something has gone horribly wrong piston hitting valve

The nut looks fine its the tabs it sits in that broke. Or am I looking at this wrong?

[chuck hahn]

Yes..but find another aluminum nut...thats what its designed to do. Break BEFORE you gunk up the crank. AND do NOT turn that engine again until the cams are out and the valves are ALL up as far as they can be.

Your gonna have to pull the head anyways to do a real inspection, so just take the cams out and get the head off. Youll need to look for bent valves and piston tops being damaged.

To turn it again is just gonna compound any problems that already exist.

Well it ended up being the tabs. Now what to do as the tabs It looks like were on the crank and the slots in the nut. Can I turn the motor with the 12mm or am I up a creek?

[chuck hahn]

Ther adjuster failure is almost always linked to how it is reinstalled.

You force the rod back and use the adjustment screw and jam nut to hold it in the retracted stance.

Next you reinsert it with the new gasket and tighten the flange bolts.

Then you undo the jam nut and back off the adjuster screw about 2 turns.

The here is where the trouble begins. Most folks turn the adjuster screw in until it touches the tensioner rod and then give it a little snug and set the jam nut against it. THIS IS THE WRONG WAY!!!

This is what you do..Once you have released the rod upon reinsertion, you turn the adjuster screw in until it touches the tensioner rod inside. Now you turn the adjuster screw OUT 1/4 turn and lock the jam nut against the body of the adjuster. You MUST WATCH the adjuster screw as you tighten the jam nut to ASSURE THAT THE ADJUSTER SCREW DOES NOT MOVE.

If the adjuster screw turns itself in and you dont realise it...then you get what has happened to this guy...it jams the tensioner rod and the cam chain skips teeth on the cams.

To test to see if the tensioner rod is working....Start the bike and EVER SO SLIGHTLY turn the big knurled knob to the left. You will hear and feel the rod clatter at that point. Release the big knob and leave it alone after that.

Okay so how is that avoided ? I read that those adjusters are not to be touched EVER but doesnt everything fail eventually? The reason i ask is because when i do my top end this winter i planned on replacing it

[sedelen]

It really hurts to read this thread.
At first I thought it was gonna read a lock nut came off one of the valve tappets or something along those lines.
I hope the damage that was done was "minimal."
it's just so easy to make a mistake or overlook something when performing maintenance on these old relics, or trying to do something you don't quite completely have a grasp on.

I know I have made my fair share.

[sedelen]

[QUOTE=Steve;1856916]Too many times I have seen tensioners that were locked in place, not allowing them to move and do their job./QUOTE]

Or the screw not backed out far enough to allow it to work correctly.

[chuck hahn]

First thing you need to do is remove the cam chain tensioner, then remove the cam chain from the cam sprockets. Next, take a shoe lace or buggee cord and go thru the chain and tie it off up to the frame so you dont drop in down inside the engine.

Then remove the cam caps...notice each one is lettered. They go back in the exact same spots.AtoA..B to B etc etc. Loosen the bolts evenly to avoid them jammimg up.

Remove the cams so all the valves will be up as far as they can. Do all this so when your working on that crank bolt you are not smashing against the valves any more than what has already been done.

NOW..you can go down to the 12MM steel bolt and try to take it out of the crank..its lefty loosey righty tighty. use a 6PT wrench or socket..12PT seems to not grip as well as 6PTers do. A few good smacks with an impact driever will aid in getting it loose. I am willing to bet the tabs on the back of the 19MM aluminum cap is what has given way..least I hope so.

Ok ill post some tomorrow. I'm in the house for the night I got frustrated lol.

[chuck hahn]

The 12MM ( the steel one ) holds on the governor behind the timing plate and the whole timing plate assembly to the crank. Take some picstures of itm as is before touchuing anything else and post them up. Itb takes a lot to strip the crank and I am thinking the aluminum nut ripped itself loose first.

Theres a slot that meshes with two tabs on the back of that aluminum nut..which will sometimes snap off ( like a shear pin does ) before the crank bolt strips. I sure hope thats the case for you!!!

What exactly does that nut hold on? I haven't taken it completely off yet.

[chuck hahn]

Well..I hate to bear bad news, but IF the crank itself is truely stripped..Youre basically bent over a pine stump and theres no Vaseline in sight!!!

There is a 19MM aluminum nut and it has a 12MM steel nut in the center...what excatly stripped? The 12MM bolt that goes in to the crank? Or the crank theads themselves?

The crank threads I'm pretty sure.

[chuck hahn]

And a terribly expensive one at that!!!!

[Nessism]

Sounds like a bunch of bent valves. Tough lesson.