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XLXBhorsepower V-Twin cylinder head development.

Second seat installed this morning so I can knock out the valve job tomorrow and finish up another set of Gen2 M8 heads....
09/27/2026

Second seat installed this morning so I can knock out the valve job tomorrow and finish up another set of Gen2 M8 heads.

When they interlock it takes twice as much time, leaving 1 old seat in, machine the first one, then after they stabilize and cool you can machine the second one, 2 day project for me.

+4’s back at the track soon.

I’m ready to finish these up and get back to a 88” Sportster top end for a Midwest racer.

+4 SE Gen2 heads getting the valve job today. Incredible what these castings are capable of flowing 🙌🏻
09/23/2026

+4 SE Gen2 heads getting the valve job today.
Incredible what these castings are capable of flowing 🙌🏻

Bench full of carburetor’s today. Venting and T-jet modifications. Even a G with a genuine Novi Stack! Black body G’s wi...
09/22/2026

Bench full of carburetor’s today.

Venting and T-jet modifications.

Even a G with a genuine Novi Stack!

Black body G’s with a larger Venturi is a great option for the larger cubic inch builds.
Regular G Venturi 1.760
Black big bore G Venturi 1.875
Super D Venturi 1.940

Anyone have a #2 cam for a Sportster in either a Buell Thunderstorm 15-2 or an Andrews N4-2 single cam in usable shape?...
09/07/2026

Anyone have a #2 cam for a Sportster in either a Buell Thunderstorm 15-2 or an Andrews N4-2 single cam in usable shape?

Trying to help a racer locate a single before ordering a new set of anyone has anything laying on the shelf

Pic for attention

Thanks
Chad Hart

4.310 M8 piston with a 1.143 Comp Height? Is anyone offering a 4.310 piston for the 4 3/8 stroke (compression height of...
09/02/2026

4.310 M8 piston with a 1.143 Comp Height?

Is anyone offering a 4.310 piston for the 4 3/8 stroke (compression height of 1.143) to make a 127.6ci out of a 107?

I use alot of the CP pistons for 4.500 stroke, seeing if anyone has anything designed for the 4 3/8 stroke

CP’s listing for the 4.500 below.
Thanks
Chad Hart

Gen2 M8 Screamin’ Eagle +2 heads, anyone seeing the seats sinking? This is the second set now that I’ve received in for ...
09/01/2026

Gen2 M8 Screamin’ Eagle +2 heads, anyone seeing the seats sinking?

This is the second set now that I’ve received in for repair. Both bikes were down on compression and leak down showed intake track loss.

New seats will be installed, along with new guides (to tighten them up)

08/18/2026

This one’s for you Steve Allstaedt, finding clean 300cfm thru a 1.780 manifold on a 1.900 valve / XB cylinder head. (7mm @ .700” lift)

These are being prepped for the new Redshift 717 cam for the 5 speed cases.

We talked many times about reaching this and I’ve only done it a few times- back and forth Flowbench to porting table than anyone would like to admit.

Miss ya dude

Anyone have any good (useable) used / new Sportster CP rods in 8.5” for the 86-99 3/5 pc bolt together flywheels with a ...
06/28/2026

Anyone have any good (useable) used / new Sportster CP rods in 8.5” for the 86-99 3/5 pc bolt together flywheels with a 1.250 crank pin?

If yes, are they .791/.792 or .927 piston pin

Picture for attention
Thanks
Chad Hart

Big win here, S&S Cycles brought the SA +.500 pinion for the Sportster builds. Thank you Jeff Bailey and the entire team...
06/05/2026

Big win here, S&S Cycles brought the SA +.500 pinion for the Sportster builds. Thank you Jeff Bailey and the entire team at S&S 🤙🏻🤙🏻🤙🏻

05/31/2026

These M8’s are making some big power on pump gas.

I can’t thank all the dealers & customers that trust our cylinder head packages.

Michael Rutherford

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Reading, PA

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