Cracked Right-side Case Question

[DesertBraap]

Severe moron alert!!!

I'll ask my question first, since it's most important, then I'll rant below, in case anyone needs some laughter tonight. 

I cracked my right side engine case trying to press a transmission bearing in.  I've attached pictures below.  Bike is a 2015 YZ 250.

Question:  can I get away with purchasing just the right side engine case from any OEM distributor (Part No. 5NX-15121-00-00), or do I need to buy both sides as a matching set?  

I'm not finding a right side case on Ebay, but I am finding it for about $465 elsewhere.  Sucks, but whatever.

I am finding both sides for about $899 on Ebay.  That hurts.  I'm obviously hoping I can get away with just buying the right side. 

The crank assembly is still inside the right side case.  I will have to remove it, but I'm also having a debate with myself whether I need to also replace the crank assembly, or if I can get away with just replacing the crank bearings and using the used crank.  The motor wasn't blown up or otherwise evidencing any other signs I need to replace the crank, but I am replacing the top end, and I've been jostling and banging the case (with crank still attached) a bit trying to get bearings in an out.  Peace of mind might be worth another $350 (ughhhh).

 

 

 

Okay, so story and rant:

I made a thread a few months ago about whether I should keep and update my 2005 YZ 250 (which was running great, by the way), or buy what seemed to me to be a pretty cherry 2015 YZ 295 for under $4k.  I chose to buy the 2015, and got it for a good price.  The kid who owned it was a beginning and hardly rode it, but the person before rode it hard but also took care of it.  The bike was in excellent shape everywhere I could inspect. 

So I picked it up and rode it a few times.  The clutch was really hard to pull, and the action was not smooth.  I took the clutch apart to inspect and found some metal debris in the motor.  I posted a thread on here earlier about it.  The consensus was I needed to split the cases and clean up and remove what looked to be a blown shift stopper lever. 

Sure enough, the bearing on the shift stopper lever was toast.  I split the cases and found some random debris in the motor, so that was a good idea.  While I was in there I decided I would replace the shift stopper lever, the shift shaft (also bent), the push lever, some other odds and ends, and all of the transmission bearings, just in case.  I also decided to install a new top end for the Eric Gorr 295.  

Disassembly went well.  The problems started when I needed to install the transmission bearings.  I tried sweating them in using dry ice and a heat gun, and the first two on the left side did not go in very smoothly, but I got them in.  All day today I debated just paying a shop to press the other side in, but decided to try it myself again.  Bad idea.

Tonight I tried letting the right side bearings set in dry ice longer, and I tried to heat the case to a hotter temperature (using a temp gun to monitor).  As it goes with me, the first bearing I tried to install went in about half way before stopping, crooked.  Because the right side case still has the crank in it I didn't want to try and hammer the bearing in (not sure if that's a good idea anyway), so I building a homemade drift and tried pressing it in.  Obviously I cracked the case because the bearing was crooked and never righted itself, and there was too much pressure.   

Live and learn, but the lesson is, ultimately: f$%# installing bearings at home, by yourself, no matter what method you use.  Always just pay a shop to do it.  Damn it. 

So, score card for this "new" bike that supposedly was 10 years more fresh than my 2005:  $150 for a new top end kit, $229 for a new clutch basket, $145 for new clutch parts, $235 for other miscellaneous motor parts I wanted to freshen up, and now another $500 bucks for a right side case and bearings, and possibly another $350 for a crank assembly and crank bearings. 

What a day.  

 

 

 

[S.O.A.N.Z]

9 minutes ago, DesertBraap said:

So, score card for this "new" bike that supposedly was 10 years more fresh than my 2005:  $150 for a new top end kit, $229 for a new clutch basket, $145 for new clutch parts, $235 for other miscellaneous motor parts I wanted to freshen up, and now another $500 bucks for a right side case and bearings, and possibly another $350 for a crank assembly and crank bearings. 

What a day.  

You forgot to add the cost of the shop pressing in your bearings - unless you want to have another go at it 

[S.O.A.N.Z]

Microfiche lists them as separate parts - not as a set - so you might be in luck

 

[EmpireofDerp]

Oh geezus bro, nightmare.

[DesertBraap]

33 minutes ago, S.O.A.N.Z said:

Microfiche lists them as separate parts - not as a set - so you might be in luck

 

Yeah, and all of the old threads I've read seem to suggest that as well.  At this point I'll wait for someone to give me a reason why I shouldn't or couldn't go with just one side.  I think I'm good.

 

12 minutes ago, HeavyRotation said:

Oh geezus bro, nightmare.

 

Yeah, no joke.  I'm not incompetent with a wrench, but I do suffer from some exploration of stubbornness and stupidity from time to time. 

 

[EmpireofDerp]

 



Yeah, no joke.  I'm not incompetent with a wrench, but I do suffer from some exploration of stubbornness and stupidity from time to time. 



 

Yeah I'm incompetent and a drunk but i try anyway so seeing stuff like this just makes me even more fatalistic lol.

[S.O.A.N.Z]

Is it possible to weld that crack - or is it in the worst spot ?

[ASP1227]

 



Yeah, no joke.  I'm not incompetent with a wrench, but I do suffer from some exploration of stubbornness and stupidity from time to time. 



 

That sucks man. When I did my main and trans bearings on my CR250 I sweated all of them in. I put my cases in my barbecue for about 20 mins at around 280-300 degrees. I had the bearings in the freezer for 2 days. Each one dropped in with no problem. I don’t think a heat gun would give off enough heat. You gotta get the cases HOT. Mine where mag, so maybe they didn’t radiate the heat off as fast but yours are aluminum, you’d have to soak those things in heat to sweat in a bearing.

[Captain.Olives]

You dont need to buy matched cases, in fact Yamaha does not sell matched cases for the YZ250.  No problems matching a new right side with a used left side.  Any 2002 or newer used case off ebay will work with your motor.  If you are not seeing any of the 02+ cases on Ebay and willing to make a very minor modification, a 99-01 case will also work.  You will simply have to enlarge the inner diameter of the swing arm bushing on the older 99-01 cases to fit the larger swing arm bolt on the 02 + bikes.  You cant just swap the case's swing arm bushing as the outside diameter of the bushing is different, you need to drill out the inner hole to the larger diameter for the bolt.  I havent just read about it on the internet, I have three motors in my garage with mixed cases.  The motor currently in my bike has a modified left case from an 01 matched to an 02 right side case. 

I've never "pressed" any case bearings in and I've also never used dry ice.  I freeze my bearings in my kitchens freezer for at least a full 24 hrs.   Make sure the receiving bearing surface is clean and burr free.  Then either bake the case your kitchen's oven (yes) or use a torch to heat your case.  If your bearing is properly frozen, the bearing cavity clean, and the proper depth of heat is applied... the bearing will slip in without any force what so ever (they just drop in).  At most a very light tap with a socket and rubber mallet.  If its cocked, NEVER force the bearing in.  Remove and start process all over as you just learned.

I'm not a professional, but this is what I have learned about the YZ250 motor cases and my experience rebuilding them a number of times.  Other's opinion and experience may vary.  Good luck! 

  

Edited March 22, 2018 by Captain.Olives

[Christoffer Brandel]

Next time, put the cases in the oven at 350-400f (no they won't melt). For maybe 30-60 mins or until they are evenly warm.

Put your bearings on dry ice / in the freezer in a oil bath for some time. 

Then the bearings will drop straight in. No need for hammering. Just finger force. Source: Just changed all my trans bearing on 2010 yz250. Real easy and no way to crack anything ?. Just give them a light tap with a socket or drift punch to make sure they are all the way in. 

As others have stated, you can buy just the one side with no probs. Good luck! 

[MaybeMe]

7 hours ago, S.O.A.N.Z said:

Is it possible to weld that crack - or is it in the worst spot ?

You could weld and machine it, if you wanted to spend the money. It’s a tranny bearing and not a lot of force is on it as far as bearings go. 

Or just JB Weld it 

[numroe]

Shit dude. Nightmare. Sorry to hear that.

Actually a 2000W heat gun is enough.   I've done it many times. Bearing falls in. "Ker-plunk".   Bearing pre-oiled then put in a sealed plastic bag in the deep freezer for 6+ hours. Heat the case area for about 5 minutes, then go get the bearing, heat the case again a little more, then drop it in. Use gloves so you can get it real close before the drop. The oil helps it slide to fully seated.

[Motox367]

Tranny bearings rarely go bad. No need to change them unless so , its very rare that i see one bad unless ran very low on oil. 

[YZDOC]

OUCH! That is a pisser.

But rest assured, the cases are not matched so find a good used one on Fleabay. Engine number can be re-stamped if Idaho needs that on the title. Otherwise you'll need to do a VIN verification, like CA.

Edited March 22, 2018 by 2 STROKE YZ DOC

[DesertBraap]

14 hours ago, S.O.A.N.Z said:

Is it possible to weld that crack - or is it in the worst spot ?

It might be, but I'm not going to bother.  I think I'll list the case on Ebay and let someone else have a go at it, if they want. 

 

 

10 hours ago, Captain.Olives said:

You dont need to buy matched cases, in fact Yamaha does not sell matched cases for the YZ250.  No problems matching a new right side with a used left side.  Any 2002 or newer used case off ebay will work with your motor.  If you are not seeing any of the 02+ cases on Ebay and willing to make a very minor modification, a 99-01 case will also work.  You will simply have to enlarge the inner diameter of the swing arm bushing on the older 99-01 cases to fit the larger swing arm bolt on the 02 + bikes.  You cant just swap the case's swing arm bushing as the outside diameter of the bushing is different, you need to drill out the inner hole to the larger diameter for the bolt.  I havent just read about it on the internet, I have three motors in my garage with mixed cases.  The motor currently in my bike has a modified left case from an 01 matched to an 02 right side case. 

I've never "pressed" any case bearings in and I've also never used dry ice.  I freeze my bearings in my kitchens freezer for at least a full 24 hrs.   Make sure the receiving bearing surface is clean and burr free.  Then either bake the case your kitchen's oven (yes) or use a torch to heat your case.  If your bearing is properly frozen, the bearing cavity clean, and the proper depth of heat is applied... the bearing will slip in without any force what so ever (they just drop in).  At most a very light tap with a socket and rubber mallet.  If its cocked, NEVER force the bearing in.  Remove and start process all over as you just learned.

I'm not a professional, but this is what I have learned about the YZ250 motor cases and my experience rebuilding them a number of times.  Other's opinion and experience may vary.  Good luck! 

  

 

I spent a few hours watching videos and reading TT threads which compelled me to try it myself.  I've done a handful of crank bearings before so I have experience with it.  For some reason these transmission bearings weren't even close to falling into place, and that's with dry ice and a case that was reading 250*.   Definitely screwed up trying to "press" them into place, obviously.

 

3 hours ago, numroe said:

Shit dude. Nightmare. Sorry to hear that.

Actually a 2000W heat gun is enough.   I've done it many times. Bearing falls in. "Ker-plunk".   Bearing pre-oiled then put in a sealed plastic bag in the deep freezer for 6+ hours. Heat the case area for about 5 minutes, then go get the bearing, heat the case again a little more, then drop it in. Use gloves so you can get it real close before the drop. The oil helps it slide to fully seated.

 

Maybe by the time I went to set the bearing I rubbed all the oil off.  Can't figure out why else it wouldn't work.  

 

3 hours ago, Motox367 said:

Tranny bearings rarely go bad. No need to change them unless so , its very rare that i see one bad unless ran very low on oil. 

 

3 of the six were in fine shape, the other 3 definitely weren't rolling as smooth as I'd like. Figured while I was in there it was worth replacing.   The lesson I continually learn is that preventative maintenance almost always causes more problems and maintenance than just leaving well enough alone!

[Motox367]

48 minutes ago, DesertBraap said:

It might be, but I'm not going to bother.  I think I'll list the case on Ebay and let someone else have a go at it, if they want. 

 

 

 

I spent a few hours watching videos and reading TT threads which compelled me to try it myself.  I've done a handful of crank bearings before so I have experience with it.  For some reason these transmission bearings weren't even close to falling into place, and that's with dry ice and a case that was reading 250*.   Definitely screwed up trying to "press" them into place, obviously.

 

 

Maybe by the time I went to set the bearing I rubbed all the oil off.  Can't figure out why else it wouldn't work.  

 

 

3 of the six were in fine shape, the other 3 definitely weren't rolling as smooth as I'd like. Figured while I was in there it was worth replacing.   The lesson I continually learn is that preventative maintenance almost always causes more problems and maintenance than just leaving well enough alone!

They always feel like that tho , you'd know if one was bad 

[YZDOC]

Bearings have always just dropped in for me at the right temp of case to freezer bearing. 

Sorry you boogered that bish, and best of luck with a new/used case.

Trans bearing are very hardy, and can take lots of abuse, and use. There are factors to a bad one, and you would know it if it was bad. Cleaning them out several times when the case is apart will usually get the rotating, and not feeling crunchy. 

[EmpireofDerp]

 



3 of the six were in fine shape, the other 3 definitely weren't rolling as smooth as I'd like. Figured while I was in there it was worth replacing.   The lesson I continually learn is that preventative maintenance almost always causes more problems and maintenance than just leaving well enough alone!

I do maintenance for a living. Rule #1 is every time you touch something you degrade it. #2 is Don't fix it if it isn't broken. #3 is If you plan ahead, you'll never have to do anything right now.

On top of these simple rules is the coffee principle. Drink more coffee and think about working instead of actually working, you'll break less shit.

[YZDOC]

3 minutes ago, HeavyRotation said:

I do maintenance for a living. Rule #1 is every time you touch something you degrade it. #2 is Don't fix it if it isn't broken. #3 is If you plan ahead, you'll never have to do anything right now.

On top of these simple rules is the coffee principle. Drink more coffee and think about working instead of actually working, you'll break less shit.

How to put 40 minutes of actual work in a 9 hour day. Takes skill... 

[EmpireofDerp]

How to put 40 minutes of actual work in a 9 hour day. Takes skill... [emoji317]

You said it brother. Its a long game, gotta stay focused. [emoji38]