crank case pressure.......250r gurus needed

[xcracer416]

about how many PSI does the crank case have around the crank shaftwhen its running? i was just wondering cause my buddies crank went down and put a hairline crank in both cases about a half inch on each case in the middle. he dont have the funds to buy two matching cases, he was wanting to jb weld it but i told him to hold off until i found out from you guys.

[HiperEX]

jb weld should hold just make sure you clean the surface real good

[wilkin250r]

It's not a huge amount. I don't know specifically, but I would venture a guess it's less than 10psi. If you get a good seal with JB weld, it should hold.

However, that hairline crack is going to be a stress point, and just get worse. Me, personally, I wouldn't go with the JB weld. You might be able to run for a while, but it certainly isn't going to last forever.

[jas250r]

is possible to take it to a pro welder and have them fix it? I see people advertise on some web sites things they can repair, even though they are mainly the typical case saver and shifter rod breaks

[wilkin250r]

Honestly, that's getting a little beyond my knowledge. I know the cases are aluminum, but I'm not sure of the specific alloy, and if it's weldable. My metallurgy is a bit lacking.

Let me pose this question to those more knowledgable than I, and I'll see if I can get a definitive answer on the crankcase pressures as well.

[matt250r21]

You can get the cases welded but you need someone who has some talent with a tig welder.

[Mechanix311]

Agreed with matt250r21. You deffinetaly need to have some one tig weld it. IF a tig welder is not available i have had alot of luck with my mig welder with aluminum kit on it. I would deffinetely weld it i hate jb weld.

[rider250ex]

my case cracked before and i took it to a pro welder. he tried his best and it worked pretty good but ended up cracking again in the same spot after some time. the problem with welding cases is that they are cast aluminum which is really porus so the oil gets trapped in it. sometimes it works sometimes it doesnt. if i were you i would just jb weld it and run it for a while until you can get a new one.

[matt250r21]

Take the cases down to bare, spray everything with contact cleaner, then take the cases to you laundry tube and scrub away with comet bleach. This stuff works great at getting any left over crap out of the area you need welded. If you get it real clean and V out the crack so the weld penetrates well it will hold great. The key is to get it clean, noched and have someone with talent TIG weld it.

[Teufel]

You can tig it with aluminum filler, Personally I would use a high grade epoxy..

[machwon]

I would JB weld it as long as you're not filling any holes. If you do need it welded, tell your welder dude it helps to preheat the cases. Otherwise chances are your welder will warp the cases and they become useless.