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Post Subject:

There's no fun like clutch fun! 1980 CB750F

Reply from: tokenhire@yahoo . com
Date: 20 Oct 2007, 10:41
There's no fun like clutch fun! 1980 CB750F

Hello all humans far brighter than I!

Recently took my 1980 CB750F on a two hour highway trek to NYC.

Pulled into a reststop a little over half an hour into the trip. As I
pulled onto the ramp and began to downshift, the clutch handle felt
funny. I initially chalked it up to my hands stiffening in the cold,
pre dawn air. However, I noticed as I approached a toll barrier that
I pulled the clutch lever in and the rpm drop was noted, but minimal.
I released the leaver and tried again, this time the rpm dropped down
to idle range.

By the time I hit the stop and go traffic in the city, I noticed that
I would stall if I stood in gear with the clutch engaged and I could
not get into neutral unless I was moving. Makes for a fun trip in
such a desolate town.

Oil was recently changed, air temp started at 40 and was up to 70 by
the time I reached my destination. Tweaking the cable length adjuster
on the lever cuff seemed to have no impact. Around town here, I seem
to have some struggles with it, but it's not as clear from where the
trouble is sourcing as there are some other excitements that the bike
is suddenly sharing with me.

Did the mech (and I will NOT be offended if it is the case) use the
wrong oil, cheap oil, etc.? Does the clutch need to be professionally
adjusted? Is it shot?


Reply from: Albrecht via MotorcycleKB . com
Date: 20 Oct 2007, 14:02
Re: There's no fun like clutch fun! 1980 CB750F

tokenhire@yahoo . com wrote:

>Did the mech (and I will NOT be offended if it is the case) use the
>wrong oil, cheap oil, etc.? Does the clutch need to be professionally
>adjusted? Is it shot?

Motorcyclists have been frustrated and annoyed by their clutches for a
century.

A motorcycle clutch has been described as a device that is never fully
engaged, nor fully disengaged. It always slips or drags.

And there are numerous possibilities as to why a clutch might drag, including
the use of a heavier grade of oil in the crankcase than is recommended for
the climate.

20w50 oil is fine when the temperature stays hot, 10w40 is recommended for
cooler climates.

If it's not the oil causing your clutch drag problem, it might be adjustment
or worn out parts. The clutch lever itself will wear at the pivot point.

The clutch throwout mechanism may be worn or out of adjustment.

* houseofmotorcycles.bikebandit . com /partsbandit/ShowSchematic.aspx?deptId=153323&machineId=1998


003 Lever, Clutch

004 Cam, Clutch Lifter

005 Lever, Clutch Adj. (Item #5 is a particularly cheaply made, Honda-esque
item that can wear out.)

006 Plate, Clutch Lever Setting

* houseofmotorcycles.bikebandit . com /partsbandit/ShowSchematic.aspx?deptId=153043&machineId=1998


Under long use, the clutch plates can dig into the clutch basket and the
clutch center hub, causing grooves that keep the clutch from disengaging
smoothly.

The metal clutch plates can warp from the heat of slipping.

--
Message posted via MotorcycleKB . com
* w w w .motorcyclekb . com /Uwe/Forums.aspx/tech/200710/1


Reply from: The Older Gentleman
Date: 20 Oct 2007, 14:21
Re: There's no fun like clutch fun! 1980 CB750F

<tokenhire@yahoo . com > wrote:

> However, I noticed as I approached a toll barrier that
> I pulled the clutch lever in and the rpm drop was noted, but minimal.
> I released the leaver and tried again, this time the rpm dropped down
> to idle range.

Um, clutches aren't connected to throttles.
>
> By the time I hit the stop and go traffic in the city, I noticed that
> I would stall if I stood in gear with the clutch engaged and I could
> not get into neutral unless I was moving. Makes for a fun trip in
> such a desolate town.
>
> Oil was recently changed, air temp started at 40 and was up to 70 by
> the time I reached my destination. Tweaking the cable length adjuster
> on the lever cuff seemed to have no impact. Around town here, I seem
> to have some struggles with it, but it's not as clear from where the
> trouble is sourcing as there are some other excitements that the bike
> is suddenly sharing with me.
>
> Did the mech (and I will NOT be offended if it is the case) use the
> wrong oil, cheap oil, etc.? Does the clutch need to be professionally
> adjusted? Is it shot?

If you don't know how to adjust it, ask SWK. It could be shot, yes, but
correct adjustment is the first stage.


--
BMW K1100LT 750SS CB400F CD250 CB125 SL125
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....

Reply from: imf
Date: 21 Oct 2007, 11:39
Re: There's no fun like clutch fun! 1980 CB750F

On Oct 20, 10:21 am, chateau.murray.takethis...@dsl.pipex . com (The
Older Gentleman) wrote:
> <tokenh...@yahoo . com > wrote:
> > However, I noticed as I approached a toll barrier that
> > I pulled the clutch lever in and the rpm drop was noted, but minimal.
> > I released the leaver and tried again, this time the rpm dropped down
> > to idle range.
>
> Um, clutches aren't connected to throttles.
>
>
>
>
>
>
>
> > By the time I hit the stop and go traffic in the city, I noticed that
> > I would stall if I stood in gear with the clutch engaged and I could
> > not get into neutral unless I was moving. Makes for a fun trip in
> > such a desolate town.
>
> > Oil was recently changed, air temp started at 40 and was up to 70 by
> > the time I reached my destination. Tweaking the cable length adjuster
> > on the lever cuff seemed to have no impact. Around town here, I seem
> > to have some struggles with it, but it's not as clear from where the
> > trouble is sourcing as there are some other excitements that the bike
> > is suddenly sharing with me.
>
> > Did the mech (and I will NOT be offended if it is the case) use the
> > wrong oil, cheap oil, etc.? Does the clutch need to be professionally
> > adjusted? Is it shot?
>
> If you don't know how to adjust it, ask SWK. It could be shot, yes, but
> correct adjustment is the first stage.
>
> --
> BMW K1100LT 750SS CB400F CD250 CB125 SL125
> GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
> BOF#30 WUSS#5 The bells, the bells.....- Hide quoted text -
>
> - Show quoted text -



No, you're right. Clutches aren't connected to throttles. The do,
however, influence RPM. Normally when I pull in the clutch lever (and
naturally throttle down) the RPM's tend to drop. In this case, the
engine maintained RPM's with the clutch lever pulled in. In some
cases there was a very slight drop, others none. As the day warmed,
the difficulty became less pronounced. Interestingly, this was the
first trip on an interstate, so I was now doing 75 mph for a sustained
period.

Your thoughts...?


Reply from: Jack Hunt
Date: 21 Oct 2007, 12:24
Re: There's no fun like clutch fun! 1980 CB750F

On Sun, 21 Oct 2007 04:39:22 -0700, imf <tokenhire@yahoo . com > wrote:

>Your thoughts...?

Grooved clutch basket.

--
Jack

Reply from: The Older Gentleman
Date: 21 Oct 2007, 13:01
Re: There's no fun like clutch fun! 1980 CB750F

imf <tokenhire@yahoo . com > wrote:

> Your thoughts...?

I'm wondering whether it's got the wrong grade of oil in it, but I'd
still start with adjusting it right.


--
BMW K1100LT 750SS CB400F CD250 CB125 SL125
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....

Reply from: Fake Name
Date: 20 Oct 2007, 17:59
Re: There's no fun like clutch fun! 1980 CB750F

On Sat, 20 Oct 2007 03:41:19 -0700, tokenhire@yahoo . com wrote:

>Hello all humans far brighter than I!
I'm not saying that I qualify as being brighter than anyone else
but...

Some people who have tried automotive oil in their bikes complain the
clutch is too grabby while other complain that it slips. The base oil
is the same as motorcycle oil but the additive packages are very
different and the auto oil's can screw with your clutch. Are you sure
your mech didn't use auto oil in your bike?

Reply from: The Older Gentleman
Date: 20 Oct 2007, 17:27
Re: There's no fun like clutch fun! 1980 CB750F

Fake Name <fakename@fake . com > wrote:

> Some people who have tried automotive oil in their bikes complain the
> clutch is too grabby while other complain that it slips. The base oil
> is the same as motorcycle oil but the additive packages are very
> different and the auto oil's can screw with your clutch.

This is only true if someone's using very pricey synthetic car oils,
some of which have friction modifiers that do make a clutch slip.

Hopwever, this is very rare, and the fact is that his symptoms don't
indicate that. His clutch is not slipping.


--
BMW K1100LT 750SS CB400F CD250 CB125 SL125
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....

Reply from: Jack Hunt
Date: 21 Oct 2007, 13:21
Re: There's no fun like clutch fun! 1980 CB750F

On Sat, 20 Oct 2007 03:41:19 -0700, tokenhire@yahoo . com wrote:

>Did the mech (and I will NOT be offended if it is the case) use the
>wrong oil, cheap oil, etc.?

It would be a lot easier to determine this if you told us what kind of oil you
used...

The key is that sometimes it released and sometimes it didn't. That rules out
just about everything except a grooved clutch basket or other mechanical failure
in the release system.

I had one clutch fail in the engaged mode (locking the vehicle in motion any
time the engine was running) because a minute portion of clutch friction disk
material had dislodged and wedged itself between the flywheel and the pressure
plate (it was a truck). Only on disassembly did I learn that it could have been
cleared by pushing in the clutch and gunning the engine with the transmission in
gear.

You'll probably find that the clutch disks have grooved the clutch basket in the
engaged position and tend to want to stay in those grooves when the clutch lever
is pulled. Thicker oil than previously used would aggravate the symptoms.

I have had some success with filing down the grooves in the clutch basket
fingers. This may be your best option, seeing as how you're dealing with a 27
year old bike that Honda no longer supports.

--
Jack

Reply from: imf
Date: 22 Oct 2007, 12:57
Re: There's no fun like clutch fun! 1980 CB750F

On Oct 21, 9:21 am, Jack Hunt <jhun...@tds . net > wrote:
> On Sat, 20 Oct 2007 03:41:19 -0700, tokenh...@yahoo . com wrote:
> >Did the mech (and I will NOT be offended if it is the case) use the
> >wrong oil, cheap oil, etc.?
>
> It would be a lot easier to determine this if you told us what kind of oil you
> used...
>
> The key is that sometimes it released and sometimes it didn't. That rules out
> just about everything except a grooved clutch basket or other mechanical failure
> in the release system.
>
> I had one clutch fail in the engaged mode (locking the vehicle in motion any
> time the engine was running) because a minute portion of clutch friction disk
> material had dislodged and wedged itself between the flywheel and the pressure
> plate (it was a truck). Only on disassembly did I learn that it could have been
> cleared by pushing in the clutch and gunning the engine with the transmission in
> gear.
>
> You'll probably find that the clutch disks have grooved the clutch basket in the
> engaged position and tend to want to stay in those grooves when the clutch lever
> is pulled. Thicker oil than previously used would aggravate the symptoms.
>
> I have had some success with filing down the grooves in the clutch basket
> fingers. This may be your best option, seeing as how you're dealing with a 27
> year old bike that Honda no longer supports.
>
> --
> Jack


Off the top of my head, I don't recall the oil grade. The local
dealer set me up with a number of things I requested over the phone
and I just picked up a box of stuff to deliver to the mechanic. I
will call him tomorrow and ask (closed on Mondays).

Since this seems like the least expensive and simplest of the possible
remedies, I'll give an oil change a shot. When it came time to do the
oil, the guy who worked on the bike suggested leaving the old filter
in, replace the existing oil with a cheap brand, running the bike
around town briefly (30 miles or so) to clean out any residue or
deposits, then replace the filter and use the oil I had purchased from
the dealer (Suzuki brand four stroke).

I took the bike out yesterday for a stretch to get a feel for the
behavior. I noticed twice that when I was trying to downshift from
5th to 4th and once from 4th to 3d (separate events) there was that
first-gear-rejection grinding as though it was in neutral. As the day
wore on I would have to find nuetral at speed as the gear shift would
go past it as I went from first to second and back several times when
still.


Reply from: Albrecht via MotorcycleKB . com
Date: 22 Oct 2007, 14:16
Re: There's no fun like clutch fun! 1980 CB750F

imf wrote:

>When it came time to do the
>oil, the guy who worked on the bike suggested leaving the old filter
>in, replace the existing oil with a cheap brand, running the bike
>around town briefly (30 miles or so) to clean out any residue or
>deposits, then replace the filter and use the oil I had purchased from
>the dealer (Suzuki brand four stroke).

So, does this "guy who worked on the bike" also do faith healing and arrange
marriages? Doesn't he know how to adjust a friggin' clutch?

The normal way to tackle this problem is adjust most of the slack out of the
clutch cable, remove the clutch adjusting cap in the clutch cover, loosen the
hex nut, and turn the clutch adjusting bolt until all the free play is taken
up, then back it off a little and retighten the lock nut. (1)

>I took the bike out yesterday for a stretch to get a feel for the
>behavior. I noticed twice that when I was trying to downshift from
>5th to 4th and once from 4th to 3d (separate events) there was that
>first-gear-rejection grinding as though it was in neutral.

You cannot get into a real neutral between 3rd and 4th or between 4th and 5th,
but you can get into *false neutral* as the shifter drum and shifter forks
get jammed up.

It seems amazing that a mechanism like this works at all, but it works for 99.
99% of all riders. If your "guy who worked on the bike" knows anything about
transmissions, ask him to explain this drawing to you.

* houseofmotorcycles.bikebandit . com /partsbandit/ShowSchematic.aspx?deptId=153056&machineId=1998


> As the day wore on I would have to find nuetral at speed as the gear shift >would go past it as I went from first to second and back several times when
>still.

Motorcycle transmissions work best when the motorcycle is moving, but when
you're stopped, you'll have problems if the idle speed is set too high and
the clutch isn't adjusted correctly.

The clutch release mechanism is shown on these two pages:

* houseofmotorcycles.bikebandit . com /partsbandit/ShowSchematic.aspx?deptId=153323&machineId=1998


011 Cap, Clutch Adjusting (remove it with a large slot screwdriver)
016 Nut, Hex. (6mm)
007 Bolt, Clutch Adjusting
005 Lever, Clutch Adjusting pivots on a steel pin and pushes against the
clutch lifter to disengage the clutch.

* houseofmotorcycles.bikebandit . com /partsbandit/ShowSchematic.aspx?deptId=153043&machineId=1998


007 Plate, Clutch Pressure
008 Plate, Clutch Lifter
009 Spring, Clutch
010 Guide, Clutch Lifter

--
Message posted via MotorcycleKB . com
* w w w .motorcyclekb . com /Uwe/Forums.aspx/tech/200710/1


Reply from: The Older Gentleman
Date: 22 Oct 2007, 17:58
Re: There's no fun like clutch fun! 1980 CB750F

imf <tokenhire@yahoo . com > wrote:

> When it came time to do the
> oil, the guy who worked on the bike suggested leaving the old filter
> in, replace the existing oil with a cheap brand, running the bike
> around town briefly (30 miles or so) to clean out any residue or
> deposits, then replace the filter and use the oil I had purchased from
> the dealer (Suzuki brand four stroke).

This guy is an incompetent arse-wipe.


--
BMW K1100LT 750SS CB400F CD250 CB125 SL125
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....

Reply from: oldgeezer
Date: 22 Oct 2007, 23:00
Re: There's no fun like clutch fun! 1980 CB750F

On Oct 22, 7:58 pm, chateau.murray.takethis...@dsl.pipex . com (The
Older Gentleman) wrote:
> imf <tokenh...@yahoo . com > wrote:
> > When it came time to do the
> > oil, the guy who worked on the bike suggested leaving the old filter
> > in, replace the existing oil with a cheap brand, running the bike
> > around town briefly (30 miles or so) to clean out any residue or
> > deposits, then replace the filter and use the oil I had purchased from
> > the dealer (Suzuki brand four stroke).
>
> This guy is an incompetent arse-wipe.
>
> --
> BMW K1100LT 750SS CB400F CD250 CB125 SL125
> GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
> BOF#30 WUSS#5 The bells, the bells.....

Or a smart-ass who knows how to sell extra oil.
If he's really smart he resells it to his next victim. It has only 30
miles on the clock. Or maybe 60, or 90...

Rob.


Reply from: The Older Gentleman
Date: 23 Oct 2007, 06:25
Re: There's no fun like clutch fun! 1980 CB750F

oldgeezer <schreuderrob@yahoo . com > wrote:

> If he's really smart he resells it to his next victim. It has only 30
> miles on the clock. Or maybe 60, or 90...

Heh. You have a nasty mind.



--
BMW K1100LT 750SS CB400F CD250 CB125 SL125
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....




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