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John and Sandy's 1990 FLHS
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When we purchased our current ride - a 1990 FLHS - the previous owner had made some nice changes, so I was calmed for a while. It had a bolt-in cam, a better carb and ignition, and pipes. It is still a dresser, though... not a rocket. Our original horsepower was 66; pretty good for 1992. Soon I discovered that a 2-into-1 exhaust is much preferable to the stock 2-into-2, even with free-flow mufflers. We started with a Supertrap, upgraded to a Samson, and ended up with a Thunder Header. Each pipe was an improvement in power. After having made nearly 1000 runs on our own bike on our dyno, we have accumulated quite a library of what performance parts work or don't work and in what combinations. We have changed cams, ignition modules, carbs, pipes, gears, and heads - until we reached our last plateu of 80", flat-top pistons, Crane 600 cam, Mikuni carb, Dyna 2000 ignition module, Thunder Header, and Wildwood Performance Heads. Our best run was 94 horsepower, while our constant average was 92 horsepower. Not bad for a dresser, but I wanted more! Se we detuned our bike. We went to a 490 lift cam, a stock c.v. carb, a set of Wildwood heads at 7.5:1 compression instead of the previous 10.5:1, and our horsepower dropped to 85. Then we put on an Aerocharger turbo and now we make 135 horsepower with 137 ft. lbs. of torque - it's scary!! Roll the throttle on, and the front end of the dresser floats off the ground while the back tire smokes. It's better than sex! I can get off every 30 seconds.... Stay tuned for more on the turbo later, including dyno graphs. |
Let's examine John and Sandy's 90 cu. in. 1990 FLHS. In January 1996 our motor fell peril to the "cracked case problem" so many 1990 models suffered from. Harley replaced the cases free of charge, but since we were not the original owner, labor was not covered. We had recently been introduced to Woody, owner of Wildwood Performance in Pompano Beach, Florida, and had tuned some of his motors. He was the obvious choice to do our engine work, because of his quality and consistently good results. If we had to pay someone to put our motor together, we wanted the most "Bang for the Buck!"
Our original setup was in the 75 to 80 horsepower range with a Viper 560 cam, CV carb with a Dynojet kit, Screamin' Eagle ignition module, 2-into-1 Supertrapp exhaust, and "Bathtub" heads shaved 0.100. Woody trued and balanced the flywheels and recommended going with heavy-duty S&S rods in anticipation of the horsepower increase we were going to be getting. We also went with forged flat-top pistons for increased strength. A Crane 600 lift cam, S&S Super "E" carb, Dyna 2000 ignition module (not single fire!), and Samson 2-into-1 exhaust finished out our package. Woody then worked his magic on our heads.
The result was 90 horsepower and 90 ft.-lb. of torque. We changed to a Thunder header exhaust and the best we ever did was 94.1 horsepower during December 1996 in Florida. The tuning setup for the best all-around street riding came in at 88 to 91 horsepower on the dyno.
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We now have a different engine configuration on our bike (in preparation for future modifications). Here is a graph showing how we picked up 6.1 horsepower by just changing from the S&S "E" carb to a Mikuni carb.
Red Line: Mikuni carburetor
Blue Line: S&S carburetor
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