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By Kally
#96174
Thanks people for the huge amount of help with this. Having fitted the Hitchcocks breather kit the problem seems to be now solved, I also park the bike with piston at tdc after use, as suggested! regards kally
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By Wheaters
#96180
I've been riding bikes since about 1967 and I've never seen another of any make with as complicated and troublesome a breather setup as the ones on these later Bullets. I can only imagine the catch can was only put there to comply with later emissions rules, rather than any other function.

My 2004, 350 Electra only has a single breather, the one on top of the oil tank. The usual one on the left side of the crankcase mouth was never fitted; the casting is blank. Having suffered from the catch can filling up some days (and causing the engine to smoke) I cleaned the can out very well one last time and it now lives in my spares cupboard. I've done the suggested mod of a downwards pipe from the oil tank breather, fitted with a simple flap type non return valve and facing the lower run of the rear chain. Problem solved. On the very odd occasion it "poos its nappy" onto the chain, any mayo type gunk gets flung off again in very short order. No oil has ever gone onto the rear tyre and the bike uses less oil than it did when the can was there.
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By PeteF
#96189
Wheaters wrote:
Thu Apr 08, 2021 5:12 pm
I've been riding bikes since about 1967 and I've never seen another of any make with as complicated and troublesome a breather setup as the ones on these later Bullets. I can only imagine the catch can was only put there to comply with later emissions rules, rather than any other function.

My 2004, 350 Electra only has a single breather, the one on top of the oil tank. The usual one on the left side of the crankcase mouth was never fitted; the casting is blank. Having suffered from the catch can filling up some days (and causing the engine to smoke) I cleaned the can out very well one last time and it now lives in my spares cupboard. I've done the suggested mod of a downwards pipe from the oil tank breather, fitted with a simple flap type non return valve and facing the lower run of the rear chain. Problem solved. On the very odd occasion it "poos its nappy" onto the chain, any mayo type gunk gets flung off again in very short order. No oil has ever gone onto the rear tyre and the bike uses less oil than it did when the can was there.
They all (I think) only have one breather. The boss at the crankcase mouth was for the older set-up and they never altered the casting. The last bike to use that set-up was (I think) the Sixty-Five models. It is possible to reinstate that breather by drilling it though.
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By Adrian
#96190
Some very late pre-EFI crankcases have no breather stub at all, just the vent on top of the oil tank.

A.
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By stinkwheel
#96192
Since we're on the subject. I took photos of all that jazz.

Here's an undrilled breather stub:
Image

Here's what it looks like on the inside:
Image

Here's one reason why the oil tank breathing doesn't work very well. Can you see the breather hole between the crankcase and the oil tank?
Image

How about now?
Image

Image

My late (2007 registered) 350 doesn't even have the stub. I eventually drilled a hole in the crankcase and fitted a taper nipple and plumbing elbow. I ran a hose from here to the rear of the bike with a diesel non-return valve in it.
Image
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By Wheaters
#96202
My Electra has a very faint, raised outline in the casting but otherwise no sign of an actual stub. I see no need to reinstate a breather there because the present arrangement, minus the catch can, seems perfectly adequate. When I drained the oil a few days ago there was no sign of water but with the catch can fitted I always found a teaspoonful or so of pure water in the drained oil, despite the engine being worked very hard in my ownership. What I find intriguing is how many manifestations of a breather system there were over time. I just took it back to basics, as per my old BSAs had many years ago and it works well.
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By Adrian
#96277
The faint raised bit is probably the bulge for the base of the cylinder stud. File that back and you'd expose the thread (I wonder if Chennai found that out the hard way?).

RE India were trying to make the Bullet more eco-friendly, though the breather seemed to get more complicated and less user-friendly at every attempt.

A.
User avatar
By Wheaters
#96279
The small bulge is there but I see no point in putting a file to it!

The outline can be seen here:
Attachments
FD7F8DE2-FDC8-4745-AA77-91C190C178B8.jpeg
FD7F8DE2-FDC8-4745-AA77-91C190C178B8.jpeg (680.37 KiB) Viewed 1638 times
User avatar
By Allanfox
#96289
and here is a drilled one!
Attachments
breather.jpg
breather.jpg (1.96 MiB) Viewed 1626 times

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