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[Was it a cat I saw]

I have a 2008 Softail Springer Screamin Eagle CVO FXSTSSE2. I’m wanting to do some DIY performance upgrades. To that end, I bought a set of SE 110 cylinders with the intention of having them bored to 4.06”, and I bought a set of SE 4.06” pistons, 21915-08*. I bought the pistons on eBay solely based on size. Subsequently I obtained a Screamin Eagle Performance Parts catalog from a local H-D. The catalog states that those pistons “will not work CVO models”. Can anyone tell me why that is?

In the future, l’ll be having some heads ported, and when I get the boring & porting done, I’ll input my volume numbers into a compression calculator to determine which cams I want to use.

My immediate concern, though, is whether, or not, I’ll be able to use the Pistons I have, and can’t find any defined reasons why not.

Regards,
Andy

[HD Street Performance]

Welcome to the forum.

OK first things first, ignore the warning.
Catalog states:
"Screaming Eagle Pro Twin Cam Forged 11:1 compression piston kit for MVA, 110+, or ACR performance heads"
Your heads are the exact same as the now discontinued 17166-08 SE ACR Performance silver heads

These are 11:1 pistons for a 110 that will now be a 113". With a proper bore and hone you are in business.
I can help you with any aspect of the job. 113" is a very strong runner with 110 ported heads and the proper choice of mating parts, especially the pipe.

[Was it a cat I saw]

Welcome to the forum.

OK first things first, ignore the warning.
Catalog states:
"Screaming Eagle Pro Twin Cam Forged 11:1 compression piston kit for MVA, 110+, or ACR performance heads"
Your heads are the exact same as the now discontinued 17166-08 SE ACR Performance silver heads

These are 11:1 pistons for a 110 that will now be a 113". With a proper bore and hone you are in business.
I can help you with any aspect of the job. 113" is a very strong runner with 110 ported heads and the proper choice of mating parts, especially the pipe.

Thanks for the info, and for the help offer.

My two thoughts were just what you said - disregard, or that maybe the Pistons are too short for the stroke, and would be pulled out of the barrel. The latter didn’t seem very likely.

Does anyone know the piston dome volume of these particular pistons? If not, no problem. I have a burette set on the way, and will test myself. I’ll post the results as soon as I have them.

I have V&H Big Shots Staggered already. Basically, a 2-into-1-into 2.  I’m thinking a true 2-into-1, with shorter pipe beyond the collector, will give me a little better torque, but I’m not sure if the amount of torque increase justifies the cost. I think I’ve decided on the D&D Fat Cat - mainly because I can’t afford the RB Racing LSR with all the attaching parts... time will tell.

I’m looking at several cams, but need volume numbers before making my final decision on that.

[HD Street Performance]

I have V&H Big Shots Staggered already.
One of the worst as far as power and torque

Rush Wrath 2.25 baffle will get the job done well and won't break the bank. The D&D works well too at a much higher price.
If you wanted duals Fullsack stuff always works well

Cam needs to have about 245° duration with an intake close about 45°. Bias, LC, and LSA will depend on the porting.
Stock heads flow a little better than the OEM bathtub heads, that's it, despite big valves.

Can't help on those pistons, have never fluid checked them. I have many others.
I will say this, you won't be that far off if you use +10cc just to run some rough numbers first.
I was told they are 9cc by a colleague.
Won't know the exact answer without a fluid check.

[Was it a cat I saw]

HDSP,

Thank you for all of your advice. You’re listed as a vendor - do yo do machine work? I’ll be looking for someone to do the boring & porting. Right now, I’m leaning towards a local dyno-tune, head porting ship, pending a visit to the ship to talk to the tuner and/or porter. Their website doesn’t mention boring, but I haven’t spoken to them in person yet.

Any recommendations for these services will be greatly appreciated.

~Andy