Big Red Rides Again

When the owner bought this 1985 FXRT in the summer of 2023, Big Red was a motorcycle mostly in name. For all practical purposes it was a 40-year-old barn find. It leaked from every place a Harley can leak, a lifter had collapsed, the brakes were finished and a fender had rusted through. It had been about ten years since the bike was last roadworthy, and probably longer since anyone rode it regularly. The odometer shows modest miles, but nobody trusts it. The real figure is likely much higher.

The FXRT is the touring member of Harley-Davidson's FXR family, with a rubber-mounted engine, a frame-mounted fairing and hard bags. This one left the factory with an 80-cubic-inch Evolution engine. The owner took it to Danny's Cycle Shop. The repair order, dated August 2023, sums up the engine work in one line: "R&R engine w/ new flywheels, cylinders, pistons, cams." Below that come brakes, tires, fork seals, electrical parts, and fresh paint and striping.

A rider, not a racer

The owner's instructions to Danny were simple. Keep the bike as original as possible. It was never going to see a drag strip. What he wanted was reliability, and power that is easy to use within what the rest of the motorcycle can handle. That meant respecting a nearly stock suspension, a five-speed transmission whose design goes back to the Shovelhead era, and an owner with nothing to prove.

The two men agreed that the bike would be treated with the respect its 40 years deserve, and that they would not trade away reliability to chase the last 5 or 10 percent of what the engine could make. Ported cylinder heads were talked about and deliberately set aside, "for the time being." Doing the porting right would have raised the cost of the build significantly and added complexity this bike does not need for the riding it was built to do. As for the exhaust, the owner already had a Cycle Shack system on hand. It probably gives up some power to a 2-into-1, but it looks and sounds great, so it went on.

Danny built the engine from notes he has refined over years of doing this work. The extra displacement comes from an S&S flywheel assembly with a 4-5/8 inch stroke (stock is 4-1/4) inside new cylinders at the standard 3.498 inch bore. That adds up to 88.9 cubic inches, the classic 89-inch stock-bore stroker. A mild S&S 510V cam, a Mikuni HSR42 carburetor and an Arlen Ness Big Sucker air cleaner let it breathe. The stock ignition had melted into a puddle, as it often does on these bikes, so an aftermarket electronic ignition took its place. The finishing touch is Danny's own tweak to the timing, which his customers have come to call "Danny Dust." It dials the power band into something very usable.

The gearing change was Danny's suggestion, made specifically to lower highway rpm. He swapped the stock 32-tooth front and 70-tooth rear belt pulleys for a 34 and a 65. The stock gearing suited 1985, when the national speed limit was 55 mph. Big Red now cruises at 80 mph all day, loping along. With the 37/24 primary, fifth at 1 to 1 and a 12.2 inch tire radius, 80 mph works out to 3,248 rpm, down from about 3,720 stock. That is right on the flat torque shelf just past the peak, and it pairs incredibly well with how this engine pulls.

How it pulls

The owner made this run in fifth gear, from about 2,750 rpm up to 4,118. The white torque line is the one to watch. It climbs fast, peaks just past 3,000 rpm, then settles onto a flat shelf of about 91 to 94 ft-lb from about 3,200 rpm, edging up toward 95 or 96 as the pull ends.

The chart labels the torque peak as 98 ft-lb at 3,050 rpm, but that is the top of the smoothed line, not a measurement. The two measured points on either side of it read about 92 ft-lb at 2,920 rpm and about 95 to 96 at 3,080. Drawn through a sharp rise, the smoothed curve bulges a little above the real points on either side. So the realistic peak is about 95 to 96 ft-lb, near 3,050 to 3,100 rpm, and the owner agrees. The stock Evo makes about 66 ft-lb there, which puts Big Red roughly 30 ft-lb ahead, about 44 percent more. Stock torque slides to about 62 by 4,100 rpm, so the lead holds all the way up.

Horsepower climbs steadily the whole way, reaching about 75 hp at 4,118 rpm. It was still rising when the pull ended, so 75 is where the run stopped, not necessarily the engine's peak. At 4,100 rpm the stock engine makes about 48 hp, so Big Red is about 26 hp ahead there, a little over 50 percent more.

For the rider, the shape matters more than the peak. In fifth gear the torque peak lands right around normal highway cruising rpm, and the flat shelf carries on well above it. Big Red pulls just as hard at the top of that range as at the bottom, fairing, bags, rider and all.

The pull ended just past 4,100 rpm, at a brisk pace, when good sense took over. A 41-year-old tourer has nothing to prove, so the rest is left to arithmetic.

A word on the numbers. These are estimates from the FXR Archive Dyno app, not a roller dyno, so treat them as good for comparisons rather than exact. Because the method follows a drum dyno's, setting them beside the stock Road King's dyno curve is a fair comparison.

The goals, and how they turned out

Everything the owner asked for has come true. The bike is reliable, it still looks and feels like a 1985 FXRT, and it has been treated with the respect a 40-year-old machine deserves. By the owner's account, it has covered about 11,000 trouble-free miles in the year and a half since the work was finished, as a working bike rather than a showpiece. Danny's careful build has given Big Red its best chance of keeping up that pace for many years to come.

And there is room left to grow. If ported heads, or even a 2-into-1 exhaust, ever do happen, the foundation is already there. For now, the FXRT does what it was always meant to do: carry its rider a long way, comfortably and without drama.