An ENIGMA wrapped up in a CONUNDRUM

[albeix]

I am working up a cost to restore a 77 XS650 Serial number is 447-900208. When I go to order brake pads none of the usual suspect sites show what this bike has??? The sites show rectangular pads and round pads but none of them are the correct shape for this bike. The pads on this bike are rectangular with cut outs in the pad backing that allow the pad to slip into the caliper bracket. Once installed the caliper slides over the pads and a small JIS screw goes through the pad opposite the caliper piston and locks the caliper and pad together. The caliper is then held in place by a single 12MM head bolt under the piston. That's the Enigma.

The conundrum is that all the sites show the bike as having a drum rear brake but this bike has a rear disc brake that appears to match the front as far as brake pads used are concerned.

Anyone have any thoughts on what the brake parts might be from or alternately what's going on with this bike???

 

[jetmechmarty]

A couple of things. First, if your bike has a disk brake on the rear, it's not a 1977, unless it has been modified. Does it have cast wheels? Is the serial no. taken from the engine or the frame? If you do have a '77 with OE caliper, front brake pads are the same 1977 to 1984. Post some pictures.

 

[gggGary]

sounds like you have a first year 78 special, Mag wheels? They start building the next model year, about July of the year before so a 1978 is likely to have a 8-1977 build date. Your VIN shows as a 1978 special for the Canadian market. 78 was the first year for the special models.

All stock disk brake pads 77 to 84 are the same.
https://www.xs650.com/threads/help-with-caliper-rebuild.41676
A picture will help us ID your bike. These Caltric pads work fine put on several sets never had an issue.

https://www.ebay.com/itm/2908688327...=2047675&ssuid=&widget_ver=artemis&media=COPY

 

[albeix]

A couple of things. First, if your bike has a disk brake on the rear, it's not a 1977, unless it has been modified. Does it have cast wheels? Is the serial no. taken from the engine or the frame? If you do have a '77 with OE caliper, front brake pads are the same 1977 to 1984. Post some pictures.

Photos as requested It seems it is a very early SE Serial number 447-900208 Also need a source for rear brake rotor.

 

[gggGary]

The rear disk was used also used on several other years models, front as well as rear placement.
But they are VERY thick and can usually be cleaned up with a flap wheel if you can spin the rotor so it gets ground evenly..

This Yamaha 1J3-25831-50-00 DISC, BRAKE fits the following models and components:
Yamaha Motorcycle 1980 XS850G Front Brake-Caliper
Yamaha Motorcycle 1977 XS750D FRONT DISC BRAKE CALIPER
Yamaha Motorcycle 1978 XS750E FRONT DISC BRAKE CALIPER
Yamaha Motorcycle 1978 XS750SE FRONT DISC BRAKE CALIPER
Yamaha Motorcycle 1978 XS750SE-31 FRONT DISC BRAKE CALIPER
Yamaha Motorcycle 1979 XS750SF FRONT DISC BRAKE CALIPER
Yamaha Motorcycle 1977 XS750-2D FRONT DISC BRAKE CALIPER
Yamaha Motorcycle 1978 XS750E_227 FRONT DISC BRAKE CALIPER
Yamaha Motorcycle 1979 XS750F FRONT DISC BRAKE CALIPER
Yamaha Motorcycle 1980 XS850G Rear Brake Caliper
Yamaha Motorcycle 1978 XS750E_227 REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1978 XS750SE-31 REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1979 XS650SF REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1979 XS750F REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1980 XS650SG REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1977 XS750-2D REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1978 XS650SE REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1978 XS750E REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1979 XS750SF REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1978 XS500E REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1978 XS750SE REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1977 XS500D REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1976 XS500C REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1977 XS750D REAR DISC BRAKE - CALIPER
Yamaha Motorcycle 1978 XS650SE-11 REAR DISC BRAKE - CALIPER

Expect that you will need to remove caliper and master cylinder and overhaul both.
Brake lines are decades past their use by date.

 

[gggGary]

Replacing the front master cylinder with a unit with smaller bore along with stainless steel brake line is a very pleasant upgrade that will greatly improve brake feel.

 

[albeix]

Replacing the front master cylinder with a unit with smaller bore along with stainless steel brake line is a very pleasant upgrade that will greatly improve brake feel.

 

[albeix]

Any suggested front master cyl recommendation(s)??

 

[gggGary]

Yamaha tt225 or tw200 are great units, nearly plug n play. Has the LH thread mirror mount, use the lever from the stock MC, works better over the throttle switch gear. electric plug on the brake light switch is a bit different but the stock switch plugs into the new MC. Seen on fleabay and mebby found at a bike wreckers. Also works better with "normal" handlebars, doesn't have that goofy angled reservoir used on the buckhorn bars.
These are 11mm bore, will change braking to a 2 finger affair. Not everyone thinks 11mm is ideal but I've done 3-4 of of these conversions and couldn't be happier.
You MUST use SS brake lines with the smaller bore cuz the rubber lines are too squishy and will make the lever action soft.

 

[jetmechmarty]

Any suggested front master cyl recommendation(s)??

http://www.vintagebrake.com/

For best results call Michael "Mercury" Morse.

 

[5twins]

That XT/TT225 MC is actually an 11mm unit. I have one on my '78 and it works well, much better "feel" and modulation .....

Mine looks a bit "weathered" but that blends well with the rest of the bike, lol. Coming from a dirt bike, many are pretty beat up, so it may take some time and searching to find a decent one.