'86 VR rear master cylinder prime?

[BlueChips84]

Hi all,

 

I have been having a problem with my rear master cylinder not pumping on my '86 venture royale. I had the brake system fully disassembled for rebuilding and inspection and it seems that I have gotten air in to the rear master cylinder. It will no longer draw fluid from the reservoir. It did draw some when I bled the rear caliper but then stopped after a bit. Is there a trick to re prime the MC to get it pumping again? It was working before disassembly and the return hole is clear of obstructions.

 

Once I have her back together I'll post the mandatory pictures:cool:

[BlueSky]

I just had a similar problem with my 07. The problem was that the bellows or diaphragm under the MC cover had become loose and was on the bottom of the reseroir blocking the fluid from going to the MC.

[cowpuc]

Did you remember to bleed the system from the highest spot of the rear brake system up on the neck?

[BlueChips84]

I just had a similar problem with my 07. The problem was that the bellows or diaphragm under the MC cover had become loose and was on the bottom of the reseroir blocking the fluid from going to the MC.

 

For easier access, I pulled the revoir out and removed the cal and diaphragm to fill more easily, so not that. I can see how it would happen though.

[BlueChips84]

Did you remember to bleed the system from the highest spot of the rear brake system up on the neck?

 

That is the point I am attempting to bleed now. The rear caliper has fluid in it but when I went to bleed the high point by the handlebars it is no longer pumping. Tried for an hour.

 

I topped the reservoir up with fluid and cracked the top bleed nipple overnight to see if maybe gravity will help things prime. Will try it again tonight.

[Pasta Burner]

I just had a fight with my 87 rear system. I didn’t run into the specific problem you’re having but I went out and bought a mitivac to do the job myself instead of begging the wife or kids to come help. It worked really well. Are you also bleeding in the correct sequence? Front left caliper, rear caliper, high point? I wasn’t doing it correct at first.

 

https://www.harborfreight.com/mityvac-vacuum-pump-39522.html?cid=paid_google%7C%7C%7C39522&utm_source=google&utm_medium=cpc&utm_campaign=&utm_content=&gclid=EAIaIQobChMI5tWniJqJ6wIVXD2tBh2GBQDrEAQYAiABEgIknPD_BwE

 

 

https://www.venturerider.org/forum/showthread.php?146323-Rear-caliper-dragging/page2

[BlueChips84]

I just had a fight with my 87 rear system. I didn’t run into the specific problem you’re having but I went out and bought a mitivac to do the job myself instead of begging the wife or kids to come help. It worked really well. Are you also bleeding in the correct sequence? Front left caliper, rear caliper, high point? I wasn’t doing it correct at first.

 

https://www.harborfreight.com/mityvac-vacuum-pump-39522.html?cid=paid_google%7C%7C%7C39522&utm_source=google&utm_medium=cpc&utm_campaign=&utm_content=&gclid=EAIaIQobChMI5tWniJqJ6wIVXD2tBh2GBQDrEAQYAiABEgIknPD_BwE

 

 

https://www.venturerider.org/forum/showthread.php?146323-Rear-caliper-dragging/page2

 

I was actually doing it in the reverse order which likely does not help but I did not think it would cause an air lock or loss of pumping.

 

I will try and stop by the local Princess Auto and grab a vacuum pump and/or a reverse bleed kit, hopefully that will help. If nothing else it will make like easier as the wife is too busy with the three kids to help on the bike.

[Pasta Burner]

Two more tips that really helped me are using a condiment bottle to dispense into the MC and sealing the bleed screw threads with some lithium grease to prevent sucking ambient air through the bleeder.

[CaseyJ955]

I had the same issue (brakes delinked). I have replaced the rear caliper for one off the front of an R6, still no joy. I removed the caliper and lifted it up and positioned it so the bleeder was as high as I could get it. That seemed to do the trick.

 

Before I did the bleeding I gently pushed the pistons back enough to get a piece of ceramic tile between the pads, tile being only slightly thicker than the rotor it worked and the caliper slipped back on nice and easy. Even vacuum bleeding did not work for me on this one.

 

I did that a couple years back and I noticed it's a little soft again this spring.

Edited August 7, 2020 by CaseyJ955

[BlueChips84]

Thanks for all the help guys!

 

I managed to get things going after I bought a large syringe at PA that is meant for measuring two stroke oil. I removed the hose from the reservoir and clamped the hose around the syringe nipple and pressurised the system that way. Eventually it took prime and was pumping properly, expelling 30yo chocolate milk looking fluid. Amazingly everything cleaned up well and was clean I sure afterwards.

 

It also appears that if you bleed the top point first before the front caliper, the fluid will run down the line and fill the front caliper before coming out the bleed valve by the steering neck. Probably another reason I felt like I was pumping forever. On the bright side, I did get to teach my 9yo son how to bleed brakes. Now he wants to bleed the rest, even though they are done now, he looked disappointed.

 

Now it's time to get her all back together and decide what to do. I sat on a 2007 RSTD yesterday and really liked it, especially the low centre if gravity. Just not sure is if I'll miss out of the sport like handling of the Gen 1 though! Those gen 2's are smart looking bikes.

 

Pics coming once I reach 20 posts, eventually.

[cowpuc]

Thanks for all the help guys!

 

I managed to get things going after I bought a large syringe at PA that is meant for measuring two stroke oil. I removed the hose from the reservoir and clamped the hose around the syringe nipple and pressurised the system that way. Eventually it took prime and was pumping properly, expelling 30yo chocolate milk looking fluid. Amazingly everything cleaned up well and was clean I sure afterwards.

 

It also appears that if you bleed the top point first before the front caliper, the fluid will run down the line and fill the front caliper before coming out the bleed valve by the steering neck. Probably another reason I felt like I was pumping forever. On the bright side, I did get to teach my 9yo son how to bleed brakes. Now he wants to bleed the rest, even though they are done now, he looked disappointed.

 

Now it's time to get her all back together and decide what to do. I sat on a 2007 RSTD yesterday and really liked it, especially the low centre if gravity. Just not sure is if I'll miss out of the sport like handling of the Gen 1 though! Those gen 2's are smart looking bikes.

 

Pics coming once I reach 20 posts, eventually.

EXCELLENT CHIPS!!!! GOOD ON YA!!! :thumbsup:O

 

Concerning the pics.. There are numerous lop eared VR mc club member varmints who can neither read nor write so one of our hidden club codes are that pics/videos are a must have... I may been wrong but I think our leader/Bossman actually reduced the post requirements for pic posting recently to 10 post so it may not be a bad idea to give it a shot at this time.. Speaking of club pics,, in the past some have had issues posting pics and the vast majority of the time, IMHO, this is a result of trying to upload to big of pictures.. I made a short video of solutions I have found to assist in this that has actually helped a couple varmints (I do customarily get more death threats over my vids than compliments but this particular video I actually did recieve a couple thank you's for so I know it might be safe) - here is a copy/paste of that vid should you get to a point where pic posting becomes an issue..

[BlueChips84]

I'm going to try linking from my image host site, Imgur and see if that works.

 

My daughter told we we had to call her Marshmallow, seeing as how my other bike is named Fudge (model is a '90 FJ600). So I present Miss Marshmallow in all her glory. Got her and a parts bike together Both were non running but since fixed and in various pieces. After some new fluid, tires and seals, brake rebuilds and scavenging a few parts, Ms. Marshmallow is now fully dressed and ready for a safety. She just needs a few new rubber grommets for mibor cosmetic fixes and to touch up the soldering on the CLASS system. I appreciate all the help so far getting her going!

 

Edited August 12, 2020 by BlueChips84

[Marcarl]

Sure is a pretty lookin scooter.

There's only a very few white ones around.