Welding the crankcase
 

So I was showing my true idiot going well over 100 when my chain snapped. Not sure why. Can't find ANYTHING wrong with the chain or either sprocket that could have caused it. Either way, it still snapped. As it flew around the drive sprocket it must have done some sort of "tail whip" and broke every bolt hole off of the main crankcase...or transmission. Whatever the book you're reading calls it (I've seen several different names - but you all know what I'm talking about). The left crankcase cover, as my book says (hold the clutch slave and covers the front sprocket) is history. No biggie. I've got a new one on the way, but I've gotta figure out a way to bolt it back on. I'm now missing the bolt holes. They seem to be intact, all thought still bolted onto the cover. Anyone ever tried welding on the cast aluminum case? I'm afraid that the cast may well crack out, even if I warm it up first. Any ideas, or maybe even an alternative method of putting the clutch slave back on? Don't care about the cover itself. I can make a cover - just worried about the slave (REALLY don't wanna have to go to a dry clutch just to keep the bike running).
Thanks for the help in advance...

You can weld cast aluminum. It is not the easiest thing to do. Some really good prep work and someone that knows what they are doing.

Good luck

I can weld cast no problem, Too bad your in Texas and im in TN

Aluminum can be welded, but don't "learn" on your bike. Aluminum welds differently that anything else.

Your closer to him then me.

WTH is the "extra" washer that's hanging down from the front sprocket bolt? And why is it hanging down like that? Is it a cushioning pad?

BTW, what type sprockets/chain were you running?

I was wondering the same thing...looks like some lateral play there may be the culprit...RC

Every time I weld aluminum, I have a craving for an ice cream sandwich! lol!

did i miss somthing? are you talking about gettin the broken bolts out of the holes? because if so get a easy out extractor set. penetrating oil and maybee a little torch to heat them if neccesary? looks like you just got some snapped of bolts? i only see two? if thats all i live in wills point texas about 30 min east of dallas and could get them puppies out in a jiffy. as far as welding cast its not an easy task and you should be really carefull with who you let do it. cast needs to be pre heated olmost perfectly to avoid pitting or a really brittle weld.

Adding to my other post, I think the first thing I'd do is get that sprocket off, clean that puppy up, and run it on the sidestand in gear. Let it get hot. I'd want to make sure the shaft seal is good before I started building anything back together. The washer that is still in place looks like it's concave now, in the wrong direction. May just be the angle of the pic.

somebody jury rig that sprocket?

looks to be cause of problem.

http://www.motobike.jp/product/749

this looks cool as a replacement...RC

http://i2.ebayimg.com/05/i/08/f2/f2/24_1.JPG

Or the one from Coerce Racing ebay link

Or MAX MC Direct

Is there enough meat behind where the bolt holes were to drill and tap deeper in and use longer bolts? (along with the old pieces to fill the gap)

Wow - guess I should have checked this sooner. You guys really know how to reply.
First things first:
I know it looks like the bolts are broken off, but the bolts are actually fine. The actual holes themselves broke off the side of the case. I've thought about trying to drill and tap just a little deeper, but I'm not sure how thick the walls of the case are at that point. At this point, I think it would be safer to try to weld the pieces back in rather than end up busting through the case.
As to the brand of sprockets/chain - couldn't tell you if I had to. Bought the bike used from a friend of mine last September. He kept good records on everything with that exception. He always had a Honda shop work the chain because he didn't want to be the crimper for the master link. As to the odd look of the washer(s) around the front sprocket - you're right. I'm not sure what the hell was going on there. There are two washers there instead of one, neither of which appears to be concaved. The sprocket is also a little loose, but I'm guessing it was from the incident or I would have seen it already. Needless to say, that will all be replaced per honda spec.
The seal seems to be fine. All the oil that you see was from me grabbing for clutch before I realized that I had no clutch anymore. At the time, I was just trying to get the bike shut down without dropping it.
Good eyes on the aftermarket replacements. Those look really clean. I may have to send the other one back...
Gonna go clean it up today and get it ready for the welder. I'll let you all know if I find something else that would be interresting.

As far as the culprit - I'm blaming a bad link in the chain. It literally broke - and it wasn't the master. Once I found the chain and got it cleaned up, it looks nearly brand new. Guess everything mechanical has a break point.

Let me know if you have any more observations of tips that could help out. Thanks a bunch, guys!

was it a 520 chain?

the washer hanging down (obviously not in the right place; should be seated on shaft properly and flush against oem washer-probably hanging down from the chain explosion...) is there to shim the extra space between the oem washer and aftermarket sprocket after the bolt is tighten down otherwise there would be side to side play/ movement. The aftermarket sprocket is thinner than the oem one which is slightly wider and has a damper built in. while, i'm not saying this is true for all aftermarket sprockets, I had to do the same with a renthal ultra-light sprocket i used. If its not there then the side to side play would cause unnecessary wear on the splines and sprocket teeth.

May be true, but if that's the case someone used a washer with way too big of a hole. That thing shouldn't droop like that. The hole should be the same size as the shaft. Looks like it got loose enough to let the washer sag, which would put the sprocket at an angle, and then it's all over.

Glad your OK. Chains coming off are never good thing.

The i/d on the "extra" washer matches the o/d on the output shaft, I've just got the bolt loose and it's hanging down on the bolt itself.

Chain SHOULD have been 520. I'm not bright enough to look and tell the difference. Know quite a bit about mechanics, but not tons about bikes to be honest. I'm learning quickly though, as you can plainly see. I also believe that the sprocket was good and tight prior to the chain break - Wear patters on the socket don't indicate any strange movement, and like I said earlier (I think), the chain was in like new condition. No unusual marks or unusual wear. I honestly believe it was just a mechanical weak spot. I can't explain it any other way - and hey, it could happen (just hope not everyday).

Thanks for the tip about the width of the stock sprocket vs. aftermarket. I probably wouldn't have looked at that too hard. I'll make sure I pay attention when I get them in.

most manufacturers dont suggest 520 chain use for 1,000cc twins.

could this have been the problem?

i have used them before,with frequent care and not all out use.

wheelies,burnouts much?

like i said i have and will use them,but with knowledge it could be over stressed.

If he was really on it, the chain was hot, under-lubed and defective from the start, this failure is possible. Like you suggest, multiple factors will work together.

I agree with your assessment that if you're built out with cams, heads, flywheel mods the 520 might not be my choice.

I just bought a couple 520 rear sprockets from a member here and my 530 is on a short-term timeline. It's starting to hook just slightly but it's showing the fun. My engine is stock so I'm ok with the switch. I'm 165lbs so anything I can do to get weight off the bike helps.

No wheelies unless accidental, and tires are something that I can avoid wearing out TOO quick to save that much money for other stuff. No burnouts.

I was wondering if that was possible. I'm sure that it was NOT under lubed. I always make sure to check that as there's lots of rain around here, followed by dust, or visa versa. Like I said, it wasn't worn out, but it also wasn't brand new. I'm betting on defect and a high-torque motor just conflicting after some time on the road. It's still a fairly stock motor, but you just can't deny the power in the Hawk to begin with...

There are different grades/tensile strength within each size classification ("520", "530" etc.). From what I've read the highest strength/quality 520 chains are fine for the VTR and even more powerful bikes, but many 520 chains aren't recommended for anything over 500cc.

So what's the "ideal" chain for our VTR's?

530

I went with the 520 last time around, but I made sure I bought the strongest 520 chain they had. The 520 setup actually took some vibs away and that was really nice:)

I would really like to hear how the welding turns out if that ends up being the route you take. I recently found a couple of cracks in the rear of my case where the shock link bracket is bolted on to it. I'm pretty sure the integrity of the suspension is now compromised and it seems to be leaking oil. I haven't dug deep enough yet to determine if that's the true cause of the leak though.

A 525 X-ring hi-strength chain should work fine. Don't forget to add two teeth to the standard 41 tooth rear sprocket. It's a hassle getting those two extra teeth welded on, and getting them all spaced evenly, but the result is worth it.

Did somebody but a smaller front sprocket on? Gotta watch that. Keep the front sprocket stock, it's already as small as it should be, and add teeth to the back.

But a lot of people are using all kinds of set-ups

What about thread inserts put into the case, after welding back what's left of the original? The only stress on the sprocket cover is from the clutch cylinder push. Inserts might be a good way to go. I doubt Honda gave us enough to thread those bolts deeper.