Topic: Broken Tappet Screw

[liPPy]

Riding yesterday I hear a loud tapping from the top end of my 1978 750k.

This morning, I pulled the tappet covers and discover the tappet screw & nut on cylinder three, intake valve, has decided to take a vacation:



Ten minutes of poking around with an extendable magnet later I discover part of the screw (sheared in half) but the rest is nowhere to be found:



I drained the oil and took off the pan to discover metal shavings and some green plastic. This is new; I changed the oil a few weeks ago and checked the pan and it was clean:



The metal is non-ferrous (does not stick to the magnet) so is not part of the screw or nut. The green plastic pieces have to be fragments of a valve seal as these are the only green plastic bits in the engine. I rebuilt it in the summer so I know!

Picture of my head before installation clearly showing the green valve seals:



None of this bodes well. The rogue hardened steel pieces are still at large and judging by the aluminium shavings have evidently done some internal damage on their travels.

At this stage the motor has to come out (I do not have a "Gordons" type kit though maybe now is the time to add one) and at a minimum I need to look at the top end to assess the carnage, but will I have to split the cases as well? Presumably if I don't find the rest of the screw & bolt I will have to dissemble the entire engine until I do.

Thankfully this happened at the end of the riding season and I have all winter to go at it.

To add insult to injury, I had just taken delivery of a new set of Hagon shocks and I haven't even had time to ride them yet grrrr!!!

Advice, comments & input gratefully accepted!!

[flybox1]

awww man, that bites.   
no luck fishing out the adjuster nut?
i hope you have a productive winter 

[liPPy]

awww man, that bites.   
no luck fishing out the adjuster nut?
i hope you have a productive winter 

I fiddled about for around and hour and all I was able to fish out was the broken screw.

God only knows where the rest of it went but judging by the pieces of valve seal and hefty chunks of aluminium in the pan it didn't go down without a fight!

[bollingball]

Man sorry to hear this. So you know the tops coming off plus engine out. Maybe then you can get it upside down and with alot of air can get the other part out keep saving all the bits so you can tell when you have it all. I got a feeling you will be talking and spending money with MRieck. I'm thinking you lost a valve keeper. Strange that nut was not on the part of the screw you found maybe the nut came off and took out the valve?
 Now let's look on the bright side . I have a 78K and if you want to I can break in your new Hagons You know I don't mind doing this for you just trying to help a fellow. I promise I will give them back.
Ken

[liPPy]

Man sorry to hear this. So you know the tops coming off plus engine out. Maybe then you can get it upside down and with alot of air can get the other part out keep saving all the bits so you can tell when you have it all. I got a feeling you will be talking and spending money with MRieck. I'm thinking you lost a valve keeper. Strange that nut was not on the part of the screw you found maybe the nut came off and took out the valve?
 Now let's look on the bright side . I have a 78K and if you want to I can break in your new Hagons You know I don't mind doing this for you just trying to help a fellow. I promise I will give them back.
Ken

Lol! I went slightly longer on the Hagons - 360mm. On the short ride around the block after fitting them turn in was notably improved. Just haven't had the time to test them on the twisty stuff as that's when I noticed the tapping noise.

I've had a look at the top of the valve and keepers look to be still there but once I lug the motor out and get it on the bench I'll know for sure.

There was a minor head gasket weep anyway so I guess I'll be able to get that fixed while I'm at it!

[mono]

yuck ...    i hope the damage is minimal.

[dave500]

whoa!thats heart breaking,ill bet the nut is down beside a valve spring?

[liPPy]

whoa!thats heart breaking,ill bet the nut is down beside a valve spring?

That's probably a fair guess given the fragments of valve seal. I'm more concerned about the aluminum shards. I dread to think where they've come from!

I hope to find the time to pull the motor this weekend so I'll found out soon.

[tomkimberly]

I doubt the damage will be as bad as you think. Remove the valve cover before you remove the engine, I sure the missing pieces dropped into a spot your magnet can't reach.

Tom

[Xnavylfr]

I'm kinda lost here, can you remove the valve cover in a STOCK frame with the two extra side supports?
You will probably find the aluminum shards are from the inside of your valve cover from the nut and screw being knocked around by the tappets until they settled in to a final resting place.
You can look at it as a GOOD thing= You have something to keep you from getting the winter blues OR a BAD thing = Damn , I have to pull that heavy beast , do some search and seizure and some rework and I just had it out 6 months ago.

BUMMER

Xnavylfr(CHUCK)

[dave500]

its a rare occurance,,not quite tight enough lock nut?ill bet it backed off and the screw wound itself inwards?

[Bailgang]

I'm kinda lost here, can you remove the valve cover in a STOCK frame with the two extra side supports?
Xnavylfr(CHUCK)

If so then someone needs to enlighten us on how because I couldn't figure out how to get the valve cover off my kids 750 while it was in the stock unmodified frame either.