250csr oil from exhaust

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Webby900
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Location: Suffolk UK

250csr oil from exhaust

Post by Webby900 »

Hi All , just trying to check where the oil is coming from. I have removed the head and this is what I discovered, also want to check the head and piston are correct the bike is a 62 250csr the head has 43 re 62 stamped on it and the piston ha bhb 042848 and g62 stamped on it. Any help would be great! :beer:
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Duncan
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Re: 250csr oil from exhaust

Post by Duncan »

For the piston the following table ( http://archives.jampot.dk/technical/Pis ... models.pdf ) gives the piston as a standard size, 7.8 compression ratio, 250 piston.
SPRIDDLER
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Re: 250csr oil from exhaust

Post by SPRIDDLER »

Welcome to the Forums, Graham.
I know little about Lightweight models but if there's oil from the zorst it must be passing through the cylinder so there's this thread in the L/W G5 section which may be of use to give you some clues as to what may be causing the issue. The topic started a year ago but was concluded in a post just yesterday.
Have a look at the story in the link here:

viewtopic.php?f=16&t=28018
I poke badgers with spoons.....from 2 metres.
56G80S
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Re: 250csr oil from exhaust

Post by 56G80S »

I can't help either, I had a 1966 14CSR and the piston was very different, very domed and I think something daft like 9.5 or 10:1.

I'd look at the thread that Spriddler has indicated. I found that copper gaskets, after several rounds of use, annealing and re-using, got thin enough that there was insufficient "pinch" between head and barrel.

Johnny B
Webby900
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Re: 250csr oil from exhaust

Post by Webby900 »

Hi guys
Thank you for your reply’s and advice, I have replaced head gasket (copper) and now have really good compression around 120-130 . When I was checking compression there seemed a lot of pressure on the down stroke and when I ran the bike briefly with rocker cover off it did seem to spurt out oil as if under pressure rather than a gentle plus? Could I also have a breather problem? As I do get a lot of oil going into the crank when sitting for a day or so. I know the pump should scavenge the oil back to the tank but wondering if the down stroke is possibly sending oil in crank area some how. Any thoughts would be great as more of a 2stroke kid of the 70’s
ChrisTheChippy
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Re: 250csr oil from exhaust

Post by ChrisTheChippy »

There should be an oil adjustment valve in the head . You turn it in so the oil to the rockers is reduced to a level you are happy with . From your description it sounds like to much oil is getting through it certainly shouldn't be spurting out .
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