Joe I'm fairly certain that your bike has "Wet Sumped" Which means while the bike has been standing for a period, the oil has seeped past the oil pump and ended up in the crankcase. Ultimately it will leak through the main bearings and into your primary case. Before you attempt to start the engine, remove the drain plug in the bottom of the sump and allow the oil to drain into a clean tub and return it to the tank. Also remove the level plug from the primary case to get the level back to normal.

One thing to do to try and avoid a repeat, is to remove the small hex plug near the bottom of the timing cover, where you will find a light spring on top of a ball bearing. Squirt it all out clean and give the ball a light tap with a punch to create a good seat. (better to buy a new spring and ball for a couple of quid. Also start the bike up more frequently will help.

If your bike starts ok when cold but not when hot, it's almost certainly that the magneto requires an overhaul. Ron

email (option): ronpier@talk21.com

Hi all

I am struggling to get a 3/16 ball and suitable spring from my usual supplier. I thought i may try a new one to see if it stops my m20 wet sumping. It cant be a coincidence that it started wet sumping the last time i removed the timing cover and the oil valve spring screw. Wonder if the ball bearing can just fall out and ive lost it ? Would it damage the engine if teh non return valve effectively didnt work ?

Is it ok to use a generic 3/16 ball bearing off ebay or can you recommend where i can get the correct item.

Many Thanks

Ant

email (option): antkenmare@gmail.com

Yes any 3/16" steel ball will do but Draganfly have them and the spring.

https://www.draganfly.co.uk/index.php/accessories-a-misc/product/21533-
https://www.draganfly.co.uk/index.php/accessories-a-misc/product/13341-

I'm also sure that Les at Russells and C&D Auto's will too.

Ron

email (option): ronpier@talk21.com

The diameter of the ball is 1/4"...not 3/16"...Ian

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

Yes I wondered about that? But couldn't remember. Drags have both, but list 3/16" for 1939 and 1/4" for 1946 to the 50's. Ron

email (option): ronpier@talk21.com

Thanks for all the help.

Joe.

Thanks Ron, will do. With reference to the hot starting, the magneto has less than 1000 miles on it from new in 6 months.

Have you got a Tufnol type spacer between the barrel and the carb flange?

If not try fitting one as this can cure many a hot starting problem as without one, fuel can boil due to the heat from the barrel.

Regards

Pat

email (option): sacombsashtrees@hotmail.com

Thanks, I think I will try a spacer, sorry to be a pain but do you know of a supplier or part number for the spacer for the WM20?

It's a 1" bore x 1/8" thick (or metric equivalent) .....90182 from here http://www.hitchcocksmotorcycles.com/amal-carburettors-miscellaneous
or the heat insulator gasket.

Or Google "Surrey Cycles" Ron

email (option): ronpier@talk21.com