b31 lubrication help wanted

[EDDIE SIMPSON]

hello,
i started up the b31 today after much oil priming but i suspect oil pump woes.
oil returns in the oil tank in dribbles rather than one long line . oil is being fed to rockers and big end but in skwerts and dribbles. i ve removed the ball bearing flow valve from the timing cover and air and oil skwerts from the hole, but nowhere near enougth pressure for a oil pressure guage.
any suggestions?

[DAVE BRADY]

Hi Eddie,

Is the oil actually getting from the tank to the engine? 

Dave.

[idie]

If the oil came out in one long line then you would have problems. The scavenge side of the oil pump is twice as big as the feed. This is to ensure that all all is removed from the sump. So most of the time it is pumping air.If it didn't as the piston comes down it pumps air into the crankcases and with reduced space due to excess oil would overcome the breather and force the oil out of any gap it can find. 

[EDDIE SIMPSON]

hello,
thanks for replys.
i am comparing the oil feed and return to my a10 and its more air than oil. i thought i could tap an oil pressure guage on the feed via the anti sython  ball and spring. wiith the ball and spring removed .  there is again more air pumped than oil. 50/50
surely thats not normal?
sae 30 mono.

[Gadorey]

Sounds perfectly normal to me. On these old bikes the return especially at or near idle is in squirts and dribbles. You can look up videos on Youtube of any classic british single where the owner shows the return into the oil tank, and it's like that. Even my Square four does the same.

[Pete A10]

My understanding was that the return oil was always in spurts due to the return side of the pump having greater capacity then the supply side. The return is emptying the sump and consequently pumps air and oil intermittently because less oil gets into the sump then the capacity of the pump to remove it. The only time I've seen full flow is when it's wet stumped and there is a lot of oil to clear but this normally settles quickly to a spurting return

[Pete C]

At tickover it will just bubble and spurt, give it some revs and you should have a continuous stream of aerated oil returning to the tank. As suggested above, have a look in U-tube.

[courtney]

Out of interest, should the oil in the tank get warm or stay at a pretty ambient temperature?

[Gadorey]

It gets warm. On some bikes it gets down right hot.  It is being pumped straight out of the engine operating at running temperature. On some bikes owner's will attest to how hot it gets by showing a burnt mark on the inside of their leg when they foolishly rode with shorts on a warm summer day and touched their leg against the oil tank. 

[EDDIE SIMPSON]

i cleaned out all oil lines and tank checking for obstructions but all clean. i am more concerned about the delivery side and until or if kicking over primes the oil feed circuit and oil pressure guage i m not going to start it up. i m concluding i didnt prime the feed side enougth to begin with.
i am hampered by the indian cast centre stand snapping on me. what rubbish. now another job to do as i will have to fabricate one myself.

[Pete C]

to prime the pump you can unscrew the oil valve spring screw (62-2188) which will take tension off the ball bearing and allow oil to flow through the pump.

Once you see oil coming oit the pump is primed on the feed side.

You can then replace the screw and kick it over a few times without the spark plug and you should soon see some oil returning to the tank.

You are not going to have much joy measuring oil pressure and it isn't necessary. All that roller / ball bearings need is a good flow of clean oil and there is little resisitance in the bearings to build up pressure.

[EDDIE SIMPSON]

i have done what you suggested pete and oil squirts out but not consistant high pressure. its like the oil is injected out then dribbles. unfamiliar with this single but  this high / low oil pressure is normal? i have put an oil pressure guage on this timing cover port using a longer spring and was hoping to measure the oil pressure to the big end from there.

[idie]

If you have a good pump and cold oil you might get a reading around 10psi which will drop to nearly zero when hot. The engine is fitted with ball and roller bearings so there is nothing for the pump make pressure against.

[Pete C]

Here's a video of Andy T. demonstrating a B31 for sale. You can see the oil returning at around 1:30 minutes in. Note he is reving the engine to get that level of oil return, tickover it will be much less!  https://www.youtube.com/watch?v=RgZt8qdMNv0

here's another at 1:10.  https://www.youtube.com/watch?v=RgZt8qdMNv0

You should try it with a Matchless G80. It took mine a couple of minutes before anything came back into the tank. I was seriously thinking the pump wasn't working at all!

[Pete C]

sorry, second one should be   https://www.youtube.com/watch?v=YxrTVcO5uCA