New guy, not new to bikes/forums Tach Slow did my research

hello all, new to your site, been reading lots. recently acquired 82 xj750. I have been tearing it down and going through it all. as in all the way down. engine out of frame down.

pretty far along the project now.

current question is my tach. when I first got it, it was very cold 20s ambient. it would slowly come up maybe to 2k but no more. did my reading on the site. pulled the cluster took apart, cleaned, light lube using a non conductive electrical lube (for slot cars/plastic models) had good success with it with mechanical clocks in cars. there was a very noticeable improvement in how freely it moved

alright put it back together. heated garage. not sure what temp got up to. but when running opened doors while doing carb tuning. outside temp low 40s.

tach will now go full range but moves slow up and down. when purchased it wasn't moving at all. the previous owner said it was working fine last season. so likely temperature related then?

is the group thinking that when it warms up to above 60s this thing will return to normal? take it apart again? I find it very annoying

 

Vintage Kawasakis used a damping oil in a small reservoir inside the speedo to keep the needle from bouncing while the bike was vibrating, could it be there is a similar fluid inside your tach, or rather is not inside it which is causing the se problems?
Not sure, but yeah the needle should move freely in just about any weather condition.

 

Re: New guy, not new to bikes/forums Tach Slow did my resear

Thank you for the response, but I don't believe that to be the case here. this is an electric only tach. I saw no such thing when taken apart

 

Super strange with an electrical tach...

Hmm, might check the wiring to make sure all of the connections are good. A poor connection might make it sluggish.

Only other option if the needle is lubed.

 

Electronic or not, there is a spot on the back where you can get a drop of lube onto the needle pivot.

It's likely just sluggish from the cold and old lubricants.

 

As stated above. I took it apart, cleaned and lubed.

Are you thinking I didn't do it good enough and should try again? It's this just the way it is in cold?

 

Probably is now. Based on the design, there has to be another, inaccessible spot inside the tach that would benefit from a drop of lube if you could get it in there. But I can't see how to get to where it must be (I have an electronic tach in hand.) They aren't as "skeletal" and primitive as the mechanical units.

 

I swapped over another known good gauge cluster from friends bike. his worked normally.

I have pulled mine off and apart again, and took the tach all the way apart. clean/lubed it all again. it moves so freely now, if it doesn't work it has to be an electrical drive problem, which I will try and track down, and or have to replace the tach unit.

so, until I put it back on tomorrow and try the results are unknown. took some pics but it is pretty self explanatory to take apart.

 

reinstalled seems to work properly now, yippy! cleaned lubed, made that movement as free as possible. I don't have any shots of it all the way apart, but I have these and well, maybe somebody might find them useful

 

well this has been very useful to me. i have mine apart as we speak and mine has been doing the same thing. it works but very sluggish and works better when its warm outside. gonna try to clean and lube it. thanks for the great imfo.

 

well i just took mine apart and cleaned what i could and lubed the stem that the needle sits on. it moves freely but it has like a dampened feeling to it. hard to explain but if i let go of the needle when its all the way up it goes back down a little slow like its dampened. i hope thats just normal. i will have it back together in a little bit and will let everybody know if it works right or not.

 

Yes, it should have a "dampened" movement to it, just not TOO dampened.

I don't know how to properly describe the difference between movement with proper dampening and sluggishness; it has to do with how it's moving reacting to what is slowing it down. It's a "mechanical empathy" thing that I honestly don't know how to describe.

 

well i just got done putting everything back together and it still doesnt work properly. it moves up when the bike is running and it moves up when u give it throttle but it moves very slow. it seems like it works better when its warmer outside and since it hasnt been real warm since i have got it maybe it will be ok this summer when its hot out, but it should still work all year round and that aggravates me. i had some electrical contact aerosol cleaner and sprayed a little of that in there but not much because i didnt like how that stuff came out real cold and fast. was just afraid it would hurt something so i put a couple little drops of some precision gun lude down around the needle stem. is there anything else i should be doing? it does seem to work a little better than before so maybe after it gets warmer and it gets used some more and that lube works its way down in there better it will work better.

 

did you pop the needle off and clean/lube the top bushing? also back off the nut on top loosens things up to clean/lube. that was the trick for me, not so much the bottom pivot but that top.

take it apart more and play with it. from my experience when it was good you would know it. it would react like a tach would react when I flick it around.

 

Yes I pulled the needle off, I actually gave both needles a nice red paint job to brighten them up. The top is where I put the lube. Maybe I'll take it apart again and do some more cleaning, maybe take it completely out of there instead of just taking the face and needle off. Thanks for all the help guys.

 

well its 75 degrees here today and after letting the bike sit in the sun for just a little while then starting it the tach seems to be working properly now. i guess after letting it sit over night and the lube/oil soak down into the needle stem it is working. i guess it was just sluggish from being gummed up and cold. hopefully now it will only get better. thanks for all the help guys. that shiny red paint on the needles really make them look good now.

 

I am having the same problem with my tach also.....electric tach on my 1982 XJ750J Maxim.....I will disassemble today & take pics along the way.....Thanks for the info here....

my tach operates electrically from a 3 wire plug ( Gy, Br, B wire )

Gy goes to the TCI / igniton Coil 2/3
Br goes to 10A signal fuse
B goes to ground

Simple & the trace of these connections is fine.....

So has to mechanical inside the electric tach.......so disassembly & lube is in order...

 

I disassembled & worked the tach needle back & forth from 0 rpm's to 12 rpm's by hand numerous times.......there is no dampened feeling to this needle....it swings pretty quick back to 500 and then settles to zero.....I did not lube it........reassembled & put back on bike....works perfect.....