piston doesnt move in caliper

front brake 81 maxim 650.i put new pads in,used mightyvac to get the air out.The rubber adapter covers the bleeder screw, so you take it off and have to quickly close the bleeder.That to me would let air in again.I was wondering if keeping the handle compressed on the mightyvac if that was equivalent to keeping the brake lever compressed till the bleeder screw was retightened.Anyhow, the brakes don't work.I took the caliper back off, I pumped the brake lever, the piston moves about 1 mm at most.I thought with the discpads not in the way,just hanging down since they arent against the rotor that the piston would move very noticably.It was also rusty inside.I ordered a complete rebuild kit,piston and all.The brakes are the most important part of the bike.I rode it around the block before I disconnected everything.The bike hesitates a little, but doesnt slow down.I figure the minimal amount the piston does move exerts a little pressure on the pads but not enough to brake. That sound right? The brakes did not work even 1 iota before I did what i did.The rear brake still does nothing.I am not going to mess with the rear brake for now, I figure the drums pads are no good. 85% of braking is from the front brake.But with no rear brake at all it for sure isnt rideable. the motor runs so good.I goosed it a little going down the street, with no brakes.It will definitely haul ass when Its rideable.

 

Did you rebuild the caliper?

[Edit] i just noticed. Could you please keep all of your questions about your machine in one thread. That will help us greatly when looking at how to help you get her back on the road safely.

 

You will need to get piston out of caliper disconnect brake line , use an air nozzle in the opening that was where brake hose was attached . Use compressed air and see if piston moves ...if not a grease gun can be threaded in and pump till piston moves ...it is messy but works well you have to clean caliper out when piston finally comes out . Do not use channel locks on piston it will gall it even if covered with a rag scratches will destroy it . Even if piston is rusted it can usually be cleaned up and reused .

 

Please delete any or all of my threads.

 

he can merge them instead of deleting them

 

you really need to look at the rear brakes if the shoes are delaminating the lining may fall off and lock up your rear wheel. not a good thing.

 

this is what happens. click on photo for larger image

 

I can no merge them I dont think.I believe that is a admin function. I dont want to clutter up the forum.Deleting wont hurt, i have the answers I need to this point.

 

OMG. Yes, that for sure means I am going to look at the rear drum.I have to change the rear tire, so thats the time.I have the bike running and rideable except for the small point it has no brakes and am getting impatient.Everything I have done so far has been fighting me. Thats the nature of a 37 year old motorcycle.I also at 24,000 miles need to check the valve clearances.I know I will screw that up for sure.On the ruined head I have in my parts container I popped out a couple shims.I thought they were supposed to have numbers on them.The 2 I removed dont have numbers.So I suppose I would have to have some sort of device to measure their thickness.This opens the door for countless more unproductive and frustrating hours.I owned 3 4 cylinder goldwings.setscrew and locknut.What a great idea.Ain't happening with the xj.But every 20,000 mile readjust means probably once every 4 years once it is done.But for now, the caliper piston problem is enough.

 

I am going today to buy a bolt to replace the banjo bolt and a grease gun.That should do it.Big question: once the piston s out, why did it get stuck.If it is rusty or scratched up, replacement will fix that.But the bore the piston was in, do you wipe it out, put some sort of fine emory cloth and smooth out the inside of the bore, or replace the whole caliper or what.And if it is stuck now and I get it out how can I prevent that happening again. I have theories.Letting the bike set unused will cause corrosion ,rust, seizing.It has to be ridden and used. dirty brake fluid causes grit, scoring, poor braking action because the fluid is not pure and freeflowing with dirt in it. I believe if I sanded or emory clothed scratches on the outside of the piston, or the inside of the bore I will decrease the dimensions since there mere thousandths of clearance and thus the brake will never work properly again,thereby meaning total replacement of all moving parts. third, the plastic plug at the bottom of the caliper hiding the head of the throughbolt- I can see how that would prevent dirt,water, grime from coming up through the spacer and to the 12mm top nut.But that should not effect braking action . It could cause rust of the bolt,make it break later and the caliper fall off, but in 37 years that hasnt happened.

each system of a motorcycle is not optional. And each one, whether it is electrical or mechanical has its challenges.The only solution is returning whichever system to their original condition, settings, clearances. The good news, doing this is most often a once in a ownership experience. lastly I would rather have a 57 chevy than a 2018 chevy. These bikes are 57s.

 

The seal inside the caliper usually hardens and grips the piston , and water getting past dust seal also causes issues . This is no different than your car caliper will do the same . Once piston is out clean the inside of the caliper , I use a dremel with a brass wire brush ( Brass is soft and will not mar surface ) , once you remove the seal make sure the groove is clean , use some silicone grease on the seal ( you can find it at most hardware stores in plumbing aisle) put a little on the piston when you put it back in caliper . Another item put a little anti seize on the bleeder screw threads ...Cheers

 

I can merge them more easily than delete them. Other people might need the same answers as you do.

There is at least one brake calipers rebuild tutorial in the DYI section. It should be pinned on the first page.

 

With the nonhollow bolt in the place of the brake line and a handpump grease gun and 20 pumps the piston came out.what a mess.the inner seal in a groove near the end of the barrel looks like it would be picked out.putting a new one in ive never done.some adhesive like permatex #2 might be needed to keep it in place.the spring and rubber boot is a nobrainer. It has some brownish discolation on the outside of the piston like from heat.question: now that all the passages are full of grease what do i soak the caliper in to dissolve it.#2 what is going to prevent this happening again?

 

It dealt most with mc rebuild.the inner seal that goes around inside the barrel- what keeps it in place?

 

Most of what happens is due to brake fluid absorbing water and corrosion builds up behind seal and puts extra pressure on piston. Result is piston stays put instead of retracting when you release the lever.
NEVER use bonding agents on brake caliper parts.
Polish the piston with 600 or finer and clean bore with brake clean and a small brass wheel to clean the groove that the seals fit into. Any left over crap in the groove will cause new seals to put too much pressure on piston and your right back to the beginning.

 

thanks toomany.I dont have a drimmel or brasswheel.But i get what you say.My other question though was how do i get all that thick black grease out i used to pop the piston out> Soak the caliper overnight in something? Thanks for your help.

 

Brake spray cleaner and some rags ...DO NOT use any type of sealant on inner seal .

 

thanks for the information

 

The seals are retained by the grooves in the caliper bore.
When you put the piston back in, lubricate the seals with new brake fluid.

 

now I need opinions, since I am waiting for a rebuild kit to come for the next 4 days.The kid I got the bike from had cut the mufflers off right at the end of the heat shields. I have a set of stock mufflers and exhausts i could put on there if nothing is missing.I would need new crush washers and some luck trying to get both sides started at the same time.I hate loud pipes.The stock ones I figure are pretty quiet. It would be easier to get some sort of aftermarket mufflers and attach like emgo or something but they have gotten expensive now. I know someone here has taken off and reinstalled the stock exhausts and mufflers before.I was going to try to take just the mufflers off the set of exhausts I have but it looks like it would take a heck of a lot of pounding and pulling to get them off.I removed one clamp between the muffler and head pipe.I gave it a couple whacks and it didnt budge.After 37 years it is probably rusted on there. The nuts and clamps holding the heat shields on dont want to budge but I figured I might cut them with something and pry them off.Opinions appreciated.

 

the mufflers have a sleave that will crumble when you remove the mufflers. you will need part 5 an6 on this parts list its about 80$ worth of parts
https://www.partzilla.com/catalog/yamaha/motorcycle/1981/xj650-xj650h/exhaust

there are aftermarket ones out there I think I have a link I will look for it.

http://www.partsnmore.com/parts/yamaha/xj650/?filters[fitting]=custom&filters[category]=engine

7$ need 1 and 8$ each need 4

 

Good links.what is the secret to getting the mufflers off

 

Patience and time (and sometimes a big hammer along with a hardwood drift, but be careful). Twisting also helps.

 

I am not looking forward to the challenge. But now that the front brake is on its way to being functional, then change out the rear tire and of course fix the back brake since it does not work at all. If I could find some sort of cheap slipons i would and may still go that route.Dumpster diving at the harley dealer maybe?

 

The issue with the maxim 650 exhaust is that the mufflers are part of each side of the collector. Meaning each side slips onto a pair of head pipes, as well as the crossover pipe. You can cut them off of what I called the collector, but then there's nothing to attach a slip on to. I went this route anyway and since I work at an exhaust shop, sized some small pieces of pipe and welded them onto the collector which then enabled me to clamp on some aftermarket "mufflers"

 

wow.thanks chitwood.I found 2 cherrybomb looking shorty mufflers for $60 on ebay.They look like if i could get the heat shildes off, they would slip over the exhaust pipe.They still would be loud but not as loud.

 

Since I rode to work today, I can show you what I mean/What I did. The red arrow is the piece of pipe I welded on where I cut the factory muffler off (Rt side was rusted completely in two) and the blue arrow is the existing factory exhaust. I trimmed back and tacked the chrome shield so I had room to work. If I had to do it over again I'd tack the pipes in place good, then remove the exhaust from the head pipes for final welding. Welding them in place was a giant PITA. It's really loud but I knew that when I started but the "mufflers" where free so I was only out some time, welding wire, and welding gas.
Also I would note that under the heat shields the exhaust isn't perfectly round so just clamping onto that, if possible, wouldn't result in the best seal

 

where your blue mark is is exactly where mine were cut.Now I know if i managed to get the heat shields off I wouldnt have a round pipe to hook onto.The edge of pipe that is even where it is cut letting the mufflers be removed is jagged, probably a reducer would have to go inside with the other end larger to go into some muffler.I think that would be the easiest route.