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View Full Version : welding a 400ex crankcase


420exJuggalo
10-05-2008, 06:34 PM
i have a 400ex bored to a 420, and i just got it back and running,and i noticed i had a verry slight leak from under the motor, i looked and found out it was right behind the front motor mount, and its just a hairline crack, i was wondering if i should find an aluminum welder or if i should j b weld , i would rather get it welded but im not shure if alum. can be welded, i dont like the sound of jb welding it because that just patches it really, not melting the alum particles together again like it never cracked, i noticed my box it came in had an indention on it like it had been droped , so i blame ups for that,becuse the motor didnt leak before i had it rebuilt and i think they would have noticed that when putting the gaskets back on it,besides im 100 % shure that it was damaged in transit by ups the marks on the box match that of the part on the bottom of the crankcase that is slightly cracked. damn ups!
rgorm2500
10-06-2008, 06:38 AM
anything can be welded if you know what you are doing. Put in a damage claim with UPS make them pay for the damage.:cool:
fx4pitrone
10-06-2008, 06:41 AM
UPS is insured for that stuff!! Put in a claim and get your money!
quad97
10-06-2008, 04:31 PM
It can be welded fairly easily by someone who knows what they are doing. The hardest part is getting the cast clean enough. It is best to have the case separated from the rest of the motor so that it can be welded inside and out, but not entirely necessary unless the crack extends to where the cases come together.
420exJuggalo
10-06-2008, 06:36 PM
i have called ups and the shipper of my motor, that is in the works right now,but i really dont want to pull my motor,its been two months and now everything is back to normal, damnn this sux
10-06-2008, 08:18 PM
if someone else was paying I would get it welded or replaced professionally. If I was paying I would be breaking out the JB weld lol
exrider87
10-07-2008, 11:42 AM
My cousin had a craked case on his 300ex and we treid to JB weld it, but it didnt even last one ride. He later had it professionally welded and i think that would have worked except it burnt the gasket out where the two halves of the case meet. So I hate to tell ya but i think your best bet would be to seperate the case if you were going to have it welded.:(
exrider87
10-07-2008, 11:42 AM
My cousin had a craked case on his 300ex and we treid to JB weld it, but it didnt even last one ride. He later had it professionally welded and i think that would have worked except it burnt the gasket out where the two halves of the case meet. So I hate to tell ya but i think your best bet would be to seperate the case if you were going to have it welded.:(
86 Quad R
10-07-2008, 04:10 PM
the right way to fix it is to have it welded up but, f you must use jb weld be sure to get the type that is formulated for aluminum. ;)
jeepthing07
10-14-2008, 06:54 PM
http://www.weld-aluminum.com/
420exJuggalo
10-18-2008, 06:28 PM
that pretty sweet, im gonna invest in that. weld with a propane torch , who'd a thunk it.

thanx
420exJuggalo
10-18-2008, 07:12 PM
I wonder how hot i will need to get the crankcase to get the metal rod to melt on it to fix it, and is it ok to put heat on that part of the motor, like right there behind the front motor mount..i mean is there n-e thing internal wise i will need to b worried about the heat affecting.