03-16-2020, 12:40 PM
Hi Dave! The physical difference in the intake cam is simply shorter duration on 1 and 2 cylinders by 10 degrees. Intake valves close 38 degrees after bottom dead center for 3-4, 28 after for 1-2. I really don't know why this produces a different tone or note to the exhaust, which with my Yosh exhaust was notable, and went away after I put the exhaust cam on the intake side. It still has a nice sound, but it sounds to me more relaxed and comfortable with what it's doing, rather than urgent and forced, or fierce.
The sound was possibly what they were going for, but what also went away was the harmonic buzz. Different than a vibration, which I believe is what you get with an inline 4.
Many either don't feel it or are not bothered by it. When my wife asked me why I was taking apart a perfectly good motorcycle and I explained it, she said " Your hands go to sleep when you watch NCIS". Hah.
But if you have the bike on it's sidestand and increase rpms steadily you may note that as you pass through 2800-3300 rpm it changes from vibration to vibration and buzz, which bothered me after a relatively short ride. Often used my throttle lock/ cruise control to free up my hand long enough to get the feeling back.
I also found that I was not as aware of the rpms. I found myself forgetting to shift into 5th.
So I can't really explain in technical terms but apparently there is a frequency that causes it. I was worried that I would get a "normal" cam on the intake side and it would still have it, but it does not. Vibration, yes. Harmonic buzz, no.
I found a cam guy that isn't sure if I knew what I was talking about because I think he just couldn't process the concept of altering a cam like that for purposes other than performance. He agreed to have a look at it and whenever that shakes out I will give him credit if everything works out.
Ben
The sound was possibly what they were going for, but what also went away was the harmonic buzz. Different than a vibration, which I believe is what you get with an inline 4.
Many either don't feel it or are not bothered by it. When my wife asked me why I was taking apart a perfectly good motorcycle and I explained it, she said " Your hands go to sleep when you watch NCIS". Hah.
But if you have the bike on it's sidestand and increase rpms steadily you may note that as you pass through 2800-3300 rpm it changes from vibration to vibration and buzz, which bothered me after a relatively short ride. Often used my throttle lock/ cruise control to free up my hand long enough to get the feeling back.
I also found that I was not as aware of the rpms. I found myself forgetting to shift into 5th.
So I can't really explain in technical terms but apparently there is a frequency that causes it. I was worried that I would get a "normal" cam on the intake side and it would still have it, but it does not. Vibration, yes. Harmonic buzz, no.
I found a cam guy that isn't sure if I knew what I was talking about because I think he just couldn't process the concept of altering a cam like that for purposes other than performance. He agreed to have a look at it and whenever that shakes out I will give him credit if everything works out.
Ben