Front master cylinder

I removed this front master cylinder from a 850 and it looks different from 750 one; If I'm not mistaken and memory serves me it seems to have a cylinder fitted inside that doesn't seem standard and inserted maybe as next upgrade.
Having regard to the measures in the pictures which type of kit should I use to repair the pump?.
Ciao
Piero

Sleeved?

pierodn said:

I removed this front master cylinder from a 850 and differently from that of the 750 it seems to have a cylinder fitted inside that doesn't seem standard and inserted maybe as next upgrade.

Click to expand...

Looks like a standard '73 - '74, 5/8" master cylinder?

Yes , photos seem regular. If bore is pitted like that piston it will need to be sleeved though.

RGM do a resleeve kit for 49 quid. 89 for the job
The place I took mine did a SS sleeve & piston it's a specialist job well worth doing and it looks like yours needs it

I suggest when you get this re-sleeved, you get the bore done to 1/2 inch and make up a new piston to suit appropriate seals. You need top get another spring as well. There are some kits around but the one that threads into the master cylinderr is tricky. I had a friend make up the bits and loctited the sleeve [ which was a mild press fit ] into the old cylinder. The original bore size meant you had to grab the brake rely hard to try to stop the bike. With the 1/2 bore, the leverage has increased and you can easily stop the bike. [ you can even lock up the front wheel if you squeeze the life out of it ] I filed the lever a bit as well so that it had a little more travel. The lever nearly touches the hand grip when pulled in hard, but you stop like a modern bike.
all the best.
ps I don't know why Norton went to a piss poor disc brake system, when the previous drum brake was far better for normal riding. I have a 71 with drum and a 74 with disc. The drum is just as good as the modified disc system .Maybe for racing conditions, the disc will be better.