[collin_vasko]

Hello, this is my first post after going through tons of forums helping me fix up my cb350, but I have hit a barrier and cannot seem to find anything on it. So, I bought a '71 cb350 which ran but not well and would require me to fight with it. It would start after fighting it, but struggling idling. If it did idle it would die after driving it in my neighborhood and going back to a stop. I cleaned both carbs, bought new spark plugs and boots, new ignition points, new condenser, new battery, timed both cylinders, and tuned both carbs. The bike starts up much easier now, but I noticed that the left exhaust pipe feels weaker than the right and after cleaning the left carb again it does not warm up. When I adjust the idle screw on the left carb it does nothing to the idle of the bike, only the right idle screw affects it. Both points seem to be getting spark. I unplugged the left spark plug boot and tried starting up the bike. The bike started right up as if nothing changed. I then tried it the other way around (right boot unplugged left boot on) and the bike would not even start. I am not sure if it is a fuel issue, compression issue, or spark issue. I do know that the bike runs much better if I add SeaFoam motor treatment into it, but after about 30 mins of idling and short riding it will turn off (compared to usual 5 mins). Any ideas on what I should be looking at? If anyone has questions feel free to ask.

 

[screamingtiger]

IM confused, you say you have issues with right side, but it sounds like the right side starts and left side does not? left side idle screw has no effect?

It sounds like your left cylinder isnt running. One way to tell, is when the bike is running, pull up on the left throttle shaft directly, see if throttle increases. The left pipe being cold, and weaker feeling is because its probably not running Im just confused by your title.

My suggestion is to leave the right side unplugged and get it running on left side.

Left side - ensure spark at plug
-Ensure fuel is in bowl (check drain plug if you got one)
-Try to use some starting fluid to get it started, if it runs then dies, after a few tries its not getting fuel.
-Check timing.

Did you clean the idle jet? Its the one under the rubber plug and it unscrews. Those get clogged easy and will cause it not to want to start.

 

[matthewc]

Hi, I just revolutionised my CL350 by fitting new coils, capacitors, and points, and making sure that the timing is perfect (it's got to be absolutely spot-on). I had lots of starting problems before this, despite having both carbs professionally claned, now all is fine and it fires on both pots immediately.

 

[matthewc]

Hi, I just revolutionised my CL350 by fitting new coils, capacitors, and points, and making sure that the timing is perfect (it's got to be absolutely spot-on). I had lots of starting problems before this, despite having both carbs professionally claned, now all is fine and it fires on both pots immediately.

Sorry 'cleaned' ...

 

[collin_vasko]

IM confused, you say you have issues with right side, but it sounds like the right side starts and left side does not? left side idle screw has no effect?

It sounds like your left cylinder isnt running. One way to tell, is when the bike is running, pull up on the left throttle shaft directly, see if throttle increases. The left pipe being cold, and weaker feeling is because its probably not running Im just confused by your title.

My suggestion is to leave the right side unplugged and get it running on left side.

Left side - ensure spark at plug
-Ensure fuel is in bowl (check drain plug if you got one)
-Try to use some starting fluid to get it started, if it runs then dies, after a few tries its not getting fuel.
-Check timing.

Did you clean the idle jet? Its the one under the rubber plug and it unscrews. Those get clogged easy and will cause it not to want to start.

Sorry, I did mean left cylinder/carb. i charged the battery overnight and the left cylinder actually started firing but very inconsistently and seemed to stop after an hour or two probably bc the battery lost some charge. There would be loud and soft pops inconsistently as the left would fire, and every now and then the bike would rev up to 3000 rpms and stay there until randomly going back down. I will probably give the carb another cleaning bc I think I did forget to clean the idle jet.

 

[matthewc]

This sort of inconsistent running sounds like a mixture of ignition timing and mixture problems. Best to be systematic and work through the electrical side first, checking the circuitry and then making sure the timing is fine. If you get good sparks on both sides after that then it's down to weak mixture, but if the carbs are okay then you should start to suspect the head / valve springs / compression. Start with the easier electrical stuff first, maybe?

 

[screamingtiger]

Im thinking ignition coil, is it connected to the condenser? Also hanging at 3k rpm suggests air leaks but who knows. zz

LIke I said, run on left side only, check for air leaks with some water, adjust the mixture per manual.