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[windmill john]

Thanks all.
Pete, that looks like what has been done to my bike. Blocked off timing chain vent, no can and hose to near back wheel.


John

[Wheaters]

All useful info!

Another reason to vent the crankcase is to minimise some of the engine’s pumping losses I.e. the energy lost to overcome the alternating unwanted pressure build up and partial vacuum in the crankcase.

[Adrian]

@ windmill john,

it looks like your engine has the final style of crankcase for the pre-unit models with the main breather pipe off the top of the oil tank.

@ Wheaters,

I'm not sure if venting the rocker box(es) make a huge difference in normal use, probably a better idea if the bike is going to get thrashed a lot. I did vent the inlet rocker cover on my AVL hybrid engine but not on my Not A Fury.

A.

[Daiwiskers]

@ Adrian I have just ordered the same one way valve as the present lot of duck bills don't seem to seal too well, I bought 3 from our host's and none seem to seal when sucked on !
How did the valve work out?

Take care all Dai

[Wheaters]

Adrian, thanks. That’s the sort of thing I was thinking of. For now I intend to try out my bike without the catch can and see how it works out. My single breather from the oil reservoir goes via a similar one way valve to the lower run of the rear chain.

Unfortunately I’m not going to be riding it anytime soon; my wife has not been well lately and from info received from the NHS this evening it looks like I am at higher risk than I had been made aware of and will now need to self isolate for another fourteen days. Bother!

[windmill john]

Sorry you cannot Get out and about Wheaters.

Adrian, thanks for below:

‘ it looks like your engine has the final style of crankcase for the pre-unit models with the main breather pipe off the top of the oil tank’

I guess then with mine, the crankcase, as in the crankcase under the crankshaft, must vent through the small hole into the oil tank then out... seems a small hole for pressure to pass.

is there anywhere information of the changes to the engine over the years, a good book for example?

John

[Adrian]

@ Dai,

There are loads of different non-return valves out there, ideally you want one that operates easily, i.e. without needing lots of pressure to operate the spring, so avoid the VERY cheap ones. If you have room my favourites are the ¼" BSP brass type which take a hose tail for the size of breather tubing size of your preference. See piccy below.

@ windmill john,

Gordon May's book "Made in India" has a section at the back listing changes to the Bullet design between 1980 and 2004. Available from ours hosts, £18.95. I think the hole between the crankcase and oil tank might have been slightly enlarged when it became the main breather hole, maybe someone could confirm?

@ Wheaters,

sorry to hear that!

A.

[Daiwiskers]

Thanks Adrian going to look into it further

To anyone thinking of using the right angle adapter in my photo take out the valve core and small brass plate at other end

[windmill john]

Thanks Adrian. Now wouldn’t be the time to say I have the book and forgot to check!
Just read through the changes.



John

[Adrian]

Thanks Adrian going to look into it further

To anyone thinking of using the right angle adapter in my photo take out the valve core and small brass plate at other end

Or dive into the wacky world of ¼" BSP pipe fittings!

A.