Sluggish Instruments

[rickt]

Both the tach and speedo on my '78 GS750C appear to move like they are trapped in glue. Given that they haven't been used in 28 years, I guess this is not surprising. Several have suggested disconnecting the cables and spraying WD40 (or ?) into the cable connectors.

What are the odds this approach will be successful. Anyone tried this approach?

Any risk of damaging the instruments?

Thanks
rickt

[duheme]

I am having the same problem with my 78 550. I have tryed spraying some PB blaster but doesn't seem to make a difference. I put about 50 miles on it to and the tach seems to be working alittle better but still way sluggish. I haven't seen much improvement in the speedo. The odo seems to be ok though so it leads me to believe the gyros in the interments are sluggish. Maybe it will take some miles to get them to work properly.

But if any one knows a fix for this please let us know...

[J Paster]

You have to hurt them to help them

I can't find the thread where I first learned about doing this, but my 78 GS550 was the same as both of you described (until yesterday!). I too tried hosing down the area where the drive cable goes in, to no avail. Here's exactly what I did to fix this:

-Remove individual instruments from pod.
-Using a sharpie, draw a line around the orange plastic "case" part of the gauge where you will end up cutting the case. On my tach, I chose to cut about 1 inch down from the black finish ring / glass; On the speedo, I cut just below where the odometer reset pin hole is. I also drew a line with the sharpie to reference where to align the case halves when going back together.
-I have an old Craftsman band saw at work. Putting the instrument up to the blade sideways, I carefully cut into the case just enough to go through the plastic, rotating around the circle I'd drawn previously until I'd cut all the way through. Then, I pulled the halves apart and set the glass half aside. I unscrewed the dial itself from the back case half and set the case aside.
-I hosed down the inner workings with contact cleaner (make sure you get the type that's safe for plastic), and then used a rag to physically wipe off the two round "thingamajigs" that rotate at an angle to each other. I found a bit of congealed grease there that seemed to be causing problems. I made sure to spray out the little pin / bushing just behind the dial, too.
-To test my repair, I removed the tach cable from the bike; Then physically pulled the cable out of the sheath. Be sure not to lose the little seal at the engine side. I put the instrument end of the cable in the instrument, put the engine side of the cable into my cordless drill / driver, set the drive direction on counterclockwise, and gave it a try. It would only raise to about 3000 rpm on the tach and about 25 mph on the speedo, but it would now get there quickly and return to zero quickly. Good to go.
-Reassembly was the reverse of disassembly, but of course, how to seal and secure it? I chose to use a solder iron with a flat "duckbill type" tip, and using small circular motions, I carefully "welded" the cut closed, providing an airtight seal. Knowing that this was not true plastic welding, and that my repair shouldn't be trusted for strength, I then used 100% silicone to apply a thin bead over all of the rejoined area. After the silicone was cured, I wrapped it with a piece of duct tape, just to be sure. No one will ever see it anyway. I suppose, in hindsight, I could've used two part epoxy instead of silicone, just didn't on this one.

My test ride was great! Now I want to try it on my GS 1000 to see if it will help with the dreaded "needle flutter" I hope this helps.

John Paster

[rustybronco]

I can't find the thread where I first learned about doing this...

http://www.thegsresources.com/garage/gs_inside_gauges.htm

[posplayr]

Rusty, I think it is easier to pry the lip back and less destructive

[rustybronco]

I sawed my tach apart, then put it back together with pipe cement covered with a single wrap of electrical tape.

I suspect both ways will work fine.

[posplayr]

http://www.thegsresources.com/_forum/showthread.php?t=119214&highlight=pry

One of the more controversial subject here on the board

I just restored the images here for the "pry technique"

http://www.thegsresources.com/_forum/showpost.php?p=753029&postcount=17

[chef1366]

My instrument is becoming sluggish also.

[posplayr]

My instrument is becoming sluggish also.

that's just because yur now running 147.5's v.s. 152.5's

[duheme]

Thanks for the replys, I will be trying this out soon. Thanks!!

[Don-lo]

that's just because yur now running 147.5's v.s. 152.5's

I think he meant something else....

[north49]

I`ve had the sluggish instrument problem on older Yamahas as well as Suzukis. The problem is that the original factory lubricant in the speedo / tachs eventually turns to syrup. The way to fix it is either cut or pry the guage out of the casing and thoroughly clean the gears and especially inside the magnetic cup to get all the sticky goo off everything.

[kcolton]

Sluggish speedo...

I had the same issue with my '79 GS850GN and this worked: I pulled out the knurled reset knob on the side of the speedo. Then I disconnected the speedo cable from the sending unit down at the front wheel. I put a standard screwdriver attachment into my 3/8 inch drill so that it would then fit in the slot at the end of the speedo cable. I shot some WD40 into the speedo through the opening where the reset knob was, and then ran the drill until the speedo eventually would go up to about 30 mph, and I did this both directions. I repeated this bout 3 times until I had actually put over one mile on the odometer. I then put everything back together and went to bed. The next day when I drove it it worked fine and has been Ok for a month now! Good luck!