Valve damage

[Dusty]

Im attaching a pic of one of my exhaust valves as Im a little puzzled as to how it got like this. All other valves are in good condition.

The bike started running rough during it's last long ride. My initial assumption was carbies, after cleaning them (twice), I bought a compression tester and... well knew the head had to come off.

Anyone seen this type of damage before?

 

[Steve]

Only time I have seen damage like that was when the adjustment interval was CONSIDERABLY longer than recommended.

How did the seat in the head look?

.

 

[sharpy]

Valve wasnt making contact with the head and getting cooled enoughed and burnt. Ignition timing or lean mixture(leaks) (maybe) or all above.

 

[Flyboy]

Agreed, valve clearance and or lean mixture recipe for heartache.
Under running conditions the exhaust valve takes the most punishment, it runs red hot, the only way it can cool down is to dissipate its heat into the valve seat and head when it is closed.
So if the valve clearance is too tight and the valve never actually gets to seat, it cannot dissipate the heat and just gets hotter and hotter until it starts burning away, and what you have there is the end result, or worse, most exhaust valves are two piece valves with a hollow stem filled with sodium, to help dissipate heat, when the valve gets that hot, it fails at the joint and drops the head of the valve into the combustion chamber, well you can use your imagination.
And then the new guys want to know why we preach like old women about valve clearances.

 

[rustybronco]

Never...
http://thegsresources.com/_forum/showpost.php?p=1238313&postcount=64

 

[Nessism]

I agree with the others, this looks like a burned valve. Rustybronco (Dale) has a similar photo (he bough the bike that way). Next question is how often did you adjust the valves, or did you buy the bike that way too?

Edit: Dale posted while I was typing.

 

[Rover]

Just curious.how many miles on the bike?

 

[Dusty]

Thanks guys, yup that all makes too much sense.

To answer some questions:
The bike (GSX1100E) has done about 110,000kms.
The valve seat looks fine (thank god).
Ive had her for about 8 years so cant blame anyone else..

Funny enough I do check the clearances ~every year, and they never need much adjustment so I believe they would have been close to spec.

Maybe it was running lean though... I do remember just when it started running rough, I was doing some long (~800km) days in the northern territory (australia) where the daily temperature was 43degC (109 DegF). So it was a stressful time for the old girl.

Arr well, I know what I have to do Lucky no damage to the head!

 

[rapidray]

I have a bunch of stock valves if you need. Ray.

 

[Dusty]

Thanks Ray, but I've just ordered some..

 

[Suzuki mad]

I would say never on a 16v or 8v motor. Plenty of bent and carbon blacked ones but never like that.

 

[Dusty]

Thought I should close the thread with an update.

Exhaust valves replaced and the old girl is back to life!
All valves adjusted (on the loose side to be sure)