runs on 2 cyls @ low revs/idle; tach goes dead.

[vmaxbx]

just started running on 2 cylinders when at idle, and tach goes dead. I twist the throttle ever so slightly, and I can feel when all 4 cylinders start firing at about 1150 rpm, and the tach simultaneously jumps to life.
very hard to start now, if it'll start at all.
when I do get it to start, I have to keep her running by twitching the throttle over n over, but once she's going down the road, the thing operates perfectly in all ways.
I searched the archives for 6 hours and couldn't find my problem; any ideas?

 

[Traumahawk]

I would say check the coils for corrosion and the like. Depending on how the diagram is read, the tach reads off of coil#1 or coil #4, but if memory serves, its coil #1 and it should be located under the seat.

http://www.morleysmuscle.com/wp-content/uploads/2009/12/Vmax-Wiring_Diagrams1.pdf

But to me, the problems sound electrical in nature.

 

[MaxMidnight]

I would check the continuity/ connections/ resistance of the pick-up coils.

 

[vmaxbx]

your assessment of the problem sounds plausible, as I just did a bigger battery mod, and I was dicking around in the under seat area something aweful. well, big red is sitting in 93 degree sunshine right now, and she will sit there undisturbed until saner temps prevail. soon I hope!

 

[vmaxbx]

this forum is the best!
you guys nailed it; it was a loose plug wire coming out of the coil under the seat. I just did seans' battery mod 500 miles ago, and I probably neglected to push that plastic ring up the wire before plugging, and screwing it back onto the coil. at least I think it was that; I disconnected, cleaned, and reconnected all the wires involved. man, what a fun bike.

 

[Traumahawk]

Glad that we could help!!!