misfiring

[pisten-bully]

Finished work for the day and pulled out the Chief, it started and misfired immediately even though the engine was cold (89F ambient). So I took Tom’s idea and jumpered from the pos on the battery to the coil after disconnecting the feed to the coil from the switch. No difference, misfiring a lot and so bad it can’t hold an idle.

Logic tells me I just confirmed the harness/ammeter/switch are not my problem? Also confuses my thoughts about it being an engine temperature related issue because it starts cold and misfires immediately now.

[ryan]

...sigh...23 miles is all I got this time. New coil is due in tomorrow.

If I put this coil in the oven, heat it up and test resistance between the two terminals, if the coil is good it should read the same, hot or cool...right? (...gotta find the actual problem before I trust it again.)

BTW, I did have a new condenser on it.

As the ambient temperatures rises, the resistance in ohms rises and voltage increases. Not sure what temperature you are going to bake it at.
I would take a ride and check resistance when it acts up. Hot wiring the coil was a good idea from the above post.
I bet your coil is breaking down with heat causing too much resistance. The resistance goes back down when cooled allowing it to run well.

[pisten-bully]

It's sounding much like a switch problem.

Thanks Brian, I’d like to see that. As Tom B. mentioned, when Tom W. suggested the harness may be the problem I disconnected the harness parts and tested each section for resistance with the multimeter, and the switch, too. BUT, as I discovered later my 20 year old multimeter was a problem and giving bad results, so I have my good one now in hand so I’ll repeat those steps!

Have to believe this is temperature related, the Chief ran really well this morning for a 15 mile test, and for 23 miles later it ran like a top....then it decided enough was enough and started misfiring with no warning and I couldn’t keep it running. It was over 90 degrees...which doesn’t happen very often here!

[brian_groff]

It's sounding much like a switch problem. My Chief has a similar situation and I'm digging into possible switch problems. Bob Stark had a different way of wiring these switches that was supposed to be easier on the contacts and more reliable. Will see if I can get the details nailed down on that and report back.

[tfburke3]

Have you thought about a jumper from the battery pos. to the coil to eliminate any switch or harness issues like Tom W mentioned?
At least it looks like you can cross dist. off the list.
Tom

[pisten-bully]

...sigh...23 miles is all I got this time. New coil is due in tomorrow.

If I put this coil in the oven, heat it up and test resistance between the two terminals, if the coil is good it should read the same, hot or cool...right? (...gotta find the actual problem before I trust it again.)

BTW, I did have a new condenser on it.

[pisten-bully]

....so that post making intermittent contact with the distributor body may have been my problem. Back together now and had a 15 good mile road test. Gonna shoot for a 50 mile ride here shortly (I still don't trust it ).

Made a new insulator strip from a plastic milk jug for the points spring, put some heat shrink on the post where it passes through the distributor body, and used nylon washers inside and out.

BTW, when my reserve tank was leaking into my oil tank I stopped putting gas in the reserve until I could deal with it. Paying attention to the mileage and stopping every 75+/- miles for gas.

[Arley]

If you have oil in the gas ,you have gas in the oil and you need tank repair or you will be rebuilding motor.
Tom

I am keeping an eye on it thanks

[tfburke3]

My chief overfills the reserve tank with oil. There must be a small seep at the top idk. What I am saying is that oil will cause it to misfire without fouling the plugs.

If you have oil in the gas ,you have gas in the oil and you need tank repair or you will be rebuilding motor.
Tom

[Lipdog]

I think Kiwi sells an improved insulator for this.

[Arley]

Thanks Arley, I'll look at that, too!

But this afternoon I determined my multimeter was giving me the same intermittent problems when checking resistance, so I went to our warehouse and picked up my newer and better one and I may have found something! The through post in the distributor that feeds the points on the inside, and receives 12V from the coil and has the condenser attached to it on the outside goes through the distributor body with two insulating washers, one inside and one outside. The outside one was half gone... so maybe, just maybe the post was intermittently grounding out on the distributor base. We'll see!

May be it, probably is. Was the the bolt loose? I ask because when they short out it is either on or off.

[pisten-bully]

My chief overfills the reserve tank with oil. There must be a small seep at the top idk. What I am saying is that oil will cause it to misfire without fouling the plugs.

Thanks Arley, I'll look at that, too!

But this afternoon I determined my multimeter was giving me the same intermittent problems when checking resistance, so I went to our warehouse and picked up my newer and better one and I may have found something! The through post in the distributor that feeds the points on the inside, and receives 12V from the coil and has the condenser attached to it on the outside goes through the distributor body with two insulating washers, one inside and one outside. The outside one was half gone... so maybe, just maybe the post was intermittently grounding out on the distributor base. We'll see!

[Arley]

My chief overfills the reserve tank with oil. There must be a small seep at the top idk. What I am saying is that oil will cause it to misfire without fouling the plugs.

[pisten-bully]

I had forgotten about this discussion here: https://forum.antiquemotorcycle.org/...ight=Condenser where Jason installed a capacitor in lieu of a condenser, so I’m going to try the same!

[indian301]

Harry,

I was on a cross country trip from NJ to CA. I decided to tune up my bike in CA, only made it 100 miles before the new condenser took a Sh^%$t. Installed the old one and rode all the way back to NJ. Jason is right, new ones are junk. I installed Clyde Crouch's electronic ignition after that trip in 1996 and have never had another ignition problem.

Dave