The valve lifter on my 1954 es2 engine has stopped lifting the valve! The lever on the handlebars moves the cable which in turn moves the lever on the side of the rocker cover but nothing seems to be happening with regard to lifting the exhaust valve off itâs seat. No reduction of compression when kick-starting and no killing the engine when running. I havenât looked inside the rocker cover as I wouldnât know what I should be looking for. Anyone got any ideas where to start? The Norton maintenance manual is a bit short on information in this regard.
Oops - correction! Mine is…
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Previously richard_tool wr…
Previously richard_tool wrote:
Pistons and bores are subject to more wear on these faces because they are the thrust faces . After TDC on the power stroke the resistance offered by the crank forces the piston against the cylinder wall opposite the crankpin. After BDC as the piston is on its way back up on the exhaust stroke the opposite wall is also effected to a lesser degree
Yes Richard, but the edge of the piston crown doesnât normally strike the bore which is what appears to have happened here. The front and back of the piston skirt are scored but the edge of the piston crown, front and back, are more significantly damaged.
Cheers,
Paul
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Previously paul_archibald…
Previously paul_archibald wrote:
Previously richard_tool wrote:
Pistons and bores are subject to more wear on these faces because they are the thrust faces . After TDC on the power stroke the resistance offered by the crank forces the piston against the cylinder wall opposite the crankpin. After BDC as the piston is on its way back up on the exhaust stroke the opposite wall is also effected to a lesser degree
Yes Richard, but the edge of the piston crown doesnât normally strike the bore which is what appears to have happened here. The front and back of the piston skirt are scored but the edge of the piston crown, front and back, are more significantly damaged.
Cheers,
Paul
Hi Paul - now that I have looked at your photos on a bigger screen I can see what you mean -( my bad ! )
You may be on the right track with the ingesting foreign material idea . I wonder if excessive ovality in the bore will allow the piston to cock enough for the crown to make contact ?
Also your lean mixture idea has merit as well in that the crown expands more than the rest of the piston due to its proximity to burning gases .
Mike Pemberton would be the go to guy for this stuff.
If you have the barrel and piston off for the engineer to scrutinize you might try inserting the piston in the bore to see how much slop there is ( as a purely academic exercise - at this point it is obvious you need a rebore / new piston job. )
Good luck and please post what you and the engineering folks have found .
Cheers - Richard
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Well, I took the barrel an…
Well, I took the barrel and piston to the local engine specialist today. He took one look at them and said âthe piston crown has expanded due to excessive heat caused by a weak fuel mixture which in turn has caused the rings to be trapped in the groove and the engine to seize â. So, obviously my fault for cleaning out the air jet and passageway and then lowering the needle! ( Not to mention the bit of high, for the es2, speed running). Oh well, lesson learned. New piston ordered from Only British, so just have to wait until that arrives before getting the rebore done and everything put back together.
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Oops - correction! Mine is 1955 with a sllghtly higher power/top speed than the '54 model so I'm guessing top speed in '54 would have been around 78/79. So 75 is going some!
George