Power Kits

A few more extra ponies for that old Big Flathead won’t hurt and you will get them fairly easy with a set of these ULR cylinder heads, made from cast aluminum. While looking quite original on the outside they feature an advanced combustion chamber design for improved combustion and breathing. Chamber volume is 100 cc, giving 6.1:1 compression on a 74” and 6.5:1 on an 80” motor. Substantially more material allows for custom milling and pop-up pistons. Another update are the 14mm sparkplug threads (3/4” long) for modern and more common plugs.
Dyno tests showed 18% more power and 13% torque increase over a stock 1946 UL with medium compression heads, just by swapping over to ULR heads! Check out the dyno diagram! These are true rear wheel numbers, power was up big time and torque curve is impressive! Remember, torque is the most important figure with flatheads!

There is NO Substitute for more cubic inches! Boost your little Flatty up to 54 cui or 900cc and experience the change from a lame duck to an agile pony. These 4.5” stroker flywheels require special stroker pistons which are also available. Recommended for qualified mechanics only because the flywheels need to be balanced and the engine cases and cylinders must be relieved for the rods to clear.
The selection includes:
flywheels for stock 45” crank pin and connecting rods, flywheels for racing purposes which work with stronger 1957-84 Sportster crankpins and connecting rods,

Of all measures to increase horsepower and torque of your factory engine, stroker flywheels are among the most effective. Boost your stock displacement 61” or 74” Knucklehead, Panhead or Shovelhead up to 84 cui or 1380cc (@ 3-7/16” bore) and experience arm stretching performance and a significantly increased fun factor.
Especially with original engine cases these 4.5” stroker flywheels are the way to go. If any, they require only minor modifications for installation and unlike with machining for Big Bore cylinders cases become not weakened. Consequently, engine life expectancy is near stock.
All versions are of Torque Monster type with thick left flywheel as original and require special stroker pistons, which are also available.
Manufactured from 80-55-06 ductile iron blanks, which are then heat treated. The 80,000 pound tensile strength blanks undergo an exacting 20-step manufacturing process, utilizing both CNC and conventional precision milling and machining. This insures accurate surfaces, legendary reliability, and excellent „truability“, an absolute necessity when setting up high performance motors to blueprint specifications. With pre-installed and replaceable connecting rod thrust washers, providing increased service-life and restorability.
Recommended for qualified mechanics only, because the flywheels need to be balanced and clearances in engine cases need to be checked.

Admittedly the investment for a set of stroker flywheels is pretty hefty and you wouldn´t crown this wonderful device with a set of inferior pistons, would you? The Wrecking Crew, for one, didn´t want to gamble and had these special pistons made by the renowend German manufacturer Graf. Those guys supply the vintage and classic racing scene since decades and you can simply trust their material. And yes, they are more expensive than your average 45 piston but a seized or broken piston at full throttle is by far more costly, guaranteed.
These special Graf pistons are made for small twin Flatheads with 4.5” stroker flywheels. They are shorter than stock pistons so the engine case baffle plates do not need to be removed. Complete with piston rings, pins and locks.

Boost any 883cc Harley-Davidson Sportster to 1200cc without hassle. No machine shop, no rebalancing your stock 883cc flywheels, no cylinder head modifications… The dished piston dome keeps compression down to a streetable 9.4:1 with stock 883cc heads. This kit includes
pre-honed cylinders, pistons, rings, wristpins, keepers ,
and is ready to assemble out of the box. Installing this kit takes then same time as replacing a stock top end. It’s just more fun when you’re done.

Forged big bore pistons by S&S for 4-1/4" and 4-1/2” stroke flywheels (88 cui./93 cui.) with stock 8-1/2" diameter. Sold as complete kits with front and rear piston, rings, bolts and clips.

Forged big bore pistons by S&S for 4-5/8” stroke flywheels (96 cui.) with stock 8-1/2" diameter. Sold as complete kits with front and rear piston, rings, bolts and clips.

Forged 3-5/8" bore stroker pistons. Applications for this piston include 88" (4-1/4" stroke). 93" (4-1/2" stroke), and 96" (4-5/8" stroke) engines with stock 8-1/2" diameter flywheels, and 98" (4-3/4" stroke) and 103" (5" stroke) engines with 8-1/4" small diameter flywheels. Sold as complete kits with front and rear piston, rings, bolts and clips. Made by Wiseco.

Bigger sometimes is better and the formula to prove this statement is: more torque + more horsepower = more performance. Available for the Directly from Milwaukee come these 3-7/8” Big Bore cylinders which, combined with a few more components, offer significantly more pull off the start than the standard equipment. Displacement is increased from 88 cui. (1450cc) to 95 cui. (1550cc) which results in torque and horsepower gains across the entire usable engine-speed range.
The Screamin´Eagle team did an excellent job in developping a product which is mainly street-oriented rather than for the race track. The chart shows clearly where the ponies are gallopping and that added potential is at command from very low rpm´s. Another advantage is the fact that the stock cases do not have to be machined for the larger cylinders. These cylinders are finish honed for the WW# 59-790 pistons, which have to be ordered separately.