Is it the brake lines?

I have a 1986 yamaha maxim xj650. The front forks and all were changed to Seca forks so there would be dual disc brakes in the front instead of the single disc.

I realized a couple days ago the bike was hard to push around in neutral. The brakes are hitting the rotor even though I am not pushing the front brake lever. My friend road my bike and noticed the same thing. We bled the brakes slightly and released the pressure and the brakes were no longer hitting and the wheel spun freely. After a couple minutes, the brakes went back to squooshing on the rotors again. This is both sides (since I have two calipers). Its not fully locking the wheel, but the brakes are constantly on the rotors.

Any ideas?

Thanks

Dan

 

Non-returning Caliper Pistons is a symptom of there being some build-up of foreign matter in the two grooved channels within the Caliper Bore that the Caliper Seals are seated in.

The build-up, a combination of brake dust, moisture and brake fluid, creates a crusty solid formation of build-up in the Inside Diameters of those Seal channels.
The build-up behind the Caliper Seal makes the Bore "Out-of-Round" and applies friction pressure to the Caliper Piston, holding it from its normal expansion and retraction within the Caliper when hydraulic pressure is applied.

You have to Pull the Calipers.
Remove the Pistons
Remove the two Seals
Scrape the foreign matter off and out of the channel surfaces down to bare aluminum.
Replace the Pistons, lubing the Piston and Seals with Brake Fluid while reinstalling the Caliper Pistons.
Remount the Calipers
Bleed the system.

After the cleaning, the Bore will be back to true-round and the Piston free to travel as it should under pressure and without.

 

Thank you for the quick reply! Do I need to get new pistons and seals, or can I reuse the old ones as long as I fully clean everything?
Thanks
Dan

 

In a perfect world, Dan ... we tell you to replace the Seals while you have the Caliper off and the old Seals out.

Give it a shot with the Seals and Piston you have ... unless they have such a hinky-look to them that you know that they're shot.

Put it together and see what happens.
Good Brakes and No Leaks ... you win!

If the Caliper seeps Fluid ... you'll have to do the Seals.

 

thank you I will try it out and let everyone know the outcome!

 

I am having a hard time getting the ring that holds the seal in place over the piston stay on. Everytime I put it on the seal slips back off. Any tips on hwo to get it on? Also, once I am done cleaning everything, shoiuld the piston easily slide back in?
Thanks
Dan

 

Dan:

You list your bike as an '86 XJ650.

I can't a listing for an XJ650 made in 1986.
Whats the VIN Number?

 

I am sorry it is an 1982. My car is an 1986, habit to type sorry

1982 Yamaha Maxim Xj650.

 

Are you talking about the spring loaded spring? There is a groove that it needs to fit into. My ring was split. I put the 'split' on, in the groove, then pressed on the end, thereby enlarging the ring, and it simply slipped into the groove all the way around.

 

The Caliper Yamaha used on the '82 650 (and some other models) is one "High Maintenance" Brake Caliper.

To keep it up to snuff, you have to do your fair share of cleaning and lubricating the Sleeve Bushing upon which it it wholly dependent of frictionless travel to stay aligned when you apply pressure to the Brake.

That, plus having the Dust Boot which, if compromised, allows moisture and other foreign matter to collect beneath it, can reduce the effectiveness of the Front Brake by causing the Piston to stick.

Combat the problem by changing the Front Pads frequently to keep the Piston from needing to extend further-out when the Pads are worn down.
Plus cleaning and treating the Dust Seal with a conditioner that will help it resist drying-out and becoming brittle.

 

Yeah, but it's a whopper of a caliper.......total pressure area of that single piston is larger than any of the dual-disc brake SYSTEMS.

Would have been nice if they made that system using two of those calipers.....you could play "human cannonball" anytime you wanted to!