Yes, I could have left the internal components of the motor alone and bolted it together after chopping off the trans, but that just wouldn’t be me. I figured that the motor was apart already, so I might as well make some upgrades while it’d be easy. No sense in keeping the displacement at 883cc either. I could have just bored out the cylinders or picked up a set already bored out, but instead I contacted Revolution Performance about a set of their crazy, iron-sleeveless cylinders sporting 1250ccs. When it comes to motors, there are very few performance add-ons that are as financially efficient as increasing displacement.
I spoke with Brian Nallin, one of the head honchos at Revolution Performance, about my build and he opened my proverbial eyes to more of their products that would help get me down the road quicker: Revolution Performance also performs head work (which I’ll cover in the next article) and dynamic flywheel balancing and lightening. Lightening the flywheels decreases the amount of power required to move the crankshaft and get the motor to rev-up faster, less reciprocating mass is always a good thing. Dynamically balancing the flywheels reduces overall vibration and increases reliability. While we might all be OK with a Harley that vibrates because of its 45-degree V-twin design, some of it robs horsepower, and any eliminated vibration pumps horsepower and reliability. Balanced parts tend to last longer because they have a regular, less jarring pattern of movement .
The new Revolution Performance cylinders are made using cast aluminum and a nickel-silicone-carbide (NiSC) coating on the cylinder wall surface that reduces the overall weight of each cylinder by a whopping five pounds. That’s only six pounds each— these cylinders alone drop the overall weight of the entire bike by 10-pounds— I know I’ve read somewhere that every 10-pound loss is the equivalent of gaining a horsepower! While other industries have been using NiSC cylinder coatings for over 50-years, Revolution brought the technology to American V-twins and is completely confident about their product, so much so that they offer a lifetime warranty against cylinder warping and plating defects.
Revolution Performance’s 1250cc cylinder bore. Less weight isn’t the only benefit of these jugs, these babies transfer heat faster than iron, have ten times more wear resistance, better oil retention, superior piston ring sealing, and a lower co-efficient of friction. These benefits combined result in a longer lasting, cooler running, and more powerful engine— basically these cylinders are awesome and there’s no reason not to use them.
I procured a set of CP Pistons’ forged units specifically designed for my motor. The pistons are designed to create a 10.5:1 compression ratio with a 0.12” dome height with an intake valve relief measuring -0.194” and an exhaust valve relief of -.0163” and a weight of 353 grams.
Balancing the pistons is a simple matter of piling up all the components that a piston requires and making sure each assembly weighs exactly the same amount. Not only will this procedure reduce engine vibration, but it also frees up some more power. Revolution piled each piston assembly on the scale including a piston, rings, pin and retainer clips, with each assembly weighing in at exactly 482.7 grams.
Another handy service that Revolution Performance offers the performance connoisseur is dynamic flywheel balancing and lightening. Here’s the stock flywheel.
Note how much steel was removed. The lightened flywheel will rev up faster, require less power to jam it up to speed, and less power to maintain speed. This bike should generate more overall horsepower and require less horsepower to sustain speed— this small change alone will make this engine more powerful and more efficient than a stock engine.
The next step is balancing the assembly after removing considerable mass from it. Revolution Performance uses a dynamic balancing method which is better than the static method that some shops use, because it duplicates the way the part will be moving in the engine and better reduce vibration.
Once the wheels are balanced, the rods are pressed and bolted back into the assembly and the truing process begins. The two blocks on either end of the flywheels are insuring that each wheel is perfectly lined up with the other one.
The finished, dynamically balanced, lightened ’93 XL flywheel assembly— almost guaranteed to make the bike faster and more efficient than its stock counterpart.
Coming soon, Little Big Twin gets some head work and the motor gets polished— only on Bikernet.com.
Revolution Performance
1312 Pilgrim Road
Plymouth, WI 53073
920-892-2109
toll free: 866-892-2109
www.revperf.com
