Inaccurate tach (or maybe speedo)

[bryan]

Ahhhh...I've finally been able to get some miles in on the new-to-me 83 GS1100ES, thanks to a lot of help from folks on this site.

With new rubber, I'm finally more comfortable cranking her up a bit. On a long, flat, empty stretch of road, I took her up to about 105. Then I looked at my tach and I was 12K RPM! I was in 5th gear, and it didn't sound like it was screaming.

The speedo should be accurate, as I've passed a few of those "warning" speed clock trailers and its been spot on at "sane" speeds.

Is there something that can cause tachs to misread? If so, what? I don't think the bike has been geared down, as I seem to be running normal RPMs at legal highway cruising speeds (about 4K at 70'ish, if I recall correctly).

[Steve]

"4k at 70-ish" sounds about normal. Why it's jumping after that, I don't know. You might find a stretch of road where you can play a bit, but watch the tach to see if it starts acting up at any particular speed. Do this in lower gears where you won't be going so fast, but it will happen quicker, so watch carefully.

.

[Griffin]

The electronic tachs found on the '83-'86 GS700/750/1100ES/1150 models are notorious for starting to jump around and read high after twenty thousand miles or so. Mine went at about 25,000 miles, and continually got worse until I replaced it. They just start failing for whatever reason.

I think Clone took one apart and repaired it himself on his '83 GS750E. You might want to PM him about it.

[bryan]

Thanks, guys.

They just start failing for whatever reason.

Yeah, I was kinda worried that might be the case. Bummer.

[Clone]

Yeah, I took it apart I swear for the last time and replaced all the electronic components except for the black chip in the middle. It is better, but still a little hinky, so I think it is the mechanism itself that needs to be repaired, I have no Idea what that would entail. But I can dig up the component specs if you want them. Otherwise, i would try to track down an actual mechanism(the brass clock like component that actually moves the needle).

[focus frenzy]

The electronic tachs found on the '83-'86 GS700/750/1100ES/1150 models are notorious for starting to jump around and read high after twenty thousand miles or so. Mine went at about 25,000 miles, and continually got worse until I replaced it. They just start failing for whatever reason.

I think Clone took one apart and repaired it himself on his '83 GS750E. You might want to PM him about it.

due to changes in racing the 1100es had to make do with old outdated mechanical tach. the 3/4 and half liter bikes got the cool mono shock and electronic tach.