RGM kit for master cylinder 13mm

http://www.britishcycle.com/Products/558/558_13_INST.pdf

Drill fully to the depth of the existing bore. 

Tomas,

i also have an RGM kit that I am shortly going to use to convert my Mk3 m/cylinder.  The RGM instructions state to drill the 16.5mm hole to a depth of 13mm.  There is no need to drill all the way down the bore, as the sleeve that screws in is a smaller diameter than the existing bore and the 16.5mm hole is merely to size the bore for tapping the M18 thread, which is only tapped to a depth of 9mm.

Andy

I have read the instructions but never used the kit.

The instructions clearly state the 16.5mm drill goes to the bottom of the current bore.

2, ARRANGE A METHOD OF ACCURATELY AND SECURELY LOCATING MASTER CYLINDER BODY AND DRILL 16.5MM TO THE BASE OF THE BORE OF THE MASTER CYLINDER. IT IS IMPERATIVE THAT THIS HOLE IS DRILLED TRUE TO THE BORE, I HAVE FOUND IT FAIRLY EASY WITH A BENCH DRILL BUT DIFFICULTY WILL BE EXPERIENCED DOING THIS JOB BY HAND.

The tapping of the thread does not go to the bottom, only 8 turns of the tap is recommended. 

I have attached a photo of my RGM kit instructions that describes how to drill the 16.5mm hole and two the thread - 7 turns in this case, not 8.  As I have not yet carried out the conversion, I could not say whether the instruction I have are correct, but why would they not be?

Yours look like more recent than mine, so perhaps the requirement have been updated? The only effect of drilling to the full depth of the bore would be to increase the amount of fluid surrounding the sleeve, which could be beneficial? 

I drill as deep as possible without removing any material from the base of the bore. Due to the angle on the front of the drill, there will be a couple of millimetres undrilled at the bottom. this is fine & will leave the bottom of the hole flat bottomed. Tap it just deep enough for the sleeve to touch the bottom without the neoprene washer, then you will know it is deep enough the squash the washer. Take it all apart & thoroughly clean, then assemble as instructions. I find the braking really good afterwards.