No pressure building on clutch. Rebuild the reservoir master cylinder?

[Davelaf]

Hi. I'm getting closer to getting O2 back on road after getting rear ended.
Clutch lever reservoir took a beating. I got new cap, filed metal for a good seating. I've tried to bleed it from lower bleed bolt, but pulling lever 5-6 times with it closed pressure doesn't build. Do I need to top line bolt bleed first, a rebuild the master reservoir piston. The foot shift lever and linkage got hammered and replaced. I don't want to do anything down below.
Please help. Thanks

 

[MaxMidnight]

Was it OK before the accident?
If so I'd try reverse bleeding the system first before considering other options.

 

[marsmax85]

Try leaving clutch master top off over night with clutch lever in the pulled position tie it back with zip ties or something..You might just have air in the system if not maybe slave rebuild time

 

[Fire-medic]

Reverse-bleed!

Doing that pushes air bubbles up to the master cylinder reservoir. At first, you see larger bubbles, and as the air is purged, they turn into "tiny little bubbles." Then you get a column of fluid erupting from the bottom of the master cyl. hole when you push on the syringe plunger.

Close the slave cyl bleeder nipple, and a few pumps on the lever of where you're bleeding, and you should have a good, firm feel.

If I am replacing a master cyl for whatever reason, I fill the slave cyl first, before bolting it into place. Follow that with the reverse-bleed, and for me, that is the quickest way to get a firm lever in the least time.

Some reading to assist with your issue:

https://www.vmaxforum.net/threads/brake-caliper-rebuild.50293/page-2#post-504787
See the 'squirt' of brake fluid, and the tiny bubbles?


An 'irrigation syringe' I fabricated using a threaded valve stem/tire nipple with the valve core removed, and with a short piece of 1/4" ID clear tubing. Directions on making it are in the thread. You can also buy a 60 ml (1 ml=1 cc) irrigation syringe at your local pharmacy, or online.



A 60 ml irrigation syringe:



Your local supermarket sells something similar called a 'flavor injector' in the meat dept, or where kitchen utensils are. Note you DO NOT NEED TO USE any needles!

 

[Davelaf]

Was it OK before the accident?
If so I'd try reverse bleeding the system first before considering other options.

Everything worked great on that bike, in fact the 4 hours before I got hit we had adjusted the kick stand safety switch and tightened up the steering bolt. So reverse bleeding sounds like the next step. I'm glad I don't have the right tool to take apart the reservoir pump? or I would have torn that apart unnecessarily. Thanks fellas

 

[Davelaf]

Reverse-bleed!

Doing that pushes air bubbles up to the master cylinder reservoir. At first, you see larger bubbles, and as the air is purged, they turn into "tiny little bubbles." Then you get a column of fluid erupting from the bottom of the master cyl. hole when you push on the syringe plunger.

Close the slave cyl bleeder nipple, and a few pumps on the lever of where you're bleeding, and you should have a good, firm feel.

If I am replacing a master cyl for whatever reason, I fill the slave cyl first, before bolting it into place. Follow that with the reverse-bleed, and for me, that is the quickest way to get a firm lever in the least time.

Some reading to assist with your issue:

https://www.vmaxforum.net/threads/brake-caliper-rebuild.50293/page-2#post-504787
See the 'squirt' of brake fluid, and the tiny bubbles?
View attachment 91594

An 'irrigation syringe' I fabricated using a threaded valve stem/tire nipple with the valve core removed, and with a short piece of 1/4" ID clear tubing. Directions on making it are in the thread. You can also buy a 60 ml (1 ml=1 cc) irrigation syringe at your local pharmacy, or online.

View attachment 91595

A 60 ml irrigation syringe:

View attachment 91597

Your local supermarket sells something similar called a 'flavor injector' in the meat dept, or where kitchen utensils are. Note you DO NOT NEED TO USE any needles!

Hey, I'm going to do this tomorrow. Thanks for the info. One more step.
If I didn't love this bike, I wouldn't probably be doing this. But I like working on Motos. Thanks again.

 

[Fire-medic]

I'm glad I don't have the right tool to take apart the reservoir pump?

I suspect you're speaking of the slave cylinder (#27, below)? Or are you referring to the clutch master cylinder?

The slave cylinder is just a couple of allen head screws (#30, 31, below). A 3/8" drive allen screw bit, and a 12" 3/8" extension will give you access to the slave cyl. behind the middle left side engine cover. Be careful that you have a good, tight-fitting allen wrench fit, because if you bugger the head, you will have an issue to remove the screws.

The clutch and front brake master cylinders use a long-reach external snap ring plier to disassemble it. I have successfully used a slender straight awl/pry tool to remove one side of the external snap ring, and then 'chase' the dislodged snap ring out of the groove until most of it is detached. At that point, the snap ring may pop out, or you can then just use the awl to get the hole of the snap ring to come-out of the groove.


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[Davelaf]

Hi. I'm getting closer to getting O2 back on road after getting rear ended.
Clutch lever reservoir took a beating. I got new cap, filed metal for a good seating. I've tried to bleed it from lower bleed bolt, but pulling lever 5-6 times with it closed pressure doesn't build. Do I need to top line bolt bleed first, a rebuild the master reservoir piston. The foot shift lever and linkage got hammered and replaced. I don't want to do anything down below.
Please help. Thanks

Hi everyone, I put the rebuild kit in. The piston seal wasn't easy. I bleed it, still didn't seem to build pressure. I can't remember if I just kept squeezing lever, or started engine and it worked. YEAH!!!

 

[Redrum]

Hi everyone, I put the rebuild kit in. The piston seal wasn't easy. I bleed it, still didn't seem to build pressure. I can't remember if I just kept squeezing lever, or started engine and it worked. YEAH!!!

Mine has a super slow leak that only appears if it sits for awhile. Adding fluid and pumping the lever works for me to bring back the prime, for now. I keep a small can on the bike just in case. I know I should rebuild it, and will when I have to refill more than once a year. I think it is number 53 on my To Do list.

 

[Fire-medic]

My results over 30 years of VMax ownership is to perform a reverse-bleed to the slave cylinder to easily, quickly get a firm lever.

 

[Davelaf]

My results over 30 years of VMax ownership is to perform a reverse-bleed to the slave cylinder to easily, quickly get a firm lever.

It got form, I just don't know why. I had to put some Slasher pipes I had, (never used them) because the OEM is 2 person job to get all 4 pipes to line up. Put a new front fork brace, OEM, on it yesterday, so had both front and back wheels off. Didn't have any extra nuts and bolts left over either. So, from thinking it was totalled, to rideable. Not sure if I would do that with other bikes.

Mine has a super slow leak that only appears if it sits for awhile. Adding fluid and pumping the lever works for me to bring back the prime, for now. I keep a small can on the bike just in case. I know I should rebuild it, and will when I have to refill more than once a year. I think it is number 53 on my To Do

 

[gentsvmax]

Hi. I'm getting closer to getting O2 back on road after getting rear ended.
Clutch lever reservoir took a beating. I got new cap, filed metal for a good seating. I've tried to bleed it from lower bleed bolt, but pulling lever 5-6 times with it closed pressure doesn't build. Do I need to top line bolt bleed first, a rebuild the master reservoir piston. The foot shift lever and linkage got hammered and replaced. I don't want to do anything down below.
Please help. Thanks

years ago I got a little Mityvac. I use this little pump to reverse bleed the brakes and clutch in minutes.
Google it, get one and be done!

 

[Davelaf]

I think I might get a mightyvac. I got a big syringe, but It didn't work on a reverse bleed. Good for getting old fluid out of reservoirs, but not reverse bleeding. I probably didn't do it right.
Anyway, I need a new to me front wheel, when car shoved me into curb and bike, and me, flew in the air, it tweaked it pretty good. If it's got good rubber, great, if not, I think it's last thing to fix.
I know the "Slasher" pipes aren't very well liked, I put a set on that came extra with bike, and I thought they sounded pretty good. I've got the Stage 7? Jet kit in, so hopefully everything is copacetic between everything. Thanks for the help.

 

[Fire-medic]

As I am a proponent of the reverse-bleed, you probably didn't perform it correctly. You need to use either a spring-steel clamp or a small hose clamp to hold the short piece of 1/4" clear plastic tubing onto the bleeder valve for the clutch, or at each caliper bleeder. As you push fluid into the opened bleeder valve, you will see the master cyl reservoir begin to fill, probably with dark, contaminated brake fluid. That's good, but be careful not to let it overflow, spilled brake fluid is a good way to ruin painted items. If you continue to remove old contaminated fluid from the master cyl reservoir, eventually you will see the new fluid you're injecting will be clear, w/very little contamination remaining. The bubbles will go from bigger bubbles as the air pockets are flushed-out, to 'tiny, little bubbles' at which point, you can close the bleeder valve. Fan the lever rapidly a few times, bleeders closed, and you should have a firm front brake lever, or a properly-operating clutch.

The Cobra 'slasher' pipes, as you call them, are one of the best-looking and worst-performing pipes for our bikes. They cost you ~10% or more of the average RWHP you have. The Stage 7 kit does nothing to help overcome the deficit of the 4-into-4 'slashers.' Unfortunately, the only thing you're 'slashing,' is your RWHP! But, your bike, your choice on what to do with it, and how to do it.

If you want to keep the 4-into-4's, I'd remove the Dynojet Stage 7 kit in its entirety, and put it on here for sale, for a couple hundred bucks. Get some money out of it.

Look on here in the search function to compare your Stage 7 needle shape with the comparison chart Sean Morley did. It shows many OEM needles for both the VMax and the Venture, and the aftermarket companies: Factory Pro, Dynojet and others. That way, you can see what exactly you have in the way of 'kit' for your carbs. Take-off one of the CV caps on the side of your bike, remove the slide, and the screw holding the needle in-place. Compare the needle you have, to the ones in Sean's picture. You might be surprised to find out what you have, over what you were told you have.

Note some needles have several grooves for adjusting the gas mix by placing the internal e-clip into another position. Moving the e-clip towards the pointed end richens the mixture while moving the e-clip towards the blunt end leans the mixture.

Here it is, saving you time.



A simple chart of the most-common choices:



Be aware there are no Stage 2-Stage 6 needles or kits!

 

[MaxMidnight]

You need to use either a spring-steel clamp or a small hose clamp to hold the short piece of 1/4" clear plastic tubing onto the bleeder valve for the clutch, or at each caliper bleeder.

As an alternative to a clamp use silicon hose which can expand over the nipple and will give good seal. But before putting the hose onto the bleed nipple put the ring spanner onto the nipple hex. The hose will hold it in place which makes opening and closing the nipple easier.

 

[Fire-medic]

before putting the hose onto the bleed nipple put the ring spanner onto the nipple hex.

Yes that makes it easier to open/close the bleeder valve. Thanks for adding to the thread a helpful & free tip.