Master Cylinder

[MrRiden]

Sorry for barging in like this after not being on for a while, hope you won't mind. My '82 LS fitted with dual ATE's and a 15mm master has developed a leak in the master cylinder. Fluid seems to be coming from the point where the master bolts to the handlebar control. I'm assuming that it's the rear seal in the master that has gone bad and was about to order the £25 rebuild kit from Moto Bins When I thought better to check with the forum first. I have a vague recollection that these kits were said to be missing some items. Is it wiser to check the cylinder bore for pitting before getting a kit?

[Bob_Roller]

Good to hear from you Rich !!!

I'd remove the master cylinder disassemble it and see what you have .

I used a Scotchbrite type material on the end of a hardwood dowel chucked into a drill motor to clean up the bore of my '82 LS, there was a little pitting in the bore .

So far no issues with it .

I ordered a rebuild kit from Motobins a few years ago and had everything I needed to rebuild it .

Don't know if that has changed or not since I ordered mine .

When my '81 R65 master cylinder start to leak, it was too far gone to attempt a rebuild .

Save the old master cylinder if you have to replace it, they can be resleeved with a brass / bronze insert .

I looked into it in '92 when my '81 started leaking, wasn't cost effective then, don't know what the cost of a new master cylinder is these days .

At that time, I contacted White Post Restorations, they are in the  Virginia, west of the DC area .

[Tony Smith]

Save the old master cylinder if you have to replace it, they can be resleeved with a brass / bronze insert .

Stainless steel is much more resilient than brass or bronze and is for all intents and purposes a one time deal in that all you will ever need to do when the seal wears out is polish it and put a new seal kit in it.
 
It is not a complicated job, but i'm told that brake cylinder refurbish shops charge $100 to sleeve a master cylinder, you therefore only want to do it once.

[MrRiden]

Thanks, I'll pull the cylinder and see what I'm dealing with. If it's rebuild able wondering if I should replace the reservoir seal while I'm at it?

[Bob_Roller]

If you've gone this far, you just need to pull the reservoir off of the master cylinder and replace the o-ring .

If you're talking about the rubber diaphragm under the resevoir cap, if it's still pilable you can reuse it, but mine have all cracked with age, probably doesn't have anything to do with the high temps here for 6 months out of the year !!!!! 8-)