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The Sputhe engine has some good parts in it, Sputhe engineers are likely smarter than me but the max machined spigot bores are going to be tested on a Evo engine. Years ago was checking into building a 106" with stock cases, spoke to a couple of companies making the big bore for Evo and they was confident the later model Evo spigots would hold up, I have seen studs pull out and cracks into the lifter bores so 50/50.
Here is the Sputhe numbers: 3.780 bore - stock is 3.498, cubes 95.888, compression 8.54 with stock heads & 9.5 with SE heads. Kit is called a Fatvo
SE heads are a good product, uses TC spark plug putting more meat in the area where Evo heads crack, I have a cracked Evo head on the shelf. Harley puts sh*t valve seals in them tho. John Sachs said the raised port design is more suitable for a light bike putting the power deeper in the rpm's where a big bike needs it lower, sold mine in favor of reworked OEM's. Sputhe ad pushes pistons are the lightest in the market and top shelf materials used in it's products.
The big bore Sputhe cylindered engine could be the cats azz living a long time, I'm just a 4 5/8 S&S flywheel guy being indestructible.
SPUTHE BIG-BORE CYLINDER KITS
Sputhe has manufactured aluminum cylinders with cast-in sleeves for Harley-Davidsons since 1977, far longer than Harley-Davidson themselves. Our big bore cylinder assemblies for Evo Big Twins have been thoroughly tested and are manufactured from the best materials available to the most exacting standards in the industry
Sputhe cylinders expand less and have better thermal dimensional stability than any iron cylinders. The 3.780” (96 mm) bore Sputhe cylinders have a greater fin area and a symmetrical fin pattern that reduces thermal distortion and allows sustained operation at maximum power. Sputhe cylinders are stock height so that the cylinder studs, pushrods, exhaust pipes, manifold and motor mounts do not need to be modified. Heads and cylinders can be removed with the engine in the frame.
Part #4003S
Last edited by 1997bagger; Feb 15, 2026 at 09:42 AM.
The Screamin Eagle heads have a combustion chamber that is 72cc's which gives the engine 9.5-1 compression ratio using a stock head gasket thickness of. 045 and stock flat top pistons.
With a cam such as an EV 27 the compression should be around 175-185 psi .
You're right, Tommy. Some of this crossed my mind 2 seconds before my head touched pillow. I don't think ever Sputhe made stock cylinders so likely the case has been hogged out. There is no telling what is in it without pulling the cam cover and heads.
I see what I think may be ACR's on the Sceamin' Eagle heads, they may have been active when the compression test was done.
150 psi would be about right on an engine pumping near 200.
edit; or is that an engine temp sensor.
I believe this is the one I am going to go with. Has 0.01" over pistons, adjustable pushrods, mild cam, and the shop replaced the base and head gaskets. Any thoughts?
It did seem like a deal, but the seller took all the stuff down off of his eBay store and will be gone for a couple weeks. He also quit replying to messages. I ended up buying this one: https://www.ebay.com/itm/236641474650
The seller worked me and lowered the price to $1,700 because I don't want any of the EFI stuff, so he kept all that. It is low mileage and is in by far the best condition cosmetically of any I looked at. And, he left the stator and rotor on it so that it saving me money not having to buy those parts. I should get it next week. I am getting near the home stretch of buying stuff, so I will do a build thread soon so y'all can follow along.
It did seem like a deal, but the seller took all the stuff down off of his eBay store and will be gone for a couple weeks. He also quit replying to messages. I ended up buying this one: https://www.ebay.com/itm/236641474650
The seller worked me and lowered the price to $1,700 because I don't want any of the EFI stuff, so he kept all that. It is low mileage and is in by far the best condition cosmetically of any I looked at. And, he left the stator and rotor on it so that it saving me money not having to buy those parts. I should get it next week. I am getting near the home stretch of buying stuff, so I will do a build thread soon so y'all can follow along.
That one looks good, those corroded engines looked like road hard & put up wet to me.
When I went with the S&S111, I sat on the take out for about a year.
When I knew I was happy with the 111, I sold the Harley factory reman takeout engine for 2k, showroom clean, 20k miles, Ev13 cam, didn't last 2 days after listed on FB marketplace.
That one looks good, those corroded engines looked like road hard & put up wet to me.
When I went with the S&S111, I sat on the take out for about a year.
When I knew I was happy with the 111, I sold the Harley factory reman takeout engine for 2k, showroom clean, 20k miles, Ev13 cam, didn't last 2 days after listed on FB marketplace.
Good luck with it.
That's what scared me about them also. If someone let the outside of the engine get that bad, I can only assume they didn't take care of the insides well either.
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