K1200S Blowing Up?

[bem136]

Was visiting a BMW dealer yesterday with my riding buddy and the manager (a very good guy to have conversations with concerning all motorcycles), said he had just replaced the engine on a "good" customers K1200S. When they split the case, he found the number 2 connecting rod all but broken on two peaces!?

When I asked him how that could possibly have happened, had the guy run it low on oil? He told me this particular customer rides his bikes very hard...often doing smoky burnouts and the like.

I find it strange that you can actually break a rod in a modern bike, with both ignition limiters and fuel-cutoffs that are now present. Even cranking open throttle on a bike in neutral as some of the more radical bikers I've seen do, and bumping up against the different limiters has not caused a rod break in my (VIEWED ONLY) experience.

To BMW's credit they did replace the motor under warranty, but does anyone have thoughts on how this guy may have broken a rod, I thought if anything you might punch a hole in the top of the piston and/or bend and break valves? (After hearing and seeing some of these abuses it sure scares a guy/gal out of buying used)!

Regards,

B

 

[jestal]

You could probably write a book about the "what if"s" in a situation like that. Much would depend on looking at the parts and determining the actual failure mode. No doubt something went wrong if they replaced the engine but it is impossible to guess what could have happened to cause it to fail. If they warrantied it I would pretty much assume it was a defect and not something the owner did. I agree with you that it is pretty difficult to simply break a connecting rod despite burnouts or holeshots.

There can often be a primary failure that results in a secondary failure that confuses the issue...i.e..an injector could stick open, flood a cylinder and cause a hydrostatic lock condition that bends the rod. The engine runs and then breaks the rod so the "broken rod" becomes the culprit and the real failure mode (stuck injector) goes unreported.

There is always the possibility that there was a manufacturing defect in the rod or the rod bolts. Slim but possible I guess. Or one of the rod bolts was torqued inadequately and with sufficient run time and stress it backed off or fatitgued.

I certainly wouldn't shy away from running an engine hard or buying something used or buying that particular model of machine because of one failure like that. Without the details of what really happened you have no way of relating the failure to anything that would affect that decision.

 

[S76]

Boy I agree with you 100%. I think there must be more to that story.

I read an article a while ago in a bike mag or on the web, can't remember which one. They took a beat Kawasaki sport bike and ran it in neutral against the limiter to see how long it would take to blow up. It wouldn't after like 15 minutes. So they drained all the oil and put back a quart, and drained all the water. This time the exhaust got so hot part of the fairing caught fire. They put out the fire, removed the fairing and ran it agin till the engine overheated and seized. The next day after it cooled they replaced the water and oil and the bike still ran OK. The point of the article was for people that worry about their temp gauges going up a notch or two in traffic have nothing to be concerned with.

The point here being like you say, it should really be near impossible to ruin a bike engine if it had water and oil in it.

"If it's made right you shouldn't be able to break it."

 

[markjenn]

There are lots of ways to break a bike and the systems in motorcycles are far from fail safe. As the simplest example, just downshift your motorcycle into 1st at 80 mph and let out the clutch. The rev limiter is not going to do squat...

And as the previous poster mentions, any one failure is purely anecdotal. That being said, I would bet a dollar to a donut that on a per 1000-bike basis, there are more catastrophic engine failures in K1200 motors than FJR motors. And this is from someone who owns (and loves) a BMW.

"If it's made right you shouldn't be able to break it."

For a complex piece of equipment like a motorcycle, this is a silly statement.

- Mark

 

[jestal]

I don't know if it is just semantics or not but the original statement of "the number 2 connecting rod all but broken on two peaces" seems odd. Connecting rods don't "all but break".... The engine might be running with a cracked rod or something like that but you wouldn't really know until it broke. To take a motor apart and find the rod "all but broken" is highly amazing to me.

I wonder what the original complaint was and what they really found???

One complaint I have encountered in the field on other engines is a knocking noise that is like a "rod knock" that turns out to be a full floating wrist pin come adrift because of a missing or mis-installed wrist pin retaining clip. If the motor is stopped the instant the knocking starts you "might" (heavy on the "might") catch a piston partially cracked and failed at the wrist pin boss....but......usually they just let go as the period that it just makes noise before failing entirely is very brief....LOL.

New stuff is much harder to break than old stuff. With the electronic controls and overrides possible parts are pretty well protected. Granted, a manual overrun of the engine is always possible (shifting into first at 80) but in those cases the trans is also likely to show damage and the tire will slide if a severe overrun is encountered partially mitigating the potential engine failure. If a severe overspeed is encountered I would think a failure of the valvetrain is far more likely than a con rod. See pictures of valves embedded in pistons in other posts....LOL

 

[bem136]

jestal - After we left the dealer, I wished I had asked that exact question about the "almost broken in two pieces" comment. I was just so surprised at a newer K12 having a rod problem, I simply didn't get clarification. When I get back to the dealer, I'll ask him to describe exactly what he meant/saw inside the engine.

Regards,

B

 

[yellowmagnaman]

jestal - After we left the dealer, I wished I had asked that exact question about the "almost broken in two pieces" comment. I was just so surprised at a newer K12 having a rod problem, I simply didn't get clarification. When I get back to the dealer, I'll ask him to describe exactly what he meant/saw inside the engine.
Regards,

B

 

[yellowmagnaman]

This is a good reason not to buy anything its first year out!

The BMW 1200GS's had driveline problems. The 1800 Gold

Wings got cracks in their frames. The Mazda RX8's also had

many bugs too! The new Norge Moto Guzzi looked great in

red, and I may get one in a couple of years after they sell

a few thousand and find out all the glitches in R+D and vendors. :clapping:

 

[mech 1 twa]

Most likely over-rev. Easy to do on a down shift.

If its done right, the rod will brake the engine case.

No need to take anything apart to see the problem. You will know, when oil hits back tire AND you crash.

 

[jestal]

If its done right, the rod will brake the engine case.

Is this a pun....?????....you know....brake....break.....?????

But he said the rod was "all but" in two pieces.... So what was the complaint if it hadn't broken yet ?

 

[BobG]

This is typical of BMW as of late.

Even models that have been out for a while are coming up with a lot of poorly engineered parts.

Frames bending, parts cracking, chrome and paint flaking off, parts falling off, rubber rotting in a year, you name it.

The quality of these machines maybe at one time were good. Not anymore.

Bob