Author Topic: Weber carb set-up  (Read 139757 times)

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Offline Don R

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Re: Weber carb set-up
« Reply #925 on: January 17, 2019, 04:00:02 am »
 I put a set on of RC webers on a cb750 head once at a swap meet, I reversed the 1-4 and 2-3 boots and the manifolds slipped right on. The guy then sold them to someone else while I was counting my money. Shame on me for setting them down.
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
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Offline Don R

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Re: Weber carb set-up
« Reply #926 on: January 19, 2019, 03:13:23 pm »
 Upon opening the fuel inlet I discovered the inlet screens. They were installed solid side up which I believe is incorrect, anyway they are torn. After my recent Goldwing fuel filter fiasco I intend to find new ones. It appears Pegasus offers replacements unless someone has a better idea.
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline scottly

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Re: Weber carb set-up
« Reply #927 on: January 19, 2019, 05:39:17 pm »
I believe they are supposed to be solid side up. I haven't figured out how to remove them without breaking something. ???
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Offline Tintop

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Re: Weber carb set-up
« Reply #928 on: January 19, 2019, 06:22:31 pm »
I believe they are supposed to be solid side up. I haven't figured out how to remove them without breaking something. ???

+1 on solid end up.  They should drop out, but may need a liberal amount of carb cleaner to loosen old varnish.  That said I have usually left them alone when they came from an application that had an inline fuel line filter.  If they're torn someone likely tried to 'pop' them with a screw driver. :(  A small hole in the solid end, then a screw to twist & lift?
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
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Offline Don R

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Re: Weber carb set-up
« Reply #929 on: January 19, 2019, 09:53:30 pm »
 I looked again, they can't go the other way. I either misread or somewhere it was printed wrong. I put the big parts in the ultrasonic cleaner. I'm not tearing these any further apart, just cleaning the jets one carb at a time and a flush with carb cleaner.  The filters are easier to find once I had the part number, 37022.010   5.49 each.  I'll wait to see if I need anything else before ordering.
« Last Edit: January 20, 2019, 05:11:36 pm by Don R »
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline Don R

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Re: Weber carb set-up
« Reply #930 on: January 30, 2019, 03:15:09 pm »
 Well I got out in the shop today and got the Webers bolted to the intake, drug out an old head and my Dad's old miter box with an antique razor sharp bread knife to cut some carb rubbers. The miter box has crooked slots and is useless. Glad I saved it all these years, L0L!
 Next,  I aligned the head and intake and it appears the intake is about 3/16 to a 1/4" too F'n wide. There is a weld in the middle so it looks like some fool broke it putting it on, and while repairing it, made it wider. Now I'm going to have to cut it apart, somehow jig it properly and TIG it back together. 
 I seem to remember Frank mentioning he made one that bolted together so it would go on easier, that might work but the cable pull is in the center of that part of the intake. I'm always buying some great stuff.
« Last Edit: January 30, 2019, 03:17:17 pm by Don R »
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline Don R

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Re: Weber carb set-up
« Reply #931 on: January 30, 2019, 05:48:04 pm »
 I'm considering making a plate bent to match the angle of the carbs.  Then I can clamp to that and install the carb rubbers to align the intake to the ports. At some point before bolting that together I'll need to split the intake leaving the cable holder intact, line it all up and weld up the split. Or make the plate permanent and leave it between the carbs to hold everything in place that way the intake halves can be installed one at a time.
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline scottly

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Re: Weber carb set-up
« Reply #932 on: January 30, 2019, 06:26:57 pm »
My manifold is the two piece version. There are overlapping "tabs" on each half with a single bolt that clamps them together. The upper tab has a slotted hole, and the lower tab has a threaded hole.
Don't fix it if it ain't broke!
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Offline Don R

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Re: Weber carb set-up
« Reply #933 on: January 30, 2019, 08:40:48 pm »
 That's probably a better design. I can make it right, I'm just grumpy about it. 
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline 754

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Re: Weber carb set-up
« Reply #934 on: January 30, 2019, 09:18:27 pm »
They are very easy to install one side at a time. Mine is a one piece that got cut or broke. I need to make what Scott has or  just make a brace that fits well to the two inner carb bolts, from one carb to the other.
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My next bike will be a ..ANFOB.....

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Lost quite a few CB 750's along the way

Offline Don R

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Re: Weber carb set-up
« Reply #935 on: January 31, 2019, 12:10:20 am »
 I can see how that's better Frank. The existing weld already interfered with the cable guide and they redrilled it. It's going to be extremely cold in the morning but I'll be out there in the afternoon. I've been wanting to perfect my fin welding so maybe it's time to tig.
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline Medyo Bastos

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Re: Weber carb set-up
« Reply #936 on: January 31, 2019, 03:29:48 pm »
I have a 1 piece that broke in half, and was rewelded


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Offline Don R

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Re: Weber carb set-up
« Reply #937 on: January 31, 2019, 11:38:57 pm »
 They must be a bit of a wrestling match to put on. I'm seriously considering the bolt up mod.
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Weber carb set-up
« Reply #938 on: February 02, 2019, 06:32:30 am »
Oh yeah! Heat and lube.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline 754

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Re: Weber carb set-up
« Reply #939 on: February 02, 2019, 11:16:44 am »
Heat, lube and green rubber gloves.,
 Fixed that for you Jerry..
If you got thin grippy gloves,  turning or twisting the rubber may help... if carbs are off the manifold you can put a block of wood on the  manifold and use a hammer.
« Last Edit: February 02, 2019, 08:37:40 pm by 754 »
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 Don R

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Re: Weber carb set-up
« Reply #940 on: February 02, 2019, 06:54:29 pm »
 I leveled out the repair weld on the too wide manifold and have the new piece made and clamped in place. I'll make the weld then cut the existing bridge piece on the weld side, mount it on the head and drill the bolt hole. It will probably need a little sanding, I doubt the saw kerf is big enough to allow for the existing width. I cut the carb rubbers an inch long on my miter saw. I rolled up heavy brown paper and slid it inside to keep the hose from flattening out. Cut like a dream. 
 I see why guys use bolts and not studs on the manifolds. The bolt holes aren't perfectly drilled and studs splay out a little. One carb falls on and one is a bit of a challenge.
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline Don R

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Re: Weber carb set-up
« Reply #941 on: February 15, 2019, 05:18:41 pm »
 I got back from vacation, rewelded and split the Weber intake. It welded nice for cast, they must be a good grade of aluminum. . It's now the proper width and lines up well with the ports. It goes on a lot easier too. One side from above, one side from below and they pop right together.

 https://photos.app.goo.gl/4boQfRhCDDSSswPa7

https://photos.app.goo.gl/iaS6FYtmS54eK7xr9
« Last Edit: February 15, 2019, 05:51:39 pm by Don R »
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline scottly

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Re: Weber carb set-up
« Reply #942 on: February 15, 2019, 08:28:56 pm »
The modified manifold looks good, Don. :D And do ditch the studs in favor of bolts. ;)
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline nick5446

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Re: Weber carb set-up
« Reply #943 on: April 19, 2019, 06:47:57 am »
I remember reading this thread YEARS ago...glad to see it's still alive now that I actually need it!

Picked up a '74 CB750 chopper a few days ago. Guy said it runs great, but it didn't run at all when I got it due the fact that it had been sitting a while. He didn't build it, but he went on and on about the bike and it quickly became apparent he didn't know what he was talking about, so I loaded it up and got out of there.

I got it kinda-barely running with a jump box and starting fluid, and I'll mess with it more in the coming days. But what brings me here is the fact that it's got some massive Webers on it that I have no experience with.

I don't see a choke anywhere on these; is that right? The throttle cable is broken, so it's pretty annoying to start.

Assuming the guy wasn't totally full of #$%*, jetting should be pretty close, so I'm not too worried about that just yet.

Any other thoughts or pointers when dealing with these?

Offline 754

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Re: Weber carb set-up
« Reply #944 on: April 19, 2019, 08:02:45 am »
Choke us at front, little box screwed on with a lever.
Unless it's real cold , giving a few squirts with the throttle will usually be enough,if the accel pumps work.
Throttle connection should be between carbs,  a cut off stock cable may work, tin the end when you cut the  end off if you can.
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 nick5446

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Re: Weber carb set-up
« Reply #945 on: April 19, 2019, 08:18:33 am »
Thanks! Re: cable - that's exactly what I was thinking. I have several, so hopefully one of them is long enough.

I'll look for the chokes.

Looking forward to messing with these things.

Offline 754

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Re: Weber carb set-up
« Reply #946 on: April 19, 2019, 11:28:18 am »
In your first pic choke is just to right of the Allen screw holding carb top on.
 I took a cut off bicycle calble, left knob on end , then ran thru chokes and clamped  then pulled and held it .
 Try priming and kicking it. First.
 Are your carbs chromed ? Odd to see big footboards on a chopper.
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 nick5446

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Re: Weber carb set-up
« Reply #947 on: April 19, 2019, 11:30:33 am »
Thanks, makes sense.

Yeah, they're chromed.

I think this bike must've been built in the OCC-era of bike building. It had a big dorky Le Pera seat and sissy bar. The floorboards and handlebars are next to go in the trash.

Offline Don R

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Re: Weber carb set-up
« Reply #948 on: April 19, 2019, 11:42:59 am »
 Mine were chromed too, the fools polished off all of the numbers. L0L! There is a lot of good info on here. Pegasus has a few parts in stock if you need small things. I haven't tried to run mine yet, too many other projects. https://www.pegasusautoracing.com/group.asp?GroupID=WEBERDCOEPJ
No matter how many times you paint over a shadow, it's still there.
If you love it, set it free, if it stays it's probably one of my 750's.
 CEO at the no kill motorcycle shop.

Offline 754

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Re: Weber carb set-up
« Reply #949 on: April 19, 2019, 11:47:53 am »
They are the original Italian Jobs..
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