Motorcycle Repair: 1974 Honda CB 360, honda cb360, emery cloth

Question
My father recently left me his 1974 or 1973 Honda CB360 as a result of a move.
The bike will turn over but it will not start.
He recently had a lot of work done on it by a local friend but they could not get it started.
From what I understand the carb has been rebuilt along with the ignition system.
I have noticed fuel leaking from the petcock when in the on position.  I took off the lines going to the carburetor to see if fuel was making it to the carb.  In the on position no fuel comes on either line.  I think it may be out of fuel now because the petcock was no longer leaking.
In the reserve selection I get steady fuel on the line connected to the left carb.
I am fairly mechanically inclined but all may experience has been with automobiles.
He has a repair manual of some kind, but I can not seem to find the information I need.
Is this something I am just better taking to a Honda dealer and let them figure it out.
I noticed Petcock rebuild kits on line.
Should I try my luck starting there.
I also noticed no lines connected to the lower bowl under both sides of the carb.
Everything else appears to be there.
Any advice would be appreciated.

Thanks!


Answer
David, bikes follow the same laws as cars, just the parts are more compactly close together and the design of the systems is a little different. They need the same thing as cars: Air, fuel (metered), compression, spark (at the right time)and correct valve timing between the cam and crankshaft.

Compression needs to be about 175 psi. Check valve clearances to see if any are tight, which reduces the compression readings.

Clean the point faces with a fingernail file or some very fine emery cloth, so the faces are clean and shiny. Often, when bikes sit for a LONG time, the mechanical spark advancer, located behind the point plate is stuck/sticking, so that would be a good thing to check before you dial in the spark timing.

Turn the motor over until the maximum point gap is achieved and adjust, if necessary, to about .014-.016"
Then you have to move the point plate around until the left side points are just opening at the LF mark. The right side ones are next and you have to do the same, so that the gap is unchanged but the point opening moment is achieved at the T mark alignment on the flywheel. When you are complete, gaps will be in the correct range and the points are just opening at F and LF marks. Once that is done correctly, then you can proceed to the carbs.

360s have vacuum diaphragm carbs and if there are any holes in the diaphragms, then they will not work. Float levels are 18.5mm with floats just barely closing the needles into the seats, but not collapsing the spring loaded needle tips. Of course, all circuits and jets must be clean.

The petcock has a screen inside. Go here: http://www.powersportspro.com/partsfish/login.asp and find the illustrations for the 76 CB360 inside, for reference, if your book doesn't show what you need. The sediment bowl is on the bottom of the petcock body, so check to see that everything is clean there. If the tank is almost empty, remove it and remove the petcock to see if there is debris down at the base of the unit, which can clog the passages.

Make sure that the fuel cap vent holes are clear and clean.

Carbs had drain tubes attached to the bottom of the float bowls, to drain flooding carb gasoline away from the top of the motor. The don't have to be there to make the bike run. If there is flooding from either side, either the float level is incorrect, the float valve is dirty or worn or the float is sinking due to internal damage.

Petcock has a 4 hole gasket that can be turned around sometimes, to help prevent leaking, otherwise put in a new one with a good screen and O-ring set. The back side of the lever can get etched and allow fuel to pass the shutoff function. File the back side smooth to help sealing the petcock lever. Parts may still be available from Honda or through aftermarket parts houses.

If people have been cranking and cranking the starter, the plugs are probably loaded up with fuel deposits, so buy some new ones to install once everything else has been attended to. Plug caps should be about 5k ohms resistance. Unscrew them from the wire and test.

You really need to follow a full tune-up procedure and be sure that all fuel circuits are clean. It should fire up after that, unless there is engine damage or carburetor parts failures.

Bill Silver