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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: dougrs on March 22, 2015, 10:04:14 AM

Title: which throttle cable
Post by: dougrs on March 22, 2015, 10:04:14 AM

Hey,
I need some assistance in sorting out which throttle cable I need. Some background first. The bike was idling high, but when I pushed on the idle adjuster screw, the throttle body would go down and the bike would idle  fine. I greased the gears up in the hand grip assembly and the stickiness of the throttle assembly improved a bit. However, when I turn the bars to either side and release the throttle, the throttle body assembly will not slap back down to the resting position. I believe I need a new cable.

So I am confused as to which cable. I have a standard '94 K75.

Do I need the longer or shorter cable?

32731457376 accelerator bowden cable Length 1025 MM (http://parts.bmwmotorcycles.com/p/BMW__/ACCELERATOR-BOWDEN-CABLE-L=1025MM/42761111/32731457376.html)

32731457378 accelerator bowden cable Length 1142MM (http://parts.bmwmotorcycles.com/p/BMW__/ACCELERATOR-BOWDEN-CABLE-L=1142MM/42761113/32731457378.html)

thanks for the help,

-Doug

Title: Re: which throttle cable
Post by: johnny on March 22, 2015, 10:27:12 AM

i thinks its the 376... (http://parts.bmwmotorcyclesofcountryside.com/p/BMW_1994_K75/ACCELERATOR-BOWDEN-CABLE-L=1025MM/42761111/32731457376.html)

says K569: K 75 85 (0562,0571): (1991-1996)

guess you really donts know untill you do this... Enter your BMW Serial Number (last 7 digits of your VIN) (http://www.realoem.com/bmw/select.do?vin=)

can getts 15% off here if you spent more that $1 hundert... (http://www.motobrick.com/index.php/topic,1680.0.html)

j o

Title: Re: which throttle cable
Post by: rbm on March 22, 2015, 02:36:01 PM

Quote from: dougrs on March 22, 2015, 10:04:14 AM

However, when I turn the bars to either side and release the throttle, the throttle body assembly will not slap back down to the resting position. I believe I need a new cable.

First check whether or not the TPS switch on the end of the TB assembly is sticking. Number 6 in this diagram:

(http://i21.servimg.com/u/f21/11/71/56/74/thrott10.jpg)

Loosen the two allen screws that secure the TPS switch to the rail so that the switch is free.  Test your throttle, also from lock to lock.  If the throttle no longer binds, the TSP was hanging up the butterfly valve shaft.  If the throttle still binds, it could be a sticky cable or it could be misrouting of the cable.  When adjusting the TPS switch, take special precaution not to press downwards on the switch as you tighten the screws; it is a natural reaction as you try to hold the switch in position but the downward pressure causes the binding.

Title: Re: which throttle cable
Post by: dougrs on March 22, 2015, 02:55:53 PM

I removed the tps and still had the issue.

Title: Re: which throttle cable
Post by: dougrs on March 22, 2015, 03:16:12 PM

I put the TPS back on, discovered that throttle cable was binding on clutch cable and I fixed this. Throttle response seems good now, No bindin when turning the bars, BUT now my tach doesn't work.  Thoughts on what I might have done to cause that?

Title: Re: which throttle cable
Post by: rbm on March 22, 2015, 04:53:38 PM

Tach signal comes from the coil primary through a Black/Blue wire to Pin 16 on the instrument cluster.  Either of those connections got disturbed - the 1/4" spade on the coil or the multipin connector on the back of the instrument.

Title: Re: which throttle cable
Post by: dougrs on March 22, 2015, 05:02:58 PM

I noticed that a vacuum tube (the one in the pic on the right side with the wire/spring around it) had come off. Everything worked once I put that back on.

Title: Re: which throttle cable
Post by: rbm on March 22, 2015, 05:06:39 PM

Did you properly set up the TPS after you disturbed it?

Title: Re: which throttle cable
Post by: dougrs on March 22, 2015, 05:15:29 PM

I forgot to mention, that I did take the TPS off again, and refit it too.

thanks for your help!