Interesting observation regarding clutches

 I keep hearing people say that they try to avoid mud holes or quick
sand (don't ask, it's not a hollywood only thing, they just exaggerate
a big bit) because it quickly wear out the clutch. I don't avoid
anything, as a matter of fact, I have abused my clutch/gearbox to the
point it starts jumping gears - I guess the "dogs" jumps out of it's
hole - and you think I stop abusing? No, I abuse it even more. Clutch
disks are cheap, really. Changing them is what's expensive, but I do
my own maintenance...

Nonetheless, I felt my clutch slipping. Well, I promptly went to the
Honda dealer and they (as always) said that I should order them, pay
in advance and wait one week (they never meet the deadline, I had once
to wait over 45 days). Screw the dealer, I went to a independent parts
shop. They don't carry OEM, but carry Fischer. Their brake pads are
great, I figure the clutch disks are same quality.

Once at home, just for fun, I decided to measure my old disks. Hmmm,
weird, it seems closer to the high end of the specs, meaning that they
are good. I don't remember the exact numbers, but for instance, if it
had to be 3.00mm, they had 2.98mm, the limit being 2.8 or something.
The Fischer disks were all below 2.98, like around 2.9. The brand new
out of the package disks are thinner than the disks that are abused
for 7 years! (man, my bike is getting old! 2002 was just
yesterday!!!). Because I ripped the package apart, I can not return
the disks to the store, so they are now stored (store, stored, this
isn't sounding good, there is a "flaw of written language" in here,
but I have no idea on how to make it right) and this puzzled me. How?
I get slipping, what now? It can't be the *car* oil, I use it for... 7
years! With no problems whatsoever... Hmmmmmmmm. I measured the
springs. They measured a little bit less than they should. Worn out!
Back to the store (that word again, <sigh>) to get new springs. I
wanted a set of CB450 springs, they are same width but a few tenths of
mm taller. Not available, so I got a set of aftermarket (dubious
chinese quality, I know, I should know better, but I can't help
myself: each spring retailed for about a dollar and a quart, US), they
measured within specs and are visibly taller than what I had in there.

This weekend I put the clutch back together. Man, day and night
difference. Same oil, old and good Shell Helix 15w50 SL of course.

Two weeks ago, a friend who own a XLR125 (same bottom end as a CRF230
engine, but this engine is a OHV engine, with the cam on the bottom
end and the clutch basket is held by a circlip instead of a screw
torqued down 1000000ft/lb, otherwise, same. The CRF230 engine has the
cam chain on the magneto side, unlike any other bike I've tinkered
with) complaining that his bike was making a weird noise when it was
high revving with a hot engine. The only way to find out why is taking
clutch apart. Disks were great, but the springs were way way way
bellow specs. New springs on it (and he put CG150 springs, the clutch
lever is now stiff as rock, but he claims bike is much faster. I bet
he had massive slipping but this guy is not an off roader, he rides
like an old nun) and all was ok again. His bike has being driver for
over 100 thousand kilometers. Quite a good mileage, when you think he
never - ever - opened the engine before... I was the first to put tool
marks on his screws and to destroy a couple of them with my impact
wrench... :-) Oh, btw, his engine was covered with sludge. He only
used Mobil MC oil, as it's the oil Honda uses in his factory and
everybody think it is the best thing after sliced bread. It was a very
boring and time consuming job cleaning the clutch side. I don't want
even think about a complete overhaul, splitting cases. I'd need one
week just to get rid of the sludge. My engine is clean, shiny and
there is no sign of sludge at all. Something to think... Friend
changed oil to Shell Helix.... :-)

I never heard that springs wear out faster than the disks. In my
assumption (there must be a reason this word start with those 3
letters), I figured that the disks were supposed to wear out and be
replaced a few times before the springs get tired.

One more lesson learned. Remember: Buy a caliper and use it. Sometimes
when you think you have a problem on a part, actually the problem is
at another place. It pays to play motor detective.

-- T

 
Where did you find the wear tolerances for the clutch plates and
springs?  Service manual?  My 02 KX125 kicks just a touch when coming
out of neutral, just enough it won’t start in gear.  All the 125s I’ve
owned/ridden have been like that, and it does not slip, so it has not
been any cause for concern to me.  Start the bike in neutral, don’t
shift out at idle, no problemo.  That said, with a brand new top end,
the carb and powervalves all cleaned, etc. she’s running better than
she has in as long as I’ve had her, so I wouldn’t mind taking a little
time to measure some clutch parts.  If something is borderline to
replacement anyway, can’t hurt to know it and get the new parts in.

 

I got them ffrom the service manual, yes...
regarding your issue, check to see if the clutch basket fingers aren't
notched. If so, you can file the fingers to make them smooth. I did
with mine, gearbox now is very soft. Before, if I didn't use the
clutch, the shifts were kind of "hard", I could feel it engaged
somewhat "forced". Hard to explain the feel. After I filed it, the
gears engage smooth, like hot knife on butter... Also, neutral is now
as easy to find as when bike was brand new, even with engine running.
I am sure filing the fingers will make the basket to wear out faster,
but weighing out the bad and the good, I guess the good outweights the
bad by far...

I've got a RM125 that doesn't start in gear (unless very hot) and is
almost impossible to find neutral with engine running because clutch
basket is so notched it's scary. That poor bike. :-( three years
parked collecting dust. Shame on me, I really should either sell it as
is or fix it. I guess 125s wear out the clutch basket faster because
you are always hard on it, high revving and clutching all the time. No
alluminum can stand this abuse I guess...

-- T

 
Cool, thanks for the tip!  I'll take a look at that for sure.  Come to
think of it, I've never seen a 125 clutch basket that was not
notched.  Until the rebuild yesterday my bike made 0 power anywhere
but WOT in powerband, so it spend a whole lot of time there.  You've
gotta work the clutch to ride a 125 anyway, but this bike was way
worse than most.  Fresh top end, carb rebuild and some clean
powervalves later it actually makes a touch of torque...  as much as
you can reasonably expect from a 125 anyway.  It can be ridden through
a flat trail outside powerband now anyway.

I think my biggest problem was the powervalve.  There was so much gunk
on it that it was literally one piece.  Couldn't tell by looking that
it was supposed to be 2 moving parts.  It was clear it had not moved
in a very long time.  The valves could not even be pulled apart by
hand.  1 Solid clump of junk, to the extent in addition to being bound
in position you couldn't even tell if it was rubber, plastic, metal,
or what.

I'm rambling again.  I'll get my hands on those specs, and check the
basket.  I may try filing the basket if there are light notches, but
it really doesn't bother me enough to replace it.  Like I said, every
125 I've ever owned or ridden has been like that.  Starting in neutral
and being on the gas a bit to shift out of neutral are as reflexive
for me as anything else I do when I ride.

What's wrong with your RM?  I'd say fix it, even if you fix it to sell
it, unless you have someone in mind you want to give a deal to.  A non-
running 125 doesn't go for much, and repairs are usually fairly cheap
if you twist your own wrenches.

 

I need new piston and cylinder re-sleeve. And perhaps, new forks... I
got serious corrosion on the upper (outer) part.

Every time I think I will be able to fix it, something happens and I
use the money for other stuff. If I did not had the XR, I'd have that
fixed... But I keep postponing... :-)

-- t