AJS & Matchless Owners Club

I would like some help with identifying the oil pump plunger types on heavy weight singles. I have been looking at Roy Bacon's restoration book page 104 which shows 3 types of plunger. He says that from 1947 they were marked 2S. From looking at the pictures it seems that only the 1947 on had the wider grove for the guide pin. I have a plunger which has a wider groove but is not stamped 2S on the end and has one small hole above the large hole with the flat and not two close together as in the book. Can the one I have be used with the later (1960 on) crank, can it be a two start if it is not stamped and why do some have one small hole and others two next to each other?
Thank you LynP

There's a comprehensive article on oil pump plungers in the Archive in the link below. It may be the same info as in Bacon but perhaps worth a read.

http://archives.jampot.dk/technical/Spe ... ingles.pdf

(My earlier final sentence deleted - addled brain ).

The small hole lines up (briefly) with the drilling in the case that leads to the head feed.

I had a '61 AJS 500 with the wrong 2 start plunger. The small hole was out of position to work with the cases. The head was surviving on oil mist up the pushrod tubes 😕.

I used a round diamond file in an electric drill to move the hole in the plunger. Then soft soldered the unwanted slot back to be a small hole in the right place.

Biggest thing wrong with British bikes? Previous owners!!!

I was lucky there then.

Steve

That wee hole must run past the head feed drilling in the case.... on the pumping (forward) stroke. Not sure how i figured it out now

The Correct one for a 1960 is the one with the two holes beside each other.

Thank you all for your input and some interesting experiences, question answered. Good link SPRIDDLER with Roy's post as well all is clear now.