Vintage Dirt Bike Q & A

Hi guys this is my first post here. I hope you guys can help me. I just picked up a 78 CR250R and finally got it running. Heres the deal the clutch doesn't work. I have removed the cover and found the everything is all there. But the clutches (fibers and plates) where stuck. Also the clutch rod will not come out of the motor. From everything I've read it should come out this side. Has anyone had this happen? What was it a bent clutch rod? I'm gonna rebuild the motor any how, so I figure I'm gonna have to split the cases to get this out. I figure the end is mushroomed out from abuse. Got any ideas? Thanks

You are most likely right, the rod will either be mushroomed on the end or its possible the rod could have bent when the plates were stuck together. You could try removing the lever from the crankcase by taking out the locating screw and then twist the lever backwards and forwards to see if it pushes the rod through enough for you to pull it out but if the engine is in need of a rebuild I would just get on and strip it.

It might be that the same conditions that caused your clutch pack to bond
together has done the same to the clutch actuating rod in it's bore. Both
ends of the actuating rod are hardened steel and the rod itself is tempered
steel. You can remove the rod without splitting the cases. You already
have the clutch cover off. Now remove the pressure plate, inner and outer
(be very careful bending the lock washer, it is NLA) and the rod can be pulled
out.

To check it, do a visual on each end then roll it on a known flat surface. if
the ends look good and it rolls without a hitch, my guess is either the bore
is fouled with "spooge", the actuator arm is faulty or none of the above and
everything will work fine once you replace the seized clutch pack and springs.

Another heads up. Once you split the cases, be careful removing the bearings.
I recommend using an oven to heat the cases (250 degrees) then carefully wack
them on a 2X4 to get the bearings to drop out. If you use a bearing puller, you
will probably destroy the blind sleeved needle bearing for the countershaft and
that opens a new "can of worms". Also I highly recommend you stick with OE
Honda seals and either Japanese or American made replacement bearings.

Keep us posted.

dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Heres a heads up. I pulled out the clutch actuator and looked down inside the whole. Guess what, the end of the rod is mushroomed. The rod would always move it wasn't seized up. The rod just won't come out. I ended up pulling the end off of the end sticking out. I ordered my gasket set and am waiting on my flywheel puller to come in.

That's semi good news. You have identified the problem and the most likely
cause. The clutch actuator rod is still available from Honda (CMS).

Did the distortion occur at the clutch hat or actuator lever? I ask because
there may be more damage to one of those parts.

I had a similar situation with the clutch on my '79 (without the mushroomed rod).
The lever moved fine but the clutch pack was stuck together. You pulled the
lever and the plates moved as a solid unit instead of separating. Also, the clutch
inner had bad chatter marks. I replaced the clutch pack, clutch actuator rod,
clutch actuator lever return spring, clutch inner and the two needle bearings. I
used an oil stone to repair the minor chatter marks on the outer and bead blasted
it and the pressure plate.

I know a lot racers ran ATF back in the day, I'm not convinced it was a good idea.

Keep us posted as you dig deeper into the motor.

dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

The problem is on the clutch actuator side(right hand side) of the motor. Still waiting on the fly wheel puller set off of ebay.

I hope it fits. The late '70s CRs had a unique ignition/flywheel setup
that was different then the CRMs and different from subsequent Rs
I found this out the hard way when I discovered the pullers I had for
my '73-76, the puller for my '92-01 and the puller for my '04-08 didn't
fit. A lot of the Ebay adds say their puller will fit all CRs - they don't.
The only one I can personally vouch for is from Motion Pro specifically
for this model.

Speaking of tools, do you have a case splitter? You will definitely need
that to open it up and you may need a crank installer to put it back
together depending on how patient and how persuasive you are.

Another useful item is an engine "stand". You make it out of 2X4s in
the shape of a rectangle with inside dimensions of 10" by 8". This is
to support the right side case while you install the tranny, shift
components and left side case. The 2X4s (on end) raises the case
high enough so the crankshaft can be installed. Just another item to
make your life a little easier.

dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

So dogger you are saying you think atf is a bad idea in these bikes crankcase? I have no idea if it is or isnt I have heard people say its good and I was gonna use it but not if you think its gonna mess somthing up, its pretty thin stuff compared to what honda recommends.

i´m useing ATF for about 15 years now in my elsie without any problems.

_________________
80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250

ATF is a compromise designed for the inner workings and super small openings found in
the valve bodies of automatic transmissions. It is very slippery and reduces drag somewhat
which are the main reasons racers used it. These same qualities make it less effective at
surface adhesion (staying on the gears) and shock absorbtion, both important points to
consider in this application.

A retired factory mechanic told me that he ran ATF in his rider's engine. He said it freed
up a little horsepower at high rpm. He also said he had to replace everything between
the case halves (except the crank) after every race due to wear. Parts were free and
plentiful and winning was everything. Wouldn't that be nice for the weekend warrior.

I used to have my race engines built by a well known ex-factory mechanic, the guy was/is
a genius at making big usable power. Engine oil is so important in his program that I would
get a manual with the engine detailing the lengthy break in procedure (using special break
in oil) and I actually had to mix two different viscosity gear oils (he recommended Redline)
to get just the right combination of protection and cushion for the tranny. He would never
run ATF in any of his engines. That's the difference between now and then.

Now I use and recommend Honda synthetic motor oil in all of my CRs. Use any good quality
synthetic or petroleum based motor oil and keep it changed (especially if you are running
aluminum clutch plates), and your CR will be fast AND reliable.

Just my two cents.

dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Dogger your right the puller set came in. WRONG ONE know what? What is the correct size of the puller 26x1 or 27x1 anybody know?

I was afraid that might happen. The correct puller is a M28X1.0
R.H. internal thread. Fits '78-'80 CR250R. Here is a picture.

I just had a similar thing happen on Ebay. I bought a Hot Rods
Crankshaft for my '93 build. The add claimed the crankshaft fit
1992-2005 Honda CR250, but to specify the year of your application
when you payed to make sure they sent the right one.

I know there is a major difference between a 1992-01 and a 2002-
05 CR250 engine (like a complete redesign), so the add was a stretch
to begin with. Sure enough I get the crank and right on the box it
says for 2002-07 CR250. Of course the seller is not responding to
my request for an exchange so I will probably have to esculate this
with PayPal. It is definitely buyer beware with Ebay.

dogger

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_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R