E: Engine Oil Consumption: 100 Miles Per Pint…
- Thread starter lee_812d
- Start date
I've had seals on the intake guides for 25,000 miles with no problems yet. Just adding to the database.
This afternoon I stripped the engine. Firstly the head and barrel came away together stuck fast which was a blessing in a way as my dad was reluctant to take the barrel off (because it's fiddly getting it back together!). Well it's good the barrel is off because there are problems with the rings - only the top one is free and behaves much as it should, the middle moves if pushed, and the oil scraper is stuck in the groove doing nothing. So only the top one was doing anything much at all. You can see the effects of combustion leaking past and discolouring the piston.
Plus there is quite a lot of carbon but doesn't look like it is damaged at all.
Plus there is quite a lot of carbon but doesn't look like it is damaged at all.
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The liner didn't look too bad at first sight although zoomed in on the photo might be more telling. I'll have a better look once the head is off. The good news is the lubrication hole appears to be low enough with the key way cut in. (I don't know if the white dots are on the camera of the liner or due to the light).
Any ideas how to separate the head from the liner? I've given is some gentle taps. The muff already has some broken fins from when it was worked on in the sixties. I don't really want any more. Of course when I get them apart it might turn out to be no good anyway.
Looks like the answers are here: Separating head thread
Any ideas how to separate the head from the liner? I've given is some gentle taps. The muff already has some broken fins from when it was worked on in the sixties. I don't really want any more. Of course when I get them apart it might turn out to be no good anyway.
Looks like the answers are here: Separating head thread
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The two halves are now separated. Half of the liner flange has cracked away, which based on the carbon looks like and old break. The piston is +0.060" - it has been pointed out to me that this is probably two re-bores (and this might explain the cracking flange as the liner is thinner?).
The valve seats look clean especially the inlet, the exhaust slightly worse - it didn't seem like there was any leakage here in the leak down test.
The lock ring is still in place above the loose valve guide, the punch lock marks line up so it doesn't look like it has unwound.
The exhaust upper valve guide was also loose, as was the exhaust valve stem collar.
Also loose is the small end bush, enough to turn a few degrees back and forth.
The valve seats look clean especially the inlet, the exhaust slightly worse - it didn't seem like there was any leakage here in the leak down test.
The lock ring is still in place above the loose valve guide, the punch lock marks line up so it doesn't look like it has unwound.
The exhaust upper valve guide was also loose, as was the exhaust valve stem collar.
Also loose is the small end bush, enough to turn a few degrees back and forth.
I have two suggestions on how to remove the head from the barrel. I am assuming that the liner has stayed within the barrel. Put the whole assembly in a large container of water, bring to the boil and simmer for a while. Alternatively, get a piece of wood, 3 x3 x12 inches long. Round the corners of one of the ends so that the end is curved a little more than the inside of the head. You are not trying to make the wood a good fit, just ensuring that it preferentially touches the centre of the head in between the valve heads. Then if you have firmly mounted vice, put the wood into that, long way vertically. Put the head and barrel over the wood and then, holding the parts by the outside of the barrel fins, lift it up and let gravity bring it down on the wood. Use more force if needed. If you use a bit of soft pine there should be no damage to the head but you might want to get someone or something to ensure that when the parts separate the head does not fall off an hit the floor.
My above was too late. Sorry, it is trying to use a keyboard smaller than my fingers. The good new is that all that looks to be recoverable and think how much nicer a bike it will be when it is sorted.
Thanks Norman. We used hot water but only dipped the head in for a short while hoping for it to expand quicker than the liner. Then used a piece of grey waste pipe that was a very good fit to the bore and being plastic wouldn't cause damage. It didn't take much force. I'm certainly looking forward to not having to put so much oil through it.
I think that is a 7.3:1 piston and due to the history of the bike it is likely to be the original one. An 8:1 would be a good choice for your intended use. Low expansion pistons are available now but just make sure that the base of the new muff is at right angles to the bore. Several members local to you can explain how and why. If you are going to get a new muff and liner that should be ok but definitely worth checking before fitting.