QuestionWe are in Newport Beach CA
We have a CB750 Year 1982 Model RS. The bike is in good condition - straight - good compression - good spark - we are planning on using the bike in a film - with a Russian sidecar attached. Upon filling the tank and turning on the fuel valve - 3 possible 4 of the carburetors leak - fairly active drips out the intake side of the units. A previous owner may have played with the system - We would like to carefully disassemble the four units and package and send or deliver the 4 carburetors to a real pro that knows the units and can repair and return the units in a reasonable time - We are planning on paying (obviously) for the service or give step by step advice (I built my own aircraft) Art Vitarelli
AnswerHello Art,
This carb problem should not be too hard to resolve.
There are only a few things that can cause
this flooding problem as follows:
1. The float needles and valve seats are gummed up
by old fuel deposits.
2. The floats have been misadjusted by a previous owner.
3. The carbs air vent passageways are plugged.
I would suggest one of two things:
Boil the carbs in lemon juice for about 20 minutes
and then blow out all passageways with compressed air
or carb spray.
Physically check all the jets and carb float needles and valves
are clean and floats lift up and down freely.
When the float lifts it should shut off the fuel flow completely.
The carb bowl should be nearly full of fuel when the float levels are
adjusted correctly.
If the float needles and needle valves are okay they
should keep the fuel from flooding.
You can replace these if they are suspect.
Method 2: This is a quick fix that might work depending on how bad the carbs are.
Go to a Yamaha dealer, (yes, yamaha) and buy the Yamaha carb cleaner.
It is good stuff. Then pull the fuel lines off the tank fuel valve.
Open the drain screws on the float bowl bottoms
and drain the old fuel from the carbs.
Tighten the drain screws and fill the carbs with the Yamaha carb
cleaner. Let it sit a few hours. Drain the bowls again
and flush if necessary with carb cleaner or fuel.
Check that the tank fuel is fresh and reconnect the fuel lines.
See if the bike runs and if any carbs leak tap the
bowls with a screwdriver handle until they stop.
Sometimes the fuel tanks can have some loose rust that
may continue to cause problems, so check
that the fuel is clean or attach a fuel filter inline.
Also download this link:
http://www.thegsresources.com/files/GS%20Carb%20Cleaning%20Series.pdf
This is a very detailed carb cleaning on a Suzuki but the
basics are the same.
Let me know if you need anything clarified.
Wayne S.
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