Hi.
As previously posted, my 1954 B31 had around 2 pints of oil behind the primary chain cover and was leaking badly when the engine was running (dripping occasionally when standing cold)
After speaking to a friend with a couple of Sunbeams and a Matchless, he said that he doesn't use oil for his primary chain, he uses a semi-liquid chain grease to avoid the leaking.
My cork gasket looks intact around the cover so I'm guessing that there's a "kink" somewhere, preventing a seal.
Rather than damaging paintwork, what do you guys think about applying this grease to the primary chain in place of the oil bath system?
Thanks
The oil splash also lubricants the bearing for the clutch drum
The primary chain case should be its own dedicated reservoir. There should not be any difference in leaks running or not running. When riding there may be a leak from the felt seal behind the clutch if the scroll is worn.
You need to confirm that the chaincase is not being pressurised by the crankcase venting through the main bearings behind the engine sprocket. Ideally there should be a spacer washer and/or a seal there to stop this.
My preunit single has alloy case and once you have flat surfaces, both dowels in place, decent quality gasket with a smear of Wellseal and fine fibre washers under the drain and level screws then you should not leak.
I use modern engine oil (same as my unit XT125. It is red, vs the green of the gearbox oil and amber of the engine so I can tell what might be leaking if it does). There should only be minimum amount of oil in case for
Is yours the machine with extra breather from the crankcase that exits behind chaincase?
Is your timing cover breather working properly?
Why do yiu have 2 pints in the primary case?
You want thin oil (ATF) in the chaincase and not a lot (about 150ml or 1/4 pint)
Quote from: neil1964 on 04 Jan, 2024, 14:33
The primary chain case should be its own dedicated reservoir. There should not be any difference in leaks running or not running. When riding there may be a leak from the felt seal behind the clutch if the scroll is worn.
You need to confirm that the chaincase is not being pressurised by the crankcase venting through the main bearings behind the engine sprocket. Ideally there should be a spacer washer and/or a seal there to stop this.
My preunit single has alloy case and once you have flat surfaces, both dowels in place, decent quality gasket with a smear of Wellseal and fine fibre washers under the drain and level screws then you should not leak.
I use modern engine oil (same as my unit XT125. It is red, vs the green of the gearbox oil and amber of the engine so I can tell what might be leaking if it does). There should only be minimum amount of oil in case for
Is yours the machine with extra breather from the crankcase that exits behind chaincase?
Is your timing cover breather working properly?
I'm really not sure about extra breathers etc - I'm really new to this and only just bought my bike.
I'll see if my friend knows
Thanks
Quote from: cdsdorset on 04 Jan, 2024, 16:31
Why do yiu have 2 pints in the primary case?
I don't know?
The bike (and old 4 strokes) are new to me
1/4 a pint is about right. It only needs enough for the chain to dip into it and throw the oil around. You can do it by eye if you can see down from the inspection hole.
If you have a large amount of oil in the primary case, then, as suggested, it may well come from the engine .
Have you looked into the oil tank to see if that level has gone down
Quote from: rhyatt on 05 Jan, 2024, 17:01
If you have a large amount of oil in the primary case, then, as suggested, it may well come from the engine .
Have you looked into the oil tank to see if that level has gone down
The oil tank had dropped to almost empty (the bike has been standing since 2016)
I drained all the oil from the engine and primary cover and filled up use reservoir with new oil.
I've not started it since doing that as was unsure about oil or grease the primary chain.
As pointed out by CDDorset a small amount of oil is best
(Some suggest ATF in the chaincase I use modern 4-stroke oil designed for engines that are wet sump with wet clutch) so I get good chain and clutch roller lube and a 6-spring clutch that behaves with a 600 Gold Star engine through it).
I would not use grease.
You need to either run the bike regularly (to keep the engine sump oil level correct, or install an anti wet sumping valve on the oil feed pipe that screws into the crankcase. Otherwise during periods of non-use oil will leak past the pump into the crankcase and then spill over into the chaincase through the main bearings behind the engine sprocket.
Common problem on these if not run regularly and causes lots smoke on start up and if you're not careful lots of oil leaks due to excess crankcase and timing chest pressure or oiled up plugs.
I used the valve on my old B33 but do not need one on my ZB34 or 600.
If fitting an anti wet sup valve i would always reccomend a manual tap with a magneto cut out switch. A manual tap cant stick open/ shut and if switched you cant start the bike until tge oil tap is turned on.
check the crankshaft oil seal hasn't failed, letting engine oil and pressure into chaincase
When I got my '48 RE Model G and started going through it, I found the primary chain was covered in a type of white grease, but the bike was used as nothing more than a display and parade bike. I figured this was to give it enough lube to do it's intended purpose and not leak on the showroom floor. This also left the clutch dry. Probably fine for a short parade, not for riding in my book. Of course, it leaked when I put oil in it, so I changed the old cork belt to a new one. I think it's rubber??? Fortunately, parts are readily available.
Quote from: Fraz on 04 Jan, 2024, 08:03
Hi.
As previously posted, my 1954 B31 had around 2 pints of oil behind the primary chain cover and was leaking badly when the engine was running (dripping occasionally when standing cold)
After speaking to a friend with a couple of Sunbeams and a Matchless, he said that he doesn't use oil for his primary chain, he uses a semi-liquid chain grease to avoid the leaking.
My cork gasket looks intact around the cover so I'm guessing that there's a "kink" somewhere, preventing a seal.
Rather than damaging paintwork, what do you guys think about applying this grease to the primary chain in place of the oil bath system?
Thanks
I use isotopic grease in my B31 primary chain box with no issues whatsoever. Was using small amount of engine oil before that, but was fed up with leaks.
Brian