Honda quad question

[handirifle]

Tomorrow I will give it one more try, bleeding that is, and I will rig up some sort of gravity fed reverse flow. The logic, to me, is sound. The bubbles are tiny any since bubbles migrate upwards naturally, I figure it's worth a try.

I will update. I was going to pull apart the master cylinder but have since learned they can be a bear to take apart, so I am hesitant, and hopeful it's a bleed issue. I will see.

I will post results.

 

[dfkrug]

I can't remember what size the slow jet was but I did go up one and then readjusted
the mixture screw. I didn't have to change the clip as mid revs the engine seamed to be fine. I had to reduce
the main jet from a 130 down to a 120, it's easy to identify using the plug if it's rich or lean. There's an order to
what to adjust first. Without a kit with lots of jets it's a slow process.

You are right, it is a lot of work. BTDT. Most folks don't have the patience, even if they know how. There
is also the "redneck repair" where you carefully increase the aperture of the jet using the tiny round files
normally used for torch nozzle cleaning. You can only make them bigger, however. My 96 TRX300 starts
and runs great, 4y after the big rebuild.

RE Honda brakes, when all else fails, replacement wheel and master cyls are quite reasonably priced. I have
also successfully sustituted new Chinese hand brake/master cyls, as well as Chinese rear m/cs.

One bleeding problem I have found on older neglected quads is that crystallized or dirty old fluid can cause
restrictions in the brake lines. Fluid may pass thru them, but air bubbles hang up. Sometimes you need
to clean out or replace the hoses.

I have successfully "gravity-bled" some brakes, where you do not even open the bleeder at the
wheel cyl at all. You let the air bubbles naturally rise to the m/c. This does not always work, AND
there can not be any restrictions. I do not use any special tools or pumps.

 

[crazyal]

If the caliper piston is out one ting you can do is leave the bleeder open for a little while (just make sure the reservoir doesn't run low). Gravity will make the brake fluid run from the mater down to the slave. As it does it will help get the major pockets of air out of the line. Then tighten the bleeder and then push the piston in as far as it will go. This will push most of the fluid back up to the master. Any air trapped in the master will get pushed out. From there you should be able to bleed it. It can be messy though. With a quad you would need to do it to both calipers and when you push one piston in you'll need to put a c-clamp or something else to keep it from coming out when you push the other in (assuming they use the same master and brake hose).

 

[handirifle]

If the caliper piston is out one ting you can do is leave the bleeder open for a little while (just make sure the reservoir doesn't run low). Gravity will make the brake fluid run from the mater down to the slave. As it does it will help get the major pockets of air out of the line. Then tighten the bleeder and then push the piston in as far as it will go. This will push most of the fluid back up to the master. Any air trapped in the master will get pushed out. From there you should be able to bleed it. It can be messy though. With a quad you would need to do it to both calipers and when you push one piston in you'll need to put a c-clamp or something else to keep it from coming out when you push the other in (assuming they use the same master and brake hose).

No calipers, it has drum brakes.

I rigged up 2 different systems today, with limited success. One, I got off youtube, where I placed an open container of brake fluid well above the MC and connected to bleeder fitting. Opened the fitting, and slightly jiggled the brake lever to release tiny air bubbles. This worked very marginally.
The second was I used the same setup, but with a sealed plastic water bottle containing brake fluid, and with the line still connected to the bleeder screw.
I squeezed the bottle to provide back pressure up to the MC. This worked much better and I saw a lot more air come out than I suspected was in there.

I actually now have about 30-35% of brake pressure in the front, so obviously, there is still air in there. I like the reverse bleed methods because it sends air bubbles the direction they naturally want to go. I am just not sure they will ALL get past the rubber cups inside the MC, to the reservoir.

At least I am making SOME progress. What a PITA this has been. I rebuilt the entire brake system on an old Heald Hauler, that I restored, last year, and I thought that was tough to bleed. It was simple compared to this.

 

[handirifle]

I have looked at the vacuum types, and the only problem I have with those, is the possibility of emptying the reservoir like I did before and caused all this crap to happen in the first place. Thus I am doing the reverse flow methods. I would like to find a method to cause a bit more pressure than I can make by squeezing the water bottle. That was very productive this morning, but there is still a bit more.

 

[HHR]

You can also try cracking the line fittings loose at each junction while applying brake pressure. Sometimes bubbles of air tend to gather around restrictions in the lines.

 

[handirifle]

I thought of that but I hate the mess brake fluid makes on stuff.

 

[mikehaugen]

The problem I have had with vacuum bleeding (on cars anyway) is that when you crack open the bleeders after attaching the suction line, air gets sucked in through the threads of the bleeder. I spent a lot of time pumping the first time I tried this before I figured out what was going on... I just couldn't stop getting bubbles! :laughing:

 

[dfkrug]

The problem I have had with vacuum bleeding (on cars anyway) is that when you
crack open the bleeders after attaching the suction line, air gets sucked in through the threads of the bleeder.

That is why I do not do it either.

When a brake system is neglected, but still working, and you introduce air into the system accidently, I have
found that difficult bleeding is usually due to crud in the system making tiny bubbles unable to move.
The crud is in the lines (as mentioned above), the m/c, and/or the wheel cylinders. Could be all three. There
is no avoiding complete disassembly when this happens.

I just drained/replaced the fluid in my 88 Samurai dumptruck, and 3 of the 4 bleeder nipples would not pass
fluid. So I removed them entirely, and let the wheel cyls drain, while adding fluid to the reservoir. You can
get away with this as long as the system is under positive pressure, slight tho it was. The small orifice in the
wheel cyls and the positive pressure keeps air from getting in. The nipples were corroded badly.

 

[KubotainNH]

I actually now have about 30-35% of brake pressure in the front, so obviously, there is still air in there. I like the reverse bleed methods because it sends air bubbles the direction they naturally want to go. I am just not sure they will ALL get past the rubber cups inside the MC, to the reservoir.

At least I am making SOME progress. What a PITA this has been. I rebuilt the entire brake system on an old Heald Hauler, that I restored, last year, and I thought that was tough to bleed. It was simple compared to this.

You got more now at least. The small reservoir does make things tougher. Curious, can you pump the brake up by pulling the lever a few times? When I got my 4 wheeler it was beat and the lines were completely empty for years. I do recall fighting to get the air out but was eventually successful with pumping it up and cracking the bleeder while under pressure. The air should go out first. This did take patience and just opening the bleeder a tiny bit so air would be pushed out and fluid would just barely dribble. Then I would close the bleeder and pump it up again. It's been solid for years now.

Sorry if I'm telling you something you already tried. One more thing, make sure you have the shoes adjusted properly. I think you mentioned it working before getting air in so just another thought.