BMWSportTouring BMWST DB
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#986717 - 05/07/17 02:47 PM Re: Bushings to Bearings-throttle bodies-easy [Re: dirtrider]
PAS Offline
Member

Registered: 06/24/11
Posts: 630
Loc: N.E.Ohio
D.R. I also wondered if the higher compression was in play to cause the wear. I have an 81 R100RT with over 170K and the shafts and bore are fine. Bike is a low compression engine.

I recently seen a post by Chris Harris and his thoughts were that the wear was due to insufficient free play on the throttle cables. In that regard, does the dealer do that adjustment on new bikes or do they come that way?

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#986724 - 05/07/17 03:19 PM Re: Bushings to Bearings-throttle bodies-easy [Re: PAS]
dirtrider Offline
The Oracle
Member

Registered: 06/05/10
Posts: 13014
Loc: Ohio
Originally Posted By: PAS
D.R. I also wondered if the higher compression was in play to cause the wear. I have an 81 R100RT with over 170K and the shafts and bore are fine. Bike is a low compression engine.

I recently seen a post by Chris Harris and his thoughts were that the wear was due to insufficient free play on the throttle cables. In that regard, does the dealer do that adjustment on new bikes or do they come that way?


Afternoon PAS

Probably not a compression related problem but could be a little camshaft profile related. The throttle plates on the BMW 1100/1150 engines are quite large so have a lot of surface area.

On the tight throttle cables-- They are ALWAYS tight while riding the bike (if they weren't then you would have poor & uneven throttle control)

Could tight throttle cables effect the bushing/shaft wear? Sure if you idle the engine for many hours at a time each day with just the right cable tightness to allow the engine firing pulses to rattle the throttle plates. (is it likely?-- Probably not)
_________________________
D.R. ___
Sent from my rotory dial wall phone!

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#986734 - 05/07/17 05:55 PM Re: Bushings to Bearings-throttle bodies-easy [Re: RayBay]
RayBay Offline
Just Joined

Registered: 05/04/17
Posts: 7
Hi guys- my 2 cents, and thanks for your excellent input, I do appreciate it

To PAS -Our throttle shafts/bushings were worn mainly on the cable/spring side.
We also had '81 and '83 R100RT's in Aussieland, we put on 30k km, carbs similar to yours , dusty conditions, shafts wore like crazy.

To nrp -Ball not roller bearings with 2 Side Shields, but I agree they may eventually become contaminated. But I avoided replacing the shafts and bushings which would fail again eventually anyway.

To Roger - I may someday turn the TPS to the indicated voltage for idle, which I believe would end up really close to the same result.
( joke) - I just checked and the throttle stop screw does fit in my lawnmower :-)

To dirtrider -Re: Bushings are a "correct choice", I could agree, especially if they lasted :-), maybe a larger diameter surface area on the cable side, different materials.
( joke) it's a Beemer, it doesn't vibrate :-)

To the world ( and Dan Cata) - ! ( light bulb) If a person ( named Dan) made a stepped nylon/teflon/oilite/unobtainium bushing that also filled the 13mm recess, with an o-ring on the end, instead of the shaft, thereby giving more surface area
And/OR made a throttle shaft with a larger diameter on the cable side ( up to the cable pulley), bored the Throttle body ( cable side) to a larger diameter, inserted a nylon/teflon/oilite/unobtainium bushing that would wear instead of the shaft,
-( joke) could also add a harley chain oiler for bushing lubrication :-) . OK, that's not funny.

--OK, back to the shop, don't touch wife's bike, don't touch wife's bike, don't touch wife's bike,
Come to think of it, It's working fine. Put my hands in my pockets, walk away.

RayBay

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#986901 - 05/09/17 06:02 PM Re: Bushings to Bearings-throttle bodies-easy [Re: RayBay]
RayBay Offline
Just Joined

Registered: 05/04/17
Posts: 7
Here ( I hope) is a picture of the shielded bearing pushed partially on the shaft, the shaft placed at the seal recess beside the bushing, the old seal on a piece of paper, the drift that I made to tap on the bearing. Also shows the throttle plate screw hole size vs screw diameter.


Attachments
TB with bearing.JPG (56 downloads)



Edited by RayBay (05/09/17 06:03 PM)

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#996698 - 09/12/17 02:20 PM Re: Bushings to Bearings-throttle bodies-easy [Re: RayBay]
RayBay Offline
Just Joined

Registered: 05/04/17
Posts: 7
UPDATE- a few thousand miles later, bike hasn't missed a stroke, runs great at low RPM. No popping from exhaust.
Here ( I hope) is a picture of the bearing pushed partially on the shaft, the shaft placed at the seal recess beside the bushing, the old seal on a piece of paper, the drift that I made to tap on the bearing. Also shows the throttle plate screw hole size vs screw diameter. Also a picture of the shielded bearing.
Added Picture location, maybe.
[img]https://lh3.googleusercontent.com/J-dWz7...No=w601-h451-no[/img]
[img:left]https://lh3.googleusercontent.com/q8W7_I...1m=w138-h137-no[/img]

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