Rear Brake Master Cylinder Kit

[shutchis]

Okay guys...I bought an XS1100 rear brake master cylinder off of ebay and the piston is 14 mm. I also have an '80 XS1100 Midnight Special and it's pistion is 1/2". What's the deal. Where can I find a kit for the 14 mm bore? Why all the different sizes for one bike? I look forward to a lively discussion. Stan H.

[DGXSER]

Depends, one, they may not be stock. Two, if someone swapped out the 81 MNS brake system, the rear was a linked brake with one of the front calipers like on the XJs. So hard to sya for sure.

[natemoen]

Some of the specials I think had linked systems with the left front caliper and the rear caliper. So you may have got one of those master cylinders.

[natemoen]

You beat me to it.

[shutchis]

Thanks guys. I've searched the web for 2 hours and I've found two different XS1100 rear brake master cylinder (MC) kits. I just ordered a kit from DarkHorseMotorcycleParts.com that looks like my 14mm piston. I was very surprised to find such a difference in the master cylinders. The '79 XS1100 MC purchased from Ebay was 14mm and the '80 XS1100LG was a 1/2" bore. Both master cylinders were designed for rear braking only; and were not built to support integral front and rear braking as you would find on the '82 XJ1100. I sure hope the kit I ordered was the right part. I'll post my findings as soon as the package arrives.

[DGXSER]

As far as I know, Never owned one, bu tthe LG or 80 MNS should have the exact same rear MC as every other XS ever made. The only one that had anythign different from the factory was the LH or 81 MNS. Now, as most of us have seen, alot of parts get swapped out form one bike to another regardless of what it was on before. Banshee was probably 1/3 Suzuki fit and finish stuff like turn signals and front cover and ovther stuff when I got it.

[SFerinTEXAS]

You should get the right kit for the Ebay m/c. All of my research suggest you somehow had a similar but not correct m/c on that LG.

[SFerinTEXAS]

I noticed in your signature you say

'80 XS1100 Midnight Special
Looks like an '82 Maxim, fuel injected

Does it have the straight spokes or curved like the maxim? The lg were straight, the lh are like the maxim. Not that it explains the confusion, just clears it up some.VIN check, motor, frame?

[shutchis]

[shutchis]

Sorry, I posted with no content, my bad. My '80 XS11 VIN is 4H3001626. Straight spokes. I'm pretty sure it's an XS1100 LG Midnight Special, but I'll let someone else verify. Ebay has several MC's listed; one claims the MC came off a '78 Yamaha XS1100 14mm, and I found a '80 XS1100 with a 1/2" cylinder. Hmm, there's a mystery a foot Watson, Sherlock Holmes; Stan H.

[natemoen]

Well by the 4h3 it does say its a LG. Here is the page that has the vin list.

http://www.xs11.com/faqs/153-serial-...ry-colors.html

[SFerinTEXAS]

80 XS1100 Midnight Special
Looks like an '82 Maxim

Just a matter of opinion I guess, my bad. I think an 80MNS looks like a black and gold SG or SH. But the swirl spokes on the LH kinda tends toward the maxim.

[shutchis]

You're probably asking...Why does his '80 XS1100LG look like an '82 XJ1100J? Answer, I swapped out the XS11's gas tank, seat, and side rails with an XJ11; giving the Midnight Special a 5 gallon fuel tank and a step seat. I'm in the process of making new side covers for the right side fuse panel and the left side battery case.

I just got the XS11 running. I'm monitoring the charging system; the battery voltage with a Fluke DVM is reading about 13.2V at 4k RPMs. Most of the time it's in the high 12V range. I've never seen a high 13+volts. I also need to finish tuning the electronic fuel injection system (EFI) and set the ignition timing curve. The XS is running with my XJ11's EFI tables, which are probably close. I have approx. 100 miles on her, and I've only broke down twice needing assistance.

I discovered the brakes were not working well, and the sight glass in the front master cylinder was bad. I got all this fix last week, which is why I posted. The eBay master cylinder I bought was 14mm and my XS11 is 1/2". The new braided stainless steel brake lines I installed really improved the feel.

Have a nice day guys, I've just got time to make the coffee, vote, and ride to work. Stan H.

[SFerinTEXAS]

AHA that clears that up. Just curious, how did or did you address the rear tank mounting? Did you grind off the original screw post and add anything? And how well do the bars clear that bigger tank? Change bars? Surely I'm not the only one wondering. How about some photos ?

[shutchis]

Good morning, the XS11 to XJ1100 transition was fairly easy and the results look pretty nice. I'll paste some pictures soon,this site wants a link.

Here was my transition process...I removed the XS fuel tank bracket and welded in the XJ bracket. I also removed the hold down bolts for the XS seat and welded in XJ latches. This was a very nice modification because removing the XS seat requires tools. I can just pop my conversion right off.

Yes, pictures would be nice. I'll get them posted soon so you guys can see different approach to a custom mc. slh