So I got my m20 starting and running beautifully but I have absolutely no oil returning to the tank. I checked the sump ball valve and its seating and loose and I also cleaned the filter. I disconnected the return just below the oil tank and kick the bike over and the line is totally dry. I was thinking that even if the pump is worn the line should fill to some degree. The bike sat for over twenty years with no oil in it. Would the pump need to be primed with a shot of oil down the return? Thanks and the forum has helped me a ton over the last few months. i appreciate everyones posts,
-RW

email (option): robwern@yahoo.com

Rob, these pumps can be problematic if left unused for a long period. The Mazak metal swells making the pump either very tight or not turning at all. It could be possible that the teeth on your worm drive have stripped.
In any event I think you need to have a look inside the timing cover first and maybe report back. Ron

email (option): ronpier@talk21.com

Hi Rob..The BSA pump doesn't need to be primed, so I would follow Ron's advice and check out the drive. If the pump hasn't been checked to ensure it will turn freely by hand it should be, before the bike is used.
I would suggest you remove the pump and drive shaft for inspection. How long have you run the engine for, or did you just try for a return by kicking it over?..Ian

email (option): ian@wright52.plus.com

I ran it a good long time (like an idiot) because I didnt at first understand how the filer shrouds the oil return. All my other bikes (not m20s) just have the oil return naked so its a bit more apparent if your getting oil.
thanks very much,
off it comes!!
-RW

email (option): robwern@yahoo.com

Rob I would remove the filter for testing purposes. In fact I don't run with a filter at all (I'm not alone). I just change the oil every 2000 miles. Ron

email (option): ronpier@talk21.com

Ron, sorry to jump in but as new M20er, is 2000 miles ok for oil change, my engine is being overhauled so i plan to change reasonably quickly once on the road but would appreciate guidance in normal oil service period, I plan to use Castrol GP50 and a filter if this make any difference.
Thanks
Pete

email (option): cruaser@aol.com

Pete. I think the book says change the oil every 2000 miles. In fact I change mine each year, which is far less than 2000 miles as I share my riding with other bikes. I use Morris's 40 in my bikes all year round.

Ron

email (option): ronpier@talk21.com

I think the 50 weight is a bit heavy for the UK unless by some miracle we have a very hot summer...Ian

email (option): ian@wright52.plus.com

pete it been said on this forum before but most say you should do the first oil change after rebuilding your engine after 50 miles

email (option): roger.beck@node6.com

Thanks for the advise, would Morris 40 be suitable for my G3L as I dont want too many oils in the shed, I will only get confused
Pete

email (option): cruaser@aol.com

Well As I said I use Morris's 40 in all my bikes and that includes Matchless. But that is just my preference!

Ron

email (option): ronpier@talk21.com

hi rob, did you take another look at your pump?have you any news on your problem?did you find the pump jammed up or does it appear normal.just a thought,are your oil lines connected the right way round?ie feed to pump,return to tank,
let us know,cheers rick

email (option): richardholt@rocketmail.com

didn't get a chance to tear into the bsa this weekend. I spent my "greasy time" doing tires, tubes ,and brakes on my old daily transport Honda CB. Now I know why bike shops charge so much to change your tires. PITA!! I think I will try switching the line around and giving it a few kicks. It can't hurt, great suggestion. The previous owner knew nothing about bikes so I'll give it a go.. I'll get back to you once I take a look inside,
thanks,
-RW

email (option): robwern@yahoo.com

Hi Rob...The 'outside' oil line is the return to the tank and the 'inside' line is the feed to the engine...The outside pipe on the engine goes to the outside fitting on the oiltank...Ian

email (option): ian@wright52.plus.com

Hi Rob, I don't think Rick was suggesting swapping the oil lines around but just checking they're the right way round as Ian's pointed out.
I think it can hurt

email (option): horror@blueyonder.co.uk

Checked it out and the lines are hooked up correctly. Was really hoping it would be that easy!! Thanks again. Unfortunately the bikes are kept outside in a tiny little shed so I wont get to tear into her until the weekend. Someday I'll grow up and get a proper workshop with lights etc... For now its the yard and daylight!! If I need a pump does anyone have any suggestions regarding who I should source it from? They must make a pump out of modern materials that holds up better. Even better if I can get it in the US. Thanks again,
-RW

email (option): robwern@yahoo.com

Draganfly make a good quality pump...but it's a bit expensive. I think they can also overhaul your own.
But don't be hasty. If no serious damage is done we can talk you through the procedure. The main concern now is to see if the worm drive gears are damaged. Ron

email (option): ronpier@talk21.com

So here are the sad results. I removed the pump today and the first set of gears inside the pump have almost all the teeth broken off and the remnants jammed together within the second set of gears to completely lock the pump. The opposing gears are intact but I am certain that the pump drive shaft is bent. It is not contacting the drive and will only turn about half way, it wont spin in place beyond a half turn. I assume I have to remove the drive from above. Does it simply slide into place from above or is it retained by a set screw or by any other means? I guess I should get a price from Draganfly. Thanks again for everyones input.
-RW

email (option): robwern@yahoo.com

On second thought can I source the first set of gears (the stripped ones) that are in the top of the pump from either a used M20 pump or from another BSA model that shares the same pump design? I believe its a 13 tooth gear and I need both. Any creative suggestions are welcome. I doubt anyone sells repro gears without buying the new pump but please correct me if anyone knows a vendor or has the top gears from a used pump they want to sell. Anyone know which non m20 models share the pump design and have interchangeable internals?
thanks,
-RW

email (option): robwern@yahoo.com

Doesn't the B31 and B33 use the same pump.

Rob, the pump drive spindle can be withdrawn from the bottom, there is a retaining pin located in a recess in the timing cover mating surface just in front of the spindle. A timing cover screw can be used to withdraw the pin, sometimes there is a washer in front of the pin, this will have to be prised out first.
I wouldn't bother replacing the damaged gears, something 's caused the gears to jam and it's probably the pump body swelling, they are made from a crap diecast.
As Ian says the B series BSA's use the same pump.

I'm sure the thread inside the pump spindle retaining pin is in fact 1/4 BSC/BSF. The timing cover screws are 1/4 BSW. I'm not knit picking! I think some of the books tell the wrong information. Ron

email (option): ronpier@talk21.com