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Twin-Cam MotorThe Mega-Sphere™
For Twin-Cam 88" - 95" and 96" - 103" Engines

The Mega-Sphere™ is a 360° squish head and piston design from Dave Mackie Engineering (DME). The DME 20° piston is made using JE or CP Pistons premium forgings.  It is a 20° full dome piston that is dished in the center.  The piston dish and the shape of the head combine to form a near spherical combustion chamber at top dead center.  The  360° squish band is created by machining the stock flat squish area of the head to an angle slightly greater than 20°.  This forms a megaphone or wedge shaped squish area.  This Mega-Sphere™ design forces the fuel/air mixture up into the sphere and toward the spark plug rather than forcing some mixture inward and the rest sideways or outward to the cylinder wall like a flat/parallel squish area does.  The result is the most efficient combustion chamber for complete burning of the fuel/air mixture which means maximum power and economy.  Frequently customers tell us that their fuel mileage is actually better than stock.

DME headwork has been ranked with the absolute best in the industry for decades.  The process begins with CNC shaping of the ports to get the ultimate shape every time.  Each port then receives either a high polish or atomization finish.  A combination of multi-angle and radius valve job is then done on air float Sunnen equipment.  Assembly is done with all premium parts and each head is vacuum tested.

Cylinder work at DME is done with state of the art air float boring, and automatic diamond honing equipment using current state of the art techniques.  The cylinders, complete with gaskets, are torqued between specially designed torque plates to simulate engine operating conditions.  This procedure allows the cylinders to take the set they will have when installed on the engine.  They are given a multi-level cross hatch pattern that is best for the application and finished off with the latest plateau honing techniques as  recommended by ring and piston manufacturers.

The final part of this potent DME package is a TC590, TC598, or TC630 cam set.  These lifts are enough to extract the tremendous flow and velocity potential of the heads with little or no valve train noise.  These cams will pull like a freight train from 2500 all the way past 6000 RPM.  The result of this DME combination is a very powerful bike with the best overall blend of torque and horsepower available.  Power is usually in the 100-120+ horsepower range with 105-120+ pounds of torque.  The actual power you realize will depend on the total combination you put together.  Carburetion/injection, ignition, exhaust system, and how well the bike is tuned will all have an effect on power output.  DME offers other cam sets ranging from .510 to .630+ lift and we will be happy to work with you to select the best choice for your application.

****The package includes: complete headwork using all premium parts; boring and honing cylinders to 95,97, 103, 107, 110 or 113 cubic inches; DME dished dome pistons, wrist pins, clips, rings; and TC590, TC598 or another cam set as appropriate.

SUGGESTED RETAIL=From $1995.00* (chain drive cam set).
From $2512.00* (Gear drive cam set, 4 Gears, install kit).
*97",*107",110" and 113" slightly more


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Some parts and services may not be legal on 1978 and later emission-controlled vehicles. Check your local, state and federal laws.*
*Dave Mackie Engineering high-performance headwork and camshafts are not legal in the state of California for use on 1978 and later emission-controlled vehicles.