Jumping Tach Needle

[Guest]

I have a 1985 GS550es I have been working on lately.

I finally got to take it out for a small ride and I noticed the tach jumps around at higher rpm.

It does seem that it has a misfire at the same time the tach jumps around.

Where does the tach get it's signal from?

Would a coil that is in its way out cause the tach to jump.

Thanks,

[Burque73]

My tach gets lazy sometimes. I just knock on the gauge and it wakes up, LOL. The speedo is real jumpy above 85 mph then settles after slowing down.

Check out the parts diagram. Hopefully this is what yours looks like. It was the most legible of the drawings. You can see number 14 is the drive gear that spins the cable so there's not an electric signal at all.

https://www.partsoutlaw.com/oemparts/a/suz/50d3f673f8700230d8b4c899/cylinder-head-cover

Not sure about your jumping gauge. Could be a worn cable or gear or if it's the engine speeding up, maybe an air leak somewhere?

[glib]

My tach gets lazy sometimes. I just knock on the gauge and it wakes up, LOL. The speedo is real jumpy above 85 mph then settles after slowing down.

Check out the parts diagram. Hopefully this is what yours looks like. It was the most legible of the drawings. You can see number 14 is the drive gear that spins the cable so there's not an electric signal at all.

https://www.partsoutlaw.com/oemparts/a/suz/50d3f673f8700230d8b4c899/cylinder-head-cover

Not sure about your jumping gauge. Could be a worn cable or gear or if it's the engine speeding up, maybe an air leak somewhere?

Take another look brother. The ES uses the plug (part #12) the E uses the sleeve and gear.

[glib]

I have a 1985 GS550es I have been working on lately.

I finally got to take it out for a small ride and I noticed the tach jumps around at higher rpm.

It does seem that it has a misfire at the same time the tach jumps around.

Where does the tach get it's signal from?

Would a coil that is in its way out cause the tach to jump.

Thanks,

I have a similar problem with my 83 GS1100ES tach which is also electrical. It seemed to stabilize after I changed the ground to single point and replaced my stator and my R/R with a series type but it still buries the needle well past redline when it's not really turning that high. I just figured it's old and would need some type of electronic rebuild that I doubt I'll ever get to.

[Burque73]

Take another look brother. The ES uses the plug (part #12) the E uses the sleeve and gear.

Thanks for pointing that out, my bad.

[Curtie94]

Yeah it's electronic. I also noticed the fuel guard jumps around as well. I'll check my grounds first.

Thanks.