Author Topic: Weber carb set-up (Read 151669 times)

Don R · « **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.

Don R · « **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.

scottly · « **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.

Tintop · « **Reply #928 on:** January 19, 2019, 06:22:31 PM »

Quote from: scottly 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.

+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?

Don R · « **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.

Don R · « **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.

Don R · « **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.

scottly · « **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 R · « **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.

754 · « **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.

Don R · « **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.

Medyo Bastos · « **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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Don R · « **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.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #938 on:** February 02, 2019, 06:32:30 AM »

Oh yeah! Heat and lube.

754 · « **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.

Don R · « **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.

Don R · « **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

scottly · « **Reply #942 on:** February 15, 2019, 08:28:56 PM »

The modified manifold looks good, Don.

And do ditch the studs in favor of bolts.

nick5446 · « **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?

754 · « **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.

nick5446 · « **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.

754 · « **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.

nick5446 · « **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.

Don R · « **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

754 · « **Reply #949 on:** April 19, 2019, 11:47:53 AM »

They are the original Italian Jobs..

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Author Topic: Weber carb set-up (Read 151669 times)