Hey HondaMan,
Got your book very helpful!
I have a problem, though I might be able to get your take on it? Also anyone reading this who has been there done that could be helpful. My 836cc engine build has gotten to the cam timing stage. The cam is a WebCams cam CX-2. I purchased it from ken at cycleX who designed it according to WebCams. Who would not answer the question? I have been unable to get through to Ken seems no one is there this Friday? Any, prior to bolting up the cam sprocket one must time the cam. Usually the cam is indexed with a square notch and sometimes also with the two lines. The notch should be up and if it has lines, they would be even with the cam bearing mount. Well the CX-2 cam has no lines, it has a notch but when the #1 cyl is at top dead Center the notch is on the bottom not the top? I must be missing something. I know about the degreeing process however my talk with Ken when I was purchasing this equipment was something like this. I'm not replacing the cam chain as I did not want to split the cases, the bike ran fine. When I told him that he kind of laughed and said I wouldn't need the adjustable Cam Sprocket (which I already had) or the degree wheel. I should just follow the normal reassembly process. I assume the cam should be in the position where both lobes are flat and there is no rise or fall of the rockers, when it is the notch is down? Anybody, any Help?
Thanks Gregory
There's several cams out there like that one!
The notch can be up or down, as the whole engine goes 180 either way and the spark is a waste spark type. But, if you don't have a dial indicator to use to try to figure out the lobe centers, try this instead:
1. Set the cam in the 'notch down' spot at #1 TDC (or #4 TDC, for that matter, which in this case would put the notch up). If you have a degree wheel, install it on the spark advancer and put the nut back on. Remove the sparkplugs. Set the cam chain tension to take up most of the slack for now. You can do it correctly later.
2. Set the valve lash at .040" on the #1 intake. (That's not a typo!)
3. Install a .001" feeler gage into the #1 valve rocker and start rotating the engine. When the feeler gage gets trapped, you are reaching the "valve opening" moment. Note the crankshaft degrees BTDC, or if no degree wheel, reach thru the points plate window and make a pencil mark on the advancer baseplate, as close to the center of the window as you can.
4. Rotate the crank until the feeler gage just gets free again. Do the pencil-in-the-window thing, or note the degrees ABDC.
Now, take a look at the degrees BTDC and ABDC. For most of these cams, they tend to make too-early opening on the BTDC, which gets your valves and pistons mighty friendly. But, if there is a long ABDC opening, the bike will not idle for beans and will be real hard to start and tune below 3000 RPM. I like to try to make them equal BTDC and ABDC if the opening at BTDC is not more than 10 degrees. This "equalness" will tend to provide the widest midrange powerband where most of us ride. If the cam is moved to have more ABDC than BTDC opening, then the peak power moves upward in RPM accordingly.
For example, the Webcam 41, if set equally, provides about 16-18 degrees BTDC and ABDC this way. This is OK with the flat-top 836 pistons or stock K0-K6 pistons. They normally recommend using 5 BTDC and 35 ABDC, because then they won't hear about your parts colliding and sue them or something. But, the bike becomes cantankerous that way, hard to start when hot, no idle until 1500 RPM, stuff like that. It also will wind off the tach, until the springs can't save the valves from float, but there is no room to ride that stuff on the street.
And so it goes with almost any cam: I usually take the post-1975 OEM cams and advance them 5 degrees when rebuilding those engines, too, because we don't have to deal with the emissions politics that Honda did in the Carter era (when they were trying to hurt Japanese imports to protect US car and bike builders), and the midrange power perks up noticeably for the change. While this may cost about 1 HP at 8000 RPM in the tradeoff, I have not built a racing 750 since the 1980s and no one has ever complained: rather the opposite.
