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fastracrew

cracked case yz450f

8 posts in this topic

Hey guys just cracked my case chain snapped on a big hip as soon as i was on the hammer so I attempt to jb weld the crack/hole the hole was behind the front sprocket which is now ok but what I didn't know is if the seal where the clutch goes inn it was hit pretty hard it seems so I started it and a bit of oil came up thro so I pulled the seal and it damaged so I changed it and put the clutch shafts back in with new seal stated it today and it leaked way worse withe new seal and all cleaned up

Looking for some advise if you guys could help thanks so much

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Hey guys just cracked my case chain snapped on a big hip as soon as i was on the hammer so I attempt to jb weld the crack/hole the hole was behind the front sprocket which is now ok but what I didn't know is if the seal where the clutch goes inn it was hit pretty hard it seems so I started it and a bit of oil came up thro so I pulled the seal and it damaged so I changed it and put the clutch shafts back in with new seal stated it today and it leaked way worse withe new seal and all cleaned up

Looking for some advise if you guys could help thanks so much

 

Sorry man that kind of damage is the kiss of death to a case half. Not much to do except split your motor and replace it with a good used case half off of ebay, and this time put a case guard on it for your chain. Sometimes your can fix cracks with some skilled welding but when it goes into that area of the case its hard to repair and make strong again. If your crack goes into a seal you can never make it right again where the seal won't leak.

 

Someone might chime in with some miracle fix that might be worth trying but for me I would just buy a used ebay part.

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The problem is that the transmission is fed high pressure system oil through a passage that passes under the clutch release arm seal into the two shafts.  You'll never get it sealed with JB. 

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I tipped as with gear set to position for getting out the crank bearing, and this little spring and plunger fell out. Anyone know where this thing came from ?

1464041592768.jpg

1464041605621.jpg

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I tipped as with gear set to position for getting out the crank bearing, and this little spring and plunger fell out. Anyone know where this thing came from ?

It goes into the end of the shift drum and contacts the neutral position sensor on the left side case.

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Sorry man that kind of damage is the kiss of death to a case half. Not much to do except split your motor and replace it with a good used case half off of ebay, and this time put a case guard on it for your chain. Sometimes your can fix cracks with some skilled welding but when it goes into that area of the case its hard to repair and make strong again. If your crack goes into a seal you can never make it right again where the seal won't leak.

 

Someone might chime in with some miracle fix that might be worth trying but for me I would just buy a used ebay part.

I thought case halves were machined together (like cam caps) and not generally swappable... are YZ case halves swappable?

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They are machined in pairs bolted together, yes, so technically, they can't be mixed with cases from other pairs.  It is done, however, and people get away with it, at least for a while.

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