Wagner Master Cylinder issue
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
I cleaned them as thoroughly as possible with Brakleen. The return hole is perfectly round and I can see light through it. The only way to make it flow any better would be to drill it larger, so I assume my issue is in the bore. It just seems odd to me that it only happens with fluid introduced.
HDF Community Team
Joined: Dec 2005
Posts: 5,421
Likes: 2,621
From: NC USA
Stuck on bottom of full stroke is very common when bleeding new or old system. If you do it many times on an old dirty system it'll damage things.
Use quick 1/2 - 3/4 travel strokes to pump until you get some resistance, then don't let it go fully collapsed when bleeding down. Sometimes it helps to have a block or stop setup so you don't go too far. Then pump fast several strokes, hold, quick bleed (probably won't get anything) then slowly let it up. Do that a few times and walk away, let it bubble and go again.
Never had much luck with vacuum pumps for bleeding but if you have one, sometimes it helps to get "some" fluid into the master cylinder to get things started.... good luck.
Use quick 1/2 - 3/4 travel strokes to pump until you get some resistance, then don't let it go fully collapsed when bleeding down. Sometimes it helps to have a block or stop setup so you don't go too far. Then pump fast several strokes, hold, quick bleed (probably won't get anything) then slowly let it up. Do that a few times and walk away, let it bubble and go again.
Never had much luck with vacuum pumps for bleeding but if you have one, sometimes it helps to get "some" fluid into the master cylinder to get things started.... good luck.
Thread Starter
|
Cruiser
Joined: May 2013
Posts: 129
Likes: 8
From: Norfolk
Stuck on bottom of full stroke is very common when bleeding new or old system. If you do it many times on an old dirty system it'll damage things.
Use quick 1/2 - 3/4 travel strokes to pump until you get some resistance, then don't let it go fully collapsed when bleeding down. Sometimes it helps to have a block or stop setup so you don't go too far. Then pump fast several strokes, hold, quick bleed (probably won't get anything) then slowly let it up. Do that a few times and walk away, let it bubble and go again.
Never had much luck with vacuum pumps for bleeding but if you have one, sometimes it helps to get "some" fluid into the master cylinder to get things started.... good luck.
Use quick 1/2 - 3/4 travel strokes to pump until you get some resistance, then don't let it go fully collapsed when bleeding down. Sometimes it helps to have a block or stop setup so you don't go too far. Then pump fast several strokes, hold, quick bleed (probably won't get anything) then slowly let it up. Do that a few times and walk away, let it bubble and go again.
Never had much luck with vacuum pumps for bleeding but if you have one, sometimes it helps to get "some" fluid into the master cylinder to get things started.... good luck.
HDF Community Team
Joined: Dec 2005
Posts: 5,421
Likes: 2,621
From: NC USA
Been too long for my memory and you didn't mention the year or model. The master valves changed in '73 and won't work with drum brakes.Did you carefully inspect the new parts against the old? I'm thinking the check valve is different and not letting it return. I've had that happen on automotive m/c's a few times over the years - wrong parts in a kit. Again, just throwing out ideas - you're there, I'm not.
Thread Starter
|
Cruiser
Joined: May 2013
Posts: 129
Likes: 8
From: Norfolk
Been too long for my memory and you didn't mention the year or model. The master valves changed in '73 and won't work with drum brakes.Did you carefully inspect the new parts against the old? I'm thinking the check valve is different and not letting it return. I've had that happen on automotive m/c's a few times over the years - wrong parts in a kit. Again, just throwing out ideas - you're there, I'm not.
Thread Starter
|
Cruiser
Joined: May 2013
Posts: 129
Likes: 8
From: Norfolk
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Thread Starter
|
Cruiser
Joined: May 2013
Posts: 129
Likes: 8
From: Norfolk
I actually just saw another thread that mentions JPCycles rebuild kits come with o-rings that may be too thick and bind the system. The thread was over 10yrs old, so it seems insane that it may still be happening. This would be an easy fix, and explain my frustrations since everything else seems to be perfect/normal, but I wont be able to check for myself until next week.
Intermediate
Joined: May 2022
Posts: 48
Likes: 41
From: Hickory, NC
Recently I had exactly the same issue, except mine are disc brakes.
I rebuild calipers, master cylinder, rubber lines, and cleared metal lines.
My master cylinder acted exactly as you described. I did all the things you did with the m/c.
After at least 10 unsuccessful attempts at bleeding, I threw up my hands in surrender and ordered a NEW m/c. First bleed after install and the system worked perfectly!
I rebuild calipers, master cylinder, rubber lines, and cleared metal lines.
My master cylinder acted exactly as you described. I did all the things you did with the m/c.
After at least 10 unsuccessful attempts at bleeding, I threw up my hands in surrender and ordered a NEW m/c. First bleed after install and the system worked perfectly!