Topic: cb750 Valve Tappet Cap... is it 17mm or 11/16"

[KirkBurner]

the 17mm wrench is rounding the edges..

spoke to a tools friend of mine he asked me this question.. cause one was slightly smaller than the other

[Dave Voss]

Mine are 17mm, its a tight fit between the hex on the cap and the wrench, but that ensures a solid fit and helps prevent rounding the hex.  11/16" is close to 17-1/2mm, so that would be a loose fit, an open end wrench would probably work alright, but a 12-point box wrench or socket might round off.

[KirkBurner]

Well.. I get the socket for one beer.. so I guess its worth a shot..

[martin99]

It's 17mm. The tappet covers are a soft alloy and are prone to damage. People do them up too tight and the threads stretch. Owners also like to keep them nice and shiny, and over the years a certain amount of material is removed through polishing, and the points rounded off. If you can find some NOS ones, you will be surprised at how much a better fit your socket will be.

You really need a six-sided socket. When you re-install, you only need to nip them up enough to compress the rubber to prevent leaks.

[dave500]

get a cheap six point socket and grind the ramps off like this one on the left so itll have more bite,only nip them back up tight not like a wheel nut!

[greenjeans]

I agree with Dave's idea.   It's weird - I have a 17mm socket that I have ground down to get more on the actual cap, but now, I use an
old 11/32 socket and somehow it fits more snug.

[DH]

New o ring and judicious use of force when re tightening goes a long way too.
I've heard that a cap will actually dig in to the valve cover if using an old dry o ring.
It doesn't dig in far, but enough to be a real b!tch to get it off later...good luck with it

[Seeker0131]

Depending on how tight the were fastened (which they don't have to be very much)...both.  Every tool manufacturer keeps different tolerances.  This why a Snap-On socket fits differently than say a Harbor Freight socket.

[ekpent]

Grab the outside edge of the large round section of the cap with a good teethy pair of channel locks and twist and get it off before you break out the middle section of the 17mm and drop crap in your engine or have to pick broken threads out of the valve cover.        Not uncommon to kill a couple when doing a renew for the first time  If the edges are gone on the 17mm don't pussyfoot around with a socket anymore.