[81CX]

I noticed a few days ago that the newer tachometer cable I installed earlier in the summer on my 1981 CX500 started to become a bit sluggish and starts to lag a bit around 6000RPM whenever I give it throttle say in 4th gear it'll rev up anywhere from idle up to 5500RPM fine with no lagging in RPM but as it climbs in RPM's past 6000, it'll start to sway and lag just a bit and not go up with the engine speed fast enough and therefore becomes inaccurate. I knew something was wrong when it was only reading 8000k RPM's whenever I was doing a quick 5th gear pull down a slight incline and the speedometer was buried for a good bit so I knew I had to be at least normally approaching 9000+ RPM (at least 100-110ish MPH) in 5th but instead was reading only 8000 RPM, cause there were other times where I've gone that fast and the tach hit 9200 in 5th and was spot on and increase as the engine speed increased.



I just put a bit of graphite powder in the cable to help lube it a bit, should i wait a few rides and see if the sluggishness goes away?

 

[MotorcycleCommuter]

You can get a special cable lube in a spray can at a cycle shop. I use it on the tach and speedometer by dripping it in the top. You can buy a special adapter for the can that injects it into the clutch and throttle cables. Your tachometer itself may also need some lube. However that may involve disassembly.

 

[marshallf3]

Neither my tach nor my speedo are accurate until they've "warmed up" a bit, it's just the old lubricant inside the gauge.

 

[Sture]

As already said.



Meter sluggishness has nothing to do with the cable - may it bee speedo or tacho.



The inner cable rotates inside the outer one quite fast. My hand-held drill, when connected to a speedo or tacho and turning ~ 2400 rpms (or so, as I remember), will give a reading something like half-way into the scale (I´ve forgotten exactly how much) but I´ve always checked instruments I´ve bought against each other that way.



If the inner cable wasn´t able to rotate at the same speed at both ends, it would snap pretty soon.



As said, you should look inside the instrument to get the reason why it´s sluggish. It´ll often get better after a little while. Frequent use over time is also good for it. More than one instrument I´ve come across have loosened up after some days.



Lubing the cable makes the inner cable spin easier (maybe curing a bouncing needle). Lubing the part of the instrument (careful and very little) that mates with the inner cable "male" square part, may take away any squealing or whining noise. If the meter is still sluggish - maybe blowing some compressed air inside will help, or you´ll have to either take it apart or replace it.



There´s no mechanical connection between speedo cable and the instrument needle (or the "cup" it´s sitting on). Only a rotating magnet makes the "cup" want to rotate too. A thin spring is holding it back. The needle bearings are quite delicate.



At least as far as I´ve learned.



Sture