Clutch problem

I have been bleeding and adjusting clutch lever, but at mornings pressure is almost gone. After a while it starts to build pressure anyway and clutch is working normally and lever is also firm and normal. (When engine is warm??) We still have quite cold nights here..is it relevant to the issue ? Clutch is overhauled last year, so inside plates etc is all ok. fluid is not leaking from anywhere. What can cause pressure lost ?? Master cylinder repair kit just installed, so can it be something wrong with work cylinder ?? Or is there still air in system..i have bleeded clutch all the ways i know, like 20 times.. so i doubt that. Please advise if similar experiences

Sounds like you do need another bleed, this time, do a reverse-bleed, using a syringe attached to the slave cyl bleeder to push fluid from the bottom-up to the handlebar master cyl. There are many threads on this if you use the search function.

Doing the reverse-bleed sequence, you should almost immediately be able to build functioning pressure in the system. Just make sure you start out w/the handlebar master cyl holes in the bottom of the m. cyl covered w/fluid, and monitor the level there to avoid overflowing the fluid as you push fluid from the slave cyl to the master cyl. The master cyl reservoir cap is normally off when doing the reverse-bleed.

If there is trapped air in the system, as you reverse-bleed, you should get big air bubbles from the master cyl reservoir big hole and small 'fizzy' bubbles from the tiny hole closest to the banjo bolt where the hose is fastened.

As you see the master cyl fill w/fluid, siphon it out while still maintaining enough fluid to keep the holes covered w/fluid. When you no longer see any bubbling, either big or small ones,, close the slave cyl bleeder, and top-off the handlebar master cyl to the 2/3 filled level, re-cap the master cyl, and then rapidly work the clutch lever repeatedly, until you feel the normal resistance and amount of free play before the clutch begins to disengage.

No, temperature shouldn't play a role in the loss of pressure.

I have done reverse bleed, pressure was perfect after that, but after a while it feels like there is air in the system again..

Take a good look as to how the clutch line is routed from the master cylinder to the slave cylinder. You want to make sure the line from where it bolts up @ the master is the highest point then has a gradual slope down-ward to the slave cylinder connection. Look for any point along the way where the line routing might be raised then slope down-ward this can cause air to be trapped.

Yeah, will check that one more time and do bleeding with syringe from down up to the fluid reservoir..these hydraulics bleeding's can sure be a pain in the ass sometimes

The reverse-bleed has never failed me in 21 years of VMax ownership, and more than that for my Yamaha liter sportbike, which has almost an identical system, and which I've had for 27 years. Quick, and if your system is in good repair, you will be able to ride as soon as you finish, no overnight waiting.

I had good luck with squeezing the lever. ...and wrapping a rag around the lever and handle. Walk away for the night. That way any trapped air in the system with work it's way back up to the reservoir.

Traumahawk said:

I had good luck with squeezing the lever. ...and wrapping a rag around the lever and handle. Walk away for the night. That way any trapped air in the system with work it's way back up to the reservoir.

Click to expand...

That's good if that works for you, or spend a half-hour completely changing the fluid using the syringe while pushing up all air bubbles to the master cyl and go riding the same day. unk:

Great, it takes me 10min push new fluids with syringe..and still the clutch is not working normally after one night. Its good to hear that this system has worked for decades, but it's not working for me this time, and im not a novice in motorbikes repairs.. so not any useful answers so far ...only thing that makes some sense, is that somehow there is still air in system...cant understand how is that possible..I'll carry on my investigation's on this issue

First thing in the morning, try burping the air out of it where the banjo bolt attaches to the handlebar master. Then make sure you have/maintain sufficient fluid level in the master to ensure no air could be reintroduced during any extreme corner riding you may do, yet low enough so that you don't force any to slop out the tiny weep hole in the cover gasket either.

Ok you didn't have results from what was suggested. No mention made of the slave cyl. Have you replaced or rebuilt it after a thorough inspection and cleaning? Evidently you have air entering somewhere after the bleeding. That's why it works ok after a bleed but over time, it reoccurs.

Since you haven't mentioned finding any leaks we will say that's not it. Sometimes a rebuild doesn't work. Replacement of the item is required. The only two items are the master & the slave besides the hose or tubing and their fittings. Bite the bullet, spend the $ and replace both the master & the slave. Have you ever disassembled the system and checked to see if your hose is passing fluid ok?

I did mentioned in my first post that there is no fluid leaks. I havent disassembled whole system, but fluid is passing thru hose just fine when pushing with syringe and also when using airpressure vacuum suction. But like you said, it looks like i must give up and get new cylinders...aaargh!! These old bikes are sometimes expensive to keep in working order, but i would never sell mine, i like it way way too much !. It's here to stay

Well be glad you can still get many parts for them, lots of bikes go to the recycler because the parts aren't easily available, and the owner gives up!

Hi all. first of all, happy to find this forum, the vmax, even getting old it is an incredible bike, having a HD sporster also, I always go back to the vmax, filling cutting the grass with an HD

coming back on this issue, I had this issue, as I wanted to purge the circuit I did and all was working for weeks till I got the no pressure.
then surprise when I opened the cover which was screwed too strong, the pressure came back... I assumed so that, as i'm loosing fluid on the slave cylinder (this I already know), if the air can't enter up under the cover of the master cylinder and the liquid level going a bit down, it is not possible to have pressure due to the lack of air compensating on the other side, I hope it is clear enough. so I re-screwed the cover with a new cover very light.. it worked a bit and again now pressure.. opening again didn't brought this time pressure.. I had to purge the circuit..
point still , all of you who have the issue, be sure the air vent on the top cover of master cylinder is still free, for example if you repainted it might not be.. and be sure not to screw like a crazy like I did
I think I will need to consider the reverse stuff, it is a bit unclear how to do.. but I also need to change the slave cylinder , this is another story when you have to work outside on a parking...

fredouille said:

need to change the slave cylinder

Click to expand...

Saves you the time to rebuild, but is more expensive.

The vent on the master cyl caps.



I realize I should have used a JIS screwdriver to point-out the vent, instead of a phillips, please don't hold that against me!

Instead of using a flathead screw for the master cyl cap, I've used a small hex head with no issues in its ability to properly seal the rubber gasket.

The thread I wrote on reverse-bleeding is straightforward, unfortunately, when the software switched-over to the new hosting system, all the pictures in the post got dumped to the end, instead of being in the narrative. It's a bit harder to follow, but it's worth it.

Read these, and get your plan active:

http://www.vmaxforum.net/showthread.php?t=21799&highlight=clutch+bleeding

http://www.vmaxforum.net/showthread.php?t=22061&highlight=clutch+bleeding

http://www.vmaxforum.net/showthread.php?t=31061&highlight=clutch+bleeding

It's not hard, but I suggest 'reverse-bleeding' from the clutch slave cyl bleeder nipple down by the left engine cover/footpeg.