131 Stage 4, why not for FXFBS?
HDF Community Team
Joined: Sep 2013
Posts: 2,386
Likes: 2,379
From: Wisconsin
I'd love to drop one of those in my 2018 LR using the stock, but slightly modified, 107 air cleaner and some non descript slip on's with quiet baffles. I'd be ok if it started running out of breath by 4 or 4.5K, I want all the torque between 1500 and 4K. I'd even remove the 131 badging from the engine. A sleeper.
Tourer
Joined: Jun 2020
Posts: 290
Likes: 67
From: Fairfax, Va
Originally Posted by Hulkss
Unfortunately, the 131 does not have a cam that produces strong low end torque. No more than stock up to 2500.
HDF Community Team
Joined: Sep 2013
Posts: 2,386
Likes: 2,379
From: Wisconsin
The Stage II torque cam 114 is the most low end torque you can get from H-D. The drive train is probably limiting what they can do.
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Grand HDF Member
Joined: Nov 2017
Posts: 4,251
Likes: 3,134
From: Texas
True, but -- I just looked at S&S. They offer a $2,200 M8 128 kit, but on their site they don't list it as available for the FXFBS. They only list the piston/cylinder kit, at $1100-ish, but not the full "Power Pack" kits. Is there some reason? Or (probably) just an error in their web search?
Road Warrior
Joined: Feb 2014
Posts: 1,851
Likes: 420
From: Santa Fe NM
Thanks for the responses. Still clear as mud, but really, who knows what goes on in Harley's head...
I thought about the legalities and EPA, but that just confused me further because the Fat Bob's exhaust header is the only one that has the catalyst integrated into it, so... Theoretically it should be the most compliant Softail, not the least compliant, right? Who knows...
I'd love to just go with FuelMoto, but they basically refused to do a big bore when I said I wanted to keep the stock exhaust header (I love the 2-1-2 header and dual mufflers look, and refuse to give it up). FuelMoto had never done a big bore FXFBS with the stock header and couldn't make any performance promises, and said the only way they would be comfortable doing it would be if I also got a D&D Fatcat or similar. That was a deal breaker for me, so as much as I would like to, FuelMoto isn't an option for this bike.
So Harley offered the 131 upgrade kit with no replacement header like the Touring bikes require, I thought that this might be the ideal match, but then they say it won't fit (except for where they say it will fit, sigh).
Well, no rush, maybe in October or November the dealers will have "free install" specials running, and maybe by that time the questions will be answered. Until then, still loving the Stage II 114!
I thought about the legalities and EPA, but that just confused me further because the Fat Bob's exhaust header is the only one that has the catalyst integrated into it, so... Theoretically it should be the most compliant Softail, not the least compliant, right? Who knows...
I'd love to just go with FuelMoto, but they basically refused to do a big bore when I said I wanted to keep the stock exhaust header (I love the 2-1-2 header and dual mufflers look, and refuse to give it up). FuelMoto had never done a big bore FXFBS with the stock header and couldn't make any performance promises, and said the only way they would be comfortable doing it would be if I also got a D&D Fatcat or similar. That was a deal breaker for me, so as much as I would like to, FuelMoto isn't an option for this bike.
So Harley offered the 131 upgrade kit with no replacement header like the Touring bikes require, I thought that this might be the ideal match, but then they say it won't fit (except for where they say it will fit, sigh).
Well, no rush, maybe in October or November the dealers will have "free install" specials running, and maybe by that time the questions will be answered. Until then, still loving the Stage II 114!
Edit- Well I guess it was on your other thread on the big bore with stock Fat Bob exhaust thread so you already know of this build.
I did the s&s 128 and 475 cam chest and SE heads with stock intake, headpipe with Tab slip ons and it worked great on my fatbob.
i eventually got the fatcat exhaust and breather but I really didn't need to, only to try to squeeze a few more ponies out it.
Go for it. It's a good sleeper build.
i eventually got the fatcat exhaust and breather but I really didn't need to, only to try to squeeze a few more ponies out it.
Go for it. It's a good sleeper build.
Last edited by Bowhunter8607; Sep 11, 2020 at 11:46 PM.
Road Master
Joined: Oct 2008
Posts: 842
Likes: 284
From: UK
True, but -- I just looked at S&S. They offer a $2,200 M8 128 kit, but on their site they don't list it as available for the FXFBS. They only list the piston/cylinder kit, at $1100-ish, but not the full "Power Pack" kits. Is there some reason? Or (probably) just an error in their web search?
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Grand HDF Member
Joined: Nov 2017
Posts: 4,251
Likes: 3,134
From: Texas
Doh! I totally forgot about that thread, and that build, but yes, thanks! That answers the question about the S&S kit, and I'm leaning heavily that way now. Thanks so much for the reminder!
Road Warrior
Joined: Feb 2014
Posts: 1,851
Likes: 420
From: Santa Fe NM
No problem and I was wrong about it being a different bike but nonetheless it seems like the 128" kit will do pretty well with the stock headers. Should be a beast! Let us know how it goes.