Does the bike just have trouble idling? Does it run OK past 2000 rpm if you're taking it up and down the road? I am unfamiliar with this model, but does the 450K7 carbs have pilot jets? I am looking on the parts diagram but I am unsure. If they do have them and if they have o-rings it may be possible that one of the o-rings on the pilot jet is bad and causing an air leak on that cylinder. It may also be the carbs need synchronized.
It was just having trouble at idle. I haven't taken it out on the road yet, but up over about 2500 RPM it was running on both cylinders, below that only the left. I accidentally figured that out by putting the tank back on and causing a bend in the throttle cable to the right carb. At the higher RPM this caused, both pipes got hot. I ended up cleaning the slow jet on the right carb and it now runs on both at idle. There is a pilot screw, and I pulled both to make sure they were clean, and the washers and o-rings intact, as well as the left side slow jet just for good measure.
This bike has CV carbs, and no vacuum port for sync gauges, so it is pretty much all careful adjustments to get it right. A member on the Honda Twins forum gave me a checklist for how to accomplish this, and I feel confident that I did it correctly.
The bike looks in great shape so I doubt it's one of the following problems but does not hurt to verify:
* Massive air leak on intake side from the spring loaded throttle linkage. If you spray this area, only use penetrating fluid. Do not use aggressive solvents as some of these carbs had felt-like material in this area and this will destroy them; it will also swell up o-rings and cause funny running until the swelling goes away or possibly melt the o-rings.
* Air leak on the choke linkage. Again, penetrating fluid, etc... I've found small air leaks from the choke linkage don't seem to affect much, but depends on the bike.
* Choke plate on one of the carbs is stuck in a certain position. Move the linkage manually by hand and verify this.
* CV piston not moving smoothly.
Good to know about the penetrating fluid only.
I was concerned about the CV piston, but was not ready to pull that apart yet, and I am glad i didn't since it looks like it was just the slow jet blockage.
Incorrect timing can cause funny idling as well. I can't guide you too much on this except get a timing light and read the FSM for the procedure. A test light is also required. I can't tell very well in the parts diagram (or parts numbers) if this is a dual coil setup. If yes, then you can swap the wires and see if the problem moves to the other cylinder then you can narrow down if it is the coil or wires running to that coil.
You mention you do electronics work as well, I do a fair amount of repair on vintage radios, tvs, and arcade equipment and I have ran into plenty of situations where things can test OK on DMM, especially resistance, but then goes haywire when being used in circuit. Especially in HV areas.
Great story and good luck to you!
I had set the timing statically, before trying to start it up. I do have a timing light, and dynamic timing is off a little bit. When I get a chance to work on it again, I will make adjustments there to fine tune it.
Yep, dual coil setup, and good point about resistance at high voltages. I haven't done much with vintage radios or TVs in recent years, but used to tinker with them quite a bit. There is actually an old floor model black and white TV sitting the garage, that I was thinking about getting rid of, since it has been there so long, and I haven't even tried to see if it works. I recently acquired an old (Pinball Wizard) pinball machine that works with the exception of some of the lights, so that is on the to do list too.
