pop, fart, sneeze....

Can you put a carb synchronizer on it , or re-check the cab slides at rest/ tip in for simultaneous lift with drill bits? I had one side lift early/late and it fouled one plug consistently
Doug

Douglass Harroun said:

Can you put a carb synchronizer on it , or re-check the cab slides at rest/ tip in for simultaneous lift with drill bits? I had one side lift early/late and it fouled one plug consistently
Doug

Click to expand...

I have a K&N filter and the early style oil tank, so I can look right into the carb mouths and see the slides are syncronised. My theory now is that my needle jets are worn out, so I am getting a mid range misfire on the most worn side. I've ordered new needles and needle jets and completely cleaned the offending carb... We'll see where it goes next...

My inclination is still something electrical but you have covered the bases, so wonder if you have looked at the float bowl needles -the vitron tip does get wear ridges that will prevent seating . Other thing to check is that the float bowl pivot- the metal rod- is secure in its slots. The float should rotate on the pivot not the pivot in the bowl. This will give erratic float level ..

oldmikew said:

My inclination is still something electrical but you have covered the bases, so wonder if you have looked at the float bowl needles -the vitron tip does get wear ridges that will prevent seating . Other thing to check is that the float bowl pivot- the metal rod- is secure in its slots. The float should rotate on the pivot not the pivot in the bowl. This will give erratic float level ..

Click to expand...

honestly, I think it's electrical related too, because it happened very quickly. It went from running great to sputtering in the midrange in what seemed like overnight. I've substituted a lot of the ignition parts to eliminate them as causes for the misfire. Here's a picture of my old lucas coils, that I removed years ago to use a single dyna coil in their place, taped to my downtubes to eliminate the dyna coil as a source of my problem...


Every cell in my battery was low on water when I checked the battery, but I tested battery voltage and it read 12.7 volts. Today, I left the headlight on for a few minutes and the voltage only dropped to 11.6 volts and held right there with the headlight on and the bike not running. I used the headlight "on" as a stress test on the battery. I'm not sure, but that doesn't seem too bad... maybe, I'm wrong there, so that is in the back of my mind too.

I've installed an automotive style fuse at my battery cable with 2 prong blades because they are easy to take in and out. I am thinking about modifying a fuse by soldiering a bulb in place of the fuse wire so I can go through the harness and have the modified fuse work as an inline test light...

I still have to check valve lift too...

Have you checked by substitution the Boyer stator plate?

I found a bare broken wire that was the ground from the recitifyer to the positive battery terminal.

I pulled the primary cover and checked my rotor/stator gap, and siliconed the wires coming out of the stator so they wouldn't jiggle around, adjusted the primary chain, and resealed to whole thing.

I didn't get my new needles and needle jets, so maybe the ground wire will solve the issue...

I forgot to switch back to the red boyer from my black one... tomorrow is another day,...

Try it with out the carb changes. It would be nice to know what the problem actually was.

I measured valve travel today. Given that I have an early bike with what I assume is a standard cam the misfire exhaust valve traveled a little more than 3/8ths " which is .375 and the cam lift is .330, so factoring in rocker geometry. I had set the valve gap a few weeks ago and it was the same now as when I set it .008. I think the cam is probably fine.

I replaced the red box boyer and started the bike and same fart, pop, sneeze intermittently on one cylinder.

I have my needles and needle jets coming soon. I wonder if I will visually be able to see a difference between new and old needles and needle jets..??

I'm still plodding along. My work is slow, so I am working on my bike every day.... oh well..

Just read this post too late. Mine had the same symptoms a backfire on the right cylinder at above 2000rpm and no tickover. I had mk1 amals with the sealed pilot bush. I cleaned everything out ( high pressure air ) but the bush has to be drilled out and as I`m not an engineer I didn't want to ruin my carbs.
In the end I bought the premiers, fitted them and no backfire and a steady tickover.
Borrow someones carbs maybe before you buy new.

Re: pop, fart, sneeze.... FIXED!!!

blacklav said:

Just read this post too late. Mine had the same symptoms a backfire on the right cylinder at above 2000rpm and no tickover. I had mk1 amals with the sealed pilot bush. I cleaned everything out ( high pressure air ) but the bush has to be drilled out and as I`m not an engineer I didn't want to ruin my carbs.
In the end I bought the premiers, fitted them and no backfire and a steady tickover.
Borrow someones carbs maybe before you buy new.

Click to expand...

WELL, YOU CALLED IT!!!!

I drilled out the back side of the pilot jet. LOW AND BEHOLD,..... stuffed with crap. The guitar string I was poking endlessly with, thinking that I was finding the jet unblocked was not poking out crapola... I took a sewing needle in a vice grip and POP! the clog busted out. I tapped the back side opening and sealed it with a threaded plug. I reassembled everything and fired it right up,

NO POP, NO FART, NO SNEEZE.. NO NEW PREMIERS... Fixed!!!

ALSO: One of the reasons it went rich was I changed plugs and put resistor plugs in by mistake, so my Boyer was running resistor wires and resistor plugs, so I was getting a weak spark...

THANKS EVERYONE, If you didn't answer me here, I may have used the search function to access information that many here share ... I'm pretty psyched..

Good for you ... now go ride ... enjoy knowing you didn't surrender ...
Craig