What's wrong with this picture? Part 2

[psyguy]

Heli-coils tend to come out each time you take the bolt/plug loose. If you get a Time-sert put in, it won't come back out. Worth the money in my opinion although you may have to pay a machine shop to put it in as the tools are not cheap. http://www.timesert.com/

i second this
i have all four of them done with time serts, have taken the plugs off quite a few times and no prob, with helicoils on another engine they would often come out on the plug

[psyguy]

Yeah, I was looking at the site and found this in the FAQs:

I will have to call them, but it appears that I might be stuck with using another Heli-coil.

.

you can use the big serts - they are like over-sized time sert, the outer size is larger than the current heli coil size hole
(i'm not sure about the inner size though, it's either a plug size already or you still need to use the time sert)
keep us posted please

[TheCafeKid]

I would think that it would have happened sooner, if that was the case. We had already done cylinders 1&2, as well as exhaust #3. We were moving to intake #3 when we could not rotate the engine enough to get the cam to depress intake #3.



This was not intended as a tutorial, but we take a few pictures along the way, just for the kid's scrapbook.



See the note above, but I think it broke after checking the shim size on exhaust #3 (the broken valve). We had checked all the clearances and were in the process of checking all the shim sizes to put into that spreadsheet that all you guys are bragging about. :-\"



Hey, I'm always open to suggestions. :shock:
I was planning on re-installing a Heli-coil, but you say a threaded insert is better?
What is the difference and where do I get them?
Can I install one after an apparently failed Heli-coil install?

.

Steve, I used that same threaded sleeve when fixing the spark plug port on my step-dads Chevy. Its the solid threaded sleeve that you took out right? Not a coiled spring like thing? If its the sleeve, those actually work well, and the directions call for high temp RVT to hold the sleeve in the head when you put it in originally, apparently this was never done, but doenst mean it cant be.

[psyguy]

if it's a SLEEVE then it's a time-sert or similar
if it's a SPRING then it's a heli-coil or similar

[tkent02]

I think whatever broke the valve is only part of the problem. Valves don't break like this, I have seen them bend into strange shapes from hitting pistons, they are not supposed to break. I bet it broke because it was weakened, something like the steel got tempered incorrectly when the engine was getting so hot the pipes were red. Where it broke it was not bent at all, looks like a piece of hardened tool steel that broke from a bending load. I know this valve was from another cylinder than the one with the red pipes, but I would not be surprised to see more valves from this engine break, don't think I would put any of them back in.
Especially given the spark plug hole issue I would be looking for a good used head if it were me.

Just so happens I have one, although it needs some work done, you can probably find a better one closer.
I believe The Cafe Kid will soon have a spare head?

[duaneage]

I'm sure you realize this but check the guides, especially the casualty hole. That head might not be worth the money, I would look for a donor head to replace it with. There are plenty available if you are patient.

[ALB80-850]

carb and valve

Greetings all,

I have a complete #3 carb that nees to be rebuilt. It can be yours for the cost of shipping. I may be able toolocate a valve as well. If the bone yard where I took what was left of my crashed bike still has it, I should be able to get one. I am not sure if the whole head assembly made it through the crash or not, but that too may be an option. The #1 plug hole will need a heli-coil, the last shop I had it in x threaded the plug. let me know if your interested.

Andy

[Nessism]

I'm curious about this engine as well. The valve head breaking off is a major concern. I wonder if the tie-wrap under one side of the valve head caused a bending load on the valve which led to the valve snapping in two? The valve should be tougher than this normally but when those exhaust pipes got red hot the exhaust valves would have gotten goodly cooked - possibly damaging them.

Good luck with this one Steve and give us an update when you figure out what's going on.

[TheCafeKid]

Greetings all,

I have a complete #3 carb that nees to be rebuilt. It can be yours for the cost of shipping. I may be able toolocate a valve as well. If the bone yard where I took what was left of my crashed bike still has it, I should be able to get one. I am not sure if the whole head assembly made it through the crash or not, but that too may be an option. The #1 plug hole will need a heli-coil, the last shop I had it in x threaded the plug. let me know if your interested.

Andy

Andy, for sure interested. The carb would be great, not a big deal needing rebuilt as Steve is already on the case with those. If you can get to a valve that would be great as well. Its an exhaust valve. Dont really need the head, unless you're not wanting to pull the valve out yourself. Send me a PM with shipping cost and what not. Thanks!

TCK

[TheCafeKid]

I'm curious about this engine as well. The valve head breaking off is a major concern. I wonder if the tie-wrap under one side of the valve head caused a bending load on the valve which led to the valve snapping in two? The valve should be tougher than this normally but when those exhaust pipes got red hot the exhaust valves would have gotten goodly cooked - possibly damaging them.

Good luck with this one Steve and give us an update when you figure out what's going on.

The valve itself has no signs of "cooking" I am inclined to think that perhaps the wire tie trick, combined with the limited surface area left behind from the plug tap PLUS *my* personal theory that the valve may have had a hairline fracture in it to begin with, put just enough lateral torque on it to snap it. Steve may think otherwise, but again the valves themselves look ok to me. After cleaning the head, it doesnt look at all like there are defects in it either.

[Dogma]

The valve itself has no signs of "cooking" I am inclined to think that perhaps the wire tie trick, combined with the limited surface area left behind from the plug tap PLUS *my* personal theory that the valve may have had a hairline fracture in it to begin with, put just enough lateral torque on it to snap it. Steve may think otherwise, but again the valves themselves look ok to me. After cleaning the head, it doesn't look at all like there are defects in it either.

I'm inclined to agree with the hairline crack theory. That break line seems to indicate some kind of defect in the stem before it finally broke. Or possibly a nick in the stem from rough handling and then fatigue failure. Hard to say without getting a real close look at the fracture zone.

It shouldn't have been a heat issue... IIRC it was 1 & 4 that were glowing.

I don't think it was the wire ties either. If the valve spring puts that much tension on the valve, then there would be a lot more damage to the wire ties than I saw when I did this to mine. Rereading the account... It's not clear if the broken valve ever had a wire tie under it. I think not, otherwise the break would have been noticed while trying to remove the shim on that valve. If I'm wrong on that, maybe the wire tie revealed the existing flaw.

Either way, y'all should be thankful it didn't pop off while it was running. I've seen what that can do to an aluminum head, and there wasn't much left of the piston. The good end of that head was was sawn off and used on another project...

With this being a mystery, are you planning to replace only the broken valve?

[TheCafeKid]

I'm inclined to agree with the hairline crack theory. That break line seems to indicate some kind of defect in the stem before it finally broke. Or possibly a nick in the stem from rough handling and then fatigue failure. Hard to say without getting a real close look at the fracture zone.

It shouldn't have been a heat issue... IIRC it was 1 & 4 that were glowing.

I don't think it was the wire ties either. If the valve spring puts that much tension on the valve, then there would be a lot more damage to the wire ties than I saw when I did this to mine. Rereading the account... It's not clear if the broken valve ever had a wire tie under it. I think not, otherwise the break would have been noticed while trying to remove the shim on that valve. If I'm wrong on that, maybe the wire tie revealed the existing flaw.

Either way, y'all should be thankful it didn't pop off while it was running. I've seen what that can do to an aluminum head, and there wasn't much left of the piston. The good end of that head was was sawn off and used on another project...

With this being a mystery, are you planning to replace only the broken valve?

Not my bike, as its Steve's sons, so i am not positive, but I think we mentioned something about replacing the seals and rings since the head and jugs are off. Wouldnt be a bad idea IMO, but as i also said, its his sons, his sons money so that i suppose is up to him He and I were also very VERY thankfull it happened then rather than when someone was on it. Could have been disaster for both the motor AND the rider. :shock:

[psyguy]

my crashed bike

that looks like a serious accident you had - "how's the rider doin'?"

[Steve]

Hard to say without getting a real close look at the fracture zone.

You just knew I couldn't resist another chance to use the super macro function on my camera, didn't you?

These close enough?








It's hard to get light in there when the camera lens is almost touching the subject, so my LED flashlight is about the only choice.
The first two pictures are of the valve, the second two are of the stem.

.. It's not clear if the broken valve ever had a wire tie under it. I think not, otherwise the break would have been noticed while trying to remove the shim on that valve. If I'm wrong on that, maybe the wire tie revealed the existing flaw.

We had just moved the wire tie from the valve that broke and were going to the other valve in that cylinder. I can understand that sideways forces would tend to break the stem, but would not think that would happen at the hand cranking speeds used while trying to position the wire tie.

And, you are correct, this is NOT one of the valves involved in the red pipes. The red pipes were 1&4, this was #3.

.

[Nessism]

So do you think the bending load from the wire tie resulted in the valve head snapping off? I'm surprised the valve didn't just bend instead of breaking.

Next question is what are you going to do with the engine now? Replace the broken valve and reassemble or replace all the valves?