If you are referring to the area where the stem gets narrower, that is just the way pretty much any valve is made.

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K5Wee in Kanada (202,000Km and climbing)
IF YOU WON'T STAND BEHIND OUR TROOPS.....FEEL FREE TO STAND IN FRONT OF THEM

 

Thanks for the confirmation.

I was thinking the valve stems are thinner than they should be because the valves had stretched as a result of overheating. That would account for the minimal clearance I was getting when I tried to adjust them. I will know more when the new valves arrive and I can measure and compare.

You know how a sample piece of steel that's in a tensile strength tester necks in just before it fails? That's what the remaining valve in my VW looked like. It sorta made sense to me that the loss of strength from excessive temp would cause failure where it met the smallest diameter, highest stressed, spot, the head-end of stem. Maybe the VW exhaust valves had flatter heads, less tulip shape, allowing extreme heat reach the stem? I don't know what they look like 'cause I had the dealer look at the engine to see if it was salvageable. I can't buy that the whole stem would stretch evenly due to overheating of the head. I've been wrong before, though.

I'm told that when my theory doesn't match the evidence, believe the evidence and get a new theory. Apparently, the heat in the head area can be intense enough to cause yielding of the tulip area in spite of its much greater cross sectional area?

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'01 TTR125L, '05 TTR230, '01 plated WR426, '00 Super Sherpa, '81 KM100, '80 SR500, '78 XS650, '06 SV650, '06 DL650, '03 DL1000
-John

Will be busy for a couple weeks but I will post when I return. Am curious about the length of the new valves.

Sleepy

Be sure you fix the cause of the high heat failure after you get the engine back together or it will do it again.

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"Life's Tough.....It's even tougher if you're stupid" __ John Wayne

He who dares to not offend cannot be honest. REMEMBER!! You can't fix Stupid and Stupid HURTS 2006 DL-1000

Thats why I asked if he had any history on the bike. I suspect that this occurred with the previous owner, who then had the valves adjusted.

Cheers

__________________
K5Wee in Kanada (202,000Km and climbing)
IF YOU WON'T STAND BEHIND OUR TROOPS.....FEEL FREE TO STAND IN FRONT OF THEM