Forum

[John M]

I am trying to help a mate with a 1951 Bullet that is chucking a lot of oil out of the crankcase breather. It vents through the timing side crankshaft on these. My question is regarding the nut on the end of the crank that holds the crank sprocket in place, the nut we have looks to have been mutilated st some point. Should there be some sort of non-return valve on the end of this nut as the one we have just has a small hole.

[Adrian]

Our hosts' on-line parts book might have the info you need:



http://www.hitchcocksmotorcycles.com/pa ... 0cc+Bullet



Did you mean the engine breathes through the DRIVE side mainshaft, as the partslist shows the breather vent in the primary chaincase? The timing side mainshaft has the oil feed to the big-end as with later Bullets, and this has a pressure release valve (ball bearing and spring).




A.

[John M]

Yes the drive side crank is hollow, and the crank case vents through this and then into airway cast into the outer chain case, which then vents out at the bottom. Strange but true. Unfortunately there is not sufficient detail in the parts book to see how the nut should be.

[simon]

Yes the end nut should have a flapper valve in it. Our hosts provide one that has a hole in it although I modified mine to remove the hole and increase crankcase vacuum. The nut holds the primary sprocket in place and locates in the primary cover with a cork sealing ring. One thing that might be worth checking is that your oil pressure relief valve is working properly. This is in the other side of the crank and was removed from the later post 56 Bullets. It's a ball and spring and sticking an appropriate sized rod down the quill hole will allow you to feel a spring resistance. If it doesn't feel that way you may have the majority of your big end oil heading straight to the crankcase without doing its job.

[John M]

Thanks for the info.