Topic: Weber carb set-up

[valt]

This is another linkage version.  I used this on the sidecar, worked very well with a nice smooth pull.  Does require a return spring, but all Weber set-ups hould have one.
https://www.piercemanifolds.com/product_p/pm40930.htm

Yah that again does not work with the R.C. manifold setup as its meant for a straight pull.

[gschuld]

I have a question for everyone, apologies if it has been mentioned before. But I have a R.C. manifold with a pair of DCOE 40s on it. What I want to know is what throttle lever to use, all of the weber ones I can find are for cars and don't allow you pull direction up on them. I have circled the part I am talking about in red in the picture below.

This is the RC Webers setup on the Vance and Hines double.

[gschuld]

RC catalog pics

[gschuld]

More:

George

[gschuld]

Close up views of the (left) sides of the Vance and Hines front and rear Weber sets.  Both are spring loaded to counteract the pull of the throttle cables.  Couldn’t tell you if there were any other uses to it.

George

[MRieck]

Boy those springs are no tension at all.

[Tintop]

Thanks for posting those George.  So basically the cable linkage is made up of 4 pieces each side (2 levers, cable stop, & return spring).  You don't want a lot of initial spring tension on a bike, hard on the wrist, just enough to make sure the throttle closes.  Different situation in a car.

[scottly]

In the first pic, the two levers on the left would match the clocking and possibly length required for the RC manifold, but the lateral off-set will only work on the right side. These levers lack the idle speed tabs, but can be fit on top of levers with the tabs. There a wide variety of levers regarding clocking, length, and handedness, and when all else fails, it's easier to weld onto an existing center than start from scratch.
Regarding springs, my original carb's internal springs were strong enough that external springs were not required. I recently fitted a set of newer, less abused carbs, and it turned out the internal springs were not as strong, and I had to fit external springs. ( I would have swapped the internal springs, if I could have figured out how to remove them without destroying something; those suckers are on there for life!)

[scottly]

What I'd like is a progressive throttle; the first 20 degrees of the throttle would open the throttle blades less than the last 20 degrees with a 1/4 turn throttle. As is, the transition from idle to low throttle openings can be somewhat abrupt. I once used one of the idle speed screws as a cruise control while on a lonely Nevada highway to maintain 60 MPH.
If the spool were a spiral, or snail, this would be possible...

[gschuld]

Apparently this was a common setup

George

[Jerry Rxman Griffin aka MuthaF'er]

What are they saying about which throttle cable is typically used?

[754]

On the RC , I bet CB 350 twin cable..
That is what they used, cut the ends off and tin them...  unless you use wheel type..
 Not sure if the threaded part is slit on the RC, I think not.

[Tintop]

Interesting they have used the throttle arms ( l & r) for the return spring that are normally used for a 'push' link that have the ball.  The other piece looks like a cut down version of the flat arm with multiple adjustment holes.  Motion Pro could certainly make a dual cable.

[754]

Boy those springs are no tension at all.

They don't need much tension, the throttle opens easily with 2 fingers..very light pull. Slides have way more friction.

Scottly I am thinking if you make the wheel type  and make the mount hole off center, you may get what you need.

[BPellerine]

450 cable is the one I found that worked with the rc man,350 too short on the carb side,the 450 cable just fits with not much to spare,oem cable.bill

[Don R]

 I wish I had a pic of a gl1000 throttle wheel, they appear to be something that might be adaptable.

[754]

Does it look like this  ?

[valt]

Close up views of the (left) sides of the Vance and Hines front and rear Weber sets.  Both are spring loaded to counteract the pull of the throttle cables.  Couldn’t tell you if there were any other uses to it.

George

Hey George,

That setup appears to be two pieces. I wonder if the part of the lever that the throttle cable connects to is keyed to the weber throttle shaft. Or if its just a hole drilled and they are relying on the nut to hold the lever tight to the keyed lever that the spring connects to.

[valt]

Apparently this was a common setup

George

The second pic here is from Kiyos bike. That actually looks like a production lever and not just something he made. I did email him and ask but I think he misunderstood exactly what I was asking him. I suspect that lever comes from a different carb but I am not able to find out what.

[gschuld]

Apparently this was a common setup

George

The second pic here is from Kiyos bike. That actually looks like a production lever and not just something he made. I did email him and ask but I think he misunderstood exactly what I was asking him. I suspect that lever comes from a different carb but I am not able to find out what.

Unfortunately, I can’t shed much light on the subject beyond the pics.  I’ve got an RC history interest, but I have never felt inclined to own a Weber carb setup.

George

[BPellerine]

on the subject of the rc manifold,it just ocurred to me that maybe they used ko carb boots on them to make them fit the stock frame,they are shorter than the later boots,and maybe would let the carbs sit level?bill

[Jerry Rxman Griffin aka MuthaF'er]

I finally got a set ok K7/K8 boots. Shorter? and 1mm larger carb opening. Won't get to install them until April.

[valt]

on the subject of the rc manifold,it just ocurred to me that maybe they used ko carb boots on them to make them fit the stock frame,they are shorter than the later boots,and maybe would let the carbs sit level?bill

I just use the inner two boots from a normal k setup. DCOE 40s also do not want to be completely level anyways to my understanding. For them to function properly they need to have a bit of angle to them.

[Tintop]

I just use the inner two boots from a normal k setup. DCOE 40s also do not want to be completely level anyways to my understanding. For them to function properly they need to have a bit of angle to them.

Actually they should not vary more than 5* from horizontal, otherwise the float level changes.  If not supported they will sag on the rubber boots.  On the CB750 most use the original air cleaner mounts, and fabricate a mount for the top of the carb(s).

[BPellerine]

I finally got a set ok K7/K8 boots. Shorter? and 1mm larger carb opening. Won't get to install them until April.

yes they are shorter jerry,main issue will be if they seal when tightened,and yes I do kind of remember having to use 4 of the same boots,inner?bill