I ride a 1982 FXRS that was given to me a couple of years ago. It sat for over 20 years on the lamb but was recovered in 2008. My problem is the aft cylinder is weaker than the forward one. At idle it hits less and the pulses are weaker and if I pull off the spark plug wires one at a time it won't idle on its own like the forward one and has less power when I ride it that way. I've looked for leaks in the intake, replaced the bands, sprayed cleaner on the manifold while idling with no effect. The compression is almost identical. The one visual difference between them is the aft spark plug gets a black oil? coating on one side of the electrodes but oil consumption seem normal and no smoke. Normal riding seems OK, it never misses under load but it seems I'm leaving some horsepower on the table. Love the Shovel and FXR frame. Any Ideas?

 

Unfortunatly, it sounds about normal. Did you run your compression check cold and hot? The proceedure is outlined in your shop manual, as is a leak down.
The only other thing you could do is replace your plugs and plug wires. You could have one breaking down. Go with a good 8mm plug wire. Plugs should be set at .0028 for points and .0040 for electronic ignitions. Check your pushrod adjustment.

 

yup the stock cam has that putt-putt-putt on the front cylinder and the rear seems to hit-n-miss (i have an old maytag hit n miss)

stick a nice aftermarket cam in it --

 

Thanks, I think both replies are probably right on. I put new plugs in and it ran smoother for a while but then the aft one starts to foul. The wires are probably original too, 30 years old but 17K miles. She probably does have the original cam, I haven't looked yet. How can I tell if the cam is stock or not? Would it be a valve guide leaking oil to cover only one side of the plug? I did the compression test cold with both spark plugs out and full throttle. They pumped up to 148 and 150 psi.

 

I would think it is a safe bet that if it has the original plug wires on it, it probably has the original cam in it. If you really want to know, the removal proceedure is outlined in your factory shop manual.
Stock shovels are low power motors. I have a lawn tractor that has more horsepower than a stock shovel has on the rear wheel. Unless you really want to get into the motor and spend a lot of money, outside of normal scheduled maintenance, leave it alone. It will give you years of relitively troublefree service.
People tend to be tinkerers, including me. We just can't leave things alone.

 

The rear cylinder on these things get less spark and fire a tad weaker than the front's , nature of the beast unless you set up a true single fire ignition & dual coils . Harley has always had a funny way of doing the timing & spark dwell on the VTwin motors and the rears are always a bit off .

If the mechanical's like comp & valve train are all in good shape just tune her up do what you have already and ride her . Starts fouling the rear plugs or you see more oil in the rear it's valve job time and check the guides real close to see if the oil is coming around the guide when it gets hot , sometimes guides will loosen in the heads and that happens .

 

Could Harley have made the aft cylinder a little weaker on purpose to reduce heat? There must be something that's been done to my engine as we rented a new Harley in Hawaii which didn't have as much kick but it was bone stock. The only thing I know is the sausage mufflers have had the baffles taken out but I put back in small ones to give a little back pressure. I'm actually not looking for more power, reliability and longevity are more important, but I want it to run as good as it can. It has enough power to get my wife and I around the slow cars that won't pull over on the coast road. Eventually I'd like to put in single fire with duel plugs as it sure makes the VW engine in my experimental airplane run better with duel plugs firing.

 

A good electronic ignition, dual plugs, a mild cam and a good carb (either a rebuilt Keihen or S$S Super E) will do what you want at minimal cost if you do the work yourself. You can pull the head and send it out for the dual plugging (might as well have it rebuilt while you have it off) and do the assembly yourself.
Do you research and figure out what it will cost you. Some of the shop owners on this forum can give you an idea of the cost.

 

Thanks, that's good advice. It's one of the things I like about having an older bike is I can work on it my self for the most part. I do it for my airplane as I wouldn't dream of letting anybody else work on it other than the machine work I can't do. It's always going to be my *** in the air test flying the work. Everything you all have said has made sense and will help me and my wife continue to have great fun riding an old Harley. Thanks.