Topic: Getting a 78 750F back on the road - runs but won't move!

[ajinreno]

So getting a 78 CB750F back on the road that has sat for 20 odd years (you may have seem some of my other posts about various problems!) Took the clutch apart and reassembled. Got the bike running, but when shift in to gear nothing happens! I tried doing it without pulling the clutch in...in 1st it makes a slight lurch forward and then nothing no matter the rpm. Where do I start? I'm wondering if I could have reassembled the clutch wrong? It seemed pretty straight forward.

[Steve F]

Is there any kind of "play" in the clutch handle at all?  You don't have it adjusted so the clutch can't engage do you?  You adjusted according to the manual? If that all seems well and good, you may have to take it apart again and make sure everything is ther, including all the clutch plates 

[ajinreno]

I originally adjusted according to the manual and it "felt" right. Then I tried loosening all adjustments so there was play, thinking the clutch might have been engaged by everything being too tight.
Also, the bike only has 5,500 miles and the PO never did any clutch work.

[Spanner 1]

Sounds like the adjuster at the clutch cover is turned-in too far to where the adjusting bolt is holding pressure on the clutch even with the cable relaxed...my 2 cents.
Wonder why you took the clutch apart, with 5,000 miles on it ?

[ajinreno]

I tried backing that aduster out. I backed it out to loose, tighted it until it felt like it was hitting and then backed it off half a turn.

The reason I took the clutch apart was when I unloaded the bike after purchase, it got knocked into gear and pulling the clutch didn't free up the wheel at all. Checked adjustments and everything seemed right, so thought the clutch had gummed up after sitting for 20 years.

[Spanner 1]

That's all I got!, but can a clutch seize, sitting ( partially at least ) in an oil bath, to where normal pressure on the 'vanes' will not release it ??, well Clutch-heads ?

[Hush]

Did you take the clutch discs apart?
One thing I always do is take them all out and clean them individually even scuff them with a bit of wet'n dry or a brillo pad to give them some grab.
Helps them let go too when clutch activated.
My old Honda mechanic gave me this hint too, works good if the plates are a bit worn or gummed up from years of sitting in relaxed position.

[PJ]

On the centerstand if you shift it into gear with the engine off will the rear wheel still spin?

[MJL]

That's all I got!, but can a clutch seize, sitting ( partially at least ) in an oil bath, to where normal pressure on the 'vanes' will not release it ??, well Clutch-heads ?

Maybe it all rusted together?

It's a good excuse to pull the clutch and inspect anyway. IIRC the clutch is a wet clutch and the spring pressure can squeeze the oil out of the friction plates if it sits for a long time. 

[Bodi]

No point in wondering about a rusted solid clutch or the plates being stuck together... this one doesn't clutch: stuck or rusty or seized would mean no declutching...
Was the bike OK when parked, or was it parked because it wouldn't go? (this is the primary question with old "garage queens" that have sat for a long time)
You say the clutch wouldn't declutch when you got it, then you took the clutch aprt, and now it won't declutch... definitely a strong clue that you put it together wrong.
However, usually this results in a stuck clutch, not an unstickable one. If the clutch turns freely with the cover off, then it's definitely assembled wrong since the declutching pressure comes from the cover.
If so, disassemble it and check that all plates are in the correct order, the pressure plate is working freely, springs are good... it is a pretty sinple mechanism and you should be able to see what's wrong.

[mrbreeze]

Bodi is right that it isn't assembled correctly and you should be able to see the problem when you reattack it. I can see how you were concerned with it sticking before. They do that when they have sat around for awhile and especially when cold. If you would have started it up and tried to take off,it probably would have clunked into gear and kinda tried to pull away with the clutch in  but would have freed itself up quickly.So get in there and put it back right so you can get out there and ride!!!!

[ajinreno]

On the centerstand if you shift it into gear with the engine off will the rear wheel still spin?

No it does not spin. What does that mean?

Was the bike OK when parked, or was it parked because it wouldn't go?

According to the PO it was fine when parked.

If the clutch turns freely with the cover off, then it's definitely assembled wrong since the declutching pressure comes from the cover.

I do remember that the clutch turned freely when i was putting the springs and the lifter plate back on, is that what you are referring to?

[mystic_1]

A common assembly mistake is to not have the splines on the clutch center aligned with the matching splines on the pressure plate.  As a result, the clutch cannot engage.

Normally their respective splines mesh like this:



BUT you will find that if you rotate the clutch center by 90 degrees, the splines no longer line up properly:




See the following posts for rambling dissertation:

http://forums.sohc4.net/index.php?topic=36525.msg377135#msg377135

http://forums.sohc4.net/index.php?topic=41454.msg427605#msg427605

mystic_1

[MRieck]

A common assembly mistake is to not have the splines on the clutch center aligned with the matching splines on the pressure plate.  As a result, the clutch cannot engage.

Normally their respective splines mesh like this:



BUT you will find that if you rotate the clutch center by 90 degrees, the splines no longer line up properly:




See the following posts for rambling dissertation:

http://forums.sohc4.net/index.php?topic=36525.msg377135#msg377135

http://forums.sohc4.net/index.php?topic=41454.msg427605#msg427605

mystic_1

Misaligned splines are usually the problem as mystic said.

[GammaFlat]

Back to the beginning of your problem.  If a bike sits for a while, the clutch can "stick" so that pulling the clutch in will not disengage.  The way that I disengage is to start the bike in neutral... roll it (hills are nice for this part) and click it into first.  Then, while running, hold your clutch in and "hit it" and "back out of it".  This will free up the clutch when stuck from just sitting too long.  Sound like you don't have this problem at the moment however. 

[754]

By asking you to turn the whel, he was trying to determine if the transmission is hooked to the motor, regardless of clutch condition.

ie, if your primary chains broke ( have never seen that), then nothing you do to your clutch, would make any difference.

just part of trouble-shooting..eliminate what you can..

[Steve F]

Back to the beginning of your problem.  If a bike sits for a while, the clutch can "stick" so that pulling the clutch in will not disengage.  The way that I disengage is to start the bike in neutral... roll it (hills are nice for this part) and click it into first.  Then, while running, hold your clutch in and "hit it" and "back out of it".  This will free up the clutch when stuck from just sitting too long.  Sound like you don't have this problem at the moment however. 

That's not his problem.  He cannot get the clutch to engage.  If it was stuck, the bike would lurch and die when put into gear.  He has just the opposite problem.

[754]

spline.mis..align..

[ajinreno]

I took it all apart today and it wasn't misaligned. Then I noticed that when the clutch center is inserted all the way the back pressure plate has some free play back and forth between it and the clutch basket. So I thought maybe when I put the lifter plate on it had wiggled out of alignment. I was careful to make sure when I reassembled it that everything was aligned including the pressure plate. Put it back together and the same problem is there!

The only thing I can think of is the first time I took it apart I broke several of the lifter plate screws, so bought new ones from a local hardware shop that were slightly longer. The pressure plate has deep threads so I didn't think it mattered. When I installed the lifter plate it didn't feel like the screws were bottoming out, but being paranoid of breaking the screws again I only used an open ended wrench instead of a torque wrench and only tightened until they felt barely snug. So three questions...
1) Could the screws being too long cause this?
2) What would be the result if I am not tightening down the lifter plate far enough?
3) Any other ideas what it could be?

[Spanner 1]

Are you sure you have all 13 pieces (discs and friction plates) in the clutch ??

[ajinreno]

Yep, all 13 including the double clutch plate in the center and the final Friction Disc B with the larger tabs and the oil grooves.

I never pulled the actual clutch basket out, I wonder if it is possible I upset the position of the clutch basket? I can't imagine so since it has a circlip holding it...

[Spanner 1]

Your 3 questions...
 1.   Longer screws....if the lifter plate screws (bolts ) were too long and projected thru' they would stop the clutch from disengaging...! , so not your problem.

2.   Lifter plate not tight enough.... would have the same effect as 1.

3.   Have you tried loosening the clutch cover screws ( all 10 of them ! ) and checked for the clutch engaged while loose..i.e. prob. in the cover components...you probably have already  !!

[Hush]

Surely if he has the clutch cover off now and he has the bike on the main stand then toes it into gear (without of course starting the bike) the rear wheel when rotated forwards should turn the motor over?
It would be just like bump starting the bike, if the clutch is all pressureised like it should be since the clutch cable is not activating the mechanism the motor should be engaged by the rear wheel being turned.
Unless as someone suggested the primary chain is broken, but the chances of that are like 1 million to 1.
If the rear wheel does turn the motor over then all good he has a clutch assembly problem which is solvable.

[ajinreno]

Your 3 questions...
3.   Have you tried loosening the clutch cover screws ( all 10 of them ! ) and checked for the clutch engaged while loose..i.e. prob. in the cover components...you probably have already  !!

No, but I've tried backing the adjuster screw on the actuator all the way out so the cam mechanism is not touching the lifter plate, which I believe tells me the same thing.

If the rear wheel does turn the motor over then all good he has a clutch assembly problem which is solvable.

When the bike is on the centerstand and in gear, the back wheel does not move. So, correct, it must be a clutch problem.

[Spanner 1]

Here's my doomsday scenario ( sorry! )...lets see...back wheel is 'locked' when in gear...hmmmm,
O.K. the final drive in the transmission is seized and the P.O. 'fried' the clutch by repeatedly 'dropping' the clutch to try to free the lockup...the clutch is fine !...except the friction discs which have lost their friction...and the seized trans.... OR can you free the back wheel in Neutral, actual not false N between gears ?