Hey Mark, will advancing the cam also decrease your redline back to 8000 from the F0 redline of 8500?
Yep, it sure does! And, it boosts the torque lower down at the same time. I call this 'making it more ridable' because it both makes it like the earlier engines (K0-K2) and puts the power on tap where you ride most of the time. It starts to run out of volumetrics at about 8000 RPM when the cam is set to open at 5 BTC and close at 35 ABC, where the post-1975 engines have it at open 0 BTC and close 40 ABC. The latter reduces emissions at 2500 RPM, which was the EPA-forced rule of the late 1970s. I don't think I have EVER ridden at 2500 RPM, though...
(Update 9/14): I used the "trapped feeler gage" method this time, as my dial indicator is busy on my lathe just now. This is in my book, too, but here's another sketch of it: set the crank with the #1 intake rocker at full slack on the cam, then set the clearance at .045". Then insert a .005" feeler gage, and turn the crank forward until it just traps the feeler gage. Check the degree wheel: this is .040" lift, which Honda used as their "valve opening" (or, 1.0mm lift) point. I had to grind the slots in my sprocket out about 3mm to get it to open at 5 BTC, which is what I want: this made it close at 30 ABC, so this cam is a little bit "short". I expected that: I started with the K6 cam from Terry, but found it further off toward the -3 degree side, so I went back to my K4 cam I had instead. Most K4 cams were short of the 5 BTC and 35 ABC spec by about 4-5 degrees, and so was this one.
My next "on the ground" setup will be with a 120-90x18 rear tire, 110-90x19 front, 18T front sprocket, so I want my torque to start at about 4500 RPM instead of 5000-5200, as I want better throttle response at 60 MPH in top gear. It will put me fully into the powerband by 80 MPH, for smooth interstate rides up ahead. This will mean that by about 7800 RPM the "show will be over": the engine will still go much further, but the power will start to fall off. I don't plan on spending much time up there, anyway.
I also did not install valve seals on the exhaust guides: I'd rather let them get a little extra oil, as the old, extra-long, pointy-top cast iron-Stellite guides went 140k miles this way with extremely small wear, because they got some oiling. Honda installed these seals so they could compete with Kawi's advertised longer oil change intervals on the Z1 (1500 miles), part of Kawi's 'nasty' marketing ploy in 1972. "K" was mentioning things like "you won't have to change oil every time you turn around" in some ads: Honda's interval was 800 miles on the sandcast and K0, 1000 miles on the K1-K2 bikes. The seals appeared during the last of the K2 engines. Adding the seals lets the oil stay cleaner longer, for sure: I change mine anyway, so I don't care.
