Author Topic: 8 pin rev-counter plug - disassemble or replace?  (Read 253 times)

Offline tunnelrider

  • Posts: 321
8 pin rev-counter plug - disassemble or replace?
« on: August 21, 2020, 05:46:21 AM »
Hi everyone,

Can anyone give tips on replacing the 8 pin rev counter plug on 81-84 model (guess the same on all R65/45's)? 
I've started trying to get to the bottom of a non existent oil pressure light when turning the ignition on - it's finally got the better of me now! I've just changed the oil and filter, cranked with empty float bowls 'til the oil light supposed to go off, after viewing the idea (think I saw that suggested here by one of our gurus) but it's already not lit 'cause the warning light hasn't worked consistently for a couple of years and it's actually kinda bugging me now ;).

A PO looks like they've done a job on the 8 pin plug but the meter itself is ok as far as the warning light bulbs go when I feed it power and ground them from the plug pole terminals. I checked continuity of the oil pressure wire and it's inconsistent from the 8 pin plug to the the two pin connector underneath the left battery cover, from there to the pressure switch it's ok.

Also any tips on replacing other terminal blocks e.g. two pin flat terminal blocks like the oil/neutral switch connector underneath the left battery cover.. I know most connector block pins are retained by one directional needles, are these serviceable or is it a case of chopping off and crimping new pins and a block on?
Any info on whether to chop and replace, or possible to fix existing terminal blocks would be greatly appreciated!
Cheers
« Last Edit: November 05, 2020, 03:58:26 PM by Justin B. »
'85 Black R65 / '74 GT185 / '83 Pantah 500 / '90 Super Tenere 750  / '01 DRZ400 dirt only

Offline Carott

  • Posts: 18
  • 1980 R45/N
Re: 8 pin rev-counter plug - disassemble or replace?
« Reply #1 on: August 21, 2020, 10:11:41 AM »
Tunnelrider,
I just had a similar issue on my 1980 R45.
I understand that you have diagnosed the intermittent fault to be with the 8 pin connector but mine was in the 2 pin connector under the battery cover.
The female brass connector for the oil pressure wire inside the plastic connector had pushed down inside the plastic and the male brass spade was only pushing against the end of the female connector instead of inserting into it. (insert off colour joke here)
I pushed the brass female connector back up in the plastic connector and secured it from below RTV sealant.
Just one more thing to check before diving into the 8 pin plug.
YRMV
Brett

Offline tunnelrider

  • Posts: 321
Re: 8 pin rev-counter plug - disassemble or replace?
« Reply #2 on: August 23, 2020, 02:23:08 AM »
Thanks, yes it could be any connector when having electrical problems that's for sure. I think I've discounted the oil pressure two pin connector under the battery cover by sticking the multimeter probe in through the rear (more great descriptive imagery) of the two pin connector and get the same inconsistent continuity readings at the 8 pin connector. I guess to be sure I should cut the 2 pin connector off and redo it before diving into the murky waters of the 8 pin, but the 2 pin connector is as it should be, no obvious problem and the wires can't be pulled out the back so I think it's probably ok. Would anyone else just cut it to discount it anyway?

The rev counter itself usually stops working properly when the bike's hot and particularly quickly in summer, although this may be a fault with the meter, so I guess trying the 8 pin plug I'm hoping might solve that problem too. Might try and tighten the circular terminals first somehow, so they fit on the poles tighter. Does anyone know what the 8 pin connector is referred to as (as in a technical name)?

Thanks for any info. T
« Last Edit: August 23, 2020, 03:12:07 AM by tunnelrider »
'85 Black R65 / '74 GT185 / '83 Pantah 500 / '90 Super Tenere 750  / '01 DRZ400 dirt only

Offline georgesgiralt

  • Posts: 1265
  • I Love YaBB 2!
Re: 8 pin rev-counter plug - disassemble or replace?
« Reply #3 on: August 24, 2020, 11:11:47 AM »
Hello,
I have a solution for you. It is not cheap but it is fantastic.
Buy a new wiring loom from BMW.
My R65 (1982) had a lot of electrical problems including bad charging. I put a new loom and everything is running like when she was new. And the new loom is supple. The old one was like a stick, every time I had to move it a bit, it was like it will break.
I was so overwhelmed that, in the following two years I changed all auxiliary wiring looms when money permitted it. if you intend to keep the bike, it is well worth the price.
At one time, the 8 pole plug was available in the BMW fiche. Maybe it is still ?
Of course YMMV and this is just my 2

Offline tunnelrider

  • Posts: 321
Re: 8 pin rev-counter plug - disassemble or replace?
« Reply #4 on: August 25, 2020, 02:17:34 AM »
Thanks George for the idea, a new main loom would be nice but not necessary yet, for the amount of owners (I'm the sixth) the wiring's pretty untouched and most things work as they should, except the rev counter and oil light. I gave my charging circuit a good clean up while replacing the timing chain a couple of years ago, even the bean can connector with the bailey wire clip is original and ok. Not bad for 200K km.

I only got back to it a for second time yesterday with a quick 10 min poke around (in a slight amount of daylight this time) and payed particular attention to the two pin plug, giving the oil pressure male pin a bit of a sand and a twist with pliers, with the added benefit of more light to identify the 7th terminal on the rev counter plug the continuity beamed zero resistance straight away, better than before. Encouraging! Thanks Carott. I'll work on the terminals from the coil then put it back together.

George I recall you saying you've replaced the capacitors on your rev counter to fix it - what was it doing before you replaced them? Did it work ok cold then stop when the temperature increased, as mine does?

Cheers.
« Last Edit: August 25, 2020, 02:50:16 AM by tunnelrider »
'85 Black R65 / '74 GT185 / '83 Pantah 500 / '90 Super Tenere 750  / '01 DRZ400 dirt only

Offline georgesgiralt

  • Posts: 1265
  • I Love YaBB 2!
Re: 8 pin rev-counter plug - disassemble or replace?
« Reply #5 on: August 25, 2020, 07:13:04 AM »
Mine was not working. At all. One capacitor was short circuit and I bet it made the signal fade to the ground. Fortunately, nothing fried.
The clock also had bad capacitors. Those open circuit and no capacitance. One of them had the wire eaten by the acid.