85 XJ700N Partial Restoration

Hey guys,

I think I went from "I'll do a few maintenance items" to basically restoring half the bike lol.

1985 XJ700N.

So far I have:

- Changed engine oil and filter
- Changed final drive oil
- Replaced rear brake shoes
- Removed rear wheel and serviced everything there
- Replaced the valve cover gasket
- Repaired the turn signal switch
- Removed carbs and diagnosed a flooding issue
- Bought float valves and carb parts
- Rebuilt one front caliper
- Bought K&L piston/seal kits for both front calipers
- Bought a master cylinder rebuild kit and sight glass kit
- Bought NGK BP8ES plugs
- Bought new grips and various OEM/NOS parts

Today I finally got the pistons out of the left caliper. That alone felt like a victory. Cleaned everything, cleaned the seal grooves, installed new seals and got the pistons back in. The pistons had some scratches. One of them I could feel slightly with a fingernail. The brakes didn't leak before, but since I already bought the K&L piston kits I'm leaning toward pulling them back out and installing the new pistons instead.

A couple things I'm still unsure about:

1. What torque are you guys actually using on the caliper half bolts? I've searched old threads and found a lot of discussion but no clear Yamaha spec.

2. What torque are you using on the caliper mounting bolts and banjo bolts?

3. If you were in my shoes, would you reuse the original pistons if they had a scratch you can barely feel, or just install the new K&L pistons since everything is already apart?

4. Any common mistakes I should watch for when rebuilding the master cylinder and bleeding the system for the first time?

Honestly I'm a little nervous about the brake rebuild. I don't mind rebuilding carbs, replacing gaskets, chasing electrical issues, etc. But brakes are one of those things where I really want to get it right.

At this point I probably have around $600+ in parts sitting in the garage and I'm committed whether that's smart or not.

Any advice is appreciated.

 

I'll offer torques for general use on other bikes..... torques are usually assuming dry threads, no lubricant. Caliper halves ~24 ft. lbs., caliper mount bolts ~25 ft. lbs, can use blue loctite. Banjo bolts ~22 ft. lbs., the crush washers (aluminum or copper) will keep those snug. Be sure to use new crush washers.
One thing I do on an empty brake system is fill the reservoir, open the bleeder and let it sit for a bit... gravity may work, and you'll see fluid dripping out the bleeder if it does. The trick is to get the master cyl. primed so you can pump. Some reverse fill with a syringe at the bleeder until you get fluid into the reservoir. Or you can loosen the banjo at the master cylinder to bleed off air and get the flow started. Vacuum bleeder will work as well to get flow started, but I prefer conventional bleed after that.
I'm sure othere with experience on these Yammy's will have some other advice or techniques.....