Exhaust valve blowed up

[rikrdo]

Hi everyone
I think I just need a hug.......

So here goes:
Bought my bike last Sept and have put 7k miles on her. Needed the big service done so took care of that 2 months ago. New rear tire also installed at that time. I knew this needed to be done and had no problem shelling out the cash to a good wrench to handle it for me. The bike ran PERFECTLY for about 1100 miles and then last week, I'm cruising along at 70mph and the bike just quits. No power at all. Pull off the road and after about 10 minutes manage to limp home and try to figure out what happened. Long story short: get towed back to my guy and he finds out that the left cylinder exhaust valve basically exploded. $1100 later and I'm wondering if this is the norm for BMW's or have I just had some bad luck? Thanks for listening

[riceburner]

That's pretty unusual!

What's the overall mileage on the bike?

[Dr. Strangelove]

and what does exploded mean?
Pix?

no it's not the norm

[rikrdo]

Sorry. Thought I had mentioned that........ 24k miles is all
I'm just looking for some reassurance that this sort of catastrophe doesn't happen to me once a year, or more often

[Lee Davis]

That is an extremely rare occurance, (a valve 'exploding') for ANY engine. Most likely it was a defect in the manufacturing of the valve, or less likely a defect in the guide.. I operated a VW and Porsche engine remanufacturing business for 8 years and we would see engines that had 'dropped a valve' quite often... but that was where the head of the valve would break off from the stem, caused by a worn valve guide that would make the valve stem sloppy in the guide. The piston would strike the broken valve head and would start to disintegrate, how much depending on how far it was driven after the failure. It took usually over 100,000 miles to wear guides to the point of a failure and it was usually the #3 cylinder that would be affected because of the proximity of the oil cooler restricting the cooling air. So that suggests it was a defective valve... just an unlucky occurance. I would not lose any sleep over it... most likely it will never happen again... but then, I thought I had left my troubles behind when I met my second ex.

[CycleRob]

An exhaust valve failure can occur with a too lean fuel mixture as would happen with a partially clogged fuel injector, so Yes, your trouble may happen again. The other failure is as was already mentioned, worn valve guide(s) that allow the valve to repeatedly hit the valve seat off center. Another is a gummed up valve stem that slows the normal weeping lubrication between the stem OD and valve guide ID. The lube starved valve stem then sticks open, to be immediately hit by the piston . . . sometimes thousands of times until the engine is shut off or stalls out from the cylinder misfiring with a bent over or broken off head. If the head breaks off, it ain't pretty and the damage will be piston, valve, head and possibly cylinder barrel. Because of the much higher operating temps possible, air cooled engines are more likely to have shorter life valve gear components.

[rikrdo]

Thanks for the posts, fellas
I am trying to remember how to post some pix so bear with me
Got the bike back today and everything seems to be better than ever. Good idle now, smooth as ever power delivery. Had all four valves replaced as well as the stick coil on right cylinder. New oil (mechanic couldnt find the piece of the valve that had broken off).
More info: I run Chevron 91 and augment with an ounce or 2 of Seafoam every 3-4 tankfuls and every 10 tanks I've been adding about a half gallon of 100 octane racing fuel(cant remember brand).
I asked about additives and my mechanic recommended a BMW product but I am wondering if I really need any of these and if they may have contributed to this situation
If you havent figured this out by now, I like to ride but dont know much about how all the pieces work together to make a bike run. Ive changed the oil and can recharge the air filter, even pulled the battery out once but thats about it so my learning curve is a steep one.
Love the forum and even though I dont post much I am a chronic lurker.
Sorry about the "exploding" discription. Didnt know a better term to use.

[Boxer]

I don't think I would be putting any more of that racing fuel in the gas tank. That sounds like it may be the culprit.

Glad you have a good mechanic who fixed it for you.

[CycleRob]

+1 on canceling the racing fuel additions! Some of them are Oxygenated, allowing extra power generation when expertly combined with a much richer mixture. Combining the racing fuel with 10% Ethanol fuel (also Oxygenated) plus sustained high speed hot weather cruising, depending only on the stock ECU to compensate, is asking for trouble.

[towerworker]

I'm curious as to why you were adding the racing fuel. I've never heard of anyone running that in an R. Running a little bit of Seafoam is a pretty common thing around here. Not too long back a fella added an entire bottle of fuel injection cleaner to a tankful on his R. One bottle was to treat about 20 gallons. So he basically had 5 times too much of the stuff. As I recall it pretty much destroyed his motor.

You have to be really careful about adding stuff to the gas. I reckon you've found that out the hard way.

Now if you need information on what type or brand of antifreeze/coolant needed for the R............you've come to the right place!