2016 FLHXS 103 to 110 Upgrade - Stock Cylinder Heads vs Ported and Polished
#1
10-28-2023, 04:25 PM
2016 FLHXS 103 to 110 Upgrade - Stock Cylinder Heads vs Ported and Polished
Just finished installing the 110 Big Bore kit from S&S w/ their 585 EZ Start Cams. I reused the stock HD 103 heads. Are there significant advantages to upgrading the heads to something like the S&S 89cc Super Stock over the stock 103 heads? Trying to justify the added expense, because they will require S&S rocker boxes. Just curious if anyone has experience with the S&S heads for this kit. Anyone done this mod with ported and polished stock HD 103 heads?
#2
10-28-2023, 07:51 PM
Road Captain
Depends what you’re looking to get out of it. What are your goals for it?
10.5:1 110” with 585 cams will wake that 103 up, but the heads will be your limiting factor (assuming a good pipe is being used).
Stock 103 heads have small valves especially for a 110”. That can be changed, though. Those S&S heads are pricey. I think I would lean towards having the right outfit set up the 103 heads to work well for you.
Once heads are done need to ask yourself if you ought to get a larger throttle body and manifold because that’s the next restriction point. Then, need to assess if comfortable putting all that power through the stock rotating assembly. Slippery slope for sure.
10.5:1 110” with 585 cams will wake that 103 up, but the heads will be your limiting factor (assuming a good pipe is being used).
Stock 103 heads have small valves especially for a 110”. That can be changed, though. Those S&S heads are pricey. I think I would lean towards having the right outfit set up the 103 heads to work well for you.
Once heads are done need to ask yourself if you ought to get a larger throttle body and manifold because that’s the next restriction point. Then, need to assess if comfortable putting all that power through the stock rotating assembly. Slippery slope for sure.
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#3
10-29-2023, 08:43 AM
Seasoned HDF Member
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#4
10-29-2023, 09:13 AM
S&S heads do not require S&S rocker boxes. Only if you intend to use S&S automatic compression releases. Otherwise they just require special lower rocker box gaskets. Usually supplied by S&S when purchasing their 89cc heads new.
That said, have your stock heads ported and you can use much of your existing stuff, including ACRs. Tell head porter your plans.
That said, have your stock heads ported and you can use much of your existing stuff, including ACRs. Tell head porter your plans.
Last edited by tdrglide; 10-29-2023 at 09:16 AM.
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samrugger (11-05-2023)
#5
10-29-2023, 09:49 AM
Depends what you’re looking to get out of it. What are your goals for it?
10.5:1 110” with 585 cams will wake that 103 up, but the heads will be your limiting factor (assuming a good pipe is being used).
Stock 103 heads have small valves especially for a 110”. That can be changed, though. Those S&S heads are pricey. I think I would lean towards having the right outfit set up the 103 heads to work well for you.
Once heads are done need to ask yourself if you ought to get a larger throttle body and manifold because that’s the next restriction point. Then, need to assess if comfortable putting all that power through the stock rotating assembly. Slippery slope for sure.
10.5:1 110” with 585 cams will wake that 103 up, but the heads will be your limiting factor (assuming a good pipe is being used).
Stock 103 heads have small valves especially for a 110”. That can be changed, though. Those S&S heads are pricey. I think I would lean towards having the right outfit set up the 103 heads to work well for you.
Once heads are done need to ask yourself if you ought to get a larger throttle body and manifold because that’s the next restriction point. Then, need to assess if comfortable putting all that power through the stock rotating assembly. Slippery slope for sure.
Goals - Get my big *** up and out of its own way! Not trying to make to the track just move quicker when I need to. And it's doing it now, just wonder if porting heads would make a huge difference to justify the cost.
I have V&H Power Duals (without catalytic) and Rinehart 4in slip-ons.
It for sure woke up and runs like a scalded dog compared to the stock 103 setup.
The problem with having a reputable wrench port the heads is "Trust". Not that they are not out there, I don't know any so I'll need to ask around.
The guys over at S&S said for the 110 the stock throttle body would suffice. Presume they know what they're talking about.
Your comment regarding rotating assembly is on point and is a concern in the back of my mind with the current set as is.
What about finding a used pair of screaming eagle heads and trying those?
Many thanks!
Last edited by samrugger; 10-29-2023 at 09:52 AM.
#7
10-29-2023, 09:55 AM
S&S heads do not require S&S rocker boxes. Only if you intend to use S&S automatic compression releases. Otherwise they just require special lower rocker box gaskets. Usually supplied by S&S when purchasing their 89cc heads new.
That said, have your stock heads ported and you can use much of your existing stuff, including ACRs. Tell head porter your plans.
That said, have your stock heads ported and you can use much of your existing stuff, including ACRs. Tell head porter your plans.
Thanks
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#8
10-29-2023, 10:22 AM
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#10
10-29-2023, 05:41 PM