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Started Engine strip & Rebuild

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Gromitdog:
Hi All

I have decided to started my strip down on a 550 engine with advice and what to beware of from Ken, which has been a great help so far.

All went reasonably well cylinder cover came off ok along with the cylinder head & all the valves bar one came off easily bar one exhaust valve which required a gentle tapping out on further investigation I found that only the small washer was fitted under the valve springs and the large washer was missing which leads me to believe that possibly the exhaust valve is slightly bent as other valves fit in that position np there is lucky no damage to the piston so have been lucky there.

The main block was really hard to get off and had to be tapped off using wood and wedges got even harder as we eased the block up the main studs This turned out to be corrosion in the holes which left a rusty paste like crud on the and below the stud top threads. So they will need a die running down them to clean them up.

The bores are looking clean and I have applied general grease to them until I get round to measuring them up. Small ends 1&4 came out easily but 3&4 needed to be tapped out with a 8mm socket and showed signs of corrosion in both of the small ends and gudgeon pins .

Would anyone have spare exhaust valve and the large washer in the spares draw that I could purchase please.  As I take it that the gudgeon pins and small ends can be repaired ?

Gromitdog

Murf:
Hi The lack of washer under the spring would not have made any difference to how far the valve was being pushed down into the cylinder when the valve was opened. The valve height is set by its seating on the valve seat and its distance of travel into the cylinder is set by the cam lift and tapet adjustment.  The washers job is to protect the soft aluminium of the head.  Clean off the corrosion from the piston pin and see if there is any pitting on the pin, if it is pitted in the areas where it makes contact with the piston or small end then it might need replacing. If the corrosion is just in the none contact areas or no pitting has occurred then I would clean everything up put the piston pin back in the small end and check if there is any discernible up and down movement in small end/piston pin joint.

Murf:
BTW if you are going to use new pistons in your rebuild they will come with new gudgeon pins. I don’t know if the small end is bushed or just bored in the metal of the con rod. I have my 550 in bits so will have a look.

K2-K6:
The missing valve spring support washer, as already noted above, won't change how far it moves but, it will decrease spring preload on the valve with the possibility of valve bounce at high rpm.

It may have been affected by that and just touched a piston, that's a possibility. Anyway, a new valve should sort it.

You can check a valve for being straight by just rolling if on stem and head periphery on a piece of glass to see of the mid part of the stem runs true.

A cooker hob, if glass, makes an easy "surface plate" to roll it across. Dont get caught by owner of surface plate though  ;D

Bryanj:
The large washers frequently are there but dont feel like it, try using a magnet to see, i can probably find a used valve and washer if needed but check for everything else you need first as postage is dear.
Replace gudgeon pins and check small end in rod, as said if you rebore piston kits come with pins anyway.
Very common for the crud in stud holes, many times have had to use the threaded ends to "ream" the holes on dissasembly.
Are you going into the bottom end?

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