SOHC.co.uk Forums > CB350/400
Smoking
Octavian:
Hi, so I put in a new wiring loom over the winter, sorted out timing, cleaned the carbs, bought some new plugs and fired her up.
It took a few cranks and a bit of tweaking of choke & throttle but she finally bubbled into life. To be fair she rattled like my grans knees, but worse.. the smoke. White smoke puffing constantly even after 10 minutes of idling and smelling of heavy petrol fumes.
She's not been on the road for about 5 years, any thoughts insights to what this might be? Could it be moisture, condensation, or worse than that.... valves and pistons?
I would be grateful if someone could provide some easy checks to isolate the potential probs.
Cheers guys.
Bryanj:
If it smaells of petrol it could be unburnt fuel and the causes of that are myriad
470four:
Firing on all four? Carb floats free to move?
I did think sticking piston rings but that would be blue smoke...
K2-K6:
Did you change the oil after sitting all that time?
If it runs without any obvious problems then you'd need to get it quite hot to make sure any oil/fuel that has got to the wrong place would be expelled fully. Thinking more of valve guide seals if they have leaked while standing then the pistons/combustion chambers can be coated and will burn off. If that was the case then you'd expect it to clear and not happen again after another cold start.
Octavian:
Hi guys, sorry for the delay in responding - I have been in France all week.
Its definitely not blue smoke, all cylinders are firing as far as I can tell - no misfiring, and when I cleaned each carb the floats were loose enough on the pins. The old oil was cleaned out and replaced last year and when checked before starting the oil on the dipstick appeared clean/transluscent.
I only ran it for maybe 10 minutes at most 3 or 4 times over the course of 3/4 hours - I didn't want all the neighbours running around screaming about pollution! Hopefully it is just burning off old gunk.
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