Swapped tachs and still doesn't work :(

[JeremyL]

I cleaned the connections behind the fuse panel and behind the headlight and even bought a used tach of a member here that looked pretty nice. The needle bounces if you smach the tach a little so I don't think its frozen. When you start the bike it doesn't move a bit. Isn't the brown/black/white 3-wire harness the one that drives the tach? I was going to find the other end but I can't remember where it went. Is there a way I can test for voltage? I revved the bike and it looked like the headlight brightened up a little when I did so that means my alt is working I guess.

[crazy steve]

Pull your headlight, and check at the plug that goes to the tach. With the bike running you should have 5-7 volts AC (not DC) between the white wire and black ground. If you get that, then check between the brown and black; you should get battery voltage (at least 12 volts, and this will be DC). If it passes both of these tests, the tach is bad. If it fails either, then you have a bad connection and you'll have to trace it out.

When testing, leave the tach plugged in and insert the tester probes in the tach side of the plug where the wires go in it; this will test all the harness connections.

[JeremyL]

Awesome! Thank you! I'm gonna try that out this evening. I was afraid there wasn't a way to test for some reason.

[tom clisham]

Jeremy: Let me know if it's the tach. I'll send your $ back

[JeremyL]

Jeremy: Let me know if it's the tach. I'll send your $ back

I really appreciate it Tom, but it's no problem. I probably needed yours anyways because the wiring harness is better than mine. I think its gotta be the wiring because it's doing the same exact thing my old one was. I just need to test and see when I get my carb problem fixed (another thread on that in a min). I say it all the time but thank God for this forum. My bike would NEVER run if I didn't get help from you guys.

[JeremyL]

Pull your headlight, and check at the plug that goes to the tach. With the bike running you should have 5-7 volts AC (not DC) between the white wire and black ground. If you get that, then check between the brown and black; you should get battery voltage (at least 12 volts, and this will be DC). If it passes both of these tests, the tach is bad. If it fails either, then you have a bad connection and you'll have to trace it out.

When testing, leave the tach plugged in and insert the tester probes in the tach side of the plug where the wires go in it; this will test all the harness connections.

I know you posted this a long time ago but with the new baby I've not really had time to check the tach until last night.

I got around 14.0v on the DC test but on the AC test I kept getting around 4.5v. Is that close enough so that it's ok or is the 4.5V the reason that my tach moves but doesn't move properly? If it's idling it will not move at all or very very little. If I'm revving it hard it will never stay steady but will bounce between 0-1500rpm. I was kind of wondering if the 4.5V is meaning there's voltage but not enough so that's why it moves but not like it should. Apparently its connected but could it be a poor connection somewhere? I only cleaned the connection behind the headlight and can't figure out where the wires go to. Any tips besides just pulling the tank and seat and just tracing it back?

Thanks again, btw, it sure sucks having a bike without a tach. Even though the idiot PO said "Oh any real rider doesn't use a tach anyways" Yeah right.

[JeremyL]

Well I'm updating this thread just in case something new comes up or in case someone is searching and it helps them out.

I followed the white wire from the tach back down the wiring harness and right above the carbs, where the original 3 white wires from the stator are going to the regulator (I think, frame mounted box), one of them has some insulation cut back and the white wire to the tach was soldered on. Looked like a decent job so I'm not sure if that's factory or not but that's how mine is.

I also reported that my tach bounced up and down around 1500rpm... well today I had kind of a "duh" moment and disconnected the tach completely. It still bounces at the same rpm and I assume it's because of engine vibration. So I'm still confused -- not sure if it's my tach and I Just got 2 dead ones or if the 4.5ish volts on that white wire is the problem and could also be a stator problem. I tested the resistance between the white wires as described in the stator testing article and it passed but barely so maybe I need to recheck it again.