tachometer gauge is jumpy

[midnight1980]

new member here
I bought another tach gauge on ebay thinking it was the problem , last fall but the needle still jumps around after around 3,000 rpms, i bet its related with a sensor some where on cam? does anyone no where its at? and if it can be replace easily.

[randy]

There is no cam sensor, the tach gets it's signal from the alternator. Most likely you have dirty electrical conncetions. Check inside headlight bucket and behind fuse panel.

[midnight1980]

the connection are tight i check them all really do you think i should replace the pickup coil wire? to the generator

[randy]

That is NOT the generator coil, that is the ingniton pickups

[midnight1980]

Originally posted by randy
That is NOT the generator coil, that is the ingniton pickups

ok so your telling me that its possable its the generator



wires shorting out maybe then?

[prometheus578]

Mine acted loopy once.(Ok, more than once... was constant)
I cleaned some bad connections, and also put in my spare regulator/rectifier. Problem solved.

[midnight1980]

Originally posted by prometheus578
Mine acted loopy once.(Ok, more than once... was constant)
I cleaned some bad connections, and also put in my spare regulator/rectifier. Problem solved.

i am going to replace the wiring harness anyway some day and i will now because its sun beat as the bike was sitting for years in the las vegas


hot
sun

[JWSanders]

Methinks my gauge would be jumpy too if I was headed towards those.

[DeanR]

My tach suddenly began jumping around midway through a 2000 mi trip last week. Worse as the revs increase. Never a problem in the past.
Randy and Prom, what connections should I be looking at? Last I checked, everything looked pretty good.
Prom, do you know if the regulator did indeed have anything to do with it?

[prometheus578]

Laxdad...
Sadly, I can't state for sure.
The tach was jumpy and the charging system was intermittent. (the engine would stumble when I turned on a turn signal.)
I replaced the regulator and replaced the main fuse(which was an inline fuse set-up) that had heated up and melted the plastic case. I was 1,000 miles from home... just wanted to fix the problem and didn't investigate any further.

[scott0757]

OK. I have this problem now: Jumpy tach, most pronounced when RPMs exceed 3K. Tach swings wildy from zero to well into the redline area, regardless of speed.
I've checked and cleaned all the connectors to the coil/stator behind the fuse block and connections in the headlamp bucket as well and all seem fine. I get bright tach/neutral/and Oil lights before starting and all directionals/headlamp (at least high beam) work fine (low beam just sucks by design I guess).

Where else can I look if it's not the connections? Regulator? Vacuum advance seems to work properly as well.

I'm stumped and tired of chasing the problem. I may just unplug the tach to save it until I find the answer. HELP!
I have a 1980 XS1100SG with about 7700 miles....Barely broken in!

[tinman905]

Mine is an 80 SG also I had a problem with my head light not working but the tach was fine 99 % of the time I check all the connectors everything seemed to be okay so I just picked up a feild coil and stat on E-bay for $5.00 and my problem was solved. I have bought a few extra parts now just to have around when I need them, finding the parts cheap is okay but waiting for them to show up is another thing.

[xsilerating]

tinman905


'tis a good thing that Ontario, Canada is such a small place... makes it easy to locate you!

905 is probably a bit closer though, huh

[egsols]

My tach was jumping around too as well as the speedo was up and down. Replaced the units with ones of my spare bike, problem solved. May be an internal problem with the tach?

I'm north of 905 in 705 but east of 519 and west of 613....

[gnevelesx08]

tach jumpy

All of these things can cause the jumpy tach problem. I had a dead tach did the same fix by getting ANOTHER tach from ebay. It fixed the dead tach problem, but I gained a drifting tach around 5K. It drifted about + or - 50-100 rpm I guess. Anyway the point is you may have another bad tach OR some other issue as stated by others. If both of the tachs are jumpimg identically then look elswhere. I know I know it doesn't help fix the problem, but it is some more feedback on tach problems.
Dan