Freaked out tach

[XSokieSPECIAL]

My tach jumps all over the place after it gets past about 3000. Do I need to find another tach, or is there some way to fix it?

[XJOK2PLAY]

Most times, bad ground connections are the culprit.

Let me ask you this, though... have you noticed any other gremlins, like turn signals not flashing right, or the lights flaring and dimming at times?

Had these things on mine... turned out to be a cracked stator.

A lot of times, if you're having a problem w/ the charging system, it shows up as a problem w/ the tach.

If you're in Tulsa, we ought to meet up sometime...
Maybe start riding together. JAT
Bob

[XSokieSPECIAL]

I haven't noticed any significant electrical problems. Sometimes my left signal won't work until I turn on the right one first and then switch back to the left. But I had to take my TS switch apart and resolder the wires to the switch itself because the solder had corroded off. But the tach was doing that before and that didn't make a dfference.

Heck ya, we could meet up and ride together, that would be cool.

You in T town too? I'm west of the river.

[XJOK2PLAY]

Yeah, I'm in Skiatook.

Let me know... that'd be cool.

I'll send you a PM.

[Silent]

Once you figgure out the problem, post it up. My tach bounces a bit too

[bikerphil]

My tach jumps all over the place

I'd start by cleaning the alternator connections located behind the fuse panel. This is a known trouble spot for corrosion and will cause a wobbly tach, since the tach receives it's signal from alternator rotations.

[XSokieSPECIAL]

Thanx Phil, I haven't been there yet. Most definitly worth a look.

[81xsproject]

I have had terrible luck with bouncing tachs. All my connections are clean and siliconed. I read in the tech tips that there is something that could stand to be lubed in there, but I am not really comfortable just hosing the inside down with silicon spray blindly.

So, I am planning to hack the back off of my junkiest one. My plan is to come up with a location to drill a hole in the back of the housing to lube or clean whatever needs it. Will post the results when it happens in all my spare time.

[Southhill101]

tach disassembly

There is a good post on here, somewhere, about how to Carefully remove and reinstall the black ring that holds the face on the tach. Worked good for me but it takes a little patience not to damage/stretch the ring too much. On mine, I found a small counterweight? on the back of the needle mechanism that had become partially dislodged and would rub lightly on the housing inside the tach when I moved the needle manually. This caused some erratic behaviors and sometimes the tach would stick around 2 or 5K. I wouldn,t blindly spray anything in there either as there is not too much for moving parts anyways.

Cheers,

[81xsproject]

I sacrificed one to trying that and though I did it with minor damage to the ring, I did still make boo-boo's that were noticeable even as careful as I could be.

[XSokieSPECIAL]

I had to take my speedo apart like that to put the screws back in the face when they fell out. It can be done. It takes a lot of patience.

[Rock&Roll]

Tac fix

Tape up the outer ring use a large screw driver to open it going around like a can.then put the driver between the can and the ring and wiggle it back and forth while working around.Take your time don't put the tip to deep. The problem is the part of the tac motor that the face is screwed to was not loctited so the screws come loose.The ground wire is connected to this and the + to the other. Engine vibration causes intermittent connection. If you remove the screws from the face plate you can rotate it to the cover screws and with a jewlers driver tighten them. I removed mine one at a time, but tighten one first.You must do this with micro needlenose plyers or the magnet will suck it in. lock tighted them in place thet solved the problem. the tape will help on reassembly, push down on the cover to compress the seal and start pushing the lip back by hand I used a hammer.work it over slowly in passes then a very large socket on its side rolling around the lip to finnish.Its not that hard just be patient.This was my third tac in 20000 miles but thats why Good Luck

[81xsproject]

You have inspired me to try dis-assembly again.

[XSokieSPECIAL]

Hey Rock I think you might be right on the money. On my way home from work today I just reached up and held my tach from vibrating and it settled right down.

Thanks bro, that's been bugging me for a while now.

Greg

[XSokieSPECIAL]

Tape up the outer ring use a large screw driver to open it going around like a can.then put the driver between the can and the ring and wiggle it back and forth while working around.Take your time don't put the tip to deep. The problem is the part of the tac motor that the face is screwed to was not loctited so the screws come loose.The ground wire is connected to this and the + to the other. Engine vibration causes intermittent connection. If you remove the screws from the face plate you can rotate it to the cover screws and with a jewlers driver tighten them. I removed mine one at a time, but tighten one first.You must do this with micro needlenose plyers or the magnet will suck it in. lock tighted them in place thet solved the problem. the tape will help on reassembly, push down on the cover to compress the seal and start pushing the lip back by hand I used a hammer.work it over slowly in passes then a very large socket on its side rolling around the lip to finnish.Its not that hard just be patient.This was my third tac in 20000 miles but thats why Good Luck

Ok, I know it has been a long time but I finally got around to tearing the tach apart. I was puting the 140mph speedo in and I figured it would be a good time to do it.

I didn't find anthing loose, unfortunatly, so I started puting it back together and CRAP I broke the extremely brittle with age needle.

I need a tach for a 80 special CHEAP!

I'm aready in the hole big time on ebay!

GT