Master Cylinder Repair

Anyone care to comment as to whether this is ok to use? 1974 850

Thanks

If the bore is smooth, or can be smoothed, you should be good to go. The picture you posted makes it hard (for me at least) to judge the bore. I suggest that you get a 20 gauge (possibly a 28 gauge) bronze/brass cleaning brush, screw it into one section of the cleaning rod and a good dose of kerosene drive it with a drill. After a few passes you'll know if the master can be re-used.

Madass sells sleeve kits that reduce the bore diameter and increase braking force, he is a forum member. I have a slightly use master in excellent condition that I'd sell, PM me if interested. There are also a number of after market masters like Magura and Brembro that can easily be adapted, but will require different switch gear.

Best wishes

Highly recommend just sleeving it to the 13 or 1/2 MC bore...low cost, removes any doubt as to bore condition, and dramatically improves braking power....it's a Win, Win, Win!

I was concerned about the end of the bore thats rough, and wasn't thinking about the inside. I'll follow your suggestion RS.

I have read about re-sleeving - thanks Tornado - I'll keep it in mind.

jimbo - thanks for the link, I'd like to go that route but I'm trying to restore the entire bike - on the cheap.

Thanks everyone for the feedback, I'm a newby at this, more questions to follow.

Here's a link to a post regarding the resleeve I purchased from madass140 on these forums:

https://accessnorton.com/NortonCommando/master-cylinder-upgrade-2011.8053/page-3#post-397286

$60 +shipping to your door. Easy to do the install. Good followup support from seller/designer/maker. Can't go wrong.

His full website/on-line store:
http://www.tritonmotorcycleparts.com

End of the bore is irrelevant. The travelled section of the bore is the only part that matters. Take a dental pick and gently run it up and down in the bore, without scratching it. You are looking for pockets of corrosion. The oxides look similar in colour to the good aluminium, except they have no strength or structure, and will not seal properly. If you find porosity or "cavities", then sleeve it or replace it.

Stephen Hill

That is good news, because the bore looks good.

Thanks for the feedback.

Stephen Hill said:

End of the bore is irrelevant. The travelled section of the bore is the only part that matters. Take a dental pick and gently run it up and down in the bore, without scratching it. You are looking for pockets of corrosion. The oxides look similar in colour to the good aluminium, except they have no strength or structure, and will not seal properly. If you find porosity or "cavities", then sleeve it or replace it.

Stephen Hill

Click to expand...

IMHO, If the pitting at the outer end is in the area where the piston seal rides and stops there will be a leak into the boot then eventually out onto the lever.However it should effect the operation very little. If the corrosion is outside of the piston seal lip at rest then you are good to go.