Cam Chain Adjustment Question

RobMan

RobMan

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I have a a question regarding the cam chain adjustment on my CB450 and if the service bulletin for the CB350 that I have seen posted by different members would be applicable for the 450 as well. The 1968-75 CB/CL 450 FSM has the following:

CB450 Cam Chain Adjustment.jpg

Here is a copy of the service bulletin in question.

Cam Chain Service Bullitin.jpeg

I had been following the FSM and seemed to have a little cam chain noise so on my 500 mile service a couple of weeks ago I adjusted using the procedure in the service bulletin and it seems quieter but my hearing is not the best so am wondering if I should readjust per the FSM. Thanks.
 
Rob, I always do the cam chain adjustment during valve adjustment so I can see both sides of the cam chain, and the position of both cams, to be sure there's no tension on the intake side of the chain from opening or closing a valve. I've never actually checked the position of the crankshaft while doing it, and I honestly can't confirm if the exact same position suggested by the 350 bulletin would be the same for the 450 - but since most of their camshaft specs for valves opening and closing are basically the same (within 5° or so) then it would seem to me to be correct. And the wording/picture in the bulletin you showed would indicate that it's 90° past LTDC on compression, since they mention continuing the rotation until you see the left exhaust valve start to open and then repositioning the crank at that 90° past LTDC spot.
 
When I did the adjustment per the FSM I could feel tension on the rotor as I turned it to LT mark but when I did it per the service bulletin it felt as though there was very little tension at that point so I think all the valves were fully closed. The next time I service the bike I will compare cam locations to the mark on the rotor to confirm. Thanks you as always.
 
Interestingly the Owners Manual provides very simple directions for adjusting the cam chain which I assume is if it's loose enough that the rider notices cam chain noise any adjustment is better than none. :D

Owners manual CCA.jpg
 
I remember reading somewhere (Chilton's maybe) that a way, but perhaps not the way, to put the crank in position for a cam chain adjustment is to kick it over. It kinda makes sense that it would naturally stop in a position where the chain is relaxed.

My only concern with deviating from the manual would be that the manual suggests adjusting at what is not the loosest position for the chain. That means it will be tighter at it's tightest spot using the 90° past TDC approach. Probably not a concern, though.
 
IIRC it's slightly past 90 degrees from LT that the valves all close - you're on point with where you feel the rotor go "loose". To some extent, it may vary a hair depending on the cam follower clearances you've got it set at.
 
stl360+450 said:
I remember reading somewhere (Chilton's maybe) that a way, but perhaps not the way, to put the crank in position for a cam chain adjustment is to kick it over. It kinda makes sense that it would naturally stop in a position where the chain is relaxed.
Click to expand...
Not necessarily. With the plugs out, there is still a serious "roll over" past various crankshaft positions and as EzPete mentioned about the bigger cams in my drag bike engine, there is a fairly strong resistance to rotation even with the stock cams (and much stronger with my .414" lift cams). Kicking it over could have the engine land prior to one compression stroke from the building cylinder pressure as the rotation approaches TDC on compression, but the other would be in the middle of an intake stroke with the intake valve opening.
 
That's funny, the cam timing is basically the same between 4 and 5 speed so I'm not sure why they suggested there was a variance in procedure.
 
Given that it's a Clymer that amalgamates various FSMs together, It may be indicative of a change in the later FSMs that they interpreted as a difference driven by the transmission?
 
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