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Cracked case, WWTTD?

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Cracked case. Didnt notice until motor was back together. Motor is totally fresh from bore to bearings to seals and crank. Would love to not tear anything up. Afraid to weld it with the motor together because the heat will probably ruin the bearing, not to mention that oil will be a challenge.

So...watch ebay for a new case half or-

take the motor apart and get it welded or

is there some kind of awesome epoxy that will hold it and prevent the crack from spreading...

or....???

What are thumpertalks thoughts?

photo3.jpg

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JB Weld is not a reliable fix for any area that is structural or stressed in any way.

I can't tell what part of the engine that is from the pic. Is it under the kickstarter shaft opening?

Did you crack it by driving a bearing in too far? If so that bearing is probably damaged.

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JB Weld is not a reliable fix for any area that is structural or stressed in any way.

I can't tell what part of the engine that is from the pic. Is it under the kickstarter shaft opening?

Did you crack it by driving a bearing in too far? If so that bearing is probably damaged.

left side crank bearing. the bearing was seated. used the dry ice/oven method. bearing seated pretty easily. a few days later after i had a few beers in me, i hit it a few times with a socket and hammer on the outer race because it looked a little high on one side. obviously it was seated already.

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left side crank bearing. the bearing was seated. used the dry ice/oven method. bearing seated pretty easily. a few days later after i had a few beers in me, i hit it a few times with a socket and hammer on the outer race because it looked a little high on one side. obviously it was seated already.
If that's the bearing pocket, no way would I run those cases.

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If that's the bearing pocket, no way would I run those cases.

Thats correct.

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Watch ebay diligently, itll keep you from going to town to buy beers.

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That's from pressing or driving the bearing in too far on that left case. I made the same mistake the first time I rebuilt my 2002 and I've seen a few other guys on the forum with that issue.

Pick up another left case and be gentle when you install the bearing. Freezing the bearings and/or warming up the case will allow them to drop right in without a press most of the time.

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I know how bad that sounds. But whats worse case on this crack? Air leak leaning it out. Or do you think its going to explode?

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It won't explode. But it will potentially allow air or crankcase oil through.

Anyway you slice it, you are going to have to split the cases again. Might as well do it now and take the case to a good welding shop and have them fix it. If done correctly, it will be just as strong as it was new.

Or, watch eBay for someone parting out an engine.

You could try JB Weld to get it running for a bit (just to really seal it from air or oil movement), but I wouldn't expect that to hold up forever. Nor would I be surprised if a lot more damage resulted from running it like that (it only takes a few metal bits to ruin your new bearings).

Oh, and I probably don't need to say this, but beer and engine assembly go together like peanut butter and sauerkraut. But it seems you now know that.

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I know how bad that sounds. But whats worse case on this crack? Air leak leaning it out. Or do you think its going to explode?

it could explode and piston fragments travel through the seat and impale the rider :smirk:

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I know how bad that sounds. But whats worse case on this crack? Air leak leaning it out. Or do you think its going to explode?
That crack is located in an area that will be subjected to forces generated by the rod-swing-induced rocking acting on the crank. The second-order vibration from the engine running WILL cause that crack to propagate farther and farther around, until it completely breaks.

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That crack is located in an area that will be subjected to forces generated by the rod-swing-induced rocking acting on the crank. The second-order vibration from the engine running WILL cause that crack to propagate farther and farther around, until it completely breaks.

...and the air leak will get worse wreaking havoc on your jetting (and possibly your top end). I don't think sealant or epoxy is safe here.

In terms of dollars and risk:

Cylinder + Piston + Head > Case

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What is the rule of thumb for the crank bearings? I'm pretty sure the manual says to replace them if you press them off and out. So case half, bearings and seals. What about trans bearings im thinking he's gonna need those too?

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What is the rule of thumb for the crank bearings? I'm pretty sure the manual says to replace them if you press them off and out. So case half, bearings and seals. What about trans bearings im thinking he's gonna need those too?

Yeah. That's because you have to pull on the inside race to pop out the bearings.

Sometimes heating the case will allow those bearings to fall right out.

If heat doesn't work, pressing the outside race on the main bearing (all the way through) will finish off the case but will allow re-use of that bearing and seal.

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I had this happen to my motor during my rebuild also because i was being stupid to say the least. However i did fix mine using loctite weld epoxy and it will fix your problem if you do it correctly. The area that split is not damaging any structural integrity, The inner diameter of the where your bearing seats holds almost all the structural integrity. Clean out the the area and use some light sandpaper on the area around the seam so the epoxy seals your case better. Use some sort of clamp to hold that seam shut also and load that stuff all around the area and dont be shy with it. Extra curing time is a good idea also. I would recommend the loctite weld because it has the perfect heat rating for this and you can machine the stuff after it sets.

If you have a hard time believing me I have alot of riding time on my my fixed case and saved myself ALOT of money on a replacement case. I have checked the fix a few times during maintenance and so far its holding up like a champ.

ybroke.jpg

Cant really get a good look in this picture but its hat I got. Ended up putting a little thicker coating on the next day also.

yzmotor.jpg

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