I fixed the problem

 

my guess is that it really wasnt your fault .Is the top mount on the motor loose as well??Before I took the motor out I would find the best welder in the land and have him look at it .I have seen a similiar repair made without welding using a billet piece of aluminum machined into a L shape that acts like a girdle or safety mount on top of the other pinching it down on the frame.Welding cast can be done but sometimes the results are less than spectacular

 

To my knowledge, the engine must come apart.
There is pre and post heating involved in weld repairs for cast aluminum from what I have been told.
When reassembling the bike, be sure to shim the engine and transmission mounts to eliminate any stress on the mounts due to variations in the engine/transmission mount alignment.
Even factory frames can require shims.

 

you are correct------------I cant even begin to count the number of cases I have seen at swap meets that you can tell they have been welded several times and then someone gave up on them.Usual story is you tear them down to weld the mount and then find other cracks so its another motor or different cases.



I would try the billet clamp for lack of a better term and use it on both sides until the engine needs to come down then attempt it then.This would be after a careful inspection of all mounts and mount bolts.My old evo keeps loosening the top motor mount and I just know some day it will break a lower tab

 

Kids eh? I dunno........... :-) :-) To be fair it probably wasn't your fault.

 

I don't see any signs of an established stress fracture, so it hasn't been brewing and waiting for its chance to split. Unfortunately it may well be the result of an exuberant ride! However it wouldn't be fair to blame you as it could have happened to your Dad when he was making that killer put down pass, on another day!

If it is any consolation my shovel split off both its exhaust fixings (one on each head) and they were successfully welded, so welded repairs can be done and survive. I had mine done by a local drag racer who knew a thing or two about fixing broken motors!

 

Yeah, I wouldn't call it your fault either, just "one of those things." You should not be able to break the motor mount by twisting the throttle.

As for fixing, well, did you find the other piece? I've seen some seriously good welding done on aluminum. It would help if you had the other piece. I would think the motor would have to come out to do a proper welding job. It may not have to come apart, but certainly come out and get 360'ed for the welding.

 

How's about removing the bolt, use a die grinder to create a flat surface, drill and tap the mount and put a piece of stock across the front and bolt it on. looks like you have enough meat there. you could do this with out removing the motor or worrying about magnatizing anything in it by welding it. If it doesn't hold you haven't lost much.

 

If I was your Dad, I'd beat you until you were black and blue..........

 

"Hammer down" should not be the cause of that break. Most likely the motor was never shimmed properly (or never checked to see if it needed to be shimmed) before being bolted in the frame.

The motor will definitely have to come out of the frame and be disassembled for repair.

Couple of sources that I have used on my 49 EL project...

http://www.carlscyclesupply.com (for rairs to a set of OEM 49 heads)

http://creeksidemc.com (for repair of my OEM 49 cases)

Can give you positive feedback about both.

While the cases are out for fixing get some brass shim stock from a place like

http://www.use-enco.com/CGI/INSRHM or

http://www.mcmaster.com

Once the cases are back and you have the lower end together, put the lower end in the frame. Next, torque to specs the rear motor mounts. Get a set of feeler gauges and see how much of a gap you have in the front mount-to-frame on bothe the right and left side. The closer you can get to zero withe the shim stock, the better. The right and left may require different thickness on each side.

And while you have the motor down for repairs you might want to check the tranny to ensure it sits flat on the mounts. From what you have descirbed I assume it is a custom rigid frame. Last thing you need is to have the tranny rocking in the frame. In rigid frames, the gap usually is found in the fifth bolt hole (the one that attaches on the right side).

Finally when all that is done and you have a new belt you need to make sure the rear belt is aligned properly and since you are running a primary belt then that too needs to be checked for proper alignment.

What you have done is mostly seen in old pans and knuckes that have been together, taken apart and reassembled in various forms over the years and put in frames that needed fixing but were not (motor mounts worn on frame and/or cases).

Good luck with the fix. Think about starting a new thread here about the fix so that someone behind you will have a resource should it happen to them. Take a lot of pictures as you go; it helps on the reassembly as well for reference. Now is the time to do some cleaning on areas you could not access before.

Good news is that by late spring you will be up and runnung again...