Clutch Binding On '83 750F

Hi guys. I have an issue with the clutch binding on my 750F that seems at it worst at cold start up. I can't engage 1st without the bike leaping forward. I've put new friction plates in, and I'm using dino oil that I put in all my bikes, but the problem won't go away. As there's no adjustment on the hydraulic clutch, I can't find a method of backing it of a bit. It grabs as soon as the lever moves. It's less pronounced as the bike warms up, but never completely goes.

At a bit of a loss really? Any ideas?

cheers

ian

Put the bike on the center stand and turn the bars right until the clutch master cylinder is level. Remove the 2 screws that hold the top and remove it carefully so you do not drip fluid on your paint. There is a small stainless steel plate inside that covers the return hole. Gently remove it and clean out the hole with a piece of wire. If the fluid is brown and dirty, now is a good time to bleed the system with new DOT 4.This should free up the slave cylinder. If not, then there are issues with the slave itself, and it will need a teardown.

Partzilla has the piston seals and the master cylinder kit, rebuild is easy. Clean and flush. I have done mine, and it still clunks going into first, but not a problem. I have replaced all rubber seals, o-rings and boots due to age.

Thanks guys. I'll give it a go. I've come across the blocked return hole in a few brake systems, but didn't put 2 and 2 together for the clutch for some reason :wacko:

cheers

ian

Well, I pulled the cylinders apart and gave them a good clean. The small hole was clear. The slave seemed to retract. Put it all back together and bled, but the problem persists. I'll order a couple of kits next and hope that fixes it.

Well, if at first you donot succeed, try agian (something else)

Take a few pictures while you're at it please!

Ian, is it possible the clutch spring is weak?

I know it will surprise you but I may have a NOS VF750F clutch spring in my box of gear.

Hi Jeff. Is that the weird disc-type spring? I haven't checked that, but I'll pull it apart and measure it. I'm still trying to figure out the mechanics of it's operation. Does that spring put pressure on the plates to keep them engaged? In that case wouldn't a weak spring encourage slipping rather than grabbing? My head's not fully in this space yet ;-)

cheers

ian

OEM or aftermarket friction disks? I know when I've installed Barnett clutches on my bikes it definitely moved the friction zone in, but got better the more miles I got on it. And if it has been sitting for a while the first shift into 1st can be abrupt.

Not as crucial these days, but might make a difference on some brands, did you soak the friction plates in oil for a while before installing?

Also, something that most people overlook or don't know about... there is a small brass bushing in the you clutch lever that must be in good condition for your friction zone to really feel right. It has to be nice and round. If it is oval shaped at all, your are not getting the full disengagement of your clutch and it will want to grab early in the release of the clutch lever. The little buggers are expensive for what they are, but bite the bullet if you need one. They make more of a difference than you will think.

Mike.

That's the one, yes I suppose you are right. Weak spring will probably allow slip.

When I got my VFR there was 10mm of travel from the handlebar to fully disengaged clutch - I thought I needed new plates.

After bleeding the clutch for a while to remove the brown sludge, the clutch now works perfectly.

That bush is another possible contributor - they can be found in tourmax kits (bush, rod, hat shaped diapragm) for less than just the bush alone from Honda. If you need one of these kits in a hurry I can send you one if you replace it.

How much is a Clutch Bush from Honda there? Here in the U.S. they are about 9$.

I experienced the same problem with the low mileage '83 VF750F that I sold last fall. http://www.vfrdiscussion.com/forum/index.php/topic/79244-shifting-hard-when-cold-possible-cause/

I went through the entire brake and clutch system and rebuilt everything, installed new pads, and new EBC clutch disks, flushed and replaced fluids, etc. The bike would do exactly what you described when it was cold and once it was warmed up, the problem went away and the bike shifted beautifully. I never figured out quite what the issue was unfortunately and told the buyer about it. He had another 750 that did the same thing and had no concerns. One thing I noticed is that the clutch slave cylinder is smaller than the one used on the '84 VF1000F. They look identical, but aren't. I was actually going to swap out the slave and sprocket cover (also different to accommodate the different slave) but ended up selling the bike.

I went through pretty much everything trying to pinpoint the problem. I found that the actuator rod was not pushing far enough to engage the clutch until the bike warmed up, so I suspect that the slave was weak and marginal in this application. That might explain why the VF1000F went to a bigger slave. Not sure if they changed the '84 750 over to the same one or not...

Captain 80s

How much is a Clutch Bush from Honda there? Here in the U.S. they are about 9$.

You can get a brand new clutch lever that comes with the new bush and push rod for not much more. Mine was in perfect shape, so I'm not sure that would cause the issue. I'm fairly convinced that the clutch actuation circuit (master cylinder and slave) is weak.

Tom

The bush is $14.30 and the rod $24.50. Complete Japanese made kit is about $20 in the US on eBay.

All in AUD.

thx113

The bush is $14.30 and the rod $24.50. Complete Japanese made kit is about $20 in the US on eBay.

All in AUD.

Thanks, just curious.

Lots of good info above.

I've got an '83 750F, '84 750F and an '84 1000F. I'm going to take a look at the slave cylinders.

Captain 80s

OEM or aftermarket friction disks? I know when I've installed Barnett clutches on my bikes it definitely moved the friction zone in, but got better the more miles I got on it. And if it has been sitting for a while the first shift into 1st can be abrupt.

I went aftermarket, but I swapped them out because the existing set was doing the same thing, and I was hoping to fix it simply :-(

thx113

That's the one, yes I suppose you are right. Weak spring will probably allow slip.

When I got my VFR there was 10mm of travel from the handlebar to fully disengaged clutch - I thought I needed new plates.

After bleeding the clutch for a while to remove the brown sludge, the clutch now works perfectly.

That bush is another possible contributor - they can be found in tourmax kits (bush, rod, hat shaped diapragm) for less than just the bush alone from Honda. If you need one of these kits in a hurry I can send you one if you replace it.

Thanks Jeff. Might try replacing the bush (nothing else left :-( ), but there's no hurry really. I'll ride the 1000R until then.

tomk1960

I experienced the same problem with the low mileage '83 VF750F that I sold last fall. http://www.vfrdiscussion.com/forum/index.php/topic/79244-shifting-hard-when-cold-possible-cause/

I went through the entire brake and clutch system and rebuilt everything, installed new pads, and new EBC clutch disks, flushed and replaced fluids, etc. The bike would do exactly what you described when it was cold and once it was warmed up, the problem went away and the bike shifted beautifully. I never figured out quite what the issue was unfortunately and told the buyer about it. He had another 750 that did the same thing and had no concerns. One thing I noticed is that the clutch slave cylinder is smaller than the one used on the '84 VF1000F. They look identical, but aren't. I was actually going to swap out the slave and sprocket cover (also different to accommodate the different slave) but ended up selling the bike.

I went through pretty much everything trying to pinpoint the problem. I found that the actuator rod was not pushing far enough to engage the clutch until the bike warmed up, so I suspect that the slave was weak and marginal in this application. That might explain why the VF1000F went to a bigger slave. Not sure if they changed the '84 750 over to the same one or not...

Yeah, I was really hoping you were able to pinpoint the cause Tom, but you up and sold the bike on me ;-) My instinct is for whatever reason there's not enough throw for the actuator rod. Just need to work backwards from there I guess.

thanks guys.

Try a stainless clutch hose?

Maybe you are losing slave cyl travel there.

My VF750F also has a tendency to bind, making almost impossible to shift from 1st into 2nd when cold. (Getting it out of 1st is very hard)

The idle was also set rather low, I adjusted it to 1150-1250 rpm, which reulted in a better shift.

When you bled the system, did you also bleed it at the banjo of the MC ? Sometimes air gets trapped at the banjo, so you might want to try to bleed it there extra.. (Beware: brake fluid is a perfect paintstripper)

I've bled this a couple of times now. I have a vacuum bleeder that seems to work pretty well.

cheers

ian

thx113

Try a stainless clutch hose?
Maybe you are losing slave cyl travel there.

might give it a try. most of the line is steel, but will still remove a variable. Waiting for parts now anyway.

Some progress. I've put kits in the master and slave and there seems to be some improvement. Also re-read the factory manual that recommends a spacer between the lever and handlebar to prevent 'over-travel' of the piston. I put my finger in the way (shades of Homer Simpson, D'oh, D'oh), and it seems to have helped. Got more feeling at the lever than I had before. Still waiting on the braided line, but for now it will launch into first with the motor running, but not creep forward like it used to. I can also flick it into neutral now, which wouldn't happen before. It's not perfect, but has improved. Haven't ridden it yet because of the weather. Will give it a more thorough bleed when the new line gets here.