Motorcycle Repair: Lean running Honda Rebel 250, honda rebel 250, vacuum leaks

Question
Sorry, but this is a condition with my 1986 Honda Rebel 250.I have been told by Honda dealers that that's just the way it is but I can't believe that Honda wanted us to warm up our motorcycles for more than 10 minutes only to find another few miles of riding is needed to pull off the choke completely and reduce the risk of stalling in traffic.  Any comments or suggestions about how this problem can be solved?

Answer
Dave, lean running conditions can be caused by worn carburetor butterfly shaft, air leaks at the rubber intake manifold or O-rings that connect the various parts together. Depending on the miles on the bike and if the carb is clean inside, often an "idle drop" can be done on these bikes to richen up the idle and transition to part throttle. Be sure that all the other parts are functioning and that there are no other vacuum leaks causing the lean condition, including carbon canister fittings on CALIF models, etc.

Honda's way of getting the idle mixture screw stopper off is to use a soldering iron (no flames please) to heat up the locktite bonding material used to keep the cap in place. Before you start working with this find the idle mixture screw, located at the bottom of the carb body and see if it will turn IN first. If the screw/cap is seized then you could be in for problems. If the screw turns in and out until it hits the stop, then heat up the cap and wiggle it off the end of the idle mixture screw. Then you can fire the engine up, unscrew the mixture screw about 3/4 turn from where it had been stopping and see if just that will do the trick for you.
The other means of attacking these things is to put a tiny thin shim under the head of the jet needle, which is part of the carb slide/diaphragm assy. This will raise the needle very slightly and enrichen the mixture at low speeds.
Go to www.bikebandit.com and search through their OEM parts locater function, so you can find illustrations of the carburetor parts.
If this seems to be beyond your scope, ask the dealer to do an idle drop on the carburetor for you. If they are any good at all, they will know what you are asking.

Bill Silver