New project GR650

[radianrider]

Originally Posted by Pablo83

what type of sprocket did you use to regear your bike?

I used a Suzuki OEM 16-tooth sprocket from mid-80's dirt bike as per the advice below:

"How can I reduce vibration at highway speeds?
Exchange the factory 15 tooth countershaft sprocket with a 16 tooth (Suzuki part number 27511-37200). The last time I purchased one it cost about $16. Note that this sprocket was originally used on a mid-eighties Suzuki motocross model and is designed for #520 chain, rather than the GR650's standard #530 chain. That means it is slightly thinner than the original sprocket. My experience has shown no problems with excessive wear when used with the #530 chain. Since the sprocket is thinner than standard, you will need to add a washer between the sprocket and lock washer when installing. If you don't, the sprocket will remain loose on the countershaft splines even after you torque the sprocket nut. With the new 16/38 gearing, expect 4700 RPM at 65 MPH verses slightly over 5000 with the stock 15/38 sprockets - with no noticeable loss in performance or problems clutching off from a stop light. At 65-70 MPH, you will be below the point were engine vibration and valve train noise becomes an issue."
http://tcmcstuff.tripod.com/GR650FAQ.htm

Worked on my bike, but I think I paid about $6.00 more.

[radianrider]

Well, put the GS500 master cylinder on, after getting a glass piece to repair the sight glass window that collapsed when I touched it.

$15 for a piece of glass, two screws and an instruction sheet. Bit steep, but it did work properly. No leaks from the window.

Problem still remains. Too much brake lever travel. Stops okay, but there has to to a leak somewhere in the system that is allowing air in.

Brake lever gets plenty firm if I tie it back overnight, but is soft again within a few hours.

[zap2504]

This is all very curious as there should be no vacuum within the hydraulic system to suck air into the lines - just pressure or lack of pressure (pressure release via the release hole in the MC). If any hydraulic fluid is seeping out (and being replaced by air) you should see the dampness somewhere.

You said "Assembled a stainless steel brake line and installed it." Was this a universal line and you added 10mm banjo fittings or was this a "raw" line that you crimped banjo fittings to? 1 line or 2? Maybe one (or more) of the fittings are leaking? You could try testing out the old brake lines to see if there is any difference. Maybe pull off the dust boots for the caliper and MC to see if there is any fluid behind them? You said that you removed some extra banjo washer(s) and re-tightened some connections - maybe the washers are too deformed/scored and should be replaced?

[radianrider]

Originally Posted by zap2504

This is all very curious as there should be no vacuum within the hydraulic system to suck air into the lines - just pressure or lack of pressure (pressure release via the release hole in the MC). If any hydraulic fluid is seeping out (and being replaced by air) you should see the dampness somewhere.

You said "Assembled a stainless steel brake line and installed it." Was this a universal line and you added 10mm banjo fittings or was this a "raw" line that you crimped banjo fittings to? 1 line or 2? Maybe one (or more) of the fittings are leaking? You could try testing out the old brake lines to see if there is any difference. Maybe pull off the dust boots for the caliper and MC to see if there is any fluid behind them? You said that you removed some extra banjo washer(s) and re-tightened some connections - maybe the washers are too deformed/scored and should be replaced?

I purchased the parts for the stainless lines from Earl's on Gasoline Alley in Indy and assembled the lines. No evidence of leaks anywhere in the line or fittings.

One line on the GR. I've pulled all boots and checked for leaks. Nothing that I can see anywhere. I've replaced the crush washers every time I've pulled the banjos off.

Don't think I kept the old line---clearly a mistake.

I replaced the piston and cup set in the original MC twice using OEM parts--that gets expensive. Thought I still had a leak in the front MC seal, so purchased an MC from a 2006 GS500 on Ebay and installed that after replacing the sight glass with real glass.

If I tie back the lever and leave it overnight the lever firms up nicely. Within a couple of hours after taking it off--soft lever pull again. Brakes work okay, but the lever travel is very long. It was doing the same thing with the old MC.

Driving me crazy.

[vtwin]

Sounds like i still needs bleeding. Try this, remove the cover and slowly, I mean slowly like a sundial, squeeze lever and release just as slowly. Sometimes the removes the last bit of air. Watch the fluid and return passage and you may just catch the one or two bubbles coming out. Good luck.

[zap2504]

...and try turning the handlebar all the way to the left while the bike is on the sidestand. This will put the MC high in the air and will aid in getting bubbles out of the system.

[radianrider]

I'll try anything at this point. Next step is to tear it back down and start all over again.

[radianrider]

Had dinner with a bunch of vintage bike types the other night. They think the only place the air can be getting in is around the piston in the caliper.

Armed with that...I took it off and tore it completely down today. Nothing looked wrong, but I cleaned it again, lubed up the seals with brake fluid and put it back together.

Had no brake pressure and no braking at all after I got done. Great.

Took the caliper back off and found that one of the clips had slipped out of place while I was busy fighting to reinstall the brake pads. Got that back in place and it seems to be working a bit better. Not enough better yet to think I've solved the issue---been down that rabbit hole a couple of times this summer---but maybe enough to confirm that is where the air was entering the system.

Tied the brake lever back and am letting it sit overnight to see if that old trick will give me some braking power. If yes, but not enough, I'll get a new piston seal and redo it. The one on there is an OEM stye from Suzuki and I bought it new earlier this summer.

Here's hoping for a better outcome. Stopping well seems like such a good option.

[SprintSix]

Remove caliper from fork. Compress the piston, air hides there. Hang with line as straight as possible. Use a vacuum pump, go slow. Compress the diaphram on the masters cap before installing.

If you have not rebuilt your "new" master, do so.

I hear the syringe method works well also.

For the record I only got it right once on my gr. Then i switched front ends (gs1100e, dual disk) and was back to square one on the brakes. Suzuki brakes of that era just plain suck. You could try what im doing and swap a front end from a different maufacturer with a better brake system.

[radianrider]

SprintSix,
It may come to that, but I'd like to win the war I've been waging all summer with this one. I am beginning to understand the definition of madness "doing the same thing over and over while expecting a different result."

Beginning to believe it is the caliper piston seal that is allow air in, but not leaking fluid out.

I may have made some progress today, but if not--new seal will be ordered.

[vtwin]

Originally Posted by radianrider

SprintSix,
It may come to that, but I'd like to win the war I've been waging all summer with this one. I am beginning to understand the definition of madness "doing the same thing over and over while expecting a different result."

Beginning to believe it is the caliper piston seal that is allow air in, but not leaking fluid out.

I may have made some progress today, but if not--new seal will be ordered.

I believe some caliper seals do have a direction. Some are square cut, others have a taper cut and that should face into the caliper.

[radianrider]

Originally Posted by vtwin

I believe some caliper seals do have a direction. Some are square cut, others have a taper cut and that should face into the caliper.

Well, I've ordered a new piston seal and a dust boot seal. Hoping the second time is a charm. Pretty sure that is where the air leak has been all along.

I'll pull the caliper to clean and paint it before the parts get here.

[radianrider]

Well, no joy in Mudville. Probably less braking power with the GS500 MC than with the original. No air bubbles and no brakes to speak of. I just don't get it.

Vtwin, when you switched yours out, do you remember if the MC shot fluid into the air while pulling the lever back? I'm getting no sense that the MC is doing much to move the fluid in the lines.

My old MC used to shoot fluid into the air if I pulled the lever back without the cap on the MC, the new one doesn't.

[Fire Escape]

Originally Posted by radianrider

Well, no joy in Mudville. Probably less braking power with the GS500 MC than with the original. No air bubbles and no brakes to speak of. I just don't get it.

Vtwin, when you switched yours out, do you remember if the MC shot fluid into the air while pulling the lever back? I'm getting no sense that the MC is doing much to move the fluid in the lines.

My old MC used to shoot fluid into the air if I pulled the lever back without the cap on the MC, the new one doesn't.

I believe that each of my master cylinders has made that verticle 'spurt' unless I remembered to be cautious and squeeze slowly, memory isn't always that good. Have you considered removing the brake 'system' (intact) so that you can suspend it with NO loops and let the air migrate. It is hard to believe that you have been through that many master cylinders/rebuilds without any of them working. It is not hard to believe that there is still a bubble of air in there somewhere and it really does not 'like' to go downhill or through constricted passages like tee's and couplings. I have suspended a caliper above the mc (yeah, fill it and leave the cap on) in the past with the bleeder at the absolute highest point. After a couple of days being 'ignored' it did bleed out OK. You could also do it with the MC at highest point and inject fluid into the bleeder. Stretching (not literally in length but enough to get most of the bends out of the system) out the system has helped me in the past.


Brce

[radianrider]

Here's what mine looks like. The clicking is the brake light switch.

http://www.youtube.com/watch?v=hTAir...&feature=g-upl