BMW K bikes (Bricks)


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1Back to top Go down    Waving rev counter on Sun Jun 15, 2014 6:25 pm

Johnser

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Went for a ride today and the rev counter started "waving" around the correct revs. Not a jerky movement, very swingy/swim my. More noticible at speed. I didn't notice it straight away when I rode home but it was soon back again.

Any ideas? Simple things to rule out?

Ps, hello if the K-bike rider with two up I passed on the a30 was you!

    

2Back to top Go down    Re: Waving rev counter on Sun Jun 15, 2014 7:23 pm

rosskko

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Morning Johnser,

Mine does the same. Has done since I got the bike.

Mine bounces due to bumps in the road while riding.

Try it. On a fairly smooth road rock the bike a bit or bounce it up and down.

I haven't bothered to fix mine. There must be a spring of some sort that is getting soft?

rosskko


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1986 K100RT VIN 0093801K100RT with summer fairing for a northern visitor

Basic/2 6308802K100CJ  05/1988

K1100RS 0194321
    

3Back to top Go down    Re: Waving rev counter on Sun Jun 15, 2014 7:59 pm

Inge K.

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You need three good connections, 12V+, 12V- and signal...the signal comes from the frontmost coil (cyl. 1-4).



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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

4Back to top Go down    Re: Waving rev counter on Mon Jun 16, 2014 5:20 am

Johnser

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Thanks for the replies.

I think it came on too suddenly for a spring to be going soft. Also, I'm sure it was ok for a while when I started up for the return journey which points me towards thinking it may be electrical.

For now, I'll check the coil feed (thanks Inge) and clean up the plug/s to the speedo unit.

It's annoying, but there is no point dismantling the speedo until I have something to fix the gear indicator too.

cheers

    

5Back to top Go down    Re: Waving rev counter on Sun Aug 14, 2016 5:32 am

Johnser

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Belated update:

I ignored this for ages but decided to investigate again last week.

Cleaned the terminals on both the back of the cluster and the front coil. It's obviously the front coil that gives the signal as pulling this double wire (black/blue??) Kills the rev counter. Not to mention making the bike run on two cylinders.

However, no difference. It still wobbles around madly when warm.

Any other thoughts? I'm thinking it's more likely to be related to the lower components rather than the speedo cluster as the cluster doesn't really get warm and symptoms should be apparent all the time.


Annoyingly, it's got to be properly hot to make symptoms appear so not easy to diagnose with the bike in bits

I need to check my manual to see if there are any other connections between cluster and coil terminal. Maybe run a new test wire externally to see if that could help

    

6Back to top Go down    Re: Waving rev counter on Mon Aug 15, 2016 7:33 am

Rickmeister

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Interesting! Symptoms appear when its HOT. Had v.similar experience, but with the speedo, not the tacho. Pulled the cluster off and a bit apart, cleaned the bowels of it with Servisol stuff, and De-oxited everything. Ran it on the bench for a day (clocked up over 1000Km over night!). Hasn't happened since, esp. during our hot summers over here.

Just a thought.


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7Back to top Go down    Re: Waving rev counter on Mon Aug 15, 2016 10:32 am

Johnser

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Thanks, good suggestion. It's happening all the time now so at least it should be easier to diagnose.

I'm reluctant to pull the assembly apart until I have sourced a spare as I already need a new neutral indicator perspex lens, a gear indicator LCD and ideally a clock!

Trouble is eBay breakers want top ££for them.

    

8Back to top Go down    Re: Waving rev counter on Mon Aug 15, 2016 5:59 pm

Crazy Frog

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@Rickmeister wrote:Pulled the cluster off and a bit apart, cleaned the bowels of it with Servisol stuff, and De-oxited everything. Ran it on the bench for a day (clocked up over 1000Km over night!).

Nice to to the Iron Butt in a reclining chair when drinking beer and the odometer is adding to the mileage on its own Very Happy


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1986 k75, 1985 K100rt, 1985 K100rt/EML sidecar.
    

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