Ok this is just a question for my own learning...with out doing
Which will produce the most power, changing cams with out doing a big bore install, or doing a big bore install with out doing cams, and just to make it interesting what about with and with out a stage 1?

Thanks
Terry

 

The cams will make a bigger bang for the buck then a big bore kit.

 

I am no mechanic but what I have researched says cams over 7ci

 

I know "torque" is the main factor, but these are the numbers I know.

Your stock bike is 65 hp.......a stock 103 limted is 67 hp..........cams on a 96 will get you 81 hp

You do the math

Go to the dealer and get a Screamin Eagle parts book and look at the charts.

 

Cams will also make it run cooler right from the start.

 

Ok I have an 88, do you know what the numbers are for that?
THanks
Terry

 

Thanks every one for the imformation.
Ok so it sounds like Cams would be the best upgrade for the buck, so why is there so much emphasis on BB kits?
Thanks again
Terry

 

Because the Motor Company can make more money selling you a big bore kit than they can by selling you cams.
Cams and head work will make a lot more performance than a big bore kit. Making the Harley Davidson engine breathe is the secret to performance. But. You will not hear that from the MOCO.

 

I was going to do the same with a BB kit but opted to install a cam myself. Biggest bang for my buck. 81 hp & 100 tq; all at 3400 rpm's.

 

The reason that cams are such a big boost is that the stock cams completely strangle the motor in the name of emissions. If you look at the specs for the stock cams in the 96 motors, the intake valve opens 8* after the exhaust valve closes. That's so no unburned fuel can escape along with the spent gasses. Good for emissions, lousy for power production. A performance cam will have some overlap built in. This allows the exiting gasses to help pull in the incoming fuel/air mix in a siphon effect. A little bit of overlap, as well as a little more duration can do wonders for a stock motor, even if there's no other changes made.

Having said that, I'm a huge fan of increasing displacement whenever possible. An increase in displacement will increase torque across the board in roughly direct proportion to the size of the displacement increase. So, a displacement increase of 10% will return an increase of torque of roughly 10%. With HD motors, the big bore kits involve changing jugs and pistons, but leaving the heads alone. This increases swept volume, as you're now pushing more air into the same size combustion chamber. The net effect of that is an increase in compression of about a half point. Increases in displacement and in compression will both lead to a performance boost.

IMO, the biggest reason there's little perceived difference between a stock 96 and a stock 103 is because they use the same stock cams, which very effectively strangle the motors. Once you start adding performance parts, especially cams, the difference in the motors becomes more apparant.