If you like our site, please consider joining our club!
By joining you will help ensure that we can continue to provide this service
JOIN HERE!

Throttle tube freeplay

tboooe
Posts: 87
Joined: Wed Aug 10, 2022 11:32 am
Location: The OC!

Throttle tube freeplay

Post by tboooe »

I recently purchased a 1967 R69s, my long time dream bike and first vintage BMW. I am still learning about these bikes so please forgive me is this is a silly question. On my bike, there is a lot of freeplay in the throttle tube. I can rotate it about 1/2" before I feel the throttle cables engaging. Is this normal for these bikes? I am used to adjusting the freeplay on my Ducatis to be around 1/16 - 1/8".

Also, I found this page explaining how to adjust the freeplay and synch the cables to the carbs. Thoughts?

https://w6rec.com/bmw-motorcycle-contro ... placement/
--------------------------------------------------------------------------------------------------------------
Tommy
1967 R69s + a bunch of Ducatis

User avatar
jeffrey
Posts: 75
Joined: Mon Jan 13, 2020 8:04 pm
Location: San Geronimo CA
Been thanked: 1 time

Re: Throttle tube freeplay

Post by jeffrey »

Welcome aboard!

1/2" is way too much play. Photo #15 in your link show the two large gears at the end of both the throttle tube and the cable end (chain). The "relationship" of those two gears determine the amount of slack in the cable.

Take the cover off the throttle housing and look at how those aforementioned gears work together. Basically - what you are trying to do is take slack out of the chain by resetting when the two gears start working together. Lift the gear with the chain attached high enough to turn the throttle tube to a new position where it will engage the chain/cable sooner than it was previously. Hard to explain this, but hopefully it will make sense when you see the two gears working together.

tboooe
Posts: 87
Joined: Wed Aug 10, 2022 11:32 am
Location: The OC!

Re: Throttle tube freeplay

Post by tboooe »

Thank you! I will give it try this weekend. I must say the procedure outlined in my first post seems pretty complicated but I am sure I will get the hang of it.
--------------------------------------------------------------------------------------------------------------
Tommy
1967 R69s + a bunch of Ducatis

User avatar
vechorik1373
Posts: 260
Joined: Fri Oct 27, 2006 3:00 am
Been thanked: 15 times

Re: Throttle tube freeplay

Post by vechorik1373 »

Try this procedure:
1. rotate the grip toward the open position, until you feel all the slop come out.
2. remove the screw that holds the P shaped lid over the gear.
3. Raise the lid, not all the way off, but just enough that when you pull outward on the grip, it moves away from the perch
4. While the grip is disengaged from the gear, rotate the grip toward the closed position, and while still holding the lid up, push the tube back on the handlebar. If you did not rotate it too far, it will go back in, and you will be able to push the lid back down. Put the screw back in.

You see, the lid has a blade near the end, that fits down inside a slot, of the throttle tube. That blade keeps the grip from coming out and off. The slot is of a certain length. You have to "time" the grip tube so when it is re inserted, into the gear, the blade of the lid will go down in the slot and leave very little rotational slack.
Vech
Technical Adviser, Former owner, Bench Mark Works
662 312 2838 cell 9 am to 4pm CST PLEASE!

tboooe
Posts: 87
Joined: Wed Aug 10, 2022 11:32 am
Location: The OC!

Re: Throttle tube freeplay

Post by tboooe »

vechorik1373 wrote:
Fri Sep 16, 2022 10:40 am
Try this procedure:
1. rotate the grip toward the open position, until you feel all the slop come out.
2. remove the screw that holds the P shaped lid over the gear.
3. Raise the lid, not all the way off, but just enough that when you pull outward on the grip, it moves away from the perch
4. While the grip is disengaged from the gear, rotate the grip toward the closed position, and while still holding the lid up, push the tube back on the handlebar. If you did not rotate it too far, it will go back in, and you will be able to push the lid back down. Put the screw back in.

You see, the lid has a blade near the end, that fits down inside a slot, of the throttle tube. That blade keeps the grip from coming out and off. The slot is of a certain length. You have to "time" the grip tube so when it is re inserted, into the gear, the blade of the lid will go down in the slot and leave very little rotational slack.
THANK YOU! So doing this procedure I wont need to do the cable "synching" to the carbs as described in the link in the my original post?
--------------------------------------------------------------------------------------------------------------
Tommy
1967 R69s + a bunch of Ducatis

cwf
Posts: 155
Joined: Sat May 15, 2021 5:52 am
Location: London, UK
Been thanked: 2 times

Re: Throttle tube freeplay

Post by cwf »

If you remove the P shaped cover, you might see that the throttle twist grip and the gear it meshes with have arrows marked on them. This is where new parts should meet and gives you full throttle movement.

If you move the point of meeting, replace the P cover, open the throttle to maximum and look at the carb intakes, you may find the throttles don't open to maximum. Unless you're racing, this probably won't matter.

On the post-1970 bikes, it was a way of getting more use from the parts, at the expense of top speed, as the gears tended to wear most at small throttle openings.

Balancing the cables is a further operation. Plenty of fun here.

Charlie.
75/7+ offroad sidecar; 50/2; R 35; XR125V; XR200A; Solex; 1939 Hillman Minx DHC.

User avatar
vechorik1373
Posts: 260
Joined: Fri Oct 27, 2006 3:00 am
Been thanked: 15 times

Re: Throttle tube freeplay

Post by vechorik1373 »

If your carbs were in sync, getting the slack out of the throttle tube to gear, will not effect the sync at all. Of course it remains to be seen, or known, if the carbs were in sync in the first place.
Vech
Technical Adviser, Former owner, Bench Mark Works
662 312 2838 cell 9 am to 4pm CST PLEASE!

tboooe
Posts: 87
Joined: Wed Aug 10, 2022 11:32 am
Location: The OC!

Re: Throttle tube freeplay

Post by tboooe »

Just wanted to give an update. Thanks to all the great advice I was able to adjust the throttle free play. By pulling the throttle tube out I was able to see the slot that the "P" cover blade goes into that dictates the fully closed and fully open limits. I rotated the throttle further forward so that the slot in the fully closed position was right up against the blade. Now I have a reasonable amount of free play, still a bit too much for what I am used to on my Ducatis but much much better now. Thank you again.
--------------------------------------------------------------------------------------------------------------
Tommy
1967 R69s + a bunch of Ducatis

Daves79x
Posts: 680
Joined: Sun Aug 09, 2015 8:13 pm
Location: Knox, PA. USA
Been thanked: 2 times

Re: Throttle tube freeplay

Post by Daves79x »

I would for sure not assume your carbs are synced at idle or at part throttle. After getting your cable free play where you want it, go through the whole carb sync procedure.

Dave
Dave

tboooe
Posts: 87
Joined: Wed Aug 10, 2022 11:32 am
Location: The OC!

Re: Throttle tube freeplay

Post by tboooe »

Daves79x wrote:
Sat Oct 01, 2022 8:09 am
I would for sure not assume your carbs are synced at idle or at part throttle. After getting your cable free play where you want it, go through the whole carb sync procedure.

Dave
Agreed, I will add that to the growing list of things I need to check out and learn about this bike. Fun!
--------------------------------------------------------------------------------------------------------------
Tommy
1967 R69s + a bunch of Ducatis

Post Reply