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Snakeoil
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Upstate NY
Joined: 10/13/2014
Posts: 3

As you can see to my post count, I'm new here. I actually registered back in 2014. Why I never posted here is a mystery. I have several vintage bikes of various marques. I'm an equal opportunity enthusiast. I have a 1978 R100/7 with 15K miles on it. Spent a good portion of its early life stored in a basement.

As I'm sure everyone knows, the throttle springs on the Bing CV's require the grip of Arnold for anything but a short trip to the store. I've corrected the problem with reduced rate springs that I got at my local hardware store. Throttle still returns nicely and is now in line with what I consider a normal throttle.

That said, I understand that the R90S and the earlier /6 machines used a different throttle cam that what is used in my R100/7. Looking at the fiche, it appears that the /6 cam has more leverage than the /7 cam. Has anyone ever swapped them out and found that to be true? Or is it so slight that it really does not make a difference?

Thanks,
Rob

sminn560sl
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VBMWMO #7977
Central Kentucky
Joined: 04/13/2011
Posts: 132
throttle springs

I personally haven't had a problem with the stock springs (and I don't have the strength of Arnold). However, if you like it lighter changing them makes sense as long as they aren't so light that they could result in throttle sticking.

The R90S doesn't have a cam and is a completely different matter since they are different carburetors; Dellorto pumpers vice Bing CV's. The Dellorto cable connects directly to the carb slide while the Bing CV cable connects to the butterfly cam.

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Steve in Kentucky
91 BMW K1 (caretaking); 87 BMW R80 (RS); 61 BMW R60/2; 66 BMW R27; 74 R90/6; 59 NSU Maxi; 71 Norton Commando; 71 BSA 250 GP; 66 Triumph TR6R; 61 Norton Manx; 59/61 Triton; 14 Triumph Thruxton

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6333
Dellorto vs Bing

sminn560sl wrote:

The R90S doesn't have a cam and is a completely different matter since they are different carburetors; Dellorto pumpers vice Bing CV's. The Dellorto cable connects directly to the carb slide while the Bing CV cable connects to the butterfly cam.

So, for my education, there's no cam and small chain up in the right hand control area for the R90S? The parts lists shows there is. I understand the issue of the Dell's versus the Bings into what the cables attach to at the carb and how they work. But I would think that the handlebar function would still be the same regardless of what carb was attached.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

sminn560sl
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VBMWMO #7977
Central Kentucky
Joined: 04/13/2011
Posts: 132
Throttle cam

schrader7032 wrote:
sminn560sl wrote:

The R90S doesn't have a cam and is a completely different matter since they are different carburetors; Dellorto pumpers vice Bing CV's. The Dellorto cable connects directly to the carb slide while the Bing CV cable connects to the butterfly cam.

So, for my education, there's no cam and small chain up in the right hand control area for the R90S? The parts lists shows there is. I understand the issue of the Dell's versus the Bings into what the cables attach to at the carb and how they work. But I would think that the handlebar function would still be the same regardless of what carb was attached.

My mistake. I thought the OP was talking about the cable at the carb. If he's talking about the throttle itself I'm not sure.

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Steve in Kentucky
91 BMW K1 (caretaking); 87 BMW R80 (RS); 61 BMW R60/2; 66 BMW R27; 74 R90/6; 59 NSU Maxi; 71 Norton Commando; 71 BSA 250 GP; 66 Triumph TR6R; 61 Norton Manx; 59/61 Triton; 14 Triumph Thruxton

khittner
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VBMWMO #8223
Joined: 02/15/2012
Posts: 364
Kurt/Steve: It's been a lot

Kurt/Steve: It's been a lot of semesters since my 90S days, but I remember them having a cam and chain in the handlebar throttle housing. They got greased as part of a standard 10K service. I'm not sure how the cam profiles compared between the /6 and /7 bikes; but I haven't had much problem with the effort needed to twist the throttles, or keep them open comfortably. The throttle set screw helps keep the throttle held open on long, droning cruises, and I've used "Fin-Q" grips on a couple of my bikes---sort of a molded-in "Cramp Buster" on the throttle-side grip that lets you use the heel of your hand, rather than the grip of your fingers, to provide most of the effort to keep the throttle open.

Harper's Moto Guzzi still sells them Fin-Q Grips, and have been my source. They're an acquired taste; they need to be precisely placed at installation so that the "fin" ends up where you want it when you're using it to maintain highway speeds for extended periods. A Cramp Buster may be a more flexible device for this purpose.

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Konrad

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6333
I've been running a "cramp

I've been running a "cramp buster" style addition to my throttle for as long as I can remember. The cramp buster product relies on the heel's action to twist the device into place and hold the throttle. What I've been using actually has a long bolt and nut to actually squeeze it to the handgrip so it stays put...once I found the position, I don't even feel it's there.

I also have another cruise control device...I've always called it a "vista cruise"...I think there is a "universal" version of it. Here's a picture of a typical example...mines all chrome:

http://www.klr650.com/images/CruiseControlLarge.jpg

I checked mine and found a patent number which brings me to this page:

https://www.google.com/patents/US3982446

Between these two, I have quite a bit of control on how much tension is in the throttle and can rest my hand at will.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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