If the front plug is not firing

[dbcooper]

Will that kill the tach? 2001 naked.

[cf828]

If it's only running on one cylinder you can tell by power loss and rough running .... If that's what you mean..

[since413]

A missfire in 1 cylinder will not affect the tach. If there is a problem in the CDI/wiring it might cause both problems.

[dbcooper]

Heres the history.Got the bike about 6 weeks ago.Didn't notice at first but the tach was doing weird things.A few seconds after start up it would jump up to 2500 (just the tach not the actual rpms) and it wouldn't indicate above 6 grand so I disassembled the speedo tach assy to see if there was anything real obvious.New tach assy is pretty pricy so I got a Veypor.Hooked the tach signal wire (black w/yellow),and hooked to yellow Veypor input.Started up.Success until the front plug stopped firing and I lost all tach indications on both the stock and the veypor.Thought maybe I fouled a plug.Got 2 new plugs this morning and got the front cylinder firing although it seemed weak.I disconnected the signal input from the Black w/yellow and it ran right.Hooked up the alternate (white wire) from the veypor direct to the white/orange of the front coil and now can't get any tach out of the veypor.Waiting to hear back from them,but that was why I asked the question.

[since413]

The B/Y wire is also the signal for the front coil, if hooking it to the tach causes a missfire, something is wrong with the way the tach is connected. The O/W wire is the 12v power to the coil and will not send the right signal to the tach.

[dbcooper]

Yea I hooked the b/y up to the yellow wire on the Veypor.Thats what fried it.:( .Don't do that.Use the white wire from the Veypor.They were good about it.Told me to send it back for warranty repair.