'79 750L clutch help please.

[Guest]

I have a 750L clutch issue that every bit of information just confuses me more. The bike was slipping when you give it an increase in power. I tried adjusting it per manual off of the one downloaded from Cliffs page with not luck of eliminating the offensive slippage.

I pulled the plates and springs and compared them to factory specs. Everything checks out and then some. The bike has a big piston kit installed by a PO, so I think the clutch may be aftermarket. The springs are longer than stock and are a dark blue almost black. I pulled 8 friction and 8 steel discs.

Looking at the parts fiche on Boulevard and the 750 manuals exploded diagram, is where I'm getting confused. The drawing may be generic, but it shows 7 friction discs and 6 steel. The parts description and quantity needed is 8 friction and 7 steel.

Ok, the PO must have goofed up and put in an extra steel disc. Well that was my guess. I put it back together at 8 friction and 7 steel and now nothing. The clutches aren't grabbing at all.

I have a spare 750 that came on a previous bike and pulled the clutch plates trying to see what the stock count should be. I get 9F and 8S and the friction plates are way past service limits.

The standard is 2.9 -3.1mm limit 2.7mm, these are measuring 2.35mm.

Barnett shows 8 friction and 8 steel for it's 77-79 750 clutch kit.

Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

PS I adjusted the clutch release mechanism to where the screw is just making contact and then a 1/4 turn out. In one of the threads I looked at to find a solution someone suggested an full turn out.:-s Am I not turning it out far enough?

I'll check to see what the hive suggests later, I have another 750 engine I'm going to pull the plates from in the mean time.

Thanks in advance.

 

[blowerbike]

1/4 turn on the worm is fine...no miracle's there..you just don't want the pusher loaded.
go back with what the previous owner had and order a set of barnett gold springs...use 3 gold and 3 factory springs then do all your adjustments.
if your bike make's much more power than stock..stock springs won't hold.
when in doubt...load up a factory set of plate's and do what i suggested on the springs.

added...
throw the clutch specs out the window on 35 year old plates...they do not have adhesion anymore or are charred.

 

[yoshisakan]

You didn't mention what kind of oil you are using. Since it's a wet clutch, it's really important to use the right kind of oil or your clutch will slip.

 

[Guest]

You didn't mention what kind of oil you are using. Since it's a wet clutch, it's really important to use the right kind of oil or your clutch will slip.

IDK, it looks clean like it was just put in there when the engine was put back together by a PO. Besides, I'm the second owner once removed.

Third engine has 8 friction and 7 steel, so I'm taking that as a standard. Springs are out but the friction plates are just in service limits. I'm going to take out the plates on the project again and double check everything maybe try the plates from the engine I just took apart, just to see what I get.

 

[Guest]

Here is a photo of the three packs I have. Bottom left is the from the bike in question. Stack has 7F and 7Sdiscs, measuring in total at 32.97mm. The top stack is the first spare engine and has 9F and 8S discs, 36.13mm total. The third is from the last engine and has what I think is the right set up of 8F and 7S discs, measuring at 34.97mm. I'm going to try taking a friction disc from the bottom right and see if that will do the trick. That will put them at 8 friction discs and 7 steel ones, what seems to make sense to me.

I know lousy photo.

 

[portdave]

Rick,

I have a bunch of extra plates and springs left over from my 750, 1000...more than welcome to try them but it might be easier to order some.....

 

[blowerbike]

the top stack looks like the evil barnett extra plate racing clutch that has steel backed fibers...
if so those need to hit the trash can because they destroy the clutch basket.

 

[Guest]

Rick,

I have a bunch of extra plates and springs left over from my 750, 1000...more than welcome to try them but it might be easier to order some.....

Thanks for the offer Dave. I'm hoping one of the discs added to the mix will be the fix. Need to get this bike out I into the market asap.

the top stack looks like the evil barnett extra plate racing clutch that has steel backed fibers...
if so those need to hit the trash can because they destroy the clutch basket.

Don't know if they are evil, but they are red and copper. There's not a whole lot of meat to them that's for sure. They can out of an engine I've never seen run.

 

[koolaid_kid]

The first thing I would do is get the clutch springs blowerbike suggested. Then put it back together and fill it with Rotella T diesel oil, since you have no clue as to what was in it when you got it. If it has energy conserving oil it will do exactly what you are describing, especially since it has a big bore kit in it..

 

[Guest]

The first thing I would do is get the clutch springs blowerbike suggested. Then put it back together and fill it with Rotella T diesel oil, since you have no clue as to what was in it when you got it. If it has energy conserving oil it will do exactly what you are describing, especially since it has a big bore kit in it..

I might go that route, but first I have to try actually putting the right amount to plates in it. That I can do now and it's free.

 

[Guest]

Looks like that did the trick. I still need to fine tune the carbs and give it a better test ride going into 4th and 5th gear, but 1st-3rd went well with no slippage. It was just a 200 to 300 yard dash, but 1/2 of that was back up hill. Yes we do have hills in Florida.

For future thread search reference, a '77-'79 750 uses 8 friction plates (drive) and 7 steel plates (driven).

To all those who replied thanks for the suggestions.

 

[blowerbike]

here's a tip on checking clutch slippage...
5th gear around 35mph...pull in clutch lever and whack throttle open and slam lever out.
if the motor bogs clutch is good...if it revs some and tries to drive through the clutch then you still have clutch slippage.

 

[Guest]

here's a tip on checking clutch slippage...
5th gear around 35mph...pull in clutch lever and whack throttle open and slam lever out.
if the motor bogs clutch is good...if it revs some and tries to drive through the clutch then you still have clutch slippage.

I'll try that this weekend, thanks.