Motorcycle Repair: Evolution 1988 FLHTC Air/Gas Mixture, ft lbs torque, ft altitude

Question
Hi Sean

Recently I pushed some more hp in my aged 1988 FLHTC by using advices from nightrider.com (stage 2 kit = upgraded mufflers, upgraded ignition with coil, module, spark plugs, spark wire, k&n filter, high flow accelerator pump, EV-27 andrews camshaft). Also I have done a dynojet diagram (run conditions 68.28°F, 33% humidity, 1200 ft. altitude. Diagram shows between 2000-4000 rpm a too rich air/gas mixture (10:1). From 4000 rpm upward it’s going leaner to 12:1 but still to rich. Funnily enough, it doesn’t affect ft-lbs or hp- curve. I drive a #60 pilot and a #165 main jet (as recommended from Andrews) on an original butterfly keihin carb. On street run, when I give full throttle in 5speed trans. about 50-55 miles per hour for a very short time gas acceptance stagnate. Engine has no back fire, no smoke, runs smooth and starts easy.

In maintime I figured out, setting on high speed (1 step in coke by 1500 rpm, as stated in clymer) was too high adjusted about rpm 2500. I have corrected this. But I am not able or better, interested to check air/gas mixture again by using a new dynojet run (too expensive, you know ;-)

My questions:
Do you know, how many hp and ft-lbs a stock 1988 FLHTC (not Californian) does actually has on rear wheel? (Literature says a lot but nothing objective, range from 40-65 hp). I’m very interest in because I didn’t do a dyno run before mod. After stage 2 modifactions, engine grow up to 57 hp on rear wheel and 71.5 ft-lbs torque. Not so many hp as mentioned by nightrider.com (64hp) but still sensible more than before J

Do you know which components affect air/gas mixture in my case, especially between 2000-4000rpm?

Also, I left by assembling air cleaner baffle plate. What’s the function of this plate (air flow reduction for preserve emissions-regulations?)

Thanks in advance and best regards, Harry from Switzerland


Answer
Hi Harry, I would say the horse power would be around 45-50 hp. The components that affects air/fuel at that range would be the Venturi. I would suggest going to the CV carb, you will get a better running and more responsive bike. The baffle plate is for an emission thing.