Topic: Welcome to my nightmare.

[blake255]

I recently adjusted the valves on my 750 K2 while keeping an eye on my boys (5&3).  I had a couple of interruptions from the little guys, but when I got finished it seemed everything was good.  I noticed it didn’t sound quite right.  Every thing went down hill from there.   Below is a picture.  Viewer discretion is advised.



My lock nut is missing.  I pulled the oil pan hoping it just fell through the cam chain void into the bottom of the engine, but no luck.  Any ideas what I might do before I pull the engine and completely tear it apart?  All help will be appreciated.

[Chester345]

Pull the head and retrieve the nut from the top of the cyl, hopefully?

A small price in man hours and gaskets to pay before you turn over the engine under power....

[Spikeybike]

Ouch ....if it's a 750 witch it looks to be ... the cover won't come off in the frame, and you'll have to pull the motor anyway....... that sucks, man

[rhinoracer]

It's not that big a problem unless it's your only means of transportation. Try fishing it out with a magnet or flush it down with compressed air, oil or diesel and leaning the bike so the locknut reaches the cam chain tunnel. Good luck.

[blake255]

Ouch ....if it's a 750 witch it looks to be ... the cover won't come off in the frame, and you'll have to pull the motor anyway....... that sucks, man

Thanks spikeybike.  I edited my post.  '72 CB750 K2 Stock.

[blake255]

It's not that big a problem unless it's your only means of transportation. Try fishing it out with a magnet or flush it down with compressed air, oil or diesel and leaning the bike so the locknut reaches the cam chain tunnel. Good luck.

Thanks rhinoracer.  I thought about a magnet, but I can't get a visual on the nut.  An oil flush sounds like it might have potential.

[MotoMartin]

Yeah, get a selection of telescopic and flexible magnets and go fishin'. Some of them have LED lights on the end that may aid in fishing it out. Remember you can unscrew all of the valve adjustment covers to hunt the nut down. I've had some good luck in the past retriving dropped parts, you don't necessarily have to see the nut, just keep moving the magnet around until you catch something.

[tlbranth]

Look around with a small inspection mirror and a good light. You might spot it and yank it out with a magnet. Are you sure it's not on the floor somewhere?

[new2novas]

+1 to the above about it being on the floor somewhere....and try blowing in there with some air and see if you can hear it (quick blasts so you can hear it movin)

[martino1972]

fishing is an option and if your lucky you catch it.....otherwise you will have to pull the motor out and remove the valve cover,it will most likely be still laying there...

[Sam Green Racing]

Don't blow or flush, it's likley to be close but just out of sight.
The cam cover can be lifted enough with the motor in the frame to get a thin pencil magnet in there for a search.
It is posible to replace the gasket as well without removing the motor.
Don't make more work for yourself unless you have to.

Sam.

[new2novas]

thats a good point sam....i said that in the hopes that he doesn't start with some sort of flushing, but would be using that as a last option rather than pullin the motor.....didn't know you could get the cover off while in the bike (looks near impossible, but haven't tried yet, was wondering about it though cause my gasket needs replaced )....

[Sam Green Racing]

We lost a nut on the CR a few years back but managed to fish it out with a pencil magnate despite not being able to see it.
I have never had to lift the cover but I know for a fact that it can be done to change the gasket so lifting it gives a little more fishing room.

Sam.

[Spikeybike]

you make an excellent point, Sam

isn't the breather cover pretty tall on the 750?
the very little i have worked on a 750, i do recall removing the breather for clearance while mounting the motor..  so there's gotta be enough room.


glad i have a 550 and don't have that problem (sorry)

[ttr400]

I had the same thing happen on a CB350F at around 10,000 rpm what I found was the nut got jammed in around the valve spring.....destroyed the valve guide into pieces, valve ended up S shaped, valve head broke off and pounded the piston into scrap.......the little nut found it's way down the cam chain tunnel....bent the rear slipper fell onto the primary chain and took a chunk out of that. found all the bits in the sump. It was a complete motor tear down and re-build.
So what I'm saying is find that sucker before you do anything else even if it means a motor strip.!..........

Kevin

[Hush]

You'll need a really really good magnet, we use some tiny but powerful ones glued onto our mustering torches at night at the prison to trip the pegging points, they would be ideal so there will be something available in your area.
TTR400 that sounds like a horror story, it just get worse...urghhhh.

[Achmed]

Wait a minute. Mustering torches? Tripping the pegging points? Are you in the Bastille or something?

And of course you would do it at night. That goes without question.

[Hush]

Ah yes Bastille close, sorry I'm a Corrections Officer at a large Prison, should have explained that I guess.

[mrblasty]

If you live near a Harbor Freight they sell rare earth magnets really cheap and they are about the diameter of a AAA battery.

[blake255]

Wow guys!  I almost didn’t even post this tread out of sheer embarrassment.  But now I’m glad I did.

I did a complete “hands and knees” search of the garage floor, praying the whole time that it was laying there somewhere.  No luck.  I actually thought about buying one of those magnet sweepers used on construction sites to pick up nails just to be sure.

I was inspecting an extra head that I have in the shop and noticed the recesses located next to the valve springs.  They’re just out of site with the cover on and the most likely place for the nut to be.  So I’m definitely going to pickup a flexible pen magnet and give it a shot.  I have a Harbor Freight close by so that seems like the least expensive, best case scenario.

I also decided to give a try to lifting the cover just enough to get a good look, but I can’t get an impact driver to the last 4 screws located directly under the frame rails.  How to I get around that?  I would love to use that method to replace the gasket anyway.

Ttr400, thanks for sharing your experience.  That situation is exactly what I’m trying to avoid.  I had a moment of terror when I realized the nut was missing. Images of a destroyed motor were flashing through my mind.  You’ve giving me the motivation to be patient and see this thing through correctly.  Sam, knowing you had to fish something out of the head cover gives me hope as well.

Hush, for a second there I thought you were trying to tell me to use a paperclip with chewing gum on a string. 

Blake

[Steve F]

I found the exhaust nut that came off one time down in front next to an intake valve spring.  Fished it out with a magnet, but I first had to loosen the valve cover to see in there.

[Spikeybike]

love the new avatar Steve , gives a better impression of badass your cockpit really is

hope to see you at Mods v Rockers

ok , thread hijack over 

[turboguzzi]

maybe i missed it but hasn't anybody thought about removing the bottom sump cover, maybe it's waiting in there?

TG

[Scrubs]

as well as going fishing inside. Use a powerful magnet on the outside of the engine, large chance it is resting against or
near the edge of the case somewhere - then you can just drag it to the inspection hole.

[rhinoracer]

maybe i missed it but hasn't anybody thought about removing the bottom sump cover, maybe it's waiting in there?

TG

I think that's the first thing he did, remove the oil pan.