Horse power 101
I have been around engines most of my life. My dad owned a large auto machine shop here in Louisville and built engine for many of the racers in the area. A race engine needs to things to be fast the ability to stay together and the ability to make Horsepower where you can use it. If you can not get the power to the track and if you can not keep the motor together the motor isn't very good.
In the modern day motorcycle you aren't going to find much power in the bottom end other than increasing the stroke of the crankshaft. The engineers decide on the bearing size at the factory, small enough as to not make too much drag and large enough to last under the loads placed on the bearing by the piston and rod.
Lightning the crank, light weight rods rods and pistons will not make much more power but it will make the engine accelerate faster. We had this problem with the 04-05 kawasaki. They made all kinds of power but they were like a 2 cycle with an expansion chamber, all off are all on. They were very hard to hook up. In the next design Kawasaki increased the crank weight by i think 6 pounds. They still had the power but they were much easier to drive.
Looking in the bottom end for horsepower increases will not yield very good results. I know for sure that stock rods can leave something to be desired for reliability, but until this year they have never been a problem. Two engine we blew this year, I hope were because of a stuck thermostat and then sticking pistons. One of the engine we blew had been raced for 4 years with just oil and filter changes, and it blew just like our 2 year old motor because we switched out the thermostats in the engine change.
Speed merchants are always looking for a sale and will recommend lightened cranks Carillo rods and maybe even ceramic bearings for the gear box. These tricks might be good for a 1 Hp increase. Then they might even suggest taking a few gear out of the gear box, but as long as there is no load on the gear it is not generating much power loss, in other words if you run in second or third gear, forth fifth and sixth are not going to be taking much power away from your engine but it will generate more money for the builder.
My fingers are starting to wear out so I think I will stop for now, but will be back later to talk about serious Horse Power.
Honest Dad himself
