Author Topic: Weber carb set-up  (Read 71682 times)

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Offline scottly

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Re: Weber carb set-up
« Reply #50 on: December 19, 2010, 05:21:58 pm »
Hey scunny,

Do you happen to have a price for the stacks?

I assume this was meant for me, rather than scunny. ;)
The price is entirely negotiable:
When I asked my friend what he wanted, he shrugged and said, "See if you can trade them for something you can use."
Do you know which length stacks you want?
 
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Offline 754

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Re: Weber carb set-up
« Reply #51 on: December 19, 2010, 05:35:36 pm »
 Re throttle;
 Is your manifold straight or splayed?

 1 pce or 2 pce?
 If one pce, do the carbs fit the manifold, without the throttleshafts touching in the middle? (ie, threads still on ends of the shafts where they meet)

 Basically the shafts have 2 flats and a nut and washer, to hold on linkage, on some they can go either end, but on some manifolds the inner throttle shaft ends are cut shorter  for clearance.
 On some setups they run a single cable to to a point between the 2 carbs, others use a splitter cable like 350 2win Honda to a linkage on the outer ends of both carbs.

 A bit of info on your setup, I can probably tell you, a bit more.
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Offline scottly

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Re: Weber carb set-up
« Reply #52 on: December 19, 2010, 05:48:22 pm »
Hey Frank, did you happen to notice what size chokes were in your Dells?
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Offline 754

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Re: Weber carb set-up
« Reply #53 on: December 19, 2010, 05:52:00 pm »
 I think 30mm..x 8.. :o
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline scottly

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Re: Weber carb set-up
« Reply #54 on: December 19, 2010, 06:26:57 pm »
That's kind of what I expected...
As far as throttle linkage, mine is fairly simple, but far from perfect: there is a link that connects the throttle levers at the inside ends of the throttle shafts. (the shafts almost touch, but I have the two-piece, angled manifold)
If I recall correctly, I had to modify one or both levers to get the correct angles. The cable hooks on to one of the levers.

By the way, from what I've learned recently, comparing Dell side-drafts to Web DCOEs is like comparing apples to oranges!!! They may work the same, but NO parts interchange.   
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Offline bwaller

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Re: Weber carb set-up
« Reply #55 on: December 19, 2010, 06:33:56 pm »
Hey guys,

It dawned on me when I went to see a nice original sandcast CB750(that is for sale by the way) that I should mention the guy also has a Corvette Grand Sport replica and wants to sell the original intake that has quad Webers (40mm chokes I believe??)

He told me he wanted $1500 for the thing so that may be pricey, I don't know.


Offline Tintop

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Re: Weber carb set-up
« Reply #56 on: December 19, 2010, 07:38:49 pm »
Hey guys,

It dawned on me when I went to see a nice original sandcast CB750(that is for sale by the way) that I should mention the guy also has a Corvette Grand Sport replica and wants to sell the original intake that has quad Webers (40mm chokes I believe??)

He told me he wanted $1500 for the thing so that may be pricey, I don't know.

That's cheap for a quad Weber setup, when you figure that a new Weber is/was around $700/each.  Plus you've got a mainfold, and all the linkage.  Probably less than 1/2 the cost to build it from new.
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

Offline 754

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Re: Weber carb set-up
« Reply #57 on: December 19, 2010, 08:05:02 pm »
 I am not sure of the 4 setup, if its down or sidedraft.. 4 sidedrafts on a V-8 look pretty cool..

 Last I checked new sidedrafts were around 400 each..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline voxonda

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Re: Weber carb set-up
« Reply #58 on: December 20, 2010, 03:05:04 am »

I assume this was meant for me, rather than scunny. ;)
The price is entirely negotiable:
When I asked my friend what he wanted, he shrugged and said, "See if you can trade them for something you can use."
Do you know which length stacks you want?


 :-[ :-[sorry for that scottly............but as far as I can tell it is  no shame to be called scunny ;)
Would like the 2 1/4" ones if possible.
Is there anything you can use?

Rob
Better sorry for failing then for the lack of trying.

Offline voxonda

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Re: Weber carb set-up
« Reply #59 on: December 20, 2010, 03:14:30 am »
Re throttle;
 Is your manifold straight or splayed?

 1 pce or 2 pce?
 If one pce, do the carbs fit the manifold, without the throttleshafts touching in the middle? (ie, threads still on ends of the shafts where they meet)

 Basically the shafts have 2 flats and a nut and washer, to hold on linkage, on some they can go either end, but on some manifolds the inner throttle shaft ends are cut shorter  for clearance.
 On some setups they run a single cable to to a point between the 2 carbs, others use a splitter cable like 350 2win Honda to a linkage on the outer ends of both carbs.

 A bit of info on your setup, I can probably tell you, a bit more.

Hey Frank,



Manifold is a Lynx, like in the pic(not mine). So straight. The present actuator is touching the manifold and cannot be used, or have to alter the (cast) manifold. Prefer the single cable setup, due to uneven cable stretch.
Thanks for the info.

Rob
Better sorry for failing then for the lack of trying.

Offline jbirdga

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Re: Weber carb set-up
« Reply #60 on: December 20, 2010, 07:00:17 am »
Scottly, I recognize these manifolds as being from Magnuson, the Supervhager people, in the early 70's.  I had the same with Dellortos on a 1000cc kit in the day - still have the setup.  Found it very difficult to run on the street without "washing down" the cylinders from the overactive accel pump.  But would it wheelie!!

Offline 754

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Re: Weber carb set-up
« Reply #61 on: December 20, 2010, 07:41:47 am »
Vox, I hope the rubber manifolds are good, I dont know of you can get them.
 Between the carbs do the shafts have threads? Your linkage would depend onwhat you can bolt into the shafts, That looks like it had a single cable. Did you check that the brass nuts on top clear the frame?
 The linkage mine had is fairly easy to make.
 With the Lynx manifold that makes 5 different ones I know of ! Scottlys manifold should be marked MPD somewhere, the early ones were 1 pce, later were 2 pce.
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline voxonda

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Re: Weber carb set-up
« Reply #62 on: December 20, 2010, 11:01:19 am »
After contacting the Lynx Corp. it seems they still can supply these manifolds! So I ordered a set. Hope it wont be long, so I can fit on the bike.
Yes, the shaft seem to be in fine order, both threaded and with two flats. Carb's came with 1 cable linkage.



Rob
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Offline 754

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Re: Weber carb set-up
« Reply #63 on: December 20, 2010, 12:00:47 pm »
How much for a manifold?

 For your linkage,  Basically flat metal plates (1mm will work) with a double d hole thru them (to fit the part of shaft with flats, then nut hold it on.
 The bigger one is L shaped, around 1 3/4 on long side,  the doubleD is in the middle the short leg approx 1 inch long. This wil be bent at 90 degree to be roughly parallel to the throttle shafts. The other is shorter and L shped and should end up about4mm from the other when mounted, both short legs of L on up side.. screw and locknut in one synchs the carbs .
 On the lower end of the big one is a hole to attach throttle cable. I used a cable fitting, looks like so;
 Small square or round block drilled thru side a bit bigger than cable, and a lock srew on side to tighten cable. The block is turned down on one end, to a smaller round diameter to fit thru small hole in the big L. The small diameter fits thru the L plate and is held with a washer and cotter pin thru a cross hole..
 maybe Scottly has that and can show a pic?
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline scottly

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Re: Weber carb set-up
« Reply #64 on: December 20, 2010, 05:56:08 pm »
Here are some pics. The blue wire simulates the throttle cable.
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Offline Tintop

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Re: Weber carb set-up
« Reply #65 on: December 20, 2010, 05:59:59 pm »
D%#m, the more I follow this thread, the more I want to do this.  I just love Webers.
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

Offline scottly

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Re: Weber carb set-up
« Reply #66 on: December 20, 2010, 06:09:51 pm »
Scottly, I recognize these manifolds as being from Magnuson, the Supervhager people, in the early 70's.  I had the same with Dellortos on a 1000cc kit in the day - still have the setup.  Found it very difficult to run on the street without "washing down" the cylinders from the overactive accel pump.  But would it wheelie!!
I never had an "over-active" accel pump problem with Webers. Problems with wheelies, though! ;)
I looked again today: there are no markings on my manifold.
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Offline fishhead

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Re: Weber carb set-up
« Reply #67 on: December 21, 2010, 02:45:56 am »
An "overactive" accelerator pump can be caused by an incorrectly sized(or clogged) "pump spill".
 Part number 43 in this link
http://www.carburetion.com/diags/40DCOEDiaginfo.asp

The "pump spill" (or bleeder valve) allows some of the "accelerator" fuel to return to the bowl when the accelerator pump is squirting. It works in conjunction with the "pump jet" (part number 57-accel nozzle/squirter) size and if the pump nozzle is too big or the pump spill is too small, it will pump too much fuel.

  The good thing about the DCOE's is that they are very adjustable. The bad thing about the DCOE's is also that they are very adjustable. Finding the correct settings can be very intimidating.

 The best book I have found for explaining the Weber carbs is the 3 part series written by John Passini (Pasinni ?)  The books describe the inner workings and the relationships that all the jets have with each other and simplifies the carbs some what. The best book of the 3 part series is "tuning and theories" book.
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Offline Tintop

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Re: Weber carb set-up
« Reply #68 on: December 21, 2010, 01:01:29 pm »
+1 that's in my library
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

Offline scottly

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Re: Weber carb set-up
« Reply #69 on: December 21, 2010, 05:47:20 pm »

The "pump spill" (or bleeder valve) allows some of the "accelerator" fuel to return to the bowl when the accelerator pump is squirting. It works in conjunction with the "pump jet" (part number 57-accel nozzle/squirter) size and if the pump nozzle is too big or the pump spill is too small, it will pump too much fuel.

Also, the rods that connect the pump piston (not a diaphragm on DCOE) to the cam on the throttle shaft come in different lengths. A longer rod gives a longer stroke, and displaces more fuel. Then there is the spring on the piston/rod assembly: a stiffer spring shortens the time to deliver a given volume of fuel. Four possible variables, just for the accel pump. Talk about adjust-ability!
BTW, does the book you reference mention another function of the accel jet? 
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Offline BLUE71TURBO

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Re: Weber carb set-up
« Reply #70 on: December 21, 2010, 06:31:49 pm »
 For you guy's interested in Webers, if you need parts, the VW racing community uses them exclusively. Here is a popular VW
 website where you can find carbs and parts.......http://www.thesamba.com/vw/classifieds/      ;D
 Use the search at the top.  ;)
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Offline scottly

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Re: Weber carb set-up
« Reply #71 on: December 21, 2010, 06:41:28 pm »
The VW folks use downdrafts; that's where the Del/Web parts I found came from. The only thing I have found that will fit my DCOEs is Weber main jets...
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Offline voxonda

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Re: Weber carb set-up
« Reply #72 on: December 28, 2010, 08:19:47 am »
Today received my brandnew nitrile manifold rubbers from the Lynx corp. Australia.

One step closer to using the Dellorto's.

Better sorry for failing then for the lack of trying.

Offline BLUE71TURBO

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Re: Weber carb set-up
« Reply #73 on: December 28, 2010, 01:15:35 pm »
The VW folks use downdrafts; that's where the Del/Web parts I found came from. The only thing I have found that will fit my DCOEs is Weber main jets...

     Not all use the down drafts. All of the turbocharged VW's use 45-48 DCOE sidedraft carbs or fuel injection.   ;D

                :o :o     
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Offline scottly

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Re: Weber carb set-up
« Reply #74 on: December 28, 2010, 05:47:17 pm »
Rob, you may want to mock up the carbs on the bike, to make sure the 2 1/4" stacks will clear. The OD of the bell end is 64.9 mm.

Blue, that is one serious grenade, I mean, VW motor!!
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

 

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