Carb designs

[ctraylor]

:think: Has anyone ever tried to build a 4 into one intake and use an automotive single carb on these bikes? There would be plenty of room for it. Also does anyone know what the CFMs of all 4 carbs are collectively.

 

Just a thought I have had,

[Yammer Dan]

Maybe a Holly 650 on top of it? Fuel pump wouldn't keep up would it? And there goes the MPG. Need a air intake like the V-Max scoop. Sure makes you think don't it?

[ctraylor]

According to my calculations, at 8000 rpm the air intake is 202 cfm at 1.10% volumetric effiency(this figure used in racing), and 156 cfm at .85% effiency( this figure used for street cars). You could use a small two barrel carb rated at 250 cfm. Has anyone tried this. It would be alot easier to adjust than 4 carbs.

 

 

RPM X Displacement / 3456 X Volumetric Effeciency (1.10% for racing and .85% for street. :confused07: :confused07:

[Yammer Dan]

Could you repeat that in English???LOL. Just a dumb old hillbilly I'd stick a 4-Barrel on there and get it some more air and see what happened!!!! Maybe a turbo to make it take the mix.

[LASER917]

How about a 2 barrel Holley Projection Electronic fuel injection system (throttle body) with O2 sensor. I think that would be trick.

[ctraylor]

At 8000 rpms the engine is sucking in about 202 cubic feet of air per minute. That is how carbs are rated by cfm. So all you need is a carb rated at or around 202 cfm which is a small 2 barrel carb. Maybe one off a geo metro would work or a small toyota. These engines are 1.3 liter engines which is about the same as a small car engine. I built an intake for a MGB once which had 2 carbs and ran one 2 barrel toyota carb and it ran great. I was just wanting to know if anyone has tried this. You could have a small scoop on the battery cover. It might look pretty cool.

[ctraylor]

Fuel injection would be nice but then you would have to deal with the O2 and the fuel pump issue and where to mount the module. I would like to try just one carb and see what happens. Sounds like a good project for this winter. If it works, I will let you know.

 

What do you guys think?

 

:stirthepot: :stirthepot: :confused24:

[Oldgold]

I seem to remember decades ago someone offering a single carb replacement for the old 70's Goldwings, I think they used a progressive

Weber 2 barrel such as was used on the 124 Fiats which were about the same displacement. Given the work necessary to fabricate a manifold and adapt the throttle,choke linkage etc. and the uncertain results I don't know if it's worth the trouble but it would make for an interesting project and the Weber jets are easy to change for tuning.

[wizard]

COOL!

[barnaclebill]

I had a GL1100 kit and they used a progressive 2bbl downdraft weber. Manifold was made by a company in Florida. Plenty of room. Main selling point was to eliminate carb synch. If I remember right, I was getting around 40 mpg.

[GeorgeS]

Remember, when you need 97 HP, all 4 of those Carbs are working !!

 

Flow !!

[ctraylor]

It is all a matter of moving the air. It the one carb will supply as much air as the 4, there should be no horse power loss. I have two ventures and may give this a try this winter and let you know how it goes. Maybe convert the battery cover to a hood scoop????????

[jasonm.]

the biggest gain is lack of parts to keep your ride running. But the idea requires a new manifold. I have only replace my slides once due to holing and one just fell apart. This was @ 50k. 4 individual carbs always gives best performance possible. So I will stick with what I have...93 rwhp. & 81 ft/lbs.

[helomech]

I suspect there would be a loss of efficiency due to the fact that the stock carb's main venturis feed pretty much vertically into the cylinder with only a slight bend, no added resistance from the extra length and bends that any adapter intake manifold would require.

[muffinman]

A few of us were talking about this at Vogel and I think I would go with a 365 cfm carb I like more carb than is needed cool with fuel Thats the way my F150 is not much on the milage but if you can get traction it will pull anything.

jeff

[Gearhead]

Interesting concept, but you get more accurate fuel metering and the best performance from individual carbs. That's why they were done that way to begin with. Would've been cheaper I think for Yammy to fit a manifold and single carb like a car, but they did it this way.

 

There's a popular retrofit for Viragos with a manifold some guy makes and a single Harley carb. People claim this and that about it, but the bottom line is there is a loss of top end HP but it is easier to work on.

 

Jeremy