Puzzling misfiring from one piston

ashman said:
Paul you aren't wasting anyone's time, as I said before it's easy to make a mistake even if you done it many times before, we all do it, sometimes the brain doesn't work right and your thinking goes way ward, I know I have done it before, lucky when I do it hopefully no one around to see it lol.
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Thanks for the supportive words ashman! Part of the problem is that the rebuild of my Norton was a super part-time project that took well over a year to complete and rarely would I get more than a couple of consecutive afternoons or evenings to work on it. As I’m finding out now, things that I thought I completed (like fully tightening nuts and bolts) the last time I had worked on it, we’re not necessarily complete. My 59 year old brain is becoming less reliable. Next time I’m going to keep a diary…
 

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The first thing to do in a case like this (if you haven't already) is to swap the spark plug leads left to right. If nothing changes then swap the carbs left to right to pinpoint your problem.
 
Semitone said:
That’s exactly what I did when I put the head back on today. I must have checked a dozen times as I started to torque down the head. I kind of go cross eyed trying to see the rods and back ends of rockers. When I finished torquing the head bolts, I made sure that all adjuster screws were in the same ball park with each other when setting the gap. I rolled it over a few times and chech gaps again. I started it and it voila. No misfire, no clanking. Didn’t run perfectly but I haven’t done a dynamic timing yet, and suspect carb needs to be tweeked as I rebuilt that as well.

So, serious user error on this one. I hadn’t put the head on the bike in probably ten years, and forgot how fastidious you need to be when doing it, to do it right. I also made some poor assumptions. I really appreciate all the input and hope you all don’t feel like I wasted your time. I learned a lot nevertheless.
-Paul
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Yes, that's a bit ugly. Are you planning to replace or is it all still nice and straight? What was it rubbing against and any concerning damage there?
 
Tornado said:
Yes, that's a bit ugly. Are you planning to replace or is it all still nice and straight? What was it rubbing against and any concerning damage there?
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I say it was rubbing on the outside of the rocker arm as when not seated it's the only place it could jam if the motor was rotated, usually when not seated the pushrod will sit on the rocker arm on the inside towards the middle of the head and is always the hardest to see if not seated right.
Well that's my opinion anyway, I have done a few Norton heads in my time and its usually only one push rod that does this, but as I had said earlier I make sure all pushrods are seated right before pulling the head down.
I like to have all the repairs done and all parts before I reassemble a motor and once started the assembly to keep going so nothing is forgotten and the last 2 rebuilds for mates didn't go that way, the first one my mate was a seaman working 6 weeks on and 6 weeks off, he brought the Norton cheap and in pieces I did the motor/gearbox rebuild for him the bike was fired up after the rebuild all working great, then 6 months later he finds out the Norton was a stolen bike, if I would have known that I would not have worked on it, so buyer aware when a deal is too good of a deal when buying off someone you don't know.
I now only work on my own Norton these days, the last rebuild I did for a mate Kim the motor was sitting on my work bench way too long waiting for the owner to get the parts needed and took up way too much room, when you leave sections of the rebuild for weeks at a time, like bottom end all together for weeks waiting for piston parts and then waiting for the head repairs to be done, and then when I do get it all together the owner sells the bike, before the motor is put back in the frame as he became sick, I would have brought the Norton off him if I knew he was selling it as I also done a few weld repairs on the frame, it was so close to being finished and would have loved to be the first kicker to fire the motor up from all my work I done.
My mate Kim pasted away 3 months later from kidney cancer, RIP Kim.

Ashley
 
jseng1 said:
The first thing to do in a case like this (if you haven't already) is to swap the spark plug leads left to right. If nothing changes then swap the carbs left to right to pinpoint your problem.
Click to expand...
jseng1 said:
The first thing to do in a case like this (if you haven't already) is to swap the spark plug leads left to right. If nothing changes then swap the carbs left to right to pinpoint your problem.
Click to expand...
Yes, I did ignition troubleshooting before I started this post. Single carb on my bike. Read beginning of post. Thanks.
 
ashman said:
I say it was rubbing on the outside of the rocker arm as when not seated it's the only place it could jam if the motor was rotated, usually when not seated the pushrod will sit on the rocker arm on the inside towards the middle of the head and is always the hardest to see if not seated right.
Well that's my opinion anyway, I have done a few Norton heads in my time and its usually only one push rod that does this, but as I had said earlier I make sure all pushrods are seated right before pulling the head down.
I like to have all the repairs done and all parts before I reassemble a motor and once started the assembly to keep going so nothing is forgotten and the last 2 rebuilds for mates didn't go that way, the first one my mate was a seaman working 6 weeks on and 6 weeks off, he brought the Norton cheap and in pieces I did the motor/gearbox rebuild for him the bike was fired up after the rebuild all working great, then 6 months later he finds out the Norton was a stolen bike, if I would have known that I would not have worked on it, so buyer aware when a deal is too good of a deal when buying off someone you don't know.
I now only work on my own Norton these days, the last rebuild I did for a mate Kim the motor was sitting on my work bench way too long waiting for the owner to get the parts needed and took up way too much room, when you leave sections of the rebuild for weeks at a time, like bottom end all together for weeks waiting for piston parts and then waiting for the head repairs to be done, and then when I do get it all together the owner sells the bike, before the motor is put back in the frame as he became sick, I would have brought the Norton off him if I knew he was selling it as I also done a few weld repairs on the frame, it was so close to being finished and would have loved to be the first kicker to fire the motor up from all my work I done.
My mate Kim pasted away 3 months later from kidney cancer, RIP Kim.

Ashley
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The pushrod was still straight Ashley, but I had another rod in my parts bin, so I replaced it. Yeah, I had a friend who had started to do repair work for others, then stopped for many of the same reasons!
 
Semitone said:
The pushrod was still straight Ashley, but I had another rod in my parts bin, so I replaced it. Yeah, I had a friend who had started to do repair work for others, then stopped for many of the same reasons!
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Yeah the last 2 jobs I did just didn't work my way, I charge a reasonable price for pull down and assembly and up to the owners to chase parts and machine work with my advice but some just think it's just a straight job but so much time is spent in preparation work and cleaning, I am very fussy in what I do, I am always willing to help anyone with problem with their Nortons, its not about making money but more the love of Norton's and so many fixes are just love jobs.
I am always willing to help but major rebuilds no more, I have my own Manxman project cafe racer to build now, been putting it off way too long.
I work at my own pace and time, every rebuild I write down what I do each day how much time I spend doing work and if they complain about anything it's all written down on paper and what trouble I have had and the fixes I had to do from someone else bodge job.

Ashley
 
ashman said:
Yeah the last 2 jobs I did just didn't work my way, I charge a reasonable price for pull down and assembly and up to the owners to chase parts and machine work with my advice but some just think it's just a straight job but so much time is spent in preparation work and cleaning, I am very fussy in what I do, I am always willing to help anyone with problem with their Nortons, its not about making money but more the love of Norton's and so many fixes are just love jobs.
I am always willing to help but major rebuilds no more, I have my own Manxman project cafe racer to build now, been putting it off way too long.
I work at my own pace and time, every rebuild I write down what I do each day how much time I spend doing work and if they complain about anything it's all written down on paper and what trouble I have had and the fixes I had to do from someone else bodge job.

Ashley
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So the Norton is my second full restoration in the past 3 years. The first being a Moto Guzzi 850T which saw a 1000cc big bore kit and I made it into kinda of a poor man’s 750 Sport. I’ve started to fantasize about opening up a shop. Not as a mechanic for hire per se, as I’d still call myself a yeoman, and for reasons discussed, but a place where folks can work on their bikes. I’d provide a space and tools; I guess it would be a collective of sorts.
 
So back to the cam break in part of this discussion, I ended up doing a combination of unloaded and loaded. The bike spent 10 min on center stand with a 770cfm electric leaf blower trained on the front of the engine. This way I could monitor things as engine warmed up for the first time. I then took it out on the road for the remainder of break in. Glad I did it this way because I had a bad oil leak from one of the head feed banjos which I’m not sure I would have seen during the ride.
 
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