1984-1999 Overview of the Harley Evolution Engine

After its introduction in the early '80s, the Evolution engine and the rubber-mounted FL chassis design changed the way the industry looked at the touring models. I just want to take a few minutes and review a few of the chassis changes that were introduced not only in '84, but were run pretty much through the late '90s. Rear axle, you'll note there's a different torque spec. It's a castle-style nut, and it's retained by a cotter pin. The rear shock assemblies have basically remained unchanged, but the rear suspension feeds are brass style, instead of a new plastic coupler. The rear belt dimensions have been reduced on the twin-cam motorcycles, are a full inch-and-a-half in width on the Evolution design. The swingarm is of a different design than what you're used to seeing nowadays. The outer primary derby cover used to have just three holes on this typical Evolution model, you'll notice the newer ones have five. All the makings of the wet clutch and primary drive system have basically remained unchanged to date. Spark plug dimensions are larger on the Evolution, but they are the same typical spark plug. There should be no substitute, other than a Harley Davidson plug. Charging system, you'll note the regulator plug, where it enters the crankcase, is accessible where it no longer is. We like to install a small wire piece onto the engine bolt. It retains the retainer plug from popping out and possibly discharging your battery while you ride. You'll note these motorcycles, up until the new electronic speedometers, have not only a speedo drive, but have a speedometer drive cable that'll lead up under into the fairing to the speedometer head. You'll note on this side of the motorcycle, we've updated the brake arm to a new forward mount. Calipers have changed. We used to use a single-piston design. Now we use a four-piston design. Basically the same hydraulic braking system, they're still bled the same way, they still work the same way, dual disc. Rotor designs have changed. Not only aesthetically, but the way they mount to the inner hub. Due to the new sealed wheel bearings, this motorcycle has tapered Timkens, which need to be repacked and serviced regularly. Heading towards the back of the motorcycle, you'll also note a few changes in the compartment. Some things are typically the same. Some things have just been modified for aesthetics and for fitment reasons. On the rear, you'll note our rear caliper is a two-piece design. The caliper can be removed from the mounting bracket without removing the bracket from the swingarm. Rear axle and the rear axle adjusters will be on the end of the swingarm, opposed to a cam-style design found on the newer motorcycles.