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[Tomshayes]

Sounds like a one way pressure relief valve would be better than a permanantly open slot vent!

[Norm]

So Tom we have gone right around and back to the idea of fitting something in the oil filler neck, because you can remove it and not run the risk of getting swarfe inside and if you do this you can then plug the slot if the tank

[Tomshayes]

Hi Norm.

What ideas have come up for this Filler neck mod, which again sounds a more favourable way to go!..
You'll have to excuse me as I am an amateur self taught at the road side mechanic and not an engineer!.

Words of less than one syllable usually help!

Tom

[Tomshayes]

Just had a thought.. It happens now and then.. What if instead of drilling through from the timing chest to the oil tank would it be feasible to fit a hollow drilled through mag/ dyno mounting bolt which would vent the crankcase to atmosphere.. A bunn valve or similar one way valve could be attached via a length of hose..

[Norm]

For starters Tom you couldn't get a big enough breather through the center of a bolt, there is a reason why the factory finally fitted a big hose on the later Inters, not because they wanted to fit a big hose but because the motor needed it

[Tomshayes]

Hi Norm.. That sounds reasonable enough.. But if the hole through from the timing chest to the oil tank is only 8mm then surely the final vent only needs to be the same internal diameter.. Or is there a reason that it would be larger..From photos I've seen of the mod the vent hose is enormous..

[Barnes]

It has been said more times than i can count in this thread. If your going to do the drilling between the timing chest and oil tank then you MUST fit the large bore breather to disperse the pressure build up. Take it from someone with 1st hand experiance if you dont you are pissing in the wind with a face full of oil. Ed

[Tomshayes]

Hi Ed

I am thinking of doing your 8mm pipe elbow out the oil filler neck and running a pipe around the back of the engine casings and onto the chain sprocket mod, instead of the huge breather job.

For clarity I assume that you still had the 8mm drilling through from the timing chest into the oil tank with this mod and are venting via the oil filler pipe adaptation?

Also am I right to assume this also included sealing up the breather slot in the oil tank below the cylinder?

I will be stripping the engine down this weekend and want to be sure of doing the right thing first time if possible.

Regards

Tom

[Tomshayes]

I dont think I mentioned that the bike does not have the crank clack valve of later twins!

Tom

[Tim NZ]

If the rocker boxes are vented, much of the internal blow-by pressure (up the exhaust valve guides) is taken out of the motor at source...


If you are planing on running a Meteor at sustained speed at which the advantages of the Large bore 3/4" breather pipe become noticeable, (+5000rpm) then you can also expect to eventually snap the crankshaft...


(The reason why the SM has the larger BE journals..)


My 57 SM has the std open 7/16" vent from out the drive side, another the same diameter from under the mag, off the timing side, both running to a Bullet style catch can with an internal Duck-bill flapper valve, with the oil-mist drain back into the oil tank via the filler neck, and the fume piped out off and out the back.