Hi guys, my '07 Fatboy currently has the Vance and Hines 2 into 2 Big Radius pipes, SE air filter, and a HD race tune. I bought the bike used and this is the combo that was on it. Is it just me or do these pipes seem to lack in producing torque or hp? The bike feels most slow/weak right out of 1st gear, which seems short on power and runs out fast requiring a shift. Has anyone switched from the Big Radius to a 2 into 1 and did this solve the problem of the anemic feeling bike? The bike has decent but slow, steady, torque through gears 2-5, which is what I would expect from a v-twin cruiser. Ultimately I want to make some engine mods later to clear the 100hp mark, but until then I'd like to consider the pipe change. Thoughts?

 

On my Slim I went from a set of V&H big radius to a D&D 2 low cat. Was running a cobra fi200 auto tuner so I did not have the bike tuned. I could tell the difference in low end torque.
My thoughts are if you plan to build the bike up with cams and heads (if you want over 100 HP you will need cams and heads), get an exhaust that will work with the build you want. Talk to who ever you intend to port your heads and get their advice on cams and exhaust. The good head Porters know which combos work...

 

For best results, match the exhaust to the engine.

 

2-1 exhaust is the way to go. And adding cams will make a huge difference.

 

Put a D&D Fat Cat on it now. It will work now and in the future when you are shooting for the 100 mark. I am making 123/126 with a regular old Fat Cat on my Deluxe...

 

2-1 is best. D&D fat cat, thunderheader, v&h propipe are some good ones. I'm running a fat cat

 

welcome - since you have an 07, your bike is always going to feel slow on take off, up through the gears, and completely useless in 6th, until you change the rear belt pulleys to a better drive ratio combo like 30/68 or 30/70. All 2007 and up bikes are geared way too tall from the factory for epa / noise regs. for about $800-ish your bike will be transformed. see the 'drive ratio' sticky at top of this softil forum. page 1, post 1 and then the last 5 pages of the thread.

your "HD race tune" is nothing more than a 100% stock timing map with a small extra amount of fuel to prevent running lean. but it is purposefully tame on spark timing in areas that affect off the line performance, roll on performance, and the fuel is still set rather lean.
HD cannot give you a tune map that falls outside of epa regs. I can hook you up with a member here that can give you a much better tune map for your bike, if you have the actual SERT module. otherwise you'll need to buy an aftermarket tuner like FP3 or powervision (recommended!). don't buy the SE tuner as it's not worth the money.

drop in some se204 cams after that if you still want to do any upgrades. but you probably won't. you'll be sickly shocked how much faster your bike is with no loss of mpg or other downside. good luck!

 

La Dog..... I've seen you mention changing out the rear belt pulley a few times on the forum. I'm open to that upgrade as it seems to be a pretty easy upgrade a fella can do himself. Are you getting the pulley's straight from HD or does a guy get them elsewhere?

Also, I've read a few threads on here about guys having that rear pulley sheer off after they messed with it..... as in the mounting bolts coming loose or sheering off. I would assume that because they are a high-torque application they would need to be replaced with new bolts similar to a fly-wheel change on a performance car.

 

I put all of the needed info on page 1 of the thread- sources, part numbers, bolts, torque values, speedometer correction values, pics etc. if you have any questions post in the thread and those of us who have done it will help you out.

I don't know where ya heard about all that scary stuff- but dismiss it. the only time you will be shearing bolts is if you re-used old bolts, used the wrong grade of bolt, used too short of a bolt, did not use blue loctite, or did did not torque the bolts to proper spec. if bolts are left under-torqued, they will shear due to excessive side loading. if bolts used are not at least grade 8, they will shear from plain being the wrong bolt. if you have less than 1" of thread going into the wheel, it can strip out. just like any other mechanical work, things need to be assembled properly or they fail.

If you do the install correct per the service manual with the correct parts, there is zero issue. anyone tells you different is full of crap.

look at all pre 2007 bikes. they came stock with combos like 30/68, 32/70, 30/70. V-rod comes with 30/72. All we are doing is "rolling back" to the days before HD started putting tall pulleys on our bikes to satisfy epa / noise regs. nothing more. but it makes a huge difference in performance.

 

Berick, welcome to the bord.
Like many often do, I was gonna do cams till LA_Dog set me straight on the pulley swap.
Always knew this to be a worth while mod. Just never thought about doin it on a HOG.
Also recommending a 2:1 exhaust for you.
Depending on what you wanna spend. But NO need to break the bank here... I went with Rush. Check out their Wrath. Start with the 2.5" baffle. The swap it out for the 3" after engine work is you need more volume.