rpm not working ok on 86 750 Maxim x

When my 86 750 maxim-x is cold, the rpm doesn't follow the real rpm, if i hold the throttle open a bit, the rpm needle will go up a bit over time. Is that rpm electrical or manual. what can i do to fix it? Any help would be appreciated.

miguellevesque@hotmail.com

 

It's an electronic tach, I would suggest checking all connections. Sounds like the vibration itself may be causing a faulty reading.

 

Takes about an hour or so ... but, this will put the Accuracy and response back into a Lazy Tach.

Pull the instruments.
Take the instrument out.
Use toothpick to spread 1 or 2 drops of WD-40 on the REAR Bushing.

Let a drop "Run down the toothpick" and lube the pivot point; inside.

 

Flip it over and add ONE or TWO drops of WD-40 on the Brass Pivot.

 

Now ... the Tricky Part.

Keep the drops from falling of the toothpick (or just go and buy a precision oiler) ... and lube the shaft where it passes through the nylon bridge.

 

I take it that this will work for all electronic tachs then?? As in my '82 J. If so then thanks.

My tachometer has not been responsive, by any means, since I bought my XJ. Just thought they were supposed to be like that.. haha It does move to the correct rpm after starting my bike from cold, but it may take it 5-10 seconds to rise to rpm .

One more project now. Thanks

 

This is an electric tach.

The Mechanical Tach's are hooked-up with cable that looks like a Speedometer Cable.

This one is wired to the lead coming up to the instrument panel.

 

Thanks alot!!

 

Alright. I have a similar situation. Riding through the chilly rain today, my tach started to fail. Shows RPMs occasionally, but usually a bit lazy. At the same time, my turn signals and temp sensor stopped working. In fact, turning the signals on will kill the tach. After a few minutes the tach will slowly resume it's duties, until the turn signal is hit again. Then it goes back to 0 revs. I would guess a fuse, but it seems odd that the tach still works occasionally...
Any ideas?

85 XJ700X

 

The first thing I'd do is Check the Alternator Brushes.

If the Brushes are causing the Charging System to not have full charging capability; the Bike is living off the Battery.
When the Battery gets to a point where there is marginally enough current to run the Bike ... all the accessories and instruments will begin to become problematic.

If its NOT the Brushes; you nee to Charge the Battery and have AutoZone measure its available Amps.

In the case of engaging a Turn Signal and killing the Tach ... you need to Troubleshoot the Charging System thoroughly.
A symptom like that indicates the Bike is running on minimum electrical current and could leave you stranded someplace with a dead Bike.