plug? Say yes, because I'm assuming you do have spark? Compression seems low, especially needing a compression loss trigger to start it. Wouldn't need those pop off's at the head to start 140 pee yes I said if spark, it's comp. Can't be the carb if it fires the other cylinder. Only think left if fuel and spark is the kinetic to build heat.

Find the working number for comp. Say it gives a range of numbers [for argue sake] of between 186 - 225 psi. 185 means breakout, thus the rebuild/out of running spec/limit of performance... think.
What should compression be on a S&S 107
 

Badazz

Member
I am completely stumped. The rear cylinder won't fire. I have put on a new coil, new ignition module, new plugs, new wires, compression is 140 on the rear 135 on the front. Anyone have any ideas here cause I don't know what else to try?
The front plug is showing signs of rich air or fuel mixture and the rear literally looks new still
 

Jersey Big Mike

100K mile club
Thank you all for your help, it was the gasket on the intake got twisted up when it was reinstalled. It fired right up both cylinders after fixing it.
this is the classic example of "what changed?"
No where in the description of the problem do I see that you mentioned re-installing the intake.
The first thing to do when you had a running system and it isn't running now is ask "What changed"
What changed includes anything that was done to the bike, it sitting unattended for a long term.
The history between it's running and when it decided not to run is IMPORTANT to know and can alleviate a lot of mis-steps in the diagnosis.
Badazz -- I'm not picking on you but pointing this out for EVERYONE, since everytime we get asked "what do I do, its important to know what happened to the bike" What did you do is not an accusation but an inquiry to get information.
 
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