just about ready to put back together after blowing the top end on my yz after getting the cylinder replated ordering parts and with a total now of 350$ I thought I was done. After changing the oil and screwing the drain bolt in the case cracks where the bolt goes, I got angry but was gonna take the engine off only to discover a motor mount cracked as well. What can I do about this

Get things welded up.

Buy a torque wrench so it doesn't happen again

Yikes,

The oil drain bolt should only be torqued to 14ft/lbs. There is absolutely no need to crank hard on it.

You just have to get everything welded. Don't fix it have assed because it will just bite you later on.

the thing is I havent torqued yet I was just screwing it in, and how could the motor mount crack to that angers me

Buster Traugz, on 19 June 2012 - 06:40 PM, said:

I'll take the motor mount over the case crack any day of the week!

Engine mount tabs on the steel frames crack.  I've seen it before on a couple steel YZs.  Strip the paint from that part of the frame, clean it up really well and have someone MIG weld it.

If your frame mounts are cracking, your engine bolts came loose at some point.  Make sure you have the OEM lock nuts and bolts.  Also, when you weld/grind the mount, make sure it is very flat so the bolt/nut can tighten down evenly.

The case can be welded...but it takes an experienced welder to do it.

A torque wrench will prevent both problems in the future.

Dude!
Your repairing your motorcycle. and your making it better.  Slow down and do the best job possible and it will reward you with many more fun miles.
Working on Dirt Bikes is the next best thing to riding them. Life Doesn't Suck!
Your attitude may need repair as well as your motorcycle. Show that bike some love and it will love you back!

thanks for the post, the thing is all I want to do is ride it and its taking lots of time and money to reach this point, the weld on the oil drain is small and looks difficult do you think it can be done with out leaking?

Buster Traugz, on 19 June 2012 - 03:55 PM, said:

Are you POSITIVE those are cracks? YZ cases have lots of little casting flaws that look highly suspicious but most often turn out to be nothing.

If it is a crack, a good weld job will not leak.

its crack alright, im holding two pieces of the drain canal in my hand

GCannon, on 20 June 2012 - 08:20 AM, said:

Now that's what I'm talkin bout!!!

My 2 center motor mounts were broken when I bought my bike. It's not a big deal to weld them.

I'm wondering if you hit a big ass rock to crack the case and maybe the motor mounts, then it just waited to fall apart in your hand.

Anyway getting stuff welded is usually NOT expensive.