Clutch Return Hole

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DocDoom

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Hey all, Merry Christmas Eve and happy holidays to those to which the former doesn't apply. I've got a question on the clutch.
Symptoms: when hot and only when hot slips like a bitch, this is exacerbated by excess clutch use such as stop and go traffic. Make your way around stopped vehicle finally and put no power to the ground unless you baby it.
Ruled out: clutch plates. Replaced the thing 80 miles ago, and this existed prior so I thought that was a good first pass and necessary maintenance to do anyway. It's not just second, it's more noticeable in lower gears, and only happens hot so transmission is extremely likely to not be the issue. Especially considering it's only got 20k miles.

I think fluid return from the clutch is the issue so that brings us to the little hole in the clutch cyl. Is this as easy as I think it is? Pop off cover, ream the thing with piano/guitar wire like you don't like it very much, pray you get a good seal on the cap and put it back on? I want to avoid drilling because that's not what mother Yamaha intended and could introduce pressure artifacts. Also obligatory cover everything with towels in case pressure is built up in there. Am I missing something? Of course I'll replace the lines/fluid etc at a later time when I've got time to really go through it. The fluid isn't in bad shape.
 
Give that smaller of the two holes a poke. Don't drill it. Some strand of wire or a pin should do it. Yes to pressure could be building up, and shoot everywhere when you remove the obstruction. What color is the fluid? If it's like black ink (which I doubt, knowing you) and opaque, it's overdue for a full flush.

I've had hoses plug-up on cars, trucks and motorcycles. It could be due to long-term storage, and non-use, or delamination of the inner hose, a motorcycle embolus. I think your symptoms sound like some solid material is migrating to the master cyl hole, and causing an obstruction. If it was a torn inner hose, causing the hose to pass fluid one way, but not to allow it to release, the caliper(s) could lock-up, and then become operable again once you cracked the bleeder.

Merry Christmas to you!
 
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Had the same problem on my Vmax and like Fire-Medic said clear the small return passage, the hole closer to the steering head.

I just used a large sewing needle and stock it in there, brake fluid shot up to the garage ceiling and I took a shower with it. Lesson learned....use a rag to cover the reservoir. I then flushed the clutch system; that was some nasty stuff that came out (bike sat for 12 years). I used my MightyVac pump to do it, didn't have to do the reverse flush. Clutch works great now.
 
Give that smaller of the two holes a poke. Don't drill it. some strand of wire or a pin should do it. Yes to pressure could be building up, and shoot everywhere when you remove the obstruction. What color is the fluid? If it's like ink (which I doubt, knowing you) and opaque, it's overdue for a full flush.
Yessir, will do. The fluid is clean, no telling what level of deterioration in the lines is though, as I changed it right after getting the bike it hasn't had enough time to give me that indicator of detritus from the lines. Does the cover usually go on without much fanfare on these models or should I grab a new gasket for it
 
No need for a cover gasket unless yours is torn or swollen so-badly, it doesn't seal.

An internally-collapsed hose may appear perfectly-fine on the outside, giving no indication of the problem internally, but is incapable of passing fluid both ways due to a full obstruction or allowing flow in one direction but not the other.
 
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Another question to ask is what oil you are using? Dino or Synthetic?

Merry Christmas back at you and a Happy new year.
 
No need for a cover gasket unless yours is torn or swollen so-badly, it doesn't seal.

An internally-collapsed hose may appear perfectly-fine on the outside, giving no indication of the problem internally, but is incapable of passing fluid both ways due to a full obstruction or allowing flow in one direction but not the other.
Yessir, I'll replace those next if this doesn't resolve it.
 
Take a look at your master cyl cap, and how the gasket sits. If you remove the gasket, you can see that there is a small cut to allow venting to the atmosphere on the underside of the cap. The gasket should allow this venting to happen. If the gasket doesn't permit venting, it could affect the fluid dynamics. The system must be vented.
 
Also, make sure you are not over filled! The fluid needs to be able to expand or it will create a run away situation where it will slip more and more as pressure builds in the master creating the same thing as if you were pulling the lever.
 
Also, make sure you are not over filled! The fluid needs to be able to expand or it will create a run away situation where it will slip more and more as pressure builds in the master creating the same thing as if you were pulling the lever.
Well I poked at it. The fluid is just below the lower line when cold. The lack of geisering could be the same because of cold. The pin did not go in very far and I tried quite a few gauges. IDK, I'm gonna say maybe 3-5 millimeters or so. We'll see. I'll keep everyone apprised if the reaming fixed it. That is a good point on the fluid though I never knew that but it makes sense.
 
I had a KZ550 LTD I bought not-running from a LEO where I worked fire-rescue. It sat unmoved, for many months in the parking lot, where people from either service parked their motorcycles.

I made some inquiries, and found out whose bike it was. The LEO had a dead battery on it, and instead of buying a new one, he abandoned the bike, unloved, unwanted. I bought it from him for $200, and after servicing it, I used it for a couple years as the 3rd bike to use. It was a great urban bike, and I eventually sold it.

The reason I mentioned it here, the LTD's had 'pullback' handlebars, which I never found comfortable. I swapped them out for a superbike bend eventually. Before I did, I discovered that if the brake fluid was too-low, the position of the brake master cyl was such that at a fluid level position about where yours is, with the shape of those pullback handlebars the small hole in the master cyl would sometimes be exposed (cavitate), introducing air into the line. Obviously not what you want! I finally discovered this because to easily fill the master cyl, the bike on its sidestand, needed the handlebars to be tilted to one side and not the other. Then I saw how sensitive to brake fluid level those handlebars made things. making sure that the fluid level was at a minimum, at the upper line in the sight-glass,

That was my experience.
 
I had a KZ550 LTD I bought not-running from a LEO where I worked fire-rescue. It sat unmoved, for many months in the parking lot, where people from either service parked their motorcycles.

I made some inquiries, and found out whose bike it was. The LEO had a dead battery on it, and instead of buying a new one, he abandoned the bike, unloved, unwanted. I bought it from him for $200, and after servicing it, I used it for a couple years as the 3rd bike to use. It was a great urban bike, and I eventually sold it.

The reason I mentioned it here, the LTD's had 'pullback' handlebars, which I never found comfortable. I swapped them out for a superbike bend eventually. Before I did, I discovered that if the brake fluid was too-low, the position of the brake master cyl was such that at a fluid level position about where yours is, with the shape of those pullback handlebars the small hole in the master cyl would sometimes be exposed (cavitate), introducing air into the line. Obviously not what you want! I finally discovered this because to easily fill the master cyl, the bike on its sidestand, needed the handlebars to be tilted to one side and not the other. Then I saw how sensitive to brake fluid level those handlebars made things. making sure that the fluid level was at a minimum, at the upper line in the sight-glass,

That was my experience.
That makes sense and I hadn't considered it. I suppose I could reverse bleed and see if there's improvement, haven't had much time to tinker. The fluid was clean though. The clutch gets real spongy when hot.

At this point I'm thinking if there's crud in a 22 year old master cylinder with 22 year old lines blocking the return, I don't want to get into shimming levers or poking and hoping it's a temporary problem [poking so far hasn't yielded much], I should probably just get a new master cylinder, rebuild the old one when it's off and keep it around. While I'm at it I may as well upgrade the lines. It's annoying to replace parts but it's worth it to me to take age/time introduced imperfections out of the calculus. Considering super fine rusty tank detritus had me chasing demons to the tune of several grand and many hours, I'm no longer a fan of half measures.
Plus, if I'm going to open a bottle of dot4 with my dog around and sterilize the bejeesus out of my work area afterwards again, I don't want to be a repeat first time offender trying to save a couple bucks.
 
I had a KZ550 LTD I bought not-running from a LEO where I worked fire-rescue. It sat unmoved, for many months in the parking lot, where people from either service parked their motorcycles.

I made some inquiries, and found out whose bike it was. The LEO had a dead battery on it, and instead of buying a new one, he abandoned the bike, unloved, unwanted. I bought it from him for $200, and after servicing it, I used it for a couple years as the 3rd bike to use. It was a great urban bike, and I eventually sold it.

The reason I mentioned it here, the LTD's had 'pullback' handlebars, which I never found comfortable. I swapped them out for a superbike bend eventually. Before I did, I discovered that if the brake fluid was too-low, the position of the brake master cyl was such that at a fluid level position about where yours is, with the shape of those pullback handlebars the small hole in the master cyl would sometimes be exposed (cavitate), introducing air into the line. Obviously not what you want! I finally discovered this because to easily fill the master cyl, the bike on its sidestand, needed the handlebars to be tilted to one side and not the other. Then I saw how sensitive to brake fluid level those handlebars made things. making sure that the fluid level was at a minimum, at the upper line in the sight-glass,

That was my experience.
Okay so I attempted a reverse bleed, and I found the amount of pressure to get fluid up the line was more or less prohibitive. I was using a clamp and 200ml syringe, and best I could do was make the fluid upstairs jiggle a bit from a couple mls of fluid. Had I tried harder I have no doubt it would have yanked itself out of clamp.

Bleeding the other direction squeezing and cracking certainly worked, and the lever firmed up a bit. The amount of pressure built up after a tiny bit of air escaped was high variance. It would spurt as id expect then kinda not really push much out after a lot of pumping, I also got a better shot at reaming the return hole and that wasn't the magic.

Based on this, I'm thinking either: the piston works unreliably/is sticking in the master cylinder, or the clutch line needs to be triaged for another one. I get pushing fluids upward would be harder than down but it felt hydrolocked from the bottom up.

I guess it could be the slave cylinder not returning from the riding symptoms but I have reverse bled other bikes and it was nothing like that.

In this situation do we vote lines or master, and if I have to open the master to see if it is the master I might as well get a rebuild kit and do it with the lines.

The recommended line replacement in the manual is like what... Every 2 years or something like that [?
 
OMG Dr., nothing like that level of effort! You have a fundamental issue there, and I think what I'd do is to disconnect the metal line and remove the master cyl, and use compressed air to blow-through both ends, trying to get things removed. Of course, you need to blow into some type of containment vessel. Something like a flexible line emptying into a 5 gallon bucket, where the air & whatever's obstructing things can fly-out without going everywhere, ruining your paint, and contaminating your room.

If I had to guess, I'd say that you have a partial failure of the hose inner lining where some of the debris is occasionally obstructing that small, forward pinhole in the floor of the master cyl. Removal of the master cyl from the handlebar, and flushing it out may help removal of anything in the area of the piston, but distal from there, towards the caliper (if you were doing the brakes) or in this case, the slave cyl, you need to disconnect the slave cyl and clear-out the rigid line. I suggest also removing the slave cyl (requires an engine side case cover gasket) to flush it out as-well. Flushing fluids into something which would allow you to see what's removed/drained, wouold show you the potential pieces of what's causing your obstruction.

I'd venture to say that if the rule of replacement is 'every two years,' 99% of us are guilty as-charged.

I have one for you. I bought an old 1974 SOHC Honda 750 from my machinist. It sat unused for years, and in a fit of cleaning up/cleaning out, I decided to move it. I like to be able to stop things that heavy which I put in-motion, and that required disassembly of the caliper and the master cyl. Both put up a fuss to come-apart. One bolt for the caliper halves I had to drill-out repeatedly in different sizes, until the bolt finally was able to come-out. A drill press made this relatively painless, including the use of good drill bits.

1708136590129.png

The second thing was the master cyl had a frozen piston. On a VMax, where the threaded hose female master cyl port comes in at a 90 degree angle, it's harder to do anything to remove the piston, maybe by drilling out the piston shaft from the lever end, or heating up the body and quenching it with PB Blaster in the piston chamber. However, on a SOHC '69-'78 Honda disc brake, the female threaded master cyl port is directly-in-line with the piston.

I thought about what to do, and came-up with a simple, inexpensive tool to drive-out a frozen piston, without having to use heat. Here it is.

1708133074352.png

You see it's a couple pieces of PVC, and the largest solid steel rod which fits into the female threaded end of the master cyl. I used a NPT male plug to give me a better chance of hitting the rod, it's drilled halfway-through the plug length to the diameter/size of the rod. It works well, a couple good whacks and the rod popped-out.

Here is a pic of seeing if my piston removal, bore clean-up and piston replacement was going to work:

1708133450342.png

I used a 1/4" long ratchet extension with something like 220 grit sandpaper wrapped around the ratchet extension , in a cordless drill, to quickly hone out the master cyl. Probably 2 minutes and it was done, checking several times to ensure I wasn't removing too-much from the bore.

That left the hose. It was to OEM rubber hose, not this SS hose pictured here. And like what Dr.Doom may be facing, it was obstructed. Except in my case, the hose appeared to be solidly-blocked. I used a red want & brake cleaner into the end of the hose which seemed open for the longer distance, and the brake cleaner wanted to spurt everywhere after a short spritz. I recommend using a heavy rag or a bunch of paper towels over the end where you're using the red wand. You need to stop the brake fluid from getting everywhere, including your eyes! Also, don't just throw the solvent-laden towels or rags into your trashcan, as you could have a case of spontaneous combustion, and start a fire. Use either a rated waste container w/a spring-loaded lid, or store the soaked rags.towels outside and away from anything flammable.

The next thing I used was a length of spring steel hobby wire smaller than the hose diameter, and I fed the wire into the hose until I hit the obstruction. Using a bit of the old in/out to quote Alex the Droog from Burgess's A Clockwork Orange, the hose was soon opened. I used the red wand and brake cleaner until the liquid was running clean. Then I flushed it with a bit of fresh brake fluid, and assembled things as you see to test the work. No leaks, the caliper worked and retracted properly, and what had been an inoperable system, was returned to service, as a functional disc brake suitable at-least for stopping a roll-around bike.

There is another part to this about using a lever-action grease gun to dislodge the one moving piston of a SOHC Honda fixed piston/moving piston brake set-up. Open the bleeder valve, and inject the caliper until the piston pops-out. Many people use an air compressor to remove piston(s) but they only generate up-to about 160 psi, while a lever-piston grease gun can approach 2,000 psi. I've never lost to a stuck piston using the lever-action grease gun, once the compressed air doesn't pop-out the piston.

1708136528279.png

I hope this helps.
 
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OMG Dr., nothing like that level of effort! You have a fundamental issue there, and I think what I'd do is to disconnect the metal line and remove the master cyl, and use compressed air to blow-through both ends, trying to get things removed. Of course, you need to blow into some type of containment vessel. Something like a flexible line emptying into a 5 gallon bucket, where the air & whatever's obstructing things can fly-out without going everywhere, ruining your paint, and contaminating your room.

If I had to guess, I'd say that you have a partial failure of the hose inner lining where some of the debris is occasionally obstructing that small, forward pinhole in the floor of the master cyl. Removal of the master cyl from the handlebar, and flushing it out may help removal of anything in the area of the piston, but distal from there, towards the caliper (if you were doing the brakes) or in this case, the slave cyl, you need to disconnect the slave cyl and clear-out the rigid line. I suggest also removing the slave cyl (requires an engine side case cover gasket) to flush it out as-well. Flushing fluids into something which would allow you to see what's removed/drained, wouold show you the potential pieces of what's causing your obstruction.

I'd venture to say that if the rule of replacement is 'every two years,' 99% of us are guilty as-charged.
Sorry it's 4 years, service manual section 2-3 paragraph/note 1 point 3. I remembered incorrectly.

Okay. So, no compressed air on hand but I do have those plugs used to clear condensate lines with c02 cartridges so that'll work.

So, maybe it's the line gunking stuff up then, but inspect/clear out the master and slave cylinders... If I have them out I may as well rebuild them. Side note, on the diagrams for the master cylinder for instance, there's a grouped part number that looks suspiciously like most of a rebuild kit, is that official or are these mostly an aftermarket item and Yamaha would prefer to sell the subassembly?

Then there's the line. So if what I'm understanding is true, I should probably replace that too.
 
Yes the pieces are in the kit as a subassembly, cheaper than buying a complete new slave cyl.

Once you have the piston out and clean up the master cyl, you can see if there's any corrosion or bad pitting on the master cyl wall. You can attempt to sand down the bore to remove any pitting, but I think in that case (significant pitting), I'd just as-soon replace the master cyl as a complete piece.

Yes I think K&L or All-Balls may sell a rebuild kit, besides the kit being avail. from Yamaha.
 
As FM suggested, something must be plugged.

In addition to the banjo bolts/lines, perhaps the bleed screw might be plugged by corrosion?
That's a good thought, I thought that too but it really only seems to be a moving toward upstairs problem, standard bleeding with the ol wrench and squeeze makes the bleed screw lively. The opposite isn't true. When I replace the assemblies and lines though I'll prolly give all the stuff still attached a good wiring with a Dremel though.
 

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