1992 CB250 Hesitates on slow acceleration

The bike: 1992 Honda CB250 Nighthawk.

The Problem: When applying the throttle slowly the engine hesitates.
This is more noticeable when the engine is cold and operating at lower
rpm range. Keeping the choke on for a longer period of time minimizes
the problem. This problem is still present when the engine is fully
warmed though not as dramatic. Moderate to fast acceleration seems
normal and the bike holds highway speed normally.

Is there a specific area of the carb I should focus on?

This condition came on suddenly last week, before that the bike ran
fine.

Any advice will be greatly appreciated.

Thanks
Carl

carl6855 wrote:

>Is there a specific area of the carb I should focus on?

The idle ports and passages are clogged up with gum and varnish. Add 4 or 5
ounces of Berryman B12 Choke and Carburetor Cleaner to a full tank of gas and
go for a slow ride at about 1/4 throttle or less so the engine will have to
get fuel through the idle circuits.

Be ready to turn the idle speed knob down as the carburetors get clean.

Avoid using high RPM with B12 in the gasoline. It contains methyl alcohol,
toluene, acetone, etc. Those solvents will tend to remove the film of
lubricating oil from the upper cylinder.

But B12 works very well for cleaning carbs without removing them.

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