Coast to Coast
teazer said:I don't disagree with Sonrier's treatise in general, but I'd add that the way to improve performance is first and foremost to reduce lost energy. That's free performance and it's there to be taken. Second is to improve volumetric efficiency and means making it breathe easier. It can include cams and porting, but that's not always necessary or desirable - it all depends on your goals.
You can't beat cubes was an old saying that holds true to this day, a bigger engine will usually make more power than a smaller one, but the costs increase even faster.
let's take some examples. I have say a CB360 and I decide I want more power and less weight. How much more power do I want and what is the path to that power? Do I need bigger pistons custom made to my spec to go into new carbide coated aluminum sleeves and a lightened crank and Titanium rods etc. And at the end of the day if I created the ultimate CB360 how much power would it make and would I have been better off just buying a more modern bike for less cash?
For me, the starting point was always to reduce weight because that's like free power - as long as I don't take that to extremes and have things break.
Then I can make sure that the wheels spin freely and brakes don't drag and there's more free performance. After that I can carefully fit thinner wheels for less rolling resistance or fatter tires for more side grip and I end up with stock sized tires in a soft sticky compound for the best of both worlds.
Then I upgrade suspension at both ends to improve handling so it goes around bends faster or at least more securely and safely.
At that point I can think about modifying pistons, lightening cranks, porting the head, increasing compression and after that I'll think about how much more I want to spend of this sweet riding motorcycle. I'm an engine guy at heart but most of my performance improvement comes from attention to detail and a logical approach and critical thinking.
In the race world, as in the custom world, most modified bikes are slower than stock until the rider starts to put the pieces together and gets the details right. How many threads are about jetting and oil leaks and ignition timing and how many are about cast versus forged pistons or ways to reduce pumping losses? Make the most of what you have with the resources you have available. It's an optimization exercise and not a maximization trip.
Motorcycles are systems and the components don't exist on their own. Everything in life is a balance, and soit is with bikes.
Bingo. First lose the excess weight. In doing so you will most likely be making other performance gains, a more free flowing exhaust system is going weigh less than the stock exhaust. An after market exhaust is going to lead to induction changes as well. Strip the frame of excess. Lighter battery, smaller of if you are inclined no signals. Ditch the steel wheels and go with al shouldered wheel. Lighter wheels will spin up faster and decelerate faster. Lighter bike same power equals faster bike. Lighter bike turns and stops better.
Little things that will improve engine performance. Proper jetting and sync along with clean carbs will make the bike run better. Proper valve adjustment and spark also will improve performance. Before building a bigger motor do these things.
As for the builder v buyer argument I put my bike together. I didn't paint it. I designed the paint scheme and helped the painter lay it out. I cant' weld so I had to have certain things done, but they were done to my design. I don't have a machine shop so some things that I put on my bike were made by people who do, like my rearsets. I did all my own custom linkage though. I've done about 90% of the wrenching on my bike. I'm a builder? Well not in the sense of say a Lossa but I also didn't hand my bike over to guy like Lossa and say "I wan't one of them style cafe bikes" either.