Motorcycle Repair: hard starting 82 v45 magna, honda v45 magna, fuel delivery system

Question
I recently purchased an 82 Honda V45 Magna. I had the carbs cleaned and synched. It is really hard to start when the bike has been sitting overnight. It will fire with the choke on and then die out. The only way it will fire again is with the choke off. It takes quite a few times to get it so you can give it throttle. very cold blooded. The bike has only 9000 miles on it.

Answer
Jeff, with any new purchase of an old bike, you need to do a baseline of the engine to determine what you have to work with.  Start with a compression check/valve adjustment so you know if you have issues with the basic engine configuration.

The fuel delivery system needs to be checked and cleaned thoroughly from gas cap to float bowls, including the fuel pump, fuel filter, fuel cut relay function and all connecting fuel lines.

There is usually a check valve inside the fuel pump and yours could be malfunctioning causing the fuel to siphon out of the carburetor fuel lines. It is important to know if the carburetors were rebuilt completely, using factory parts or just the bowls and jets cleaned out and the rest left as-is. Aftermarket carb kits are often incorrectly calibrated or some of the parts are not a proper fit. All the start valves on the end of the choke cables need to be checked for proper function.

There are two spark units mounted on the back fender, beneath the seat, that may be causing issues once they get warmed up a bit. They are known troublemakers.

http://www.sabmag.org/maintenance.htm  for links to repair suggestions.  Honda had a bad time with the early V-4 models, especially with camshafts/rockers and camchain tensioners.

http://www.v4hondabbs.com/ is another source of info.

If the tachometer gets twitchy, then the coil to that set of cylinders is going out.

The "choke" system is a plunger for each carburetor that opens a fuel and air passage that gives extra fuel, plus the added air to raise the idle speed. The plungers must all seat down to seal off the fuel/air supply when the choke cable is pushed closed. The cable can be adjusted to a certain extent at the hold down clamp on the cable stay.

Check all the plug wires for about 5k ohm resistance from spark plug connection back to the end of the wire that connects to the coil. Fresh spark plugs should be installed, as well. There are idle mixture screws that need to be uncovered by drilling out the protective plugs, so you can make accurate idle mixture adjustments.

Bill Silver