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Change ‘76 R90/6 with stock carburetors to ‘92 GS carbs?

tanker4me

New member
The R90/6 has the 1000cc Siebenrock kit installed and I’m happy with the stock 32mm carbs low end response. The heads were rebuilt at the same time to stock spec.

The stock carbs are now due for a rebuild.

I have been told a pair of ‘92 GS carbs can be installed with little modification.

The question is, would the newer 32mm carbs off a ‘92 preform much differently than the /6 32mm carbs?

Has anyone done this mod before?
My hesitation to do it is getting the tuning right.

Bill
 
Your guess is as good as any. I'm kinda thinking not primarily because they're both 32mm carbs. Clearly the jetting would need to change. I think the mantra with these bikes is it's a zero sum game. Make a change in one region will result in a change in another region which you might not like. But if the swap is easy enough to do, and you have the GS carbs sitting around, might be worth the "test". :thumb
 
was going to check my Bing Book

But it must not have survived the Harvy flood. I can't see replacing your carbs with GS carbs would be cheaper than rebuilding your own, but if you called Bing, I am sure they can suggest any jetting changes you should make, and would be more than happy to sell you the required jets. I put MAC whispertone muffs on mine and they suggested the proper needle valve and hit it right on the head eliminating a lean running condition.
 
The R90/6 has the 1000cc Siebenrock kit installed and I’m happy with the stock 32mm carbs low end response. The heads were rebuilt at the same time to stock spec.

The stock carbs are now due for a rebuild.

I have been told a pair of ‘92 GS carbs can be installed with little modification.

The question is, would the newer 32mm carbs off a ‘92 preform much differently than the /6 32mm carbs?

Has anyone done this mod before?
My hesitation to do it is getting the tuning right.

Bill

Bill,

IIRC, the choke cable is different between these carburetors as the R90 used the stiff solid inner cable while the '92 carbs use a flexible cable with return spring and so won't work with the stock R90 choke lever. You would need to add the handlebar mounted choke lever and that requires a different left control casting. So, not cheap.

If it were me, I would stick with stock and rebuild them. But that's just me :)

Best.
Brook Reams.
 
I don't know if the same applies to the Bings on a BMW, but I remember that the carbs on 90s Japanese bikes often were made so as to discourage owners from making modifications. Things like jets that in pre-emissions control years were accessably installed with threads ended up being pressed into place or blocked with plugs.
 
I don't know if the same applies to the Bings on a BMW, but I remember that the carbs on 90s Japanese bikes often were made so as to discourage owners from making modifications. Things like jets that in pre-emissions control years were accessably installed with threads ended up being pressed into place or blocked with plugs.

HI Anyname,

Well, that's not the case with BING carburetors. You can easily change all the jets at will.

Best.
Brook Reams.
 
Carbs

I have a R75/6 with 32mm Delortos on it. They've been on there for 30 years. They work well and all parts are available for rebuild.
 
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