Motorcycle Repair: Motorcycle problem, honda magna v45, baw baw

Question
Hi Wayne, I have asked you about my bike before but you asked me to try to find out more info. So this is about my 84 honda magna v45 vf75c. So i switched this motor into my bike it used to have a sabre motor in it but this is the motor that belongs in it. I got the wiring diagram for a magna and made sure everything was right for it and stuff right carbs. So the problem is this bike idles like a DREAM. You rev it up and it gets to just a little over 2 and it stays there and goes baw baw baw and keeps at the same idle speed. I took the carbs off and notice a black oil film on the butterfly flaps on the cylinder 1 and 3 side. Why would this be? I do know this motor was sitting for about 8 years in an enclosed garage. I have no history on the bike but was told it was running fine with that motor. One other thing is when you rev it up and it makes the baw baw baw sound the rpm gauge goes wonky and flickers down to 0 and back up again and keeps doing that. Any Idea?

Answer
Hi Reid,

It sounds like the problem is isolated to cylinders 1 and 3
due to the tach bouncing and the oil film on the
butterflies.

This could be the #1/3 pulser coil, the spark unit
or ignition coil acting up.

I would try switching or substituting any of
those to see if the problem changes over
to cylinders #2/4.

Also clean the connector on the #1/3 spark unit
and check for bent pins.

The pulser coil is about 480 ohms I believe.
It has an air gap of .012"-.035"
The wires to check the ohms on are white/yellow to yellow under
the right side cover.

It sounds like a problem related to cylinders one and three
so I suspect the coil, pulser or spark unit or their
connections. The tach bounce is either cylinder #1/3 ignition related or
a poor ground or wiring connection. This is the clue to check
the #1/3 ignition components as the tach is related to those.

Good luck!
Wayne S.
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