CV carb discussion
CV carb discussion
I don't ride as aggressively as I did when I was younger. I appreciate the Super E carb, great for hot rods. I've had it on other bikes and I like how simple it is to tune. Now days it's a little too sensitive for me. I'm a big fan of the CV40 carb, I like that it's smooth and forgiving.
Now here is the issue, I'm strongly thinking of building (or maybe just buying) a bigger displacement engine. I am considering the S&S 96" which will be okay for the CV40. I'm also looking at some larger motors like a 107", 111" or 113". A lot of research I've been doing says that the CV40 carb is only good for motors up to 100".
So here is my question . . . will the CV40 be sufficient for the larger displacement motors? Who has done it?
Now here is the issue, I'm strongly thinking of building (or maybe just buying) a bigger displacement engine. I am considering the S&S 96" which will be okay for the CV40. I'm also looking at some larger motors like a 107", 111" or 113". A lot of research I've been doing says that the CV40 carb is only good for motors up to 100".
So here is my question . . . will the CV40 be sufficient for the larger displacement motors? Who has done it?
I don't ride as aggressively as I did when I was younger. I appreciate the Super E carb, great for hot rods. I've had it on other bikes and I like how simple it is to tune. Now days it's a little too sensitive for me. I'm a big fan of the CV40 carb, I like that it's smooth and forgiving.
Now here is the issue, I'm strongly thinking of building (or maybe just buying) a bigger displacement engine. I am considering the S&S 96" which will be okay for the CV40. I'm also looking at some larger motors like a 107", 111" or 113". A lot of research I've been doing says that the CV40 carb is only good for motors up to 100".
So here is my question . . . will the CV40 be sufficient for the larger displacement motors? Who has done it?
Now here is the issue, I'm strongly thinking of building (or maybe just buying) a bigger displacement engine. I am considering the S&S 96" which will be okay for the CV40. I'm also looking at some larger motors like a 107", 111" or 113". A lot of research I've been doing says that the CV40 carb is only good for motors up to 100".
So here is my question . . . will the CV40 be sufficient for the larger displacement motors? Who has done it?
Seasoned HDF Member
Joined: Dec 2006
Posts: 8,216
Likes: 6,126
From: Black Hills
Wood Performance used to offer high flow CV carbs designed specifically for the fuel delivery needs of big inch engine. The carbs were modified for greater bowl capacity and larger fuel line inlet, allowing them to pull big numbers on the dynos with a variety of configurations and Wood posted the runs on their website. Unfortunately, it looks like they no longer offer carbs for sale.
Road Captain
Joined: Jul 2023
Posts: 519
Likes: 398
From: So Western Ohio
A big bore engine sucking through a small carb does have some advantages. If the owner isn't too concerned about high RPM horsepower output, jetted correctly he can have some really sweet running characteristics off the bottom and mid-range. The big displacement draws air in at a higher velocity, atomizing fuel better, metering gas better.. until those WFO charges up to redline, where it would fall on its face. Run out of breath so to speak. But 90% of all riding is not done anywhere near redline. So...
I considered lower comp pistons for my bike once- softer exhaust note, cooler running, long engine life and nice everywhere but approaching redline. I wouldn't actually do it, the cam timing might not work out, or something. Nobody does it so it must be a pretty bad idea. On the 1600cc Yamaha I had (98 cubes) guys would bump the compression from 8.5 to 10 to 1. On the dyno they only picked up about 6 hp, all else unchanged..
I considered lower comp pistons for my bike once- softer exhaust note, cooler running, long engine life and nice everywhere but approaching redline. I wouldn't actually do it, the cam timing might not work out, or something. Nobody does it so it must be a pretty bad idea. On the 1600cc Yamaha I had (98 cubes) guys would bump the compression from 8.5 to 10 to 1. On the dyno they only picked up about 6 hp, all else unchanged..
Grand HDF Member
Joined: Mar 2018
Posts: 3,860
Likes: 3,447
From: Arizona
Wood Performance used to offer high flow CV carbs designed specifically for the fuel delivery needs of big inch engine. The carbs were modified for greater bowl capacity and larger fuel line inlet, allowing them to pull big numbers on the dynos with a variety of configurations and Wood posted the runs on their website. Unfortunately, it looks like they no longer offer carbs for sale.
Seasoned HDF Member
Joined: Oct 2019
Posts: 10,796
Likes: 7,422
From: OH
Surdyke had an NOS unit a while back (27934-99)
I couldn`t find the correct manifold ( 29635-99) or I would have bought it
Last edited by eighteight; May 13, 2026 at 08:16 AM.
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Joined: May 2025
Posts: 70
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From: South Carolina
i have a "racer" 100 ci revtech that goes like a scalded ape. I ended up puttiing on a Mikuni carb. very easy to set up and adjust when needed
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Grand HDF Member
Joined: Sep 2022
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From: Florida
I’m interested in a super hot chick, but I think she’s gonna want to have sex all the time.
Do you think maybe I can talk her into just playing canasta and holding my hand?
What’s the point of even getting a big motor if you’re gonna make it run like a little one? Will a large body builder be strong if you give him 500 calories a day?
A big motor needs a big carb. People don’t think of fuel as being a cooling circuit, but the proper amount of fuel at the proper velocity also helps keep the motor running cool. Somehow, somewhere along the 90s, everybody started looking at some dumb formula thinking they needed smaller carburetors on everything. But it’s just a proven fact the 289 ran better with the 715cfm carb that Carrol Shelby put on it compared to the 450 that the formula says it needs.
My 113 in my big heavy road king runs so much better with the bored out G carburetor over the stock G carburetor. It idles smoother, better throttle response and quite frankly, I think it has more power at the bottom end. My 127 used to have that bored out G carburetor, and I can tell you with absolute certainty that it runs better even on the street with the D carburetor.
I’d look for one of those discontinued, bigger, CV carbs used, or just bite the bullet and get an S&S. If you had an S&S on a hopped up little 80 inch you’re gonna be surprised how much smoother that carburetor will be on a higher compression, larger displacement motor. Back when I was Dyno comparing and drag racing the 93 cubic shovel, Gary from F&S Harley was absolutely convinced that I would go faster with a highly modified E carburetor with two thunder jets. So I took off my stock G carburetor and ran that thing three Saturdays in a row. He came out and even fooled with it himself, at the end of the day that little 93 inch shovel needed the bigger G carburetor to run, smooth and run faster. It was better on the street as well.
Do you think maybe I can talk her into just playing canasta and holding my hand?
What’s the point of even getting a big motor if you’re gonna make it run like a little one? Will a large body builder be strong if you give him 500 calories a day?
A big motor needs a big carb. People don’t think of fuel as being a cooling circuit, but the proper amount of fuel at the proper velocity also helps keep the motor running cool. Somehow, somewhere along the 90s, everybody started looking at some dumb formula thinking they needed smaller carburetors on everything. But it’s just a proven fact the 289 ran better with the 715cfm carb that Carrol Shelby put on it compared to the 450 that the formula says it needs.
My 113 in my big heavy road king runs so much better with the bored out G carburetor over the stock G carburetor. It idles smoother, better throttle response and quite frankly, I think it has more power at the bottom end. My 127 used to have that bored out G carburetor, and I can tell you with absolute certainty that it runs better even on the street with the D carburetor.
I’d look for one of those discontinued, bigger, CV carbs used, or just bite the bullet and get an S&S. If you had an S&S on a hopped up little 80 inch you’re gonna be surprised how much smoother that carburetor will be on a higher compression, larger displacement motor. Back when I was Dyno comparing and drag racing the 93 cubic shovel, Gary from F&S Harley was absolutely convinced that I would go faster with a highly modified E carburetor with two thunder jets. So I took off my stock G carburetor and ran that thing three Saturdays in a row. He came out and even fooled with it himself, at the end of the day that little 93 inch shovel needed the bigger G carburetor to run, smooth and run faster. It was better on the street as well.
Last edited by Rains2much; May 16, 2026 at 05:43 AM.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,079
Likes: 2,151
From: Ohio
CV40 can support up to 100hp, still have one with Yost items, 205 jet provided 13.2 @ 6400. CV did the job but a Mikuni 45 had better throttle response, both CV and Mikuni was consistent on the Wego. Bigger cubes you need a big carb or a bored Super G or R1 when really big, Sachs explained slower velocity through the carb produces good street manners which it does and giddy up available.