NEED HELP BAD!

[solman]

One of the guys I know with a Bandit 1200 with 1900 miles on it.  I assisted him in adjusting the valves.  He never did his initial valve clearance check.  We took our time and adjusted the valves to spec.  When it was all said and done, he started the motor and it ran great for about 15-20 sec and then CLUNK!  It just seized up and we can turn it a little back and forth, but that is about it.  We took the cover back off and look in the head and found nothing wrong in the top end.  Only thing I can thing of that didn't go as planned is when he rotated his motor backwards a little bit.  Any ideas because I am utterly stumped and really need some ideas!

[txbanditrydr]

Sorry to hear about the troubles....  some more information might help point you in the right direction.

With the spark plugs loosened, can you rotate the motor 360 degrees with a wrench via the sig gen nut??

Are both dowel pins in place as opposed to wedged somewhere?

Have all tools been accounted for??

To start fine is a good sign....  might check the kill switch too.  Just grasping for straws here.

[Rocketjock]

What TX said. Yep, it sounds like a classic case of something got dropped inside. An alignment pin perhaps. If you can't see it around the cam area then it may have been small enough to go down an oil way, maybe jamming in the cam chain on the lower end. If this is the case...well, I don't even wanna think about that.

[solman]

We took the valve cover off and accounted for everything.  I was looking at the manual and I am wondering if it might have something to do with the starter clutch.  My first thought about something missing and falling was my first thought as well.  But all the parts and tools were all accounted for.  I am stumped on this one for the most part.  I have been doing valves on bikes including my Bandit for years.  I have never came across something like this before.  Only possibility that I can think of at this point at one point when he turned it backwards, it screwed something up.  I haven't torn a Bandit motor down yet, so I can't get a visual picture of what the inside looks like.  BTW, is the cam chain tensioner automatic on Bandits? I know that on my Honda, I loosen the nut and it then adjusts itself.  Is the Bandit something like this?

[Daytona]

One of the guys I know with a Bandit 1200 with 1900 miles on it.  I assisted him in adjusting the valves.  He never did his initial valve clearance check.  We took our time and adjusted the valves to spec.  When it was all said and done, he started the motor and it ran great for about 15-20 sec and then CLUNK!  It just seized up and we can turn it a little back and forth, but that is about it.  We took the cover back off and look in the head and found nothing wrong in the top end.  Only thing I can thing of that didn't go as planned is when he rotated his motor backwards a little bit.  Any ideas because I am utterly stumped and really need some ideas!

Holly Kry'kee! I thought this stuff only happened to me! The drive gear for the starter, nut back off ?

[solman]

Well, we checked the starter and a few other things and came up with nothing.  He is going to try and take it in tomorrow to get it done using the warranty.

[CWO4GUNNER]

Oh boy, mums the word.  That is why I learned long ago that the only mechanic work or supervision I provide is to wife and mother who cant give me the evil eye when bad things happen to good engines through no fault of my own. Even until this day I rotate and check my valve adjustments 6 times and 6 rotations as I was taught and it has saved my hiney more then once, not that it happened in your case but even the experienced human mind can miss an obvious mistake.

He is going to try and take it in tomorrow to get it done using the warranty.

[Daytona]

Well, we checked the starter and a few other things and came up with nothing.  He is going to try and take it in tomorrow to get it done using the warranty.

Ok good luck on the Warr. Maybe U need to edit or make this post go away! Dealer and warr! 

[CWO4GUNNER]

Although I don't know what the TDC squish clearance on a B1200 engine, I read that with the combination carbon build up and close squish clearance on modern engines, it is very possible to have a catastropic failure if valve clearance is set too loose. Especially as the engine warms up and higher RPMs diminish the already close clearance to almost zero and the extra loosened valve clearance allows it to be held open on its seat when it should be closed, resulting in a collision with the piston followed by a crank, cylinder and crankcase train wreck. 

[solman]

I think you mean if it is set too tight. 

[txbanditrydr]

I think you mean if it is set too tight. 

+1.... too tight is major bad.

[CWO4GUNNER]

NO, if the valve clearance is too small the valves will leak and hot gases will burn the exhaust valves, fixable. If the valve clearance is too large, the necessary gentle opening and final closing contours of the cam lobe will become ineffective resulting in violent impacts taking their place. The resulting pounding quickly becomes a failure as the loosened seat holds the valve open when it should be closed and the piston hits and broken in the process, not so fixable especially when the crank & cylinder get involved. But hey its rare OK?

[Rocketjock]

Wow. That just doesn't jibe with me CWO. I have to go with the other guys and say if you have a loose (ie. bigger gap) at the adjustment, then, with the help of the spring, the valve is going to open less. Thus, less chance of anything hitting it. Of course, I am dyslexic so there is a small chance I am thinking backwards.

[Heyu]

Gunner are you refering to it being "too small" as the clearance from the tappet to the valve? if so that would mean the clearance is too tight meaning not enough for the valve to close properly andit would open to far for too long which would not be good. Or did I misunderstand??

[txbanditrydr]

The resulting pounding quickly becomes a failure as the loosened seat holds the valve open ...

Would you by chance be referring to the valve guide instead of the valve seat??