Author Topic: Throttle Butterfly Installation question  (Read 2944 times)

Offline Supershooter

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Throttle Butterfly Installation question
« on: May 09, 2020, 04:59:53 PM »
As I clean the throttle bodies, I remove the butterflies, as I go to reinstall the butterflies, I’m fighting to get them to reinstalled so the fully close. Is there a tip or trick to get them positioned correctly?
Supershooter
  • Liberty Township, O'brien County, Iowa
  • 85 K100 RT

Offline Supershooter

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Re: Throttle Butterfly Installation question
« Reply #1 on: May 09, 2020, 05:14:25 PM »
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  • Liberty Township, O'brien County, Iowa
  • 85 K100 RT

Offline Laitch

  • Faster than a speeding pullet
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Re: Throttle Butterfly Installation question
« Reply #2 on: May 10, 2020, 11:54:01 AM »
I consider removal of the valves a step too far. This thread suggests the use of drill bits or wire gauges to bring them at least to uniformity of distance. Read the entire thread before taking action. Whether that results in equal flow rates is unknown but without the use more specialized equipment, it's probably the approach you need to take.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline The Mighty Gryphon

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Re: Throttle Butterfly Installation question
« Reply #3 on: May 10, 2020, 01:28:48 PM »
Somewhere is a set of instructions for setting the butterflies without a flow bench, but I haven't an idea of where I saw it.  Good Luck!
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Laitch

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Re: Throttle Butterfly Installation question
« Reply #4 on: May 10, 2020, 01:46:12 PM »
Somewhere is a set of instructions for setting the butterflies without a flow bench, but I haven't an idea of where I saw it.  Good Luck!
Posts in the link I supplied Supershooter cover it close enough that I would use them to tackle that.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline rbm

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Re: Throttle Butterfly Installation question
« Reply #5 on: May 10, 2020, 01:57:28 PM »
That same issue happened to me when I replaced my K75 TBs with K1100 TBs.  It was necessary for me to disassemble the butterfly valves to fit the K75 shaft to the last K1100 TB.  Anyway, it is a very fiddly adjustment process.  You have to loosen the two screws that fix the valve to the shaft and carefully wiggle the butterfly valve to the point where it closes completely.  There are very fine tolerances between the diameter of the valve and the diameter of the TB throat so the process of fitting it is incremental.  You won't be able to synchronize the TBs with the butterfly valve in the state is is in now.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline alexg

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Re: Throttle Butterfly Installation question
« Reply #6 on: May 10, 2020, 03:51:07 PM »
You have to back down the stop screw (count the turns) to allow the butterfly to fully contact the body to center as described above. Once the butterfly is centered, then screw the stop back to where it was.
  • Michigan
  • '93 K75S, 1975 BMW R75/6 & 1984 Yamaha RZ350
Alex G.

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