Seeking advice: 81 GS650EX: rear brake plunger??

[Anonymous]

Hi all,

Man, I just finished sweating, cursing, wrestling my carbs back onto the bike, said a quick prayer, primed it and OH MY GOD!!!!!! It started!!!!! AND IDLED!!! Not perfect but, I am a major novice and did not expect to see this bike run again without professional intervention. Took it for a quick spin and noticed the rear brake was sticking HARD. Back to the shop and out with the Haynes AGAIN. Thought I would start by bleeding the rear break system. but, could not get ANY fluid to come out of the bleed valve (even all the way open.) I first loosened the banjo bolt at the caliper end and that freed the caliper and the rear wheel would spin by hand. But when I tightened the bolt back up, it froze the caliper again.

Called a local Suzy shop and they said to look at the plunger. I pulled the rubber boot back and RUST, DUST, CRAP galore. The reservoir is full (I was anticipating bleeding a lot of fluid through since this had not been done in a year or more), I loosened the banjo bolt at the front (plunger side) of the system and could not get any fluid to come out of that end of the hose.

Questions: does this indicate that I need to replace the plunger unit? What would an expert suspect/check first? This bike sat all winter and most of the spring and I don't know when the brake system was last worked on................bought it last March and rode it only about 400 miles before I pulled to carbs to see it I could work on them and make it run better.

Can anyone advise where to start and if the plunger must be repaired or replaced, where to get part(s)?

Thanks.

[ptm]

Congratulations - it's a great feeling when it starts adn runs after all that work.

As far as the braes, I would start with getting a new piston /cup set for the rear master cylinder. That should be all you need. Number 1 in the schematic http://houseofmotorcycles.bikebandit...id~1015426.asp TH emaster cylinder will have to be completely disassembled, cleaned and the new parts put in.

If the master cylinder is that bad then the rear caliper should be gone over as well. You will need at least the piston seal (number 3), and possibly the piston boots (number 4) http://houseofmotorcycles.bikebandit...id~1018677.asp Again, completely disassemble clean out all the muck and put it together with the new parts.

Follow the directions in the manual and it's not too hard. You might consider going through the front brakes as well - they do most of the work.

[Anonymous]

Paul,

Thanks for the post and the advice. Being the utter novice that I am, I have addl. questions based on what you advised:

I followed the link that you sent. I want to make sure that you understand that the "plunger" I refer to in my post is that part that sits up above and slightly behind rear brake lever and is just a few inches from the rear master cylinder. Your link to Bike Bandit shows the rear caliper assy. and the other link shows the front master cylinder assy. I'm presuming that they also have parts for the rear master cylinder/plunger?

The plunger has this circlip (my name for it, the circular retaining clip that you need that special plier type tool to remove) that can be seen when you pull back this rubber boot. That is where I noted rust, dust and what seems to be crystalized brake fluid. If I can find the tool, I'll take that off and see what's inside (Haynes probably has an exploded view if the thing, just need to look.

I am completely in synch with your advice to go through BOTH brake systems top to bottom (I absolutely DO NOT want to find myself coming up on some immovable object at 75mph realizing I don't have the stopping power I need and wishing I'd taken more time to make sure my brake system was tuned 8O

Again, thanks for your help guy. What part of this wide nation do your tires roll around?

Peace.

[ptm]

Yeah, that's what I get from answering questions so late...

Here's the schematic for the rear master cylinderhttp://houseofmotorcycles.bikebandit...id~1028711.asp Number 2 is the piston and cup set you need.

There are a number of sites that have the schematics for these GSs. Bike Bandit is one http://www.bikebandit.com/partsbandit/ and alpha sports is another http://www.alpha-sports.com/suzuki_parts.htm- You can get a lot of information by looking at the schematics.

I'm from Oregon. Some fabulous motorcycle roads around here.