How to build a single carb manifold. (HOTT's build reposted)

Borrowed from hott on NGW forum. See original here. https://www.ngwclub.com/forum/viewtopic.php?f=47&t=37639

While building Ol' Sparky I found the perfect opportunity to try a single carb system. I couldn't
find any so I made it myself.

What you see here is sectioned pieces of 1 3/4"od pipe bent to 70deg. Mitered to fit with 4 inserts. Stock runners are screwed into plywood to assure spacing and hold work.

the inserts are made by stretching a piece of 1 1/2"od to 1 11/16"od . This will give a snug factory type fit in the rubber boots.

Here is the cross-tube. Using the 1 3/4"od. Measure long and miter to fit. This one was about 6 1/2" long

A small piece of 1 3/4"od for the plenum riser. photo is 1st generation Ol' Sparky manifold. I now weld the riser to the mounting plate BEFORE welding to crossover tube.

The adapter plate is a 3"x3"x3/16". (I welded 2pcs. of 2" side by side)
I used the adapter kit gasket as a template for the bore and mounting screws.
TIP; tack two bolts on the L & R sides of the plate from the underside. This makes install & removal of the carb much easier.
photo; tapping the carb hold down bolts.


photo; using hole saw to cut welds and pass thru.

photo; manifold ready for Holley or Weber, 1 or 2bbl carb (32/36 Weber shown)

.when we last left our induction system it was awaiting an air / fuel mixture devise...
I like the Weber 32/36. Price, easy to service, parts availability.
Although I must say I got my eye on that Holley Avenger EFI setup (that's another thread).
Whatever your choice you will need a working throttle set-up.
I used a GL-1000 pulley and welded the cable anchor yoke to a bolt on bracket. (you can also see the 2bbl to 1bbl adapter)

this is a pulley from a 1200. Smaller=quicker to WFO

I like to put the 2bbl in L to R with the fuel inlet to the front. Thus the cables look like this...they also could come in from the left side of the pulley. Depending on model. GL 1000 note; depending on filter choice you may lose your tool tray, but shelter thumb screws will still work.


There are manual choke kits available after market, but the accelerator pump provides a good spray to fire you up.
Fuel pump?
electric is the best way to go. I have been using a freshened up stock mechanical pump, and it works very well. Its shortcoming is after a long brisk highway stretch (prolonged 80-85mph) the idle is sketchy. Although it quickly recovers, an electric pump is probably a better choice.

Quote:
What size jets are you running?

Jet sizes that are finding 'happiness' with my systems are in this area..
idle 1...............55,65
idle 2...............55,50
primary............135,145
secondary........150,170
air prime..........170
air second........180
Emulsion..........F-6
Will these #'s work for you? I don't know and I'm not making any claims.
(the system is real forgiving, a tinker-er's dream)
Ric

OMG... That's nice!

~O~

Awesome job done there ,,,,hows it run and hows the mpg..

that's a very impressive piece of work slabghost. :good:

South Tx Wingman":5vlw0wnd said:

Awesome job done there ,,,,hows it run and hows the mpg..

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reported to run good. No idea on mileage but I can ask. I'm guessing around 30mpg as that is common on these setups.

Any problems or increase in induction noise?

On that one I'm not certain but I'd guess yes. I know my setup has very noticeable induction noise and mine has the same filter and pretty much the same carb. I haven't put the shelter back on yet so that may mute the sound some. So far I'm pleased with mine.

That is one very very nicely done Mod..My hats off to you Vince..Thanks for sharing..Sweet..

I cannot take credit for this fine build only for putting together this thread. See the very first line of the first post. There is a link to the original thread over on NGW.

Sir, your work looks fantastic, you can take credit for that .. I'm very impressed, it's nice a neat, and it looks like you care, did you paint them with a special heat paint..?

,,,,hows it run and hows the mpg

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Fires right up. Idles at 850rpm, and has no problem doing the ton.
MPG? My '83 Ol'Sparky got 42-45mpg in the Black Hills this past week.
You can expect the same kind of mileage as a well tuned set of carbs.
I have a customer who recently completed a AR to MA round trip, and was heading home from SD.
He told me the best thing about the carb setup was, no tuning issues ever. He worries more about
wearing out tires than fiddling with carbs.

Any problems or increase in induction noise?

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Everyone asks about freezing. Not with this design. There is a subtle difference
that allows riding into the 30's. (too darn cold for me. lol)
Intake noise; It can be noticeable with a full dress. Mostly under acceleration, but I haven't heard of it being objectionable.

HOTT

could you post the procedure to jet that carb? Mine is running badly. Higher rpm is fine but it won't idle.

Let me try to help quickly. (I will post photos later)
The 32/36(shown in photo) loads primary jet from the side of carb body.
No need to disassemble anything.
Barring a clogged passage it should idle like a rock with 55-65 jets.
I would look at the large gasket between carb and 2to1 adapter.
The casting webbing on the underside of the Weber may not be
sealing with the current gasket. It MUST seal around the two venturies.
EZ fix.
Check all connections for leaks. (it will be small).

HOTT

HOTT":1s59z3ya said:

Barring a clogged passage it should idle like a rock with 55-65 jets.

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Sorry....but you walked right into this one.....

"How does a rock idle?" :headscratch:

:smilie_happy: :mrgreen: :smilie_happy:

The set-up looks super nice, and professional. I ain't got near enough cajones to even attempt a change-over like that. Much respect for anyone that does, tho! :clapping:

Yep. Got no one to blame but myself for that :doh:

...were talking to the man in the areana...that has done it ...im very impressed

dan filipi":pxfcndr8 said:

Nice build HOTT.

Do you have pictures posted somewhere?

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Ummm you might want to check the first line of this thread. Those are HIS pictures. It's hott's build that I posted.

slabghost":23m0woox said:

dan filipi":23m0woox said:

Nice build HOTT.

Do you have pictures posted somewhere?

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Ummm you might want to check the first line of this thread. Those are HIS pictures. It's hott's build that I posted.

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Yes of the manifold, I want to see more of the bike in the video in post #15!