1982 CB750 Power Loss after about a mile

[Patrick Stultz]

got an 82 cb750 and the thing runs perfect during idle, but after taking it down the road about 2 miles it begins to bogg and lose power at a high rpm. let off throttle and all is fine more a minute and then continues to happen until little rpm is utilized and you have to twist it wide open to get anywhere. Possibly think its a short in the wiring or ignition timing is off or carbs out of sync. I think wiring because it runs great then this happens, shut it off and let it cool, everything is fine, also wires out of solenoid are showing smoke because they get so hot, any suggestions?

[TOOLS1]

It sounds to me like a fuel issue. Start with the fuel cap. Is the vent plugged? To check this simply loosen the cap when it bogs down. If that does not make it pick up then go to the fuel petcock, and line. Take the line lose from the carb, and see how fast the fuel comes out. If that is not it then check the carbs. The fuel inlets, or needle valves might be plugged, or even the carb bowel vents.
As for the wires smoking. You probable have a bad connection somewhere. This is very common on these old bikes.
Hope this helps.
TOOLS  

[LukeM]

Smoking starter wires indicate either a ground in the +V line where there shouldn't be, possibly in the starter or the wiring.  My Shadow had a VERY shorted out brush assembly in the starter motor: I could push start it, but not with the starter.  I found a used one on EBay, and it's been fine ever since.  I may get a rebuild kit and make the old one like new, but I haven't had time.  Been too busy riding!!!

Easy enough to check:  Remove your starter, find a pair of jumper cables, connect the ground to the case and to the negative terminal of a car battery (make sure the engine is NOT running) and connect the positive cable to the battery and the lead wire.  The motor should spin freely.  Careful, there is a LOT of torque when this motor spins.  If it gets hot, runs slowly, makes screeching noises, or puts out a burning insulation smell, there's your problem.  The good news is: rebuild kits for these are readily available, and simple to install.

I hope this helps.
Luke M