QuestionHi Bill, I have a 1970 Honda CB250 and have found the right carburetor not revving properly. I have cleaned the carbys and the left one works fine and there is plenty of spark at the plugs. Any suggestions? If you think the float is out the manuals are a bit vague on how to adjust it. Thanks.
AnswerDavid, do be sure that the rubber diaphragm on the slide is intact with no holes/tears. That will stop carb function immediately or at least affect it noticeably.
I don't know if you took the carb completely apart, but there are emulsion tubes up inside the carb body, that are often overlooked when cleaning. They will come out, if they aren't corroded in too tightly and will require cleaning the cross-drilled holes.
All the numerous O-rings have be sealing properly and the float level is important. If you know the specification, the level adjustment is measured from the carb body to the outside of the float with the float tang NOT compressing the spring loaded float valve pin.
Be sure you have good compression on both sides. Watch the ignition points for signs of excessive arcing (loose or bad condenser). Spark plug caps can go bad, so look for closely matching resistance values around 5-8K ohms.
Ignition timing must be correct before carbs can meter properly, as it affects the manifold vacuum signal.
Bill Silver
