front master cylinder replacement

[paulpops55]

I have an aftermarket front master cylinder that I bought for my 83 Goldwing and didn't end up using. I was thinking about using it on one of my 80 SG's that I've changed to the superbike handlebars. Have any of you used one of the aftermaket master cylinders or am I looking for trouble by using this ?

 

[XSLeo]

It depends on the bore size. If it has a 14 mm bore then it will work just about the same as the stock M/C. If larger, as in 16mm or bigger, it will be harder to pull the lever and the brake won't be as effective. It may even at as an on/off switch. You pull the lever and nothing seems to happen, you keep pulling and suddenly the wheel locks up. Not fun.
A smaller, like 12 or 11 mm, the lever will pull a bit easier but you will feel what the brake is doing better and the grake will be morer effective.
Usually the bore size is marked on the M/C somewhere. The stock ones, on the M/C next to the bars. Others I have seen, on the bottom. They are marked in both inch sizes as well as metric. The stock ones I have are marked 5/8 which is 16 mm, off my 75. the later 14 mm are marked 14. Some of the cheap after market ones are not even marked.
Leo

 

[angus67]

if you have duals on your gold wing, the bore size is too big.
i have the one that is listed second on mikesxs mc brake list, with a stainless brakeline. stock rebiult caliper on my sg

 

[XSLeo]

angus, item #08-0255? That's a 13 mm bore. I have one very much like it. It works slightly better than the stock M/C with a single disc. Item # 08-4003 is an 11 mm bore, Much better with a single disc.
I have experemented with a 16 mm bore, 14 mm bore and the one I have like yours. I'm not sure if it is 12.7 or 13 mm. I have tried all these m/c's with both a single and dual disc brake set ups using the later single piston calipers.
The 16 mm was ok with the dual disc but very wooden with the single. The 14 mm was ok with a single, very good with duals. The 12.7/13 was good with the single but almost too much with a dual disc.
Right know I'm running the 14 mm with dual disc. Very good brakes.
I plan on getting an 11 mm bore M/C to try with a single disc.
Leo

 

[paulpops55]

It depends on the bore size. If it has a 14 mm bore then it will work just about the same as the stock M/C. If larger, as in 16mm or bigger, it will be harder to pull the lever and the brake won't be as effective. It may even at as an on/off switch. You pull the lever and nothing seems to happen, you keep pulling and suddenly the wheel locks up. Not fun.
A smaller, like 12 or 11 mm, the lever will pull a bit easier but you will feel what the brake is doing better and the grake will be morer effective.
Usually the bore size is marked on the M/C somewhere. The stock ones, on the M/C next to the bars. Others I have seen, on the bottom. They are marked in both inch sizes as well as metric. The stock ones I have are marked 5/8 which is 16 mm, off my 75. the later 14 mm are marked 14. Some of the cheap after market ones are not even marked.
Leo

Thank you Leo for your insight. I'm going to check the bore size of the spare m/c that i have. My GL is an 83, which is the first year of the linked brakes, so the front m/c only actuates one disc. The rear m/c actuates the rear disc,as well as one of the fronts. I had already taken onto consideration the single disc vs dual disc differance in bore size. I also have been considering going to a dual disc setup in the future.

 

[paulpops55]

if you have duals on your gold wing, the bore size is too big.
i have the one that is listed second on mikesxs mc brake list, with a stainless brakeline. stock rebiult caliper on my sg

Thanks for input on this Angus. I just might have to buy a new m/c if my spare doesn't work out.
Paul

 

[Panabikerxs650]

i have a 1981 heritage special with a 14mm nissin..can i use one of those repair kit 13mm sell by mikexs on it????

 

[gggGary]

I would seriously doubt it.

 

[jd750ace]

On bore size, I have a 11mm Brembo master from a Moto Guzzi on my 79 Special with a stock caliper and a SS one piece line and the front brake has awesome feel. Feels at least as good (if not better) than the brakes on my SV650. It's a worthwhile move for sure. The stock master always felt a little wooden to me, but manageable. This 11mm is top notch paired with the later single caliper and stainless line.
The Brembo part number is
10.4620.80 11mm master - the one I have
10.4620.62 12mm master - 12mm version of mine.

Even came with a left hand threaded boss, so my Road Star mirrors threaded right on it, but this depends on which clamp it comes with. $28.00 on E-bay, but it took 3 months to get what I wanted.

What it looks like:

 

[gggGary]

+1 11mm works very well with the 77 up stock caliper, IMHO SS line is mandatory with that small bore, I have plenty of room between the lever and the grip. I go for the 650 Central Vesrah pads, it's an aggressive pad that's hard on rotors but worth it.
I haven't found/done the hot combo for early brakes yet but it's on my list. Anyone with a smaller bore MC that "looks" stock? ie a round cap model.

 

[jd750ace]

Round cap small bore might be KTM enduros or something like that. I need to get back to Dallas and make a run through L&L on some of this stuff. lol

 

[XSLeo]

I think if some one could come up with an easy way to reline a early round master cylinder from the 16 mm to 14 mm and 11 mm would please a lot of folks.
Leo

 

[Brassneck]

Old thread, but thought I'd ask to keep this info together...

Does anyone know if Mike's MC (# Part #08-0255), will allow the use of use my current stock lever? Or if there's an even smaller piston bore (11mm?) that will fit my stock lever?

(I really like to keep things balanced, and for me levers just have to be the same left/right)

I'd even swap my clutch/MC as a set if needed...but wanting the old school look to them...and just haven't found a set (yet).

Thanks!