Yes, that is a 1.2 mm shim installed and you are right, the bucket rests on the spring retainer.
I pulled the valves and the guys at the local shop said the valve faces are shot. I can't tell but I will compare them with the new valves I have just ordered. I will post pics. The good news is that the valve seats appear to be in good condition. The mechanics said all I need to do is drop the new valves in, install the proper shims and I should be good to go.
I cannot find a service limit in the shop manual for valve length. I have measured mine and will compare them with the new valves.
The question is, why did this happen? I believe this engine is pretty bullet proof and with only 24k on it, I am a bit surprised. The service manager said it is obvious the valve have been run hot. Possibly from pre-ignition as a result of bad gas. The bike was ridden a lot in Canada and he claims Canada and Mexico figure octane ratings differently then the US does. 87 octane in the US is higher than 87 octane in Canada and Mexico. Even if that is true, I find it hard to believe that would ruin the valves on this bike.
I will post more pics when I get the new parts.

 

I would say that makes no sense what so ever..the gas part. I have run 87 "Canadian" gas since new and have yet to even adjust a valve. Canada and the US use the same octane ratings, Gas pumps may show two octane numbers: RON and MON. The Research Octane Number, or RON, is measured under fairly easy test conditions. The Motor Octane Number, or MON, is a tougher test measured at higher engine speed and temperature. The average of these two values: Road Octane Number = (RON + MON)/2 and that is the number we commonly see at the pumps.

Long term pre-ignition tends to affect the crown of the piston more than anything, and the resulting "detonation" creates havoc with items such as piston rings, ring lands and piston pins. Pre-ignition and detonation are 2 seperate, but connected occurances. I could go on, but suffice to say I have never in almost 35 years of building and repairing high performance engines seen the results of "pre-ignition" affect a valve and not show any other indications of excessive heat. I am very interested in seeing pics of the valves, combustion chamber and hearing about your findings.

According to the manual, the valve face (actually seating area) should measure .9-1.1mm. They do not list an installed height.

Why yours did what it did I cannot guess, but to blame Cdn gas??

One might almost suspect something amiss at the factory, although every thing is highly automated with probably next to no if any manual machining done.

Cheers!

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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

How's the rear jug? If it's only happened in the front you should take a look at the TB and injector

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DL650AK7 totaled 7/24/08 5,000 Being reborn as the ADV-Strom
06 F650GS Wife's new ride
DL650AK7 totaled 7/24/08 21,000 miles
Stromtrooper offroad club #20
Accident details
"Aerodynamics are for people that can't build engines"-Enzo Ferrari
"Wave to Cows, They Taste Good"-Stolen from Brendan, adapted by me

A vacuum leak causing lean burn equals high combustion chamber temps. Will cause the valve head to tulip and recess into the head. Most commonly occurrs to the exhaust valves. Extended adjustment periods can also cause the valve to not seal properly which will over heat the valve head and cause this problem. Somtimes you just luck into bad valves from the factory but if this is the case there should be several engines having this problem.

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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

Yes, I have the same problem with the rear cylinder as well

That makes me think your bike got a batch of improperly heat treated valves.

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Pat- The wolf with an E in grey.
2007 DL650 w/ABS AMA Life Member #755148

You certainly know more about this business than I do. I don't really buy into the "bad gas" idea either. All I know is that I have 4 bad exhaust valves and the intake valves are fine. I did measure the exhaust valve shaft diameter and they are all under spec (they are thinner than they should be). I suspect the valve has stretched but since I don't have specs for the valve length, I will have to wait until the new valves arrive and compare. I will post pics of the offending valves tomorrow.

Maybe I'm way off, but it sounds like your engine had the wrong exh valves. If the valve stems stretched, I would certainly not expect them to stretch evenly along their length, where you could discover it as undersized. The failure mode/location that I would expect from overheating would be where high temperature (valve head) meets the most highly stressed (minimum diameter = stem diameter) material. I would expect to see a "necked" area right where the stem starts to swell into the head, caused by the metal yielding.

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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

Its amazing how little most of you know yet you continue to offer up opinions that are based on what you don't know any thing about. Girls I deal with engine failure problems everyday for more years than I care to think about, yet the unknowing refused to listen to common sense. But Hell I don't know a damn thing about engines. I am just saying.

__________________
"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

Tell us what you really think Mort

I do like your style tho

Cheers!

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