80 GS550E, tach reads too high?

[Anonymous]

So it appears that my tach may be reading too high. 8000rpm at 70mph in 6th gear is way higher than what others have told me it should read.

Yesterday I stopped by the local UJM graveyard to find the GS550E they have in the basement and compare tachs. They appear to be the same, so I think I have the correct tach. (I also snagged the plastic trim piece fits between the seat and tail light to replace my broken one. )

What would cause it to read so high? I don't believe the bike's gearing has been changed, though I haven't checked for sure. The 550E is geared so low anyway that I would imagine any non-stock gearing would RAISE the ratio, not lower it, and as far as I can tell the bike's completely stock anyway. I can see how something like a worn tooth in the gearing would cause the tach to skip or read too low, but I can't quite grasp how it would read high. Any thoughts?

[Anonymous]

Has it always done this? or has it been getting worse?
If your sure its not gearing, then it could be your clutch slipping.
You can tell if its clutch by putting the bike under load when in a high gear. Example: only cruising at like 20K/hour and put it in like 5th or 6th gear and open the throttle up.

[focus frenzy]

or it is just a bad gauge, I picked up a cluster for a 83 1100es and the speedo is WAY off (140mph showing at 6500rpm indicated) and the tach reads high also.

[Anonymous]

Well, I decided not to test this theory by taking it out on the highway and up to a steady 11,000rpm to see if the engine frags or not.

The clutch does slip a little on occasion, but if I'm on the highway and let off the throttle, the revs stay at 8000 and drop with speed, rather than shoot down to 5000. I also don't smell the clutch burning at all.

Hmm, I wonder if the place I checked out the parts GS550E in the basement would allow me to grab one of their Suzuki tachs (there's a box with a few in it), plug it into my bike, and see what it reads, just to compare it with mine...

[Anonymous]

So I did what I said I was going to in my last post. Sure enough, the other tach read idle right around 1000, where it should be. I hadn't been able to get my idle below an *indicated* 2000 (with the original tach) without stalling, which was my first clue the tach was weird.

I couldn't afford to buy an entire instrument cluster off the GS550E in the basement, nor did I really have any reason to since everything else on my cluster works (well, except the gear indicator, which I can live without). Since they had a few clusters, they offered to sell me just the tach. Done! After plugging it into my bike to make sure the tach I was about to buy read accurately.

During the swap, when I removed my original tach I found electrical tape all around the edges, as well as some extra rubber bits that didn't exist on the one that replaced it. To me, that's further evidence that the original tach had been busted - perhaps when the bike got dropped before I got it (dent in the gas tank is evidence of that) - and hacked together again rather than fixed properly.

Took it out on the highway after reassembly. 70mph = 5500rpm. 75mph = 6000rpm. This is all in the range that, with stock gearing, many of you have told me is normal for a GS550. Sounds like I've fixed my problem!

Anybody want a GS550 tach that reads way too high for cheap? Could be a useful tool to drop into somebody's bike who you want to slow down a bit... :twisted: Seriously, those times I got up near redline and thought I was really hammering it, I now realize I was only at midrange RPMs, nowhere near the power peak.

On the plus side, I'm that much more impressed with how much torque the bike has at the low RPMs it turns out I've actually been running it at all this time. I'd expect it from a 1000, but not a 550.