Author Topic: Weber carb set-up (Read 151754 times)

scottly · « **Reply #775 on:** May 10, 2017, 08:22:54 PM »

Hey DB, welcome, even if your bike has an extra cam.

Is it a 750? How did you manage the manifolds?

754 · « **Reply #776 on:** May 10, 2017, 08:33:41 PM »

The choke he showed is probably off a Keihin HD carb. Now if you machined a few grooves in the shaft, and screwed a cartridge in the threaded hole with a ball detent inside..... You would have a very nice choke. .loks good on the DOHC.. The manifold looks fabricated from tubing and plate .

DB Durf · « **Reply #777 on:** May 13, 2017, 01:01:33 PM »

Quote from: scottly on May 10, 2017, 08:22:54 PM

Hey DB, welcome, even if your bike has an extra cam. Is it a 750? How did you manage the manifolds?

754 nailed it. CNC'd a steel plate then bent the tubing and welded it all together. And yep, that's the choke off my Keihins. The choke works great. Surprised you didn't call out the 3D printed throttle cable splitter box 754.

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DB Durf · « **Reply #778 on:** May 14, 2017, 08:49:49 PM »

Quote from: scottly on May 10, 2017, 08:22:54 PM

Hey DB, welcome, even if your bike has an extra cam. Is it a 750? How did you manage the manifolds?

Sorry, didn't respond. Yes, it is a 750.

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scottly · « **Reply #779 on:** May 14, 2017, 09:02:57 PM »

So how is it running with the Webs?

DB Durf · « **Reply #780 on:** May 17, 2017, 07:29:41 PM »

Quote from: scottly on May 14, 2017, 09:02:57 PM

So how is it running with the Webs?

She's not yet. I have to order new jets. They are too big. I'll be working on it again Memorial weekend.

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RAZZ · « **Reply #781 on:** December 26, 2017, 01:09:50 AM »

Hi im looking in to buy some filters for my webers and want to hear you all for inspiration and exspiances any maybe some photos of your Weber and filter setup? I have Stock frame and MPD manifold

Thx
Razz

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Yamahawk · « **Reply #782 on:** December 26, 2017, 04:20:15 AM »

Quote from: seanbarney41 on April 22, 2017, 11:34:18 PM

ha ha...I call the kickstart the poser lever

...real bikes have kick starters lol.

Quote from: Bill/BentON Racing on April 24, 2017, 05:24:16 PM

Well, I've cranked a few by hand....think it would take Atlas to crank my current build by hand.....lol.

"You know that picture of At-lass.. I mean Atlas... where he's holding the world on his shoulders...? What's he standing on??
Better than that, where are we when we see him doing this?" - Brother Dave Gardner - "It's Bigger Than Both Of Us" -1966
Charlie

Swoop · « **Reply #783 on:** December 26, 2017, 04:33:02 AM »

Quote from: RAZZ on December 26, 2017, 01:09:50 AM

Hi im looking in to buy some filters for my webers and want to hear you all for inspiration and exspiances any maybe some photos of your Weber and filter setup? I have Stock frame and MPD manifold

Thx
Razz

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The MacGyver in me produced this on my previous build.

scottly · « **Reply #784 on:** December 28, 2017, 07:00:33 PM »

I'm using some Uni filters; IIRC, they were 6" long with an ID of 2 1/4"? I had to trim the length quit a bit, as well as the springs that fit inside. They fit over the stacks, and are held in place with cable ties. They aren't pretty, but do a decent job of passing air while stopping a good bit of grit from entering the engine.

754 · « **Reply #785 on:** December 28, 2017, 08:56:38 PM »

On the Amen project, I might run the RC manifold cuz they are straight, then run big honking K+N straight long filters, to get a bit of the look of the TZ flattacker.
Looks like 90 mm centers, should fit 3.25 inch filters.

RAZZ · « **Reply #786 on:** May 17, 2018, 12:50:32 PM »

HI

I finally had time to put filters on my Webers, it runs nice until about 60 to 70% open / WOT, and then its starts sputtering and hesitates on acceleration, and i guess its because of the limitation of air the filters makes - so IM I Right, if I change the Air correction jets to lets say 165 or so ? or do I have to change more ?

the bike ran super nice before i put the ITG sockfilters on

I have following parts inside:
Start jet 150 / 85-F9
Idle jet: 45 F9
Emulsion tube: F9
Main jet: 105
Air correction jet: 185
Accelerator pump jet: 35
Intake and discharge valve for accelerator circuit : 50
Needle valve 1,75
Float height approx 11 to 12 mm
AUX venturi : 4,5
Chokes 28 mm

Thanks

Razz

RAZZ · « **Reply #787 on:** May 17, 2018, 12:53:45 PM »

Here a photo

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scottly · « **Reply #788 on:** May 17, 2018, 06:29:54 PM »

Razz, is it running very rich? Spark plugs sooty? Smaller air correction jets will make it even richer. Even with 125 mains, instead of the 105s I'm running now, my bike was never so rich that it sputtered or hesitated.

Tintop · « **Reply #789 on:** May 17, 2018, 06:43:32 PM »

my .02 - there isn't enough air gap inside the filter between the bell mouth & inner filter face, effectively chocking it as rpm's & air demand increase. Biggest issue will be #'s 1 & 4 because of the down tubes.

I ran stacks on my Lotus that had a 15* bend so the filter would clear the fender. Wonder if something like that would solve the down tube clearance issue, and allow for proper filtering. Properly fitted that ITG filter should support more than HP than a CB750 can make.

scottly · « **Reply #790 on:** May 17, 2018, 07:11:58 PM »

I suspect that there is no internal support inside the filters, and they are being sucked up against the ends of the stacks, choking it as rpm's and air demand increase.

RAZZ · « **Reply #791 on:** May 17, 2018, 11:06:52 PM »

Hi

The socks is a quite good quality with good support so i dont Think they her socked in.. scotty - do you Think i schuld try a 100 main jet instead ? - by changing the air corrector jet ( to larger / more air size 165) by justadding

more air to same amount of gas or Im wrong here ?

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RAZZ · « **Reply #792 on:** May 17, 2018, 11:14:07 PM »

And yes its runs a little sudy - but my theory is, it dosent get enough air to burn all the gas - due the new filters in High rpms sorry for the unfocused Picture

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Tintop · « **Reply #793 on:** May 18, 2018, 11:55:50 AM »

Couple of questions - it was running fine before the filters...was that OK fine, or Great fine?? How was roll-on from 1/4 throttle (transition from idle jet to main)??
I'm wondering if it was always a bit rich (main jet), and the filters just compounded it.

RAZZ · « **Reply #794 on:** May 18, 2018, 11:57:29 AM »

It was really fine, no flat spots, fine spakplugs

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scottly · « **Reply #795 on:** May 18, 2018, 06:09:58 PM »

Yes, try the 100 mains, and keep the current 185 air jets for now. You may need to install new spark plugs, or at least burn the black off the old plugs with a propane torch. And make sure the cold-start valves are fully closed.

RAZZ · « **Reply #796 on:** May 24, 2018, 12:42:32 PM »

Hi I now have the 100 mains in, it is much better, but still a little hesitation the last 5 to 8 % to WOT - schuld i now change mains to 95 or change air correcter jet size ?

Thnx

Razz

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ivanhoew · « **Reply #797 on:** May 24, 2018, 12:50:00 PM »

i would go air correctors now , maybe a 190 at first. although that may bring the mains down a bit to being lean in mid range , so if it feels slower in the mid try the 105 again with the 190 airs.

scottly · « **Reply #798 on:** May 24, 2018, 08:41:00 PM »

The air correctors have much less effect for a given size change than the main jets; a 100 main with a 200 air will probably be richer than a 95 main with a 185 air, for example.
Razz, what is the RPM when you feel the hesitation?

RAZZ · « **Reply #799 on:** May 24, 2018, 11:20:15 PM »

My tacho dosent work, so not sure - byt lets say from 7500 and up

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Author Topic: Weber carb set-up (Read 151754 times)