misfiring

[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.

[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!

[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]

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]

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.

Going, going, gone type deal I bet. The old cars use to act that way. Did you check the resistance?

[pisten-bully]

Going, going, gone type deal I bet. The old cars use to act that way.

Not really sure what that means Ryan!

[Arley]

I have a new guess. When you converted to 12 volt did you put a resistor in the feed to your coil? I have converted tractors and trucks from 6 to 12. It is better for the points.

[ryan]

Not really sure what that means Ryan!

When the coil was going out of an old car it would run for a bit, then misfire then die until the coil sat for a while then it would take off again. It would do this cycle till one day it would not run any longer.
That is what I meant by going, going, gone.

[pisten-bully]

Not confident that it's the coil, the old coil and the new coil test the same (+/- .1 ohm) for resistance when cold.

I've got every wire off its terminal right now and have checked each one (again): battery+ to ammeter, ammeter to switch, switch to coil, coil to distributor, generator to switch, battery- to gearbox and they all show .1 to .2 ohms resistance. Then all wires tested with one of the meter's lead on a good ground and none show continuity to ground. The only anomaly I found was when I tested the wire (disconnected) from the switch to voltage regulator, still attached to the B post, the meter went searching for a high resistance, never settled into a reading or 0L. When I disconnected the wire from the B terminal and tested the wire, the wire itself, end to end, was good at .1 ohms, and no continuity to ground...then tested the B terminal continuity to ground and found none. Reassembled and tested again for continuity to ground, none this time.

Switch in the run position has a bit more resistance between the two switch terminals, .9 to 1.2 ohms.

I've reached out to Indian Frank just in case he may have an idea, as Dave mentioned earlier when the ground wire broke on his Chief it wreaked havoc with his regulator. AND, when I tested using a jumper yesterday from the battery+ to the coil I simply clipped onto the battery+ terminal and left the wire going to the switch attached... I probably should have removed that wire!

[tfburke3]

It may be time to take another look at the carb.
I think I would pull the bowl,reconnect to the fuel line,hold a piece of gasket paper to the bowl stem hole and turn on the fuel.This will let you view fill rate to eliminate and fuel restriction issues and fuel level,not just float level.Clean the main nozzle and idle passages and try again.
Also are your new points still pristine?
Tom

[pisten-bully]

It may be time to take another look at the carb.

Thanks Tom, checking fuel flow is a great idea. That’ll happen next. Indian Frank was very helpful in walking me through some checks of generator/regulator including the diode. He may have some more advice but until I hear back it sounds like the problem is elsewhere.

And no, the points are not pristine. They were new the other day and only have about 35 miles on them but they’re slightly dirty looking already. New Greer condenser.

[pisten-bully]

Still poking around trying to find the problem. Yesterday Indian Frank suggested I remove the generator belt and disconnect the wire to the generator and try it like that. I did, it started well, idled well, so I headed out....1/4 mile later it was misfiring again so I turned around and herky-jerkied back to the barn. The silver lining is that it’s not a generator or regulator problem :-)

Checking fuel flow next.

[ChiefTwoKicks]

Harry- in a previous post re; misfiring... you stated the rear cylinder valves were tight and had no lash or clearance. After resetting the valves (you should check both cylinders), have you rechecked them again, after you got the bike running and still had the intermittent misfiring (more extreme, as you stated) ? Might be a good idea to take a compression check of both cylinders. After riding your bike for a hundred miles or so, its possible (unlikely) you may have burned a valve seat or the edge of the valve itself. It may be a longshot, but tight valves is NOT healthy, and if damage has occurred, it will only get worse.
I'm sure you're pulling your hair out over this. Might very well be something very minor, sounds like you've been going over you investigation time and time again. Suggestion: Try making a documented check list, in writing. Go through the list checking off EVERY item, specifically. Leave nothing to "I already checked that". Do one item at a time, check your list and start your bike. Next item, if it passes the check list successfully, move to the next item. One step at a time. This will take some time, as tedious as it may be. Go slowly, take your time to think through your every move. If you have completed the meticulous check list and the engine still continues to misfire, there maybe something bigger to the problem.
Although this kind of malady rarely happens, you have to attack your investigation from a different angle, you can't seem to solve this with the tried and (usually) true methods. Is it possible to have a friend lend a helping hand ?
There's a lot of folks here on the forum who have offered good advice, and sometimes a different perspective can help, i.e., a different pair of eyes. We're all pulling for ya !!
Frustration can sometimes get the best of anyone of us. Don't let that happen... it has caught every one of us, at one time or another. I'm sure there many here that would offer to take the wrenches out of your hands and try to help. We're just built that way. I will speak for many here... its like I said, We're all pullin' for ya'.

C2K

[ryan]

I am pretty sure this is not your problem. I had an ignition mounting screw come loose and fell out and landed between my pos coil post and the coil cover which killed the bike dead on its wheels. It took me a week to find the issue. You will find the issue eventually and let's hope it is something easy.
I know this was unmentioned before. You can bypass your whole wiring harness and switches by hooking the coil straight to the battery. When running a new wire, also run a new wire to your points from the coil and unhook the wire from the distributor. If the bike still acts up, run the another coil, still acts up, change condenser etc. If it still acts up by disproving the electrical, then move to the mechanical, like compression test etc.
You will find it by process of illumination. That is the only way.

[pisten-bully]

Thanks Roger, I think that's really a good idea to document what's been done and systematically work through it! It's my nature to try and take that approach but it's also my nature to get sidetracked...like yesterday when I was going to drop the bowl and check fuel flow I instead removed the sediment filter and replaced the filter element and cleaned the inlet and outlets...never got to the bowl! And then there's the issue of finding other things to take care of while taking things apart, like the cracked muffler hanger I found when I pulled the exhaust to check the valves.

You're right that there's been lots of good ideas and advice from the crew here, all much appreciated! I can't deny that I'm a little frustrated, but I do like working on the bike... but it really stinks not to be able to ride right now. I'll get it eventually, it's a pretty simple machine in reality.... I once had one of the machines I sell with a a running problem the customer couldn't figure out... I tested every single sensor as well as the ECU and wiring harness, and every component of the ignition and fuel systems...turned out to be that the timing belt had slipped two teeth but it took me a looong time to get there.

I've re-read all my posts and will start a log! I'll put valves on it, too!