Ouch, never heard of this before (cam sprocket shattered)

Well, I was out on my bike and suddenly heard a noise and the xj650 died immediately. Got her loaded up and back home and took off the cover and this is what I saw. The inlet cam sprocket was pretty much shattered. What I'm wondering is if I'm looking at a complete tear down or if it would just be a matter of dropping the oil pan? Additionally, anyone have any idea how much a new/used cam sprocket runs?

 

WOW! I've NEVER seen anything like that happen. Congratulations, you've impressed me. lol. I'm sure someone else will chime in with some more professional advise, but i would take a look at your valves and pistons and make sure nothing got damaged. It is likely that you bent a valve during this. Take a scope and look at them through the spark plug holes as you turn the cams to move the valves, and inspect each one, along with the pistons. Look for signs of the valves hitting the pistons, and check for free and straight movement of the valves. If somehow that all looks good, it's time to remove the broken pieces. I would suggest taking the motor out of the bike and removing the lower case half. This way you can be sure to get all of the broken pieces out. while you're in there, you can check all the usual things also (chain guide, starter clutch, etc.). Once the pieces are all removed, use some yamabond to seal the case up (don't skimp, leaks suck), and do an oil flush.

Good luck!

 

*bows*

I do always try to impress! Just wish it were for something other than this though, lol.

I hate to do a tear down simply because I did last year when I got the bike and rebuilt the engine. Was only a top end one though and didn't have to pull the whole thing. Guess it does make sense to go all the way on down on this one though.

$&@! and other choice words to follow.

 

Re: Ouch, never heard of this before (cam sprocket shattered

I'd sure want to know why that sprocket shattered too.

Is the center of it still bolted to the camshaft? Do the bolt holes show any wear? Are the bolts beat up?

If the bolts and/or holes are beat up it probably means the sprocket wasn't torqued properly. If that's all still in good shape you'll need to look for another cause.

 

Carl, I have a good idea it wasn't torqued correctly. When I was buttoning it up, I had someone help me out getting it to TDC when putting on the camshafts. I remember him messing with the sprockets. Just checked and no wear on either.

 

Sprockets aren't expensive. If you can locate ALL the shrapnel, get a new sprocket and put it back together (new bolts too.) You don't have to split the cases necessarily, if you can't locate all the pieces then I'll bet you find them if you simply drop the sump. That can be done with the engine in the bike. If the bolts weren't tight you might be lucky and all the debris may still be up top.

Ouch.

 

I know on the X it is a zero clearance motor as in if you are off by one tooth on the cam gear the valves(some of them anyway) hit ths pistons.(good to tell you if you have the cams in properly)but sucks otherwise if the airheads are the same you are looking at some bent valves and hopefully not valve guides and a piston. Were you in high rpm or just cruising? Have you tried to rotate the motor at all since? Manually not with the starter. That is was one of my worries when I had to remove my cams for the valve adjustment. I have spunj it up pretty good and no disasters yet so I am keeping my fingers crossed.

 

bigfitz, any hints on how to do that with the engine still on the bike?

Was just cruising and I think I got lucky. Everything is looking good on it so far.

 

Man that sucks! +1 on the zero clearence.... just to be on the safe side i would pop it open, check the valves pistons etc.

 

Well, bad news... I don't just need a sprocket. I took the camshaft off and looks like a piece has broken off of it as well. If anyone has one, let me know. The sprocket at the dealer was a little over $30... I don't even want to know what they're going to want for the whole camshaft.

 

Ouch man! Wish i had one to send you. Look in the sell, swap, trade (or whatever it's called) section to see if anyone's parting out a motor. Also check ebay. Sometimes you can pick up a whole motor for cheap $$.

 

Coach, I should have a good used one if you're still in need (and new or used sprockets), drop me a note if you still need one.

 

The exact same thing happened to me this morning, intake cam sprocket broke in 2. I was able to fish them out with a magnet but coulndt get to the other pieces.
Coach, what was the outcome of this? did you have busted pistons, bent valves, etc..? or were you able to get all the broken pieces out form the bottom?

 

Was there anything different to let you all know this would happen? Knock? Scraping? Anything?

 

In my case, I'm pretty sure it was because i didnt torque the sprocket bolts. I just tightened them by hand. I had to remove the head to get some broken exhaust studs replaced. After I put the head back on, I torqued the head bolts and cam caps but not the sprockets...live and learn i guess...
There was no wierd noise, the engine was just idling when it died.

 

If you're tearing it down anyway, why not replace both srogs if they're 30 bucks each, just on the slimmest possible chance that it was metal fatigue. I'm the type that if one headlight blows, or a wiper starts streaking, then the other can't be far behind and will replace both.
My two cents.

 

I'm pretty sure I have a set of cams that I pulled from a running 650. You can have them for the shipping.

 

I wished i had checkd the forum 5 minutes earlier, i just bought a pair on ebay...but thanks, i'll hit you up if those dont work out.

 

Wellp, glad I asked. Not that it helped me.
I had a valve clacking a bit after my recent replacement of seals (and a new cam shaft) which I thought was strange, because I checked all the clearances, and they were to spec.

Everything torqued to spec.

And right around ~6500-7000 RPM acceleration not only did my exhaust sprocket shatter (and I mean shatter), it took out a portion of my valve cover in the process.

Have a feeling this is more deep-seeded than your problem, though, as a cam shaft randomly snapped at one point during the rebuild, too.


But we're not the only cam-sprocket-shatter-ers.

iirc, (I don't remember the member's name, but) he did a pretty cool green and maple leaf (Canadian) mod of his SECA, then shippped it to some norweigian port to take a tour of europe.

He had similar issues.

 

Re: Ouch, never heard of this before (cam sprocket shattered

Alchai, did your valves hit your pistons? or just bent valves?
I havent removed my oil pan yet...kinda nervous, I would hate to have to replace the whole engine...mine snapped at low RPM, around 1500