1975 Commando 850 restoration

Larry S

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I hope that this master cylinder is rebuildable since I've already purchased the rebuild kit.
 

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Richard Tool

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You should consider having the master cylinder sleeved down for smaller piston - rebuild is generally part of this service.
Old Britts used to offer this on an exchange basis but I don’t know if they still do.
 

L.A.B.

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On my oil tank I noticed what looks like an overflow tube is pinched and brazed shut. It also has a small hole drilled in the side upper of the tube. Is this a modification and if so why?
It's original, as johnm and Richard Tool said.

I'd say it was almost certainly done to increase the rigidity of the joint where the return tube enters the oil tank, and there's another hole opposite.
 
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Larry S

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Here's the front master cylinder disassembled. I don't think it's salvageable.
 

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Fast Eddie

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If the oil return pipe wasn’t blanked off it’d pump oil up at the cap, mucho leako.

Blanking and drilling was probably the easiest, cheapest method of avoiding that, and putting the oil return outlet in a place where it can be seen / checked.
 

grandpaul

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When the piston comes out of the master cylinder looking that rusty, it likely scored the cylinder walls and will never pump up well after that...

(bore and sleeve is the best fix if that is the case)
 
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Larry S

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Then the piston comes out of the master cylinder looking that rusty, it likely scored the cylinder walls and will never pump up well after that...

(bore and sleeve is the best fix if that is the case)
The 13mm brake mod from Old Britts? If not there, where? Thanks.
 

Larry S

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More progress. Rear master cylinder was rebuildable. Complete pic after painting.
 

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Larry S

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Awhile back I was assembling my switch clusters after painting and I got them all finished except one. The internals of two of those switches contain a small spring and a small ball bearing and are somewhat difficult to assemble. If you are not careful that tiny spring will launch that tiny ball bearing into oblivion. Yep, that happened. The ball bearing was lost forever. Do you know how hard it is to find an exact size bearing to operate those controls? I looked at different places to no avail and I had this wild idea to call a bearing distributor just for fun. I'm sure the girl on the other end of the phone thought I was crazy ordering single bearings but she found them for me. Minimum order of twenty for a total of around six dollars. They just arrived today and I got my switches finished.

Trivia question. What size is that tiny ball bearing in mm's. First one to answer correctly gets bragging rights.
 

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L.A.B.

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It's approximately 4.0mm but could be an Imperial size so is perhaps 5/32"?
 

Larry S

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It's approximately 4.0mm but could be an Imperial size so is perhaps 5/32"?
Wow, that was quick. I measured 4.0mm on the bearing from the other control with my micrometer. Just curious as to how you came up with your answer? Congratulations on the correct answer, sir.
 

Fast Eddie

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You’ve not been on the form long Larry... the only time you should be surprised is when LAB does NOT know....
 

storm42

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When the question was asked, I had a switch on the bench in bits so I nipped out and measured it. Could there have been different sizes fitted?
Edit, just seen your pic, I measured a older type switch.
 
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