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Old 06-07-2009, 09:41 AM
dogger315's Avatar
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Default CR250 Engine build - Combining Center Cases, Seals, Primary Gear

     

This one covers combining the two center cases, installing the seals,
clutch lifter lever and primary gear.

Tools needed: Case splitter or crankshaft installer/remover, engine stand,
torque wrench and standard metric tool set.

Now that you have installed the transmission gears, crankshaft and gear
shift mechanism you are ready to join the two case halves. Apply
transmission oil to the two dowel pins and push them into the holes
located at the top left and right corners of the right side center case.

Lay a new center case gasket on the right side center case using the
dowels you just installed to properly locate it. Install the vent breather
tube into the left side center case and place the case on the ignition side
of the crankshaft. Install either a case splitter or the crankshaft installer
to the left side of the crankshaft. Ensure the cases have a constant gap
and begin tightening the installation tool checking that the gap stays
constant the whole time. Use your hand or lightly tap with a rubber mallet
to help coax the constant gap and alignment while tightening.

Once the cases are seated together, install the eleven 6mm hex bolts and
torque them to 7 lb.ft. in three steps using a cross hatch sequence.


Cut and trim the excess gasket material being careful not to damage the
cylinder base surface. Also, don't let any of the gasket material fall into
the crank well.

Spin the crank and the primary gear shaft to check for binding. Everything
should turn smoothly and quietly.

Turn the engine over with the ignition side face down in the stand. Fill the
lips of the right side crank seal with grease and place it around the crankshaft.
Use either the appropriate size seal driver or a socket will suffice. Install
the case splitter again and drive the seal into the case until the seal is
exactly 1mm below the case lip (this is why you can't use a socket and a
hammer). Flip the case over and repeat the process with the left side
crank seal only this time the seal has to be exactly 2mm below the case lip.
Repeat the process once again for the countershaft seal placing it exactly
1mm below the case lip. Finally install a new seal in the clutch lifter lever
seal boss (no depth requirement here). These seal depths are important and
are well documented and diagramed in the Honda service manual.

Once the seals are done, install a new Oring in the countershaft collar, coat
the collar with grease and install it with the Oring side toward the engine.
Next apply grease to the crankshaft collar and install it between the crank
and right side seal. Coat the clutch lifter lever with grease and insert it
into the hole inside the ignition housing


Last item is to install the primary drive gear. Temporarilly install the clutch
outer onto the mainshaft. Place the primary gear on the crankshaft followed
by the correct washer and bolt. Place a gear jammer (or a penny) betwwen
the primary gear and the clutch outer gear and torque the primary gear to 33
lb.ft.


Next up will be the installation of the kickstart gears, shifting mechanism and idle wheel.

dogger

Last edited by dogger315; 06-13-2009 at 01:17 PM.
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Old 06-26-2009, 03:18 AM
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You make it all look so easy. Do you have pictures of the case splitter or crankshaft remover tool?

I'm picturing it as the tool that I used to use to get the crank off my bike (bicycle) when I was into Mountain biking.

Like this:

Seriously, thank you for these threads. You documentation skills are awesome, and I love reading them. I know they will help many people down the road.
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Old 06-26-2009, 10:26 AM
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Quote:
Do you have pictures of the case splitter or crankshaft remover tool?
Good point, I didn't think to show what the tools look like. I will post pictures
of various specialty tools used to assemble a motor.

Thanks. And thanks for changing "part 5" to "6" on that post.

dogger
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Old 06-26-2009, 02:08 PM
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Awesome thank you.
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Old 08-26-2010, 06:29 AM
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Hi Dogger315

Create pics and nice clean work dude. Quick question.....
On your first pic there is a cavity with a little hole close to the drain plug. I've got a little oil dripping from here constantly. About 1 or 2 drops a day. What can cause this and do i have to split the motor to fix this or could it be something i'm overlooking?

Please advise
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Old 08-26-2010, 11:51 AM
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Quote:
I've got a little oil dripping from here constantly. About 1 or 2 drops a day. What can cause this
That hole drains fluid/crap from the ignition cavity. The first picture below
shows the drain hole in the ignition (arrow). The second picture shows
where that drain ends up.

If oil is constanly leaking from that drain, I suspect you have a bad seal
at the clutch actuator. Remove the ignition cover and look for tell tale
signs of leaks. I would replace the seal regardless.

First, clean the entire cavity with an electrical safe cleaner like CRC. Then
blow out the cavity with compressed air. Then remove the actuator and
replace the seal. When done, spray the ignition components with WD40 or
MTTL and wipe off the excess. It's a good idea to clean, dry and coat the
ignition components after every ride. I leave the ignition cover off over night
to insure everything is dry. The stock plastic cover is next to worthless
when it comes to moisture.

dogger


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Old 09-09-2010, 10:36 AM
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great thread. i am getting ready to rebuild an 02 cr125. where can i find round 1 & 2 threads? Thanks
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Old 09-10-2010, 12:11 PM
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Quote:
where can i find round 1 & 2 threads? Thanks
Go back to about page 34. The other six parts are in that area.
Or you can follow the CR500 engine build I'm doing now. Part 2
will be posted this weekend.

dogger

Last edited by dogger315; 09-10-2010 at 03:47 PM.
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Old 09-10-2010, 03:26 PM
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Awsome tutorial dogger.
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Old 09-10-2010, 04:00 PM
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any chance you want to rebuild a yz250f motor?

great tutorial!
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