Bike in question is the fatboy in my sig. Built it about a year ago, bike runs great but since ive gotten it back together i keep wondering if a bigger carb would help this thing breathe better. Priced out a 44 screming eagle carb and manifold. Cost would be about 300 dollars. IDK if the cost would out weigh the performance benefits or if i should just leave well enough alone. Any input would be much appreciated

 

What do you currently have on it...? When you had it built did you dyno tune it....? Cause it will show if you need more air.... Also do you know what your heads flow, CFM?

 

Currently have the stock CV40 on the bike. Jets are a 235 main, 50 idle and a .020 shim under the stock needle. Stock slide drilled out, stock spring. Bike gets about 40 mpg

Not sure of the head CFM. Really wish i knew that but I just got some low mile take off new style heads and sent them straight to big boyz to have them ported.

I had the bike dyno tuned shortly after the build. Numbers were 85hp and 102 torque. I found out after the fact that the exhaust sniffer was not calibrated due to some kind of error so the air/fuel portion of the dyno printout is not correct.

Full specs on the bike:
95ci screaming eagle forged high compression pistons. 200 psi ccp.
Beehive style heads ported and polished by big boyz. heads milled to set volume @ 85cc. Stock size valves. .030 head gasket
S&S forged rocker arms, stock ratio
Andrews tw37 cams
Daytona twin tec ignition with timing settings as aggressive as i can run without pinging
3.37 final drive ratio

 

What exhaust is installed?
That is a huge main jet for a 40mm CV carb. The 40mm will support close to 100 HP. I doubt the 44 would reap large gains.
I would have expected bigger horsepower from your current setup.

 

I was expecting bigger numbers myself. Im wondering if i should go have another dyno run done. If the AF was off on the dyno that day perhaps the whole machine was out of wack. When i dynoed the bike I didnt have the DTT properly setup. I was still trying to figure it out and was mainly focusing on the carb while it was on the dyno. Now that the DTT is properly set im sure that will help the numbers a little. But idk if thats worth the 100 bucks plus for an hour on the dyno.

Exhaust is a Cobra power pro 2 into 1. Havent been super happy with the exhaust. But it is what it is.

My buddy running the dyno and I were really surprised we had to go that large on jets.

 

i would think there is more power in that motor if the carb was jetted correctly. i have done a lot of 95" bikes and have never had to use jets that big. i would think it is so fat on the top that it can not accelerate. jmo i would try something like a 85 main and a 45 or 48 intermediate jet. dsv

 

intermediate jet? you talking the idle jet?
85 main? did you mean a 185 jet? A 185 seems awfully small given the build. Not immediately doubting you, just trying to clear this up for myself.

 

I have a 10.5:1 compression 95" running S&S 585 EZ starts. My bike dyno'd at 102/108 back when it was injected and running Woods TW8 cams.

I did the carb swap and I am running a CV40 with the DTT ignition. I have not had it dyno'd again since the swap, but my *** tells me I am around the same power level, if not a bit more.

I am running a carb modified by 'Killer carbs' - he put a 220 main and 52 pilot when he set it up. I also installed a wide band and gauge at the time (worth it's weight in gold for tuning). His set up was too rich. I am down to a 190 main and a 48 pilot. I would tend to agree with others you are likely too rich right now.

I was going to try a 44 set-up on mine, because top end, flat out I run out of air. But really, I only ran top end flat out to see what it would do - not probably going to do it after that and I could care less about the numbers - bike runs great.

 

I think you are right where you should be. Maybe a pinch higher on the hp but that could be the pipe... Makes awesome torque... Carb ain't gonna do it... If you had the heads done why did you go with such a soft cam... I would contact big Boyz and see if they could pull up the file on the heads to see how much lift they can handle and maybe a cam change in the future. Hell for $400 Dyno tune you could install a new set of cams yourself.... What you have is not bad at all.... But I think a cam would make a lot more difference than a carb and Dyno tune, as it is... I believe that Andrews currently are grinding a 57 cam for the older TC's that are becoming quite common of 96 and 103 builds. Talk to your local Indy or give Kirby or Scott a buzz... It's a 37 with more lift and just a little more aggressive ramp.

 

Interesting. Looking thru my stash of main jets I have a 205, 210, 225 and a bunch of 190s. Think I should put in the 205 and see how that does? I may need to adjust my timing leaning it out that much.