classic motorcycle forum

Out the exhaust pipe?

Hopefully as an almost-invisible blue haze. Get it wrong and it's dripping out the exhaust, and covering your boots and trousers and the back half of the bike as it spews out from every conceivable joint.

The presence of the built-in return pump makes your engine "dry sump" rather than "total loss" (or "wet  sump" as Haycraft rather misleadingly calls it in his Book of the JAP Engine). In principle the oil goes back to the oil tank after it's had a lap through the engine.

There were many JAP oiling systems, but 1932 was the first year of dry sump: first with a double-acting Pilgrim, then after with a built-in double acting JAP pump built in. I guess the racy engines were a bit weird. What year's you engine?

You'll be able to see the oil going into to the engine through the window on top of the Pilgrim pump. Make sure you understand where it goes next: as it goes into the end of the timing-side main shaft there is often a seal of some kind (e.g. a sprung brass quill) which can be missing, and then an oilway should be drilled all the way to the big end. Use your oil can to give a good squirt of oil into the main shaft - it should come out of the big end bearing. If not, double check with your JAP engine man. (I bet he checked!) The big end will die first without oil, so it pays to be certain.

Have fun!

Leon

Edit: OK, I've been back through the thread (not much of it!!!!) and found photos on p7 that show the oil layout. There's no return pump per-se? Just the oil pushed through the flappers into the small chamber underneath, with the neck at the back where the oil exits. Onto the dirt track originally, but better just dump it into a catch bottle for the road. What a waste of good oil!

Nice.

I know nothing about these modern (!) JAP engines, but from 1914 JAP started using the "oil box" under the timing chest as part of the oiling system, which was powered by crankcase compression/vacuum. Are the four little round things flapper valves that power the oil circulation? How does the oil get to the big end?

The oiling system in veteran/vintage JAP engines works well, but I've seen more than one engine where owners have tried to "help" oiling by drilling extra holes that in fact stop the oiling system from working properly. Although the engines are "total loss", properly set up essentially no oil should end up on the road.

Leon

The oil is fed in fro mthe side of the timing case by a double Pilgrim pump (with another pump inboard of it, which is a return pump  - long story), the feed from the Pilgrim that goes into the engine is (iirc) fed down timing-side crank shaft, and into the cases (whether it's fed direcly to the big end or not, I'm not sure, I'd have to refer to my Fenner).  The other feed from the Pilgrim goes up to the rocker box where it's gravity fed onto the rocker-shafts and elsewhere.

Eventually all the oil end up in the sump where it's fed by piston pressure into the oil-trap chest and (as designed) out to atmosphere via the "flapper" valves in the photo (there's little metal discs inside those silvery circles that move freely (when clean....).

On this engine the oil that gets through the flapper discs is then routed into a return pump that feesd back up to the oil tank.  I think this was a modification that came out of Formula 500 racing where the original design of the engine: total loss, wasn't really acceptable on tarmac race tracks (while being absolutely not a problem for shale).  These engines were the best available for Formula 500 racing before the Manx Norton 500 single came along: good spread of torque, simple to work on, and reliable (or so I've read!)


If your older engines are total loss, but no oil is getting to the road.... where is it going?

Wicks don't always seem to be fitted to mags, same as the little felt effort that used to be in distributors years ago.
 As the post above says, a tiny bit of grease on the face cam or cam ring is more than enough.

Or the tiniest smear of grease on the cam. I mean a drop, smeared over the cam and more-or-less wiped off until there is nothing to see. Redo every ten years, unless you're desperate for something to do. Not sure which magneto you have - ring cam or face cam - but the fibre rubbing block does wear a bit over the years. If it's badly worn you can probably find a new one.

Leon

I recently picked up a 1949 BSA B31 in pretty much complete condition.  I've been getting acquainted with it before I start any serious work.
  I have a question concerning the magneto and how the ignition points cam is lubricated.  The points spin around while the plate cam stays fixed.  The mechanics manual gives directions for oiling a wick.
 I can't find wick anywhere in the points compartment.  The manual shows a picture of a fixing screw for the oil felt, but nothing resembling a felt.
Can anyone tell me where to look and what it might look like? A picture would be fantastic.
Thanks.