Splitting Cases

[airmanloco]

hey guys you won't believe this. I bought a used 06 yz250, test rode it (they started it for me), had only a hour to hop on it a week later and so didn't go through it real thorough (should have), it started making bad noises 45 mins in to the ride, stopped, had to run to work, came back and looked into it and low and behold it had no oil in the tranny and no air filter. :yikes: So now I'm rebuilding it. Motion Pro sells a case splitter for $170, will I need that or is there another way. I tried with a hammer and screw driver to no avial. I assume most everything that moves will need replacing, any thoughts. This totally sucks, any help would be greatly appreciated. :pissed: :yell: :ohmy: :(

 

[IZ 250]

Where did u buy that bike? Who the heck sells a bike without an airfilter and with no trans oil. Man im suprized it even lasted 45 minutes. U shold be able 2 split the cases with a dead blow hammer by tapping on the cases following the case halve center all the way around. If u try to use a screw driver to pry the cases open you will ruin the case mating surface and you will get a leak. Also I wouldont even go anywhere near that motor with hammer aside from a soft faced hammer or a rubber mallet. Good luck.

 

[94formy]

tap the case with a soft hammer and work it apart. If you can't just pull it then get a real wide blade like a putty knife and work it into the seam where the halves meet and work it all the way around. If you're taking the crank out then a good trick is to put the case in the oven then the crank should jsut tap out.

 

[airmanloco]

IZ250
Ya I know, I can't believe they missed it either. The guy I bought it from is actually a Pro Racer on the AMA National Arena Cross circuit. It was a deal where after the last race with that bike they dropped the oil while it was warm pulled the filter and then forgot about it, and never got back to it. They where busy with a new bike for the new season. I won't say who it is because they do feel real bad about it and say they are going to make it right but so far they have been dragging their feet and haven't done anything. I kinda feel like I would rather be the one to decide what need replacing anyway, hence my question. Ya it actually went for just over an hour total and it shifted fine the whole time, in second gear it wasn't making any noise at all. When I took the clutch cover off there was a lot of small metal flakes, some iron and some aluminum, one fiction plate was broken but still in one piece. The gears on that side actually don't look damaged at all but when I pulled the rod out that goes through the shaft the clutch is on over to the clutch acuating arm a lot of large chips of iron came with it so I'm expecting the worst in the tranny. Thanks for your advice. I didn't pry on any of the mating surfaces but was using a steel hammer, I won't anymore.

94formy
Do I need to do anything to loosen the crank rod where it comes out the cases before I try to split the cases? I mean of course I have the nut and gear off the right side and the stator off the left but I assume the main bearing are pressed onto the crank. Is that what is making this so difficult?

 

[KXtrailrider]

I use a harmonic balancer puller for a car on the stator mounting holes with the pulling screw against the crank, use a puller if at all possible. Good luck Ed

 

[airmanloco]

I use a harmonic balancer puller for a car on the stator mounting holes with the pulling screw against the crank, use a puller if at all possible. Good luck Ed

Thanks Ed, I think I might have one of those, I'll give it a try.

 

[94formy]

The guy who did my head and crank work said he is always aprehensive to use any kind of a puller that relies on the aluminum threads in the case. He's the one who told me to just use a wide blade and work my way around the case and it worked prettyg ood. Just be careful not to marr up any of the mating surfaces, nothing worse than putting a motor all back together and back in the bike just to find that it leaks tranny fluid. I would also use a thin coat of hondabond or yamabond on the case gaskets just to be sure.

 

[SKIDOOrider800]

i split an 02 yz250 case a few weeks back without one. Just take out all the bolts (don't forget the ones behind the magneto). Then put the engine down on the clutch boss. take a rubber hammer and start tapping around the outside. there are some protrusions on the case you can use to your advantage. Pull up slightly on the top half while your doing this, and just keep going around so you bring the half of the case off straight.
I've been told you need to be really carefull or you could bend a shift fork? <shrugs>
hope this helps

 

[Ol'89r]

The guy who did my head and crank work said he is always aprehensive to use any kind of a puller that relies on the aluminum threads in the case. He's the one who told me to just use a wide blade and work my way around the case and it worked prettyg ood. Just be careful not to marr up any of the mating surfaces, QUOTE]


NOOOOOOOOOOOOOOO. Don't do that. :yikes:

Use a case puller. Buy yourself a small butane or propane torch from your local hardware store. Remove all of the case screws and lay the engine on its right side. Heat the left side case and using the puller, push against the crank while tapping against the countershaft with a SOFT hammer. The left side case will come off leaving everything in the right side.

Prying with anything between the cases will damage the gasket surface.

There is a good chance that the only thing damaged is the bearings.

If you don't already have one, buy a service manual.

Just my $ .02

 

[keithb7]

NOOOOOOOOOOOOOOO. Don't do that. :yikes:

Use a case puller. Buy yourself a small butane or propane torch from your local hardware store. Remove all of the case screws and lay the engine on its right side. Heat the left side case and using the puller, push against the crank while tapping against the countershaft with a SOFT hammer. The left side case will come off leaving everything in the right side.

Prying with anything between the cases will damage the gasket surface.

There is a good chance that the only thing damaged is the bearings.

If you don't already have one, buy a service manual.

Just my $ .02[/QUOTE]

That's good advice. Do not pry with anything. Other than pry open your wallet and buy a puller. I bought a harmonic balancer puller from NAPA for $11. Worked like a charm and I never had to heat anything up.
Get a manual too and read it and understand the scope of the work involved before you tackle the job. Think about your ability and limitations, can you do what the manual specifies?

For Godssake man, never pry with metal tools or use a steel hammer. A deadblow or rubber mallet are fine.

 

[airmanloco]

Man you guys are great, thanks so much for all your experience and advice. That balancer puller from Napa for $11 sounds a lot better than $170 from Motion Pro. I never knew Motion Pro offered so many specialized tools until I went to their website looking for this one, nice to know, how about that blind bearing remover for close to $300.
Ol89r,
You really think there's a chance that only the bearing are bad, that would be great. And yes normally I would have studied this all out in the manual before I even began, the guy has one that he's supposed to be sending.
Skidoorider800
I've heard the tranny can be difficult to get back together correctly what with the shift forks being all on the same shaft or something, how was your 02?

 

[SKIDOOrider800]

Skidoorider800
I've heard the tranny can be difficult to get back together correctly what with the shift forks being all on the same shaft or something, how was your 02?

taking it apart really didn't seem like a big deal. The wristpin went bad in the engine, and i found it more cost effective to replace the engine (cylinder needed work, pinhole in case), so i never ended up putting it back together. but from what i can see, it doesn't look that fragile. you'd have to try if you wanted to really mess things up.

when I split it both shafts stayed in the right side of the case and it would seem out of harms way.

hope this helps.



want to buy an '02 tranny in good condition? :laugh: j/k

 

[ryan callies]

Use a heat gun and a rubber mallet if you cant afford special tools

 

[94formy]

You don't pry with anything, just slip the blade between the halves and work it around the case. Once you have them split a little bit it comes pretty easy and no damage is done. It sounds like the puller should be safe too though since there is enough people who has done it without issues.

 

[johnsta6262]

u better clean out the carb 2!!

 

[airmanloco]

Ok guys I working on it right now, its still being stubborn, I let you know.
Thanks

 

[2strokerfun]

Come on guys, these "special tools" cost about $10. Just get an auto timing gear puller and buy two long metric bolts to split the cases. If you can afford the bike and the bearings, you can afford this.