Topic: No more valve clearance / shorter valve CL350

[Tanerrx]

Hello, I'm not sure if this is a common issue or not, but I searched through the forum and online and couldn't find any info. I recently rebuild a 1971 CL350 engine and had the valve seats cut. Now one of the valves has no clearance and I can't get any clearance on it. The adjusting system this engine uses seems to just be using some kind of cam on the camshaft to move the tappet further and closer to the valve end. So I can keep rotating it and it just moves in and out, in and out without over moving out far enough. I've read the manual and have adjusted valve clearances on several bikes and got the other three clearances set but can't seem to get one valve the correct clearance. I was wondering if anyone knows of a way to shorten the valve or find a shorter valve. Or am I doing something wrong?

Has anyone else had this problem?

Thanks,

[spurlock]

It sounds like either the valve seats have been ground down too far or possibly you have some aftermarket valves that are too long. Since the valve adjustment on this bike is by eccentric rocker arm shafts there is only so much range available for clearance adjustment. The logical option would normally be to "tip" the valve (grind it a bit shorter). However if these are OEM valves they are Stellite plated on the seats and stem ends with a hard coating only a couple of thousandths thick and any grinding will destroy that. More info here: https://www.motorcycleproject.com/text/valve_jobs_done_right.html
So grinding that off leaves the end of the valve too soft to resist wear. The only options I can think of are valve seat replacement or grinding and resurfacing the rocker arms to create more adjustment range. For seat replacement I would inquire with EDCO, (http://www.enginedynamics.com/services.shtml#service_2). And for rocker arm reshaping an option might be someplace like https://www.megacyclecams.com/

-Bill

[754]

Early 350 used different rockers, and I be live the big cam users prefer them.
 Not sure if that may help adjustment, or not.
 But if it does, might be doable without removing head.

[Steve_K]

I seem to remember that there was a mark in the adjuster that was, I think should point to the out side of the engine.  I mean that the there is an orientation to the shaft.  I can not remember any more details and if it would cause your problem,  Good grief, it has been 45 years since had mine!
Steve

[tbpmusic]

It's called excess valve extrusion, common to CB/CL450 (the torsion bar preset is a critical issue here too), also seen in CB/CL/SL350, which also use the eccentric tappet adjusters.
Caused by having to remove too much material to reestablish the valve seat geometry, the valve sticks up further into the head by a small amount.
One solution is to install new valve seats entirely (very expensive, but the ultimate solution in many aspects).
Another solution is to "tip" or shorten the valve - most machine shops can do this, my guy has an actual dedicated machine for this. I'm not sure how these stock valves harden the tips, it may be possible to grind through the hardened area.

[Tanerrx]

Valves are all new OEM so I guess I can't tip them, right? I'm not sure what 754 is talking about at all so I guess that's not an option. I know what the adjuster marks are and where to direct them so it's nothing caused by that. So my only options are to either have the seat refaced or buy an aftermarket valve and have it tipped. Does that sound right?

Thanks for all the help guys.

[754]

No, you can resesearch whether early rocker have wider clearance or adjustment range.
 And it sounds like you can get a rocker pad re ground to get the clearance you need. ... without removing the head.