Topic: Weber carb set-up

[ivanhoew]

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?

absolutely Scottly , i usually think 3 to 1  , however  i set up a formula 1 1968 cooper with 4 downdraughts on it  alfa v8 , on my dyno one time ,and have found that some engines react more to a/c than others , so was creeping up on it ....depending on what a 190 did i was going to go with maybe more a/c if necessary .


regards
robert.

[RAZZ]

When i got the webers (with no filters) it had 100 mains and 225 A/C’s


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[scottly]

I did back-to-back runs with the only change being the air correction jets. This was on an 836 motor, with 30mm chokes, 4.5 aux, 105 mains, and F16 emulsions. Note that at about 6100-6200 RPM, the A/F is the same for both the 185 and 200 airs, and at about 8000 RPM and up the A/F is the same for both the 200 and 210 airs.
Razz, if your plugs are still getting sooted up, I would try the 95s, keeping the 185 airs.

[RAZZ]

Hi got a little Challenge here, tried to order some new 95 mains, but Weber only make the main jet size starting from 100 - so now what to do ?


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[Tintop]

Hi got a little Challenge here, tried to order some new 95 mains, but Weber only make the main jet size starting from 100 - so now what to do ?

Pierce Manifolds lists DCOE main jets starting @85. https://www.piercemanifolds.com/product_p/73401.htm

[scottly]

You might as well try the 225 air jets since you already have them, but I'm concerned that the filters require such a drastic change in jetting; they must be more restrictive than they look to be??

[Tintop]

You might as well try the 225 air jets since you already have them, but I'm concerned that the filters require such a drastic change in jetting; they must be more restrictive than they look to be??

The restriction could be coming from the end of the stack being too close to the end of the filter scottly.  Note that there are multiple layers at the end vs a single layer for the sides.  I agree with you that the addition of filters should not require such a drastic change.  While the ITG filters are top quality, I'm thinking a different solution is required that allows more & freer air flow.

[RAZZ]

Hi I talked to my Weber dealer today and Weber makes main jets Down to 80, so i ordered a set, so I Will Wainwright an see, if that dosent work I Think its time for a different plan..


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[Bill/BentON Racing]

Got a set for sale....pics later today.

[754]

Bumping up to top.
 Jerry there are linkage pic on page 1 and 2 , fishead converted an RC  to single cable..

[754]

Don't make us come to Colorado ...Jerry ....

[scottly]

Here a photo


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I just noticed that the zip-tie holding your filter on is further away from the carb body than mine. You must have longer air horns than mine, which only extend 18mm from the carb?

[Jerry Rxman Griffin aka MuthaF'er]

Looks like Razz is using radiator hose or something else for home-made intakes?? That would/might provide slightly more room?? Are you using Honda intakes Scottly?

 

[RAZZ]

Hi yes you are right, my airhorns are 38 mm - by the Way just did a 735 km test ride with the 95 main jets ( from Oslo to Copenhagen ) they work Well, the plug are ”ok Brown” and the bike puls clean all the Way up


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[RAZZ]

Hi its a one piece MPD manifold and i use 36 or 35 mm radiator hose ( Cannot remember for sure) started out with some fancy gas resistant silicone hose, it did not work


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[754]

Rad hose is not always fuelproof.
 We are using blue silicone hose, seems to work.
 JERRY THE REASON YOUR USES stock rubbers is your head spigot are angled and theyare not on the RC Manifold.. like stock..but another drawback it movesceverything back.
 I think if you got preformed silicone bent hose, you might be able to shorten the distance. Or if you luck into another manifold, there us a guy on here looking for an RC manifold.

[scottly]

You might as well try the 225 air jets since you already have them, but I'm concerned that the filters require such a drastic change in jetting; they must be more restrictive than they look to be??

The restriction could be coming from the end of the stack being too close to the end of the filter scottly. 

Yes Brian, I think you are correct; there can't be much space with 38mm stacks.

[scottly]

Hi its a one piece MPD manifold and i use 36 or 35 mm radiator hose ( Cannot remember for sure) started out with some fancy gas resistant silicone hose, it did not work


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What was the problem with the silicone hose? The stuff I got from Frank works very well for me, and is easy to install. The gas pump hose I was using before was a serious pain in the ass to install (but not as bad as the RC manifold on Jerry's bike; at least I could do it by myself. ).
 

[Tintop]

You might as well try the 225 air jets since you already have them, but I'm concerned that the filters require such a drastic change in jetting; they must be more restrictive than they look to be??

The restriction could be coming from the end of the stack being too close to the end of the filter scottly. 

Yes Brian, I think you are correct; there can't be much space with 38mm stacks.

My feeling is that at lower speeds / throttle openings the frame rail doesn't interfere with the air flow enough to be noticed, but as air demand increases the blockage is causing an artificial choking (rich) condition at 1 & 4.  Short stacks like scottly's will certainly improve air flow.

[RAZZ]

Hi its a one piece MPD manifold and i use 36 or 35 mm radiator hose ( Cannot remember for sure) started out with some fancy gas resistant silicone hose, it did not work


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What was the problem with the silicone hose? The stuff I got from Frank works very well for me, and is easy to install. The gas pump hose I was using before was a serious pain in the ass to install (but not as bad as the RC manifold on Jerry's bike; at least I could do it by myself. ).

It was leaking, the material was quite thick -

You Think i Will get better (more) airflow with shorter airhorns ?


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[754]

The spigots on the head and the MPD manifold are designed for narrow clamps. We have been getting away with wider clamps, but keep in mind, very tight on a wide clamp, May cause the spigot lips to bite into or maybe split the hose.

[scottly]

You Think i Will get better (more) airflow with shorter airhorns ?

Yes. The 20mm shorter air-horns will increase the inside surface area of the filters by 36-38 square centimeters, which may double the area, or more, of what you have now. More surface area = less restriction.
Also, how long are your hoses? Mine are about 26mm, and I'm using the stock Honda clamps. The blue hose has a wall thickness of about 5mm. Do you have something supporting the rear of the carbs, or are they just hanging on the hoses?

[RAZZ]

I Think the hoses are aprox 30 mm I made a support bracket in the back it hangs to the frame by a ziptie it works well

I Think i Will try these: https://www.ebay.com/itm/Weber-40-DCOE-slide-in-Velocity-Stack-ALLOY-air-horn-ram-pipe-trumpet-16mm-5-8-/292131778610?_ul=DK





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[Tintop]

I Think the hoses are aprox 30 mm I made a support bracket in the back it hangs to the frame by a ziptie it works well

I Think i Will try these: https://www.ebay.com/itm/Weber-40-DCOE-slide-in-Velocity-Stack-ALLOY-air-horn-ram-pipe-trumpet-16mm-5-8-/292131778610?_ul=DK
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Those should help the situation.

[xriccix]

Hi Guys,

Sorry to being these thread back from the dead, are manifolds still made for a dual webber set up?