78 GS550 tachometer lags / reads low

[MikeJ]

Been checking over the operating condition of my newly added 78 GS550 and so far only one thing appears not up to snuff. The tachometer does sit with the needle at 0 with the engine off, and responds by moving clockwise to show about 1200 rpm idle when the engine starts, but twisting the throttle to anything past idle results in the tach needle moving up very slowly, clearly not keeping pace with the increase in RPMs. In fact I haven't been able to get the tach needle to go above about 4000 RPM or so at all even when the sound the engine makes continues to increase in pitch (indicating further increase in RPM). I've disconnected, lubed, and re-attached the tach drive cable at the bottom of the tach, and it still does this, so I think it's something internal to the instrument housing.

Do these instruments need lubing of some kind? Can they get dirt, etc. in them that would clog up the works and make them respond slowly like this? Are the springs, magnets, etc. just getting worn out? I'm happy to disassemble the tach myself and play with it, if that would do any good, but am not sure I would iknow what to do once I got inside, and don't want to try that if others advise against opening it up. Thanks for any pointers.

Mike Jacobs
Columbia, MD
1984 Moto Guzzi V65SP
1985 Honda VF700S Sabre
1996 Kawasaki EX250 Ninja
1982 Yamaha XZ550 Vision
1978 Suzuki GS550

 

[friedshrooms]

doesn't need anything it'll go away as the lubricant in it breaks apart might take a few rides

 

[MikeJ]

doesn't need anything it'll go away as the lubricant in it breaks apart might take a few rides

Thank you sir. With that good advice, I think I'll go out tomorrow and take a long ride on the old beast. I suspect most else what the rest of its parts need is also just to get its juices flowing again after sitting for the winter and then some before I bought it

Mike J