Sluggish tach

85 XJ700 airhead, the tach is very sluggish to respond to rpm increase. Can anyone give me some insight as to possibles causes? Thank you.

 

They are electronic and run off the coil wire orange i believe first check connections . The black wire that goes into the assembly not the lights make a jumper with a piece of wire and a paperclip try re grounding it see if that fixes it that way you don't have to cut wires.

 

Even though it's an "electronic" tach, it's still "electro-mechanical" and susceptible to getting gummed up. If you pull the instrument itself out of the cluster, you can put a drop of lube in the pivot bushing on the back.

 

just repaired mine again last night.

I noticed that the needle was a little sticky leaving from the 0 RPM position, i could feel almost like a tackyness. Undid the speedo face so i could rotate it around without removing the needle of course, then losened the one screw on the left (there are two) behind the speedo face and then removed the small brass piece that the screw held down. that brass piece was the rest for the actual tach needle. I then cleaned it with some wd-40 and sandpaper, put it all back together and it works better than ever.

 

Thanks for the tips guys.