misfiring

[ChiefTwoKicks]

Thanks for the response to my suggestion, Harry. I said that, not to be critical of your knowledge or approach to finding your gremlin. However, as you can see, with this example, there may be more than one gremlin, maybe several. With the check list, you will be able to pick-'em off one at a time, you'll discover how much actual maintenance these old bikes really need.

I sort of like to compare these old bikes,and what you have to do to keep them to keep them performing optimally... like owning an mid-sixties VW Bug... cheap to operate, fun to drive, fairly reliable, air cooled (thats your first clue,here) and most importantly they always need a little tweaking every 1000 miles or so (valve adjustments,or at least checking them),etc. Those old VW's are famous for checking the valve lash at proper intervals, or you can end up with tons of heart ache, for lack of ROUTINE maintenance.... moving on...

Here's where I'm going to beat on you a bit... man, that original gas filter looks REALLY filthy !! I don't know what your gasoline additives are up there in the northeast, we don't have much of an issue out here in California. But it appears that your fuel may be of major concern for contaminants. Cotton often speak about this. While you're at it, you might want to pull your tanks, and rinse them out real good. All that crap that gets past the filter element goes right through the needle and seat, maybe restricting the flow to the bowl. If that junk sticks to the filter element, it likely sticks to everything else on the way to the combustion chamber, and out the exhaust pipe. Obviously, you can't get rid of it all, but you can clean most of the sludge (non-burning fuel additives),before it gets too bad. Even pulling the heads, and scraping off the carbon deposits.

You're certainly making progress, and again, one by one, you eventually will conquer these issues. Just remember, don't lose hope. Soldier on, slow and steady. Stay with the check list, you may be adding even more to it, too !! Patience, is you best ally.

I'm thinking, (that may get me in trouble here...) you guys back east, generally have a much shorter riding season than we do here on the west coast (at least, west of the Mississippi). In many cases your bikes sit, unridden for long periods of time. When the weather breaks, or you have a few hours of free time, you roll out the bike and take it for a spin. (I'm embellishing here to make a point). OK, your bikes really likes to be ridden. And when you ride them often, you naturally pay more attention to the maintenance intervals. When they sit, often times the maintenance intervals get moved back to the end of the list. Not blaming anyone, its a natural thing to just go out to the barn, jump on the bike, go for a spin and tell yourself you'll do the maintenance later. Doesn't always end up that way, things come up and the "I'll do it later" card is now on the table !! I'm guilty too ! Probably way more guilty than many others.
I ride almost everyday, so my spectrum is at the other end of the scale, but I think you get my point. I've been caught in this trap many times,too. I'm getting better... and my bike thanks me for it.

I apologize for my long, essay-like musings here. Its my nature to be quite descriptive in communication skills. I wanted to be a professional story-teller at one point in my life, but thats no excuse. It's a few of my thoughts, meant hopefully to encourage you in your quest for Victory. I know you'll win this battle and get your bike fixed before too long.

C2K

[exeric]

This has been a very interesting thread for me, as I'm not a good mechanic, or diagnostician. I feel bad for what you're going through, Harry but I'm learning a lot. I know you'll get there.

[pisten-bully]

Dang! False alarm....sheesh. I had 40 miles since my last fill, there shoulda been a gallon left but the main tank is empty. Running the reserve through and there’s good flow into the bowl....feel like an idiot. Removing the carb and sediment filter three times and losing all that gas, plus lots of idle time shouldn’t account for a gallon. Back to the list I guess.

[pisten-bully]

I may have found my "AHA!" moment here, thanks to Tom. Yesterday I changed out the modern paper sediment bowl filter back to the old, original style element but I never tested fuel flow beyond that point:



This morning I removed the carburetor again and reconnected the bowl to the fuel line and opened up the petcock.... I stopped counting when I got to 60 seconds and the bowl wasn't even half full!



I don't know the spec for fuel flow, but that seems waaay too long to fill the bowl. Now I've got something to fix! Thanks Tom!

[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!

[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.

[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

[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.

[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.

[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]

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!

[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.

[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.

[pisten-bully]

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

Not really sure what that means Ryan!

[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?