Topic: Tappet lock nut

[jwurbel]

Thanks.  Not reassuring.  Already pulled the oil pan and removed the screen.  No nut.  So I will start again.

[Floshenbarnical]

So it's not in the oil pan, did you check all the horizontal surfaces above and around the oil pan? The ledges and crannies etc.

If you have a well-lubricated top end it's possible the nut may be in a pool of oil around one of your valve springs. Did you take the fasteners off the cover and lift it yet? I got my fingers all up in and around every reachable crevice. Some of those oil ponds are quite deep.

If I was you I would make the cam chain tensioner your next step. Be very careful when you remove it. If it's on there then it is literally balanced on top of it so make sure you have a steady hand and go slowly. My nut wasn't on the CCT itself but was stuck to the wall next to it with oil tension. I didn't bother trying to touch it as it was so precarious, so I pulled it with the magnet.

If the worst comes to the worst you can always bounce the front tire off the ground until you get sick of it. Maybe it'll jostle it loose from wherever it's hiding and fall out the oil pain. Just put a metal tray on the ground underneath it so you can hear it clang!

[PeWe]

I have lost nut on my CB750K6 back in the 80's.
I guess twice. Found nut near the valve, in a hole beside. I only had to remove tappet cover to find and fix it.
It was covered by oil.

[jwurbel]

Can’t find much on the top end so am looking to remove cam chain tensioner cover.  Should the crank shaft be at any position, as in TDC ETC and if so on which cylinder?  I know the normal  adjustment calls for 15 degrees past TDC on the #4 cylinder.

[denward17]

^I don't think I would turn it until the nut is found.

[PeWe]

I think it was a post where a nut was hidden behind the cam chain tensioner. Maybe into the tunnel for tensioner shaft.
Last year or year before.

[Floshenbarnical]

Can’t find much on the top end so am looking to remove cam chain tensioner cover.  Should the crank shaft be at any position, as in TDC ETC and if so on which cylinder?  I know the normal  adjustment calls for 15 degrees past TDC on the #4 cylinder.

I pulled mine without checking the crank position. Everything worked normally after I put it back in. It's just those three bolts and mine required a couple taps with the back of a screwdriver to unstick the gasket a bit

[jwurbel]

Pulled cam tensioner cover and nothing.  Have  been using endescope and magnets to probe with no luck on top or bottom. Last thing to do would be to drop engine in frame to loosen valve cover and go underneath.  If that doesn’t work, it looks like the engine would need to come out.  Due to my age and physical condition I will have to use a local repair.  Anyone out there in metro Phoenix area have a recommendation?  Used a dealer years ago and they gouged my generator and transmission cover.  Wasn’t a pleasant experience.  Any help would be appreciated.

[HondaMan]

A looong time ago...I pulled apart a 750 engine for a rebuild and found a valve adjuster nut sitting in the rocker box! All of the rockers had their nuts intact, so I supposed the owner lost the nut one day, couldn't find it, put on a new one, and rode on. The engine had been sitting a long time (the whole bike, actually) when the new owner bought it, and the engine was locked up from rusty cylinders (no spark plugs), so it was sent here for rebuild. I still have that nut in my 'spares' of used parts. It was locked into place with the black gritty goo that often collects in the front side of the rocker housings, so it had been there a lot of miles.

At least one of our members, a guy in TX who once sent me the top end to rebuild, had this happen to his 750, and it was after he was riding a month or more following his rebuild. He was able to pull the engine mounting bolts to drop the engine lower in the frame, then he pulled the valve cover and found the nut. When he put it back together he used Allen-head bolts on the valve cover (and later the side covers, too) because he didn't think he could get the middle 4 long screws tight enough on reassembly, as he had removed them with small Vise Grips because the frame was in the way. The Allen-head screws let him reassemble easily.

[jwurbel]

Thanks again, as usual.  My Sunday project….

[HondaMan]

I just remembered, from looking at an old picture of another engine I did, of a 750 that had a tappet nut sitting in the bottom end, stuck in the crusty sediment next to the 'blade' that helps prevent the cam chain from falling off the crankshaft's sprocket. Th goop was almost as thick as the nut. The top end of that one had all 8 nuts on it, too, was obvious it ran that way a long time. The #2 exhaust valve cap had little dents on the inside, I supposed that was where it came from.

[Floshenbarnical]

I just remembered, from looking at an old picture of another engine I did, of a 750 that had a tappet nut sitting in the bottom end, stuck in the crusty sediment next to the 'blade' that helps prevent the cam chain from falling off the crankshaft's sprocket. Th goop was almost as thick as the nut. The top end of that one had all 8 nuts on it, too, was obvious it ran that way a long time. The #2 exhaust valve cap had little dents on the inside, I supposed that was where it came from.

Haha, I have those little dents on my #3 intake cap

[jwurbel]

I got it finally.  However it wasn’t by the methods discussed. Talked to an old riding buddy in Illinois.  Said it had happened to him before.  He took compressed air and shot it through the intake manifold ports.  He said it would cause the nut to move around and you would then know where it was.  So that’s what I did. And sure enough, once I knew where it was, it was a “simple” matter of using a magnet to fish it out.  Actually wasn’t so simple, but it worked.
Hope this option helps others because it eliminates pulling the engine, removing the valve cover, and then reassembling.

Thanks to all who contributed.

Jim

[Floshenbarnical]

What a relief! Where did it end up?

[jwurbel]

You’re telling me!

Came off the #3 exhaust tappet.  Found it underneath #4. 

[newday777]

Good to hear you found it

[HondaMan]

Congrats!