Cracked crankcase - Yamaha ATV Forum
 
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post #1 of 10 Old 01-14-2012, 09:46 PM Thread Starter
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Cracked crankcase

What is the YFZ450 crank case made of? Aluminium? Can it be welded?. A small cracked appeared when my chain came off and got stuck between the sprocket and frame. Its leaking oil from it, pretty seriously. I am going to try J-B weld it too if all else fails. Its hardly an inch long.

Any ideas?
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post #2 of 10 Old 01-20-2012, 01:21 AM Thread Starter
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JB Weld worked but my focus now turns to the oil leaking form the oil seal where the clutch cable connects to a shaft. Not sure the seal can be replaced from the top, so my only option is to make another seal that fits on top and use/mod the little plate that hold the spring in place to help seal it.
Some more JB weld and maybe gasket sealer and I should be up and running with a motor that Yamaha has written off.
I will get a good camera and document the fix once successful. Anyone with something similar let me know I am open for ideas.
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post #3 of 10 Old 01-25-2012, 10:57 AM
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JB weld dude? seriously? get a case half off ebay, fix it right, and make the rest of us honkies proud!!!!!
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post #4 of 10 Old 01-25-2012, 11:04 AM
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The aluminum case can be welded, but it would probably be cheaper to find a used one. I would only use JB weld for a temporary fix. It will probably work for a while, if you cleaned the area really really well. but don't consider it a permanent fix.

2008 Raptor SEII
2006 YFZ450
2008 Raptor 250
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post #5 of 10 Old 01-26-2012, 01:46 PM Thread Starter
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Fixed

JB weld worked for the crack, however with the new seal it still leaks a bit. I glued the edge with silicone and that stopped the leak. Taking the engine apart to fix a small leak is not worth it. This fix need to last at least half a ride And Id be happy to do it everytime. labour cost is $NZ80-100/ hr, + parts. I can buy a complet bike o fthe same year at the price a rebuild whould cost me.

Engineering shop could weld it but again the seal is no longer sealing as the crack makese the housing not 100% round.

I will be riding the 450 hard this year and plan a complete rebuild by the end of the year. (If nothing else breaks)

I may buy a new (2008) Kawasaki KXF450 and use the Yamaha as backup. Or vice versa.
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post #6 of 10 Old 01-26-2012, 02:11 PM
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Quote:
Originally Posted by flippinz View Post
What is the YFZ450 crank case made of? Aluminium? Can it be welded?. A small cracked appeared when my chain came off and got stuck between the sprocket and frame. Its leaking oil from it, pretty seriously. I am going to try J-B weld it too if all else fails. Its hardly an inch long.

Any ideas?
i have used jb weld on some small wholes and cracks seemed to work fine the case is usually some kind of cast alluminum and is hard to get clean enough to get a good weld it is possible if you know the right guy that knows how to weld alluminum
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post #7 of 10 Old 02-03-2012, 08:59 AM
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even if you got it clean enough to weld you're going to melt the shift shaft seal. it only takes about an hour to get the motor out and might takeanother three hours to swap out the case. The beautiful thing about this bike is when you split the case the whole trans. assembly stays in the right side so it's just a matter of splitting it and replacing the left side. I'm not a mechanic but I did it and it wasn't that bad.......
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post #8 of 10 Old 02-03-2012, 09:28 AM
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Also yamaha doesn't sell just that side. they come as a set, and I would guess that if you look for used ones you will find alot of good right sides but few left ones for the same reason. new crankcase assembly is $399. Keep in mind that the new case won't have any bearings or seals in it either. The seal is replaceable from the top but you will have to take the clutch cover off and remove the clutch pressure plate to get the arm out of the case.
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post #9 of 10 Old 02-03-2012, 05:46 PM
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Yeah, it is tough to find just the left side and you usually will have to buy both sides but you don't necessarily have to use both sides. Really, you should use both sides as a set because they are line bored as a set but I just did one side and had no problems and I was lucky to find a left side. As far as bearings all u need are the right size sockets, maybe a drill, some dry ice and a propane torch. Sweating them is the best way since there is no banging involved but you have options. as far as JB weld........that's a temporary fix that could fail while you are riding and cause a major catastrophe.
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post #10 of 10 Old 11-15-2012, 08:38 PM
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It can be welded My son in law had his broken right off his and we got it welded for 20$
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