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Discussion Starter #1
When dialing in the position of the camshaft on a 1971 CB350 K3, should the rotation of the engine that displays and aligns all of the indicator marks for TDC be on the same stroke that generates compression in the left cylinder, I/E the compression stroke?

When turning the rotor with a spanner my engine is currently producing compression in the left cylinder while the "L" mark is 180 degrees from the visible TDC position indicator of the engine on the cam sprocket. All of the indicator marks on the rotor and on the cam sprocket line up and the valves are opening and closing in their proper sequence without any interference with the tops of the piston heads. By my logic, whether the indicator marks for TDC are visible on the compression stroke or not, the engine is still timed properly and everything should be fine.

I guess what it all boils down to is should the compression stroke also correlate with all the other TDC marks for the engine or does it not matter as long as everything else is timed accordingly? I'd like to know for certain before going through the trouble of breaking my cam chain and potentially undoing all of the work I've put into timing everything.
 

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When establishing cam to crank timing, you align the " LT " line with the index.....
The left piston will be at top dead center...There are NO compression (or any other) strokes until after the cam sprocket and chain is oriented and bolted onto the cam.....Simply piston position...
But, WHY would you break an endless cam-chain?.... The 350's cam to crank can be, (and usually is) timed in with an unbroken chain....

Please phone if this does not answer your question....540-525-5199... Steve
 

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I believe when the cam timing marks are lined up the piston is at tdc on the exhaust stroke. Look at the cam lobes for the left cylinder, they will both be slightly up, meaning both valves will be slightly open.
 

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Sensei
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Mike is correct...... Assembly is on the "off" stroke (pin up).......Ignition is during compression (pin almost down)......
Been helping so many members get their points timed in my "mental" picture was skewed.......
 

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Discussion Starter #7 (Edited)
So, for the sake of clarity here's exactly what I'm looking at.

camshaft position 1.jpg

camshaft position 2.jpg

camshaft position 3.jpg

camshaft position 4.jpg

This is the rotation of the engine that is producing compression in the left cylinder. Take note of the orientation of the cam sprocket as well as the orientation of the camshaft lobes for the left cylinder and the placement of the pin on the end of the camshaft. The piston is at TDC in the left cylinder and the LT mark is perfectly aligned with the index mark on the generator rotor. Likewise, the right piston is at TDC when the rotor is turned to the RT mark and is producing compression in the right cylinder when the engine is turned a full rotation. I am of course only making full rotations in a Counter-Clockwise direction as indicated by the arrows on the generator rotor.

So run with me on this and tell me if I'm understanding this right...

In the second image, it appears that on the compression stroke (moving in a counter-clockwise rotation), the lobe for the left exhaust valve on the camshaft is coming around to open, meaning that the lobe for the intake has already passed and has opened and closed that valve. So at that point, there is compression in the cylinder in close proximity of the LF mark. This is about the time the spark plug would be igniting the mixture of fuel and air inside the cylinder under the strain of compression. Which is then shortly followed by the opening of the exhaust valve to clear the chamber and prepare for the next firing of the cylinder.

As a point of clarification, the camshaft that is in the engine currently is a transplant from another engine of the same make and model. To avoid any issues, I made sure to use the same Cam sprocket that came with the transplant part to make sure there were no compatibility issues with the gearing or size of the sprocket. I was told the camshaft was taken from a CB but it's not impossible that it could have been removed from a CL instead and the seller just didn't know what he was giving me.
 

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Sensei
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Your cam to crank timing is off IF all those pics were at the same LT index alignment.....

Crank held at LT......
Place chain on sprocket so when the cam is slid through, the L mark is up and the "flat" of the rubber cushion is parallel to the gasket surface of the cam box with the front run of the chain pulled tight, and Camshaft with pin up and aligned with the imaginary center-line from cam, through cylinder, and to crank....
You can slip the cam back out and "skip" the chain on its teeth to effect that...
Fully threaded bolt goes in top hole first, then lift cam to lightly maintain tension on chain and turn crank one complete CCW rotation back to LT.....Install shouldered bolt.....Use locktite on both bolts...Torque to specs....
Then install tappets and add head-covers at 90 degrees CCW past TDC on compression stroke of left cylinder......Tension chain....
 

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Definitely off, in the picture both rockers are still on the base circle of the cam.
 

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Discussion Starter #10 (Edited)
Ok, so update time. Work has been a bit nuts, so it took me a few days to get an evening free to turn some wrenches. On top of that, I had to source myself a replacement Cam Box on eBay and wait for it to ship to me. Why did I need to do such a thing? Because...reasons. I also had to get myself a roll of gasket maker and cut myself some new seals for my Cam Box Ends because the other two were severely damaged from repeated assembly and disassembly of the cylinder head.

Here's what everything looks like now...

camshaft fixed 1.jpg

Camshaft fixed 2.jpg

Camshaft fixed 3.jpg

Take note that the lobes on the cam rod are in the proper orientation with the LT/Index mark and that the horizontal L line is parallel to the gasket surface at the top of the cylinder head. I torqued down the retainer bolts on the sprocket to Honda specs and used thread-loc on both as suggested, so they're not going anywhere. All the indicator marks as well as the piston in the left cylinder are uniformly at TDC and everything appears to be in sequence with the proper compression strokes. I retensioned the cam chain and set my valves as well so now I am working on getting the engine back into the frame and torquing down the motor mounts to specs. From there, I'll set my breaker points and get all my other side projects all shored up.

Going on the information provided to me by both you gentlemen and the Honda FSM, I do believe the matter is resolved. That is unless any of you can see or think of anything I may have missed?
 
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