CB900 cams and top-end should-dos

[timpetou]

Aloha,

I am about to purchase CB900 cams for my 81 CB750 and trying to get all my ducks in a line.  I need to change the valve cover seal, but what else can I take care of while "in" there? Thought of checking valve clearance, but not certain if that oughta be done with the 750 cams in or the 900 cams in. This will be a quick Saturday job, so no time for any biggies. Perhaps you guys can come up with something that will definitely be worth taking care of. Oh, one more thing. CB900F cams or CB900C cams? Does it matter at all? I will try to get it dynoed before and after, simply to satisfy my inner scientist.

Cheers.

[shinyribs]

A dyno comparo of before and after would be awesome.  ;)

I'd almost bet the F Cams will breathe better on top end.

Checking valve lash will be a must. No way out of that.

And you probably already know, but leave the silicone in the toolbox.  :)

[Re-run]

The f cams will most likely be better. You will need to check valve clearance but after you have the 900 cams in.

I would maybe just check the cam chains and tension units. May as well since you are in there.

from my understanding, the 900 cams give a nice little boost.

[timpetou]

Ok, thats what I thought. Made little sense to work on clearance before, but then a lot of things I do every day does...I have toyed with the dyno idea for a while now. Because I feel some( actually a lot) of the mods discussed on all the various CB 750 forums lack cold hard facts to back them up. Sure, some of the stuff looks real nice and all, but it's hard to come by the kind of "peer reviewed" stuff a beginner can trust when looking for a little performance improvement. I guess what I mean is, even on a website like dynoman austin that sells 500$ ignitions I can only find claims but no facts. No curves, no graphs. Sure, each bike is different, especially with the nuerous amounts of add-ons and take-offs, settings and mods but I feel it's prudent to take reports from all the builders out there with a grain of salt. Surely, there is a fair bit of placebo and bias involved. For example, I fitted some new parts to my bike and thought it made a world of difference. When a friend who has used my bike extensively tested it out he wanted me to explain exactly what I thought was different....
Chances are we dont have a dyno in this town, but I would love to see a more scientific approach to matters that are objectively quantifiable. Hard to do, but worth it I think. On that note, I'd like to ask what you guys consider (done and tested) your top 3 performance improvements that can be done by a shady-tree mechanic like myself. I am talking drop-ins and bolt-ons. What I'd like to do is work my way down that list and eventually find myself prepared enough for the more advanced stuff.