Spark Missing When Cold??

[Lannyl81]

I have noticed since the cooler weather arrived (Oct- present) that upon engine start that one cylinder is not firing all the time.  Depending upon the length of time since last ride and the air temp determine how long I let the engine warm-up before taking off.  After about 2-3 minutes of slow riding through the neighbor and then out on a main road for a mile or so, all is fine and running strong and is fine the rest of the ride, but this returns for the next ride which is usually a week + later.

I have not changed or even checked the plugs yet.  I did pull the carbs off at the end of my first summer due to fuel leaking and then the next summer I had to replace the coolant O rings due to a coolant leak...but nothing else "engine-wise" in my five years of ownership other than oil changes.

 

Just thought I would ask for comments/suggestions......thanks

[Wayfarer]

Looks like it's time to do the maintenance. Five years is quite a good result, how old is your bike? I think new spark plugs will help you to get rid of this issue.

[squirrelman]

most likely a clogged idle jet i'd guess  😣

[Lannyl81]

Since I have no idea the age of the plugs I do plan on replacing them before Spring arrives here.  Clogged idle jet....guess it could be....if something got through the filter and into the float bowl on one carb and then clears-up after getting up to full temp....but then becomes clogged again when it cools down.  I need to determine which cylinder it is somehow.....IR temp gun on the exhaust might tell me.  Although just pulling the plugs and taking a look at the color might tell me or I could also measure the resistance of each one to see if one is higher than the other three.

Things to try....when I have time.

Thanks for the thoughts.