Advice for fixing/replacing my front brake master cylinder

First Time poster...and by no means experienced with motorcycles, so please keep the heavy technical terms to a minimum.

A couple of months ago I bought my first motorcycle, a 1982 XJ750 Maxim, In all seriousness, it's probably a parts bike, but I didn't do research, and now that I intend to fix it, i'm in for the long haul.


Master Cylinder by USAF559, on Flickr

Anyways, the front Master Cylinder is in seriously bad shape, there is no cap for it and it looks likes it's rusted to death, So, I would like to ask where should i go from this, should i buy an aftermarket part such as this one:

http://www.ebay.com/itm/NEW-FRONT-BRAKE ... 823wt_1265

Or try to fit a different model of the same year, such as this:

http://www.ebay.com/itm/Yamaha-1982-XZ5 ... _877wt_905

Or is the damage just superficial? If i could find a cheaper M/C and just swap out cover plates, would a simple rebuild kit be all I need?

Also, the PO had no love for this bike (I got it from a cop buddy who had seen it at the impound lot, the PO didn't want it anymore), so assume that everything has been neglected for at least a couple years.

Oh, and any other advice on what to check on the bike before it's ride worthy would be appreciated. Thanks

 

It's alloy. It's NOT rusted. That's dried brake fluid.

If you can get that cover screw out ok, the determining factor for rebuild vs. replace will be the condition of the cylinder bore.

Dismount it, take it apart (one internal "C" ring) and carefully inspect the bore. As long as it's not pitted, then you've got a solid rebuild candidate; have at it.

 

Im new with these older bikes, but I would think the first thing you would want to do is to tear that one down to get a look at the bore then move from there. Its likely pretty rough if everything has been exposed to the elements. Its still worth a try. If the bore turns out to be good and glossy then just buy a rebuild kit and a cover. If its dull and pitted then its a no go. Some bores can be salvaged with a cylindrical honing stone if the surface is not pitted. Was there still some fluid in there? It is aluminum though.

Youll likely need new lines too. do not skimp on the brakes. If there is a drum in the back check for brake pad delamination. I wonder if the PO was driving around with only a rear brake. real old tires are supposedly a no go and get a shop manual.
Lubricate all lines, clutch, throttle, choke. If it runs then stick to safety and lubrication. Ill let the XJ gods chime in now. Edit: Fitz beat me to it

 

Re: Advice for fixing/replacing my front brake master cylind

Wow, you guys are fast 8O

Thanks bigfitz and Buffalony, I'll try to get to the cylinder bore tonight, if i get any free time considering fathers day and all.

Speaking of which Happy Fathers Day!

 

I'm surprised Fitz didn't mention valves and rear brake. :lol:

Major things to check:
Front brake line age - more than 4 years old, toss them.
Tires - more than 6 years, toss them
cylinder compression (above 120 on all 4 is good)
valve shim clearance
carbs cleaned religiously

That's the short list, but by no means all that you'll be doing.

As for that MC, like they said - bore not pitted it's rebuildable
IF you need a replacement you need an MC from any 750 Maxim or Seca, or a 650 Seca - they all had two disc brakes. the 650 Max and 550s had singles.

 

XJ4 Ever is a GREAT source for parts.

If you need to clear the "really small" hole in the MC, the end of a .011" E-string will do the trick well.

 

Good Idea Stump, but remember to be delicate with that string as it's likely nickel or nickel coated and that is tougher than aluminum. Nylon strings are a different story. correct me if I'm wrong, I dont believe a nylon high E is that thin. sometimes the metal strings arent exactly round at the ends too. even if its a copper string, chances are its built to be tough for the application hence possibly a stronger alloy than the aluminum body.

Im a fan of thin copper wire because I know its softer than the aluminum, but not everyone has the right size just laying around and sometimes its not tough enough to break the grime. Use what ya got. A toothpick up to a fine/sharp sewing needle will do the job, but just thinking about what your doing before ya do it is usually key.

Always gotta think about what your doin and how your effecting it, as most jobs are 90% planning and 10% execution.