It had oil in it from the day I bought it until I took it apart.  Same thing with coolant.  Granted that wasn't very long, so the PO could have run it dry by mistake then refilled it and dumped it off on the next sucker (me)...

Is there anything specific I should be looking for that would point out the chain of events that caused the failure?  There's no sludge, I have a bad transmission bearing, a bad rod bearing, and a scarred oil pump.  What failed first and how can I tell?

I really don't want to do this again

Usually a rod bearing goes due to lack of oil.  But then lack of oil can take out a lot of items.  Don't forget, these engines are highly stressed.  If you take the power output and run the numbers up to 5.0L, you will see that it will compare to a 5.0 mustang putting out over 400HP.  That's a lot.  Piston pins, rings, rods, cams, they all take a beating.  Also this engine is highly over square.  The bore is the size of a lot of 4T 350s from the 70s and the stroke is more like that of a 175, very short.  All that boils down to tremendous pressures on all rotating components.  With all that stress AND the high rpm this engine is capable of, 13,500, I wonder how long they can hold together, yet they keep running even after they knock.  Mine was making a lot of top end noise before I last rebuilt it.  The piston pin hole was worn, the wrist pin was worn, the rod small end was loose, the rod was loose on the big end, and cam chain was worn, ....it all added up to over 2mm of movement at the top of the piston.  So you see, it only takes a little wear, to make a huge difference.  Just know that it is a highly stressed race engine, and as such, its going to require rebuilding every so often.

Are all dirt bike engines like that, or just race ones?  What if I take it easy on it?  In retrospect, I probably should have bought a more trail oriented bike like a TTR, DR-Z or KLX

Also, after researching honing / deglazing, I'm heavily leaning towards the green scotch brite method.  Only thing I'm worried about is there a little bit of scratches on the cylinder from the piston skirt.

No, but ALL RACE oriented equipment should be intrepreted (high wear, additional maintenance).  One of the best trail bikes around that should be included in your list is the Honda CRF230 with its E-start.  All the trail cutters use them for cutting out new trails here.  I have one and a KLX300.  The KLX has more torque and is heavier, no e-start.

A bottle hone will also de-glaze, scotchbrite, or you can use a hone.  I did last time, just limited it to slow turning and counted 8 turns total thru the bore.  The coating is very thin and all you want is enough cross hatch to break in the new rings.

" it will compare to a 5.0 mustang putting out over 400HP"

actually at aprox 30hp to every 250cc.. that 5liter mustang would be pushing 600 normally aspirated hp!!
that's done with no blower, no turbo, no NOS....that's pretty impressive.
It's truly amazing they stay together as well as they do.

So the oil pump arrived, not sure if it is good or not:

That looks like a used pump.  The pump is 2 parts, the gear and gearotor.  A new one will be perfectly smooth.

Edited by ronbuell, 21 May 2012 - 08:23 PM.

It is used.  I guess my question is, is it any good?  what's the difference between normal wear and scarring?

This is what the old one looks like

Will it work... probably.  But then I buy new pumps because I want to make sure I get full oil pressure and volume.  Oil.... the life blood of your engine.

Try again, buy new this time.

Edited by ronbuell, 22 May 2012 - 03:22 PM.

Ok, ended up getting all new bearings.  Put them in dry ice and put the crankcases in the oven at around 200F.  If I lined up everything perfectly, the bearing just popped right in.

Before I put the crankcases back together, I found that there is an extra ball floating around. Not sure where it belongs.


I've found balls on the following parts:
*Oil pump (x2)
*Rocker assembly (2 on intake, 2 on exhaust)
*crankcase cover

Any ideas where its from?  None of the old bearings were missing any balls.

The ball belonged between the clutch push rods.

Should have everything back together tonight.

Any tips for breaking it in?  I was thinking of filling up the oil, kicking through a couple times, then draining the oil to get any extra pieces of dirt/metal out.  Is that excessive?

Got it running.  New crank, new oil pump, new main bearings, new transmission bearings, new countershaft bearings, new piston and rings, and so much more.  It's running great though!  Gonna hit the trails this weekend.  Thanks again everyone for the help!!!