AJS 16M 1951

[dynamic]

I have an oil leak from the lower oil pump / timing case (lower slot screw ) I need to replace the gasket

 also is this chain in need of replacement ?

I notice there are no timing marks on crank / magneto do I just centre punch each sprocket and mark chain cover casing

all input gratefully recieved

[dynamic]

pic 2

[Rex]

No, you can't just centre pop the gears as you need to synchronise the position of the piston on the firing stroke with the position of the mag points.
Simple enough if you have a manual. FW Neill is a good one.

[R]

Since the sprockets look to be in excellent condition, the chain may not be worn ?
Can you just pack the magneto up a bit higher on its platform ?
Or is the platform adjustable even, with slotted holes on one side ??

[john.k]

Loose enough to wear away the case ............I d replace the chain.......you could pack up the mag ,its base mounted

[dynamic]

thanks all for posting I will post my progress soon.

[esoracer]

I have one of these models. The magneto chain is adjustable by moving the magneto platform which is designed for that purpose. The sprockets are not keyed, they just have a tapered fit and if you use a puller to get them off the taper you will have to re time the ignition.

[esoracer]

Also, as you have to remove the sprockets in order remove the timing case  to change the gasket I would try just removing the bottom screw, cleaning it and coating it with silicone jointing compound and replacing it and see if that slows the leak.

[dynamic]

thanks for the info esoracer bike is losing approx. 300ml each time engine is run, I will keep all posted on progress

[R]

That screw also possibly needs a fibre washer under it/them ?

[dynamic]

thanks R will fit fibre washers to all screw and post results .

[dynamic]

oil weep problem found I think  bottom screw hole on gasket slight left ?
 now cannot get it to start , when I removed the timing/magneto case I was very careful to keep the inlet/exhaust cams in situ,
 all went back together no problem maybe timing has slipped ,I have points just opening at 7/16 BTDC then full open at 12 thou , I have a strong spark, what have I missed
 all input gratefully recieved
PS I started bike this morning ran no problems

[R]

Is that a particle of debris ye refer to ?
Good that its sorted then.

PS I started bike this morning ran no problems

Its not clear if this comment supercedes the non-starting issue.
Good if its all good again but ...
Have fun !

[dynamic]

yes a piece of "debris" inpregnated into the gasket , now I have a non starting machine, before I took the cover off I marked mag /crank sprockets lining up to the marks I put on the timing case
I feel sure I put back both sprockets as they were when the bike ran earlier in the day before I removed the sprockets /casing 
 I have checked many times the points just starting to open at 7/16 /12mm BTDC then fully open at 12thou just before TDC if anybody could post re timing engine /magneto I would be very grateful  thank you

[Vreagh]

Is it possible the crank moved while working on the gasket?