Stuff Clymer won't tell me

[YZ250H]

Hi Guys,

Have got 250H motor apart as far as Clymer will tell me.  Happy to report transmission etc is in very good shape .
Based on my 125H/J experience I was going to replace the crank seals etc whole I have the thing apart.  No problem for the rotor side as it comes off easily.  Then Clymer tell me they don't recommend taking crankshaft out of the other side.  "If you need to do that you should take it to Mr Yamaha".  Based on what I paid last time I was going to try to do all the work myself.  Opinions please .  Is this too much for me to take on - i.e. professionals only ?

Cheers
T.J.B.

[TonyB]

heat and serve, when the missus is watchin her fave soapy  just heat in oven to about 120 degrees and the case half will come off with gentle tapping.(support case on plastic bucket etc to protect mating surface and tap on crank .. heat when you put it back together again. (this all worked on my 465h so I am sure it should work for you.

[vandy010]

i'm not familiar with the 250h motor, but all the yammy donks i've split the cases on i use a crankcase seperating tool. this tool splits the cases evenly and the crank usually stays in one case. the same tool is then swapped over into the half with the crankshaft in it and used to push the crank out. this leaves both seals exposed for easy replacement.
one bearing usually stays in the case while the other stays mounted to the crankshaft. the bearing in the case is easy enough to remove by the oven and tap method, the bearing fixed to the crank has always been my problem so i usually take that to mr yamaha for them to remove and it don't cost too much either.
i usually fit the bearings myself. bearings are cold from the freezer with cases warm {100degrees celcius or so} from the oven.

[wesley]

YZ250H............do yourself a favour and buy a good copper hammer and a heat gun thats all you need,as thats all i have ever used,heatguns from bunnings(electric one) copper hammer (allied bearings)i have a brand new bearing puller but i have never needed to use it as the old yammy motors seem to come apart without much fuss......or come and borrow mine....wes..

[YZ250H]

Thanks for the tips guys.
Vandy - did you make that case splitter yourself ??  One very important lesson learnt is to make sure you have ALL the case screws removed before attempting case splitting.
Wes - good to see you you back - where have you been ?  Obviously cane hauling season is over .  I've got a dead blow rubber hammer that I use all the time (a great thing) - will that do ??  Got a heat gun too - should I be trying to heat the whole case or just the immediate area around the bearing??.  If it's the whole case I will probably send the missus shopping and use the oven .
Is there any issues with "Crank Alignment" ??  Thats one of the things Mr Yamaha charged me for last time
With a combination of the methods mentioned here I reckon I can get it sorted.
I was just curious (scared) as to why Clymer would say not to do it yourself.  As long as there is nothing terminal I can do I will go for it.  Thanks for your help guys.  I'll give it a go on the weekend and see what happens.

[vandy010]

here ya go champ,
a piece of 50x12 flat with a big bolt through the guts and two "long" bolts to screw into the motor. with the flat bar, i can drill more holes to suit more motors if neccesary so only one tool will be needed.
my "long" bolts are around 120mm in length and you'll need at least that to get the tool over the end of the crank.
i just shot this pic just then so it's kind of a mock-up in action shot.
excuse the bench folks, i'm still in holiday mode hangin with my kids.

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[YZ250H]

That's awesome Vandy.  Thanks for sharing mate.  Surprised / delighted by the simplicity.
Nothing wrong with your bench  - it looks pretty spacious to me (I have to share mine with 3 other inlaws - or is that outlaws ).  One day I'll get my own bench and they can all get stuffed .  Until then I have to stay in good with them 'cause I can't weld (yet) and I need a tool made on the week-end 
Enjoy the time with the kids.
Cheers
T.J.B.

[BONEHEAD]

the 2 motors i have built came apart with no worries, just gentle tapping with a copper hammer and a few beers,i have about 4 gearboxes for the yz 250 g 6 speed and a good gearbox for the h modle, i also have a spare engine for the g just needs piston and rings to go in and also complete clutch and magneto,if anyone could help with mag i would be most greatfull. chees bonehead 

[YZ250H]

Ok,
So I tried the heat gun and the deadblow rubber hammer on the left hand case - magic 
Except for two of the bearings.  The one that supports the clutch actuator and the other one in the same area that the clutch rod goes through the centre of.  I don't know if I didn't get it hot enough or too hot.  didn't try the spit test - although that's a good tip.
Also tried the oven on 120 degrees to no avail.  What am I doing wrong???  Do I need to borrow Wes's bearing puller.  The little one around the clutch actuator is a bugger as it is pushed right down and you cant get behind it .
Apart from those 2 minor hitches it's all good.  Then for the other side.
Made one of Vandy's nifty little separators and will use it after I finished with the LHS case.
Open to suggestions - I know you blokes always have the answers.
Cheers
T.J.B.

[TonyB]

You should leave it in the oven for quite some time untill its really hot ( takes some time to heat soak), and the spit frizzles, then tap the case down sharply on a wooden board ( remove dowels before hand) and make sure the surface is soft pine wood and nice and flat, like an el cheapo cutting board. The bearings should come out or start to come out enough to pry out. The hotter the cases the more the clearances between bearings and case. I once nearly shat myself as i put the oven on to 140 and put the cases in thinking ( incorrectly of course) that it would get hotter quicker if i set the dial up. Then I went through to the garage and started doing some other bits on the bike. 2 hours later i suddenly remembered the damn case, i ran like mad to the kitchen expecting to see a molten blob in the oven but instead it was fine and i removed it with oven gloves and the bearings just fell out,

[DJRacing]

The clutch actuator bearing is a shit of a thing to get out. The only way I know of is by using a slide hammer.

[YZ250H]

Thanks guys,
Maybe I didn't leave the case in the oven long enough .  Had to take it out 'cause the mother in law wanted to start the roast - true story    At least the oven was pre heated .  I will give the oven another go.
Have to pinch the missus' chopping board  .

I have been eyeing off those slide hammers in the tool shop DJ .  Another tool I don't have yet.  If the second crack at the oven doesn't work I will go and get one and see how it goes.  Obviously it will come in handy for a heap of other jobs around the workshop too.
thanks for your help - i'll have another go at it.
 
 

[TonyB]

The other thing I remember doing while the thing was hot once was to insert a 6inch long coach bolt ( thin slightly domed head with square neck under dome) and rest the head on bottom of hole where bearing is , lean bolt over so the edge of the head fits under the bearing, or bearing roller, and pull bolt over rocking on curved head and you get a lot of leverage under the bearing and it starts to lift.
I might even have ground the head to create a kind of foot so it can fit down the middle of the bearing.