White smoke from right exhaust

kickstand

kickstand

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I started my '71 CB350K today for the first time this season. At first, it idled high (around 4K rpms). So, thinking something was wrong, I shut it off, checked a few things and started it again. This time, it ran much better, but it blew a lot of white smoke from the right exhaust. After a minute or two, the smoke got lighter but never quite went away. After 10 minutes of idling, the smoke would occasionally stop, but would then return (light smoke).

I had done some maintenance since the last time I started it, so I'm wondering if it could have been caused by something I did, specifically the float adjustment that I did on the carbs. Last season, the left carb was overflowing. So I replaced the float and needle valve, and adjusted the float to 23mm. For consistency, I did the same to the right carb even though it hadn't been overflowing. Now, neither are overflowing. But is it possible for the right carb to be delivering too much fuel to the cylinder if the float isn't adjusted quite right?

Other things I did since the last time the bike ran: new ignition coils, new condenser, cleaned and adjusted the points, adjusted the cam chain tensioner.

EDIT: The more I think about it, it seems more likely that I wasn't precise enough with my points adjustment and that it's firing late. I'll check that soon. But I'm still curious about the carb float height and if that, by itself, could cause a rich mixture
 
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Incorrect float adjustments certainly can affect mixtures. In your case I would be more likely to suspect moisture condensed in the exhaust which has not completely burned off. Take it for a ride (you're supposed to do that anyway), get it completely warmed up (10 miles or more), then check the spark plugs, they'll give the best indication of a rich/lean condition.
 
J-T said:
Incorrect float adjustments certainly can affect mixtures. In your case I would be more likely to suspect moisture condensed in the exhaust which has not completely burned off. Take it for a ride (you're supposed to do that anyway), get it completely warmed up (10 miles or more), then check the spark plugs, they'll give the best indication of a rich/lean condition.
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Thanks, J-T. I had planned to take it for a ride yesterday, but we had a storm here. I'll be sure to take it for a ride soon to see if that takes care of it. If it doesn't, I'll take another look at the floats.
 
crazypj said:
White 'smoke' is probably water vapor, oil burning gives definite blue/white tinge.
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The term "white smoke" has always been a pet peeve of mine, any real smoke from these engines always has a color whether gray/black from too much fuel or light blue from burning oil. Anything white is typically water vapor as PJ mentioned.
 
ancientdad said:
The term "white smoke" has always been a pet peeve of mine, any real smoke from these engines always has a color whether gray/black from too much fuel or light blue from burning oil. Anything white is typically water vapor as PJ mentioned.
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That's good to know. Thanks for mentioning it. Hopefully it was just water vapor. If there was a color to it, it was too faint for me to notice. But if it continues, I'll pay attention for the color as well as the odor (fuel, oil, etc).
 
The easiest (but probably least convenient) check is at night, no street lights, hot engine (10~15 mile run) and have a car about 20ft behind you, on low beam. (obviously while stopped)
If your burning any oil at all you will see blue tinged 'smoke'.
You can only see it from bike looking back.
I did a bit of photography years ago so light has to be at 'correct' angle and you view from a different angle, (when I get a new hobby I go a bit crazy learning everything I can about it)
Almost every bike more than 10 years old will show a tiny bit of haze, even brand new ones often show it before rings fully bed in.
You will often see oil/water vapor coming out of engine breather on a hot engine, (on older engines that didn't run breather into air box)
I haven't found any better method of checking
 
crazypj said:
The easiest (but probably least convenient) check is at night, no street lights, hot engine (10~15 mile run) and have a car about 20ft behind you, on low beam. (obviously while stopped)
If your burning any oil at all you will see blue tinged 'smoke'.
You can only see it from bike looking back.
I did a bit of photography years ago so light has to be at 'correct' angle and you view from a different angle, (when I get a new hobby I go a bit crazy learning everything I can about it)
Almost every bike more than 10 years old will show a tiny bit of haze, even brand new ones often show it before rings fully bed in.
You will often see oil/water vapor coming out of engine breather on a hot engine, (on older engines that didn't run breather into air box)
I haven't found any better method of checking
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Thanks for sharing that trick. I never would have thought to check that way.
 
Oil smoke and fuel smoke also smell, and steam not so much. You could also try holding a cold, flat piece of metal a few inches back from the muffler, while it's running and smoking, and see what condenses on the plate.
 
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