Well before you pull the barrel off, I'd say it's worth mopping the oil up and popping the head back for a few more miles to bed the rings in a bit....I presume the breather is working ok. Push a piece of rubber hose on the end of the pipe. You should be able to suck but not blow.
HI Ron,
The breather isn't doing anything, I can blow and suck either way, not good, the reason for embarking on this top end rebuild was lack of power and unreasonable oil consumption.
On inspection you could drive a bus through the gap in all three rings, There was an oiley coked up residue on the piston top. Obviously becase of the increased compression its causing problems. So it's a strip down of the breather valve tomorrow, I assume it can be repaired?
Thanks again to everyone who's replied
Alwyn
It can often take quite a few miles to bed the rings in...If your breather was working, you might get a common symptom...For around 100-200 miles oil will 'spit' from the breather...If you were to place a clean sheet of paper under the bike with the engine ticking over, a few small spots of 'blown' oil from the breather would be apparent...Generally, this stops when the engine has run for a good 100 miles...I've noted this more than once...
If I were you I'd sort out the breather function and the head gasket to ensure it's correct and then do the 'paper test'... Then do some more miles before you start to worry over much......Ian
HI Ian,
The breather wasn't working at all but it is now, what is the disc inside the breather made from? When I blow there is some air getting past, I thought I'd make a new disc.
Ok I've just made a new disc from a piece of commercial vehicle mudflap I purloined from a previous life, would the breather not working force oil past the rings and on to the piston top? One more thing how many miles do I need to do before I could consider in run in,
Thanks for everyone's responses
Alwyn
Yes, you are correct Ron it has had a rebore less than 25 miles ago, I'll double check the head bolt lengths again in the morning before I aneal the gasket and.......start again 😂
Alwyn
Did you anneal the head gasket before fitting it ?
As supplied most gaskets are some where between 1/2 to full hard because soft copper does not cut on a punch cleanly
If full soft you can leave a cresent indentation by rolling your thumb nail across it
The breather is a standard flap valve and needs to be hard, fairly sure it is bakealite
It does not move when you blow or suck through it because you can not do it fast enough or strong enough
Best test is to remove the pipe then hold some tissue near the outlet
You should see it blow quite hard but suck just a little
The flap valve material was 'Tufnol'...The same material that carb heat insulation washers and some electrical components are made from...I test the flap valve operation before fitting it to the crank case...It's easy to operate by 'blowing and sucking' when off the engine...Interestingly there are three versions of the fitting that holds the flap valve in place. BSA made changes both to the air capacity and material of the fitting at various times...OHV engines also use a larger diameter breather pipe than the side valves...Ian
Hello,
I didn't aneal the gasket because when I bought it from someone on this forum he stated it didn't need anealing as the copper was soft enough from new. I will aneal it when I refit it now for sure. As for the flap material I assumed it was made from a hard rubber and that mine had gone hard...DOH it's meant to be like that.
I've only anealed copper washers in the past and they turn dark when quenched, do you do anything to clean the gasket after anealing?
Thanks Alwyn
Some people say you have to get the whole gasket cherry red, But I hang them on a hook and chase the red round with a gas torch. I never bother to quench, it works just the same if you quench or cool slowly. Once cool I clean them with wire wool on a flat surface.
Jan V. Who works with copper, told me that my method is quite acceptable and that's how he does it too. Ron
Hello Chaps,
Just a quick update on the problem I reported just before Christmas, I anealed the copper gasket that had failed and refited it with welseal and it still leaked. I took it back off again but this time there was substantially less oil on the top of the piston than the first time, (suggesting Mr Wright knows what he's talking about)😂😂
I had a spare new copper gasket and this time I anealed it before fitting even though it felt soft at the start, afterwards it was very pliable indeed, Again I used a very thin coating of welseal on all surfaces as recommended by Ron, I torqued everything a couple of times and it looks like the Jobs a good-un. What did we recommend on running in miles 400-500?
A big thank you to all for your help and Happy New year to Everyone.