Hitting the Rev Limiter?

[boxermania]

Ooops....that valve burned, big time....looks like there were some high temp issues. If my eyes don't deceive me there appears to be some aluminum metal deformation (of the head) around the burned area of the valve. Let me take a closer look at it.

The carbon build up seems a bit more than what would I expect for 40K miles. Your bike JB?

[jb44]

Not my bike, a member from another forum (I have his permission to post the pics).... piece broken/burned off left rear exhaust valve.

On my bike, before I sold it at 24,000 miles, I put a gooseneck LED flashlight through the spark plug holes for a look. It didn't look much different, except for the burnt valve (that wasn't the reason I sold it however).

jb

[Samiam]

So, what caused this much crud in only 40,000 miles? As I said, my old Sporty was actually clean after years and miles of commuter traffic. Is it really the engine layout and cylinder lining that causes this? Is it actually common in BMWs? And how can I prevent it?

Somehow, this just dosen't seem right.

[jb44]

...Is it really the engine layout and cylinder lining that causes this? Is it actually common in BMWs? And how can I prevent it?

I'm afraid I can't answer those questions. Boxermania, one of the most knowledgeable about engines, has already expressed his view.

The carbon buildup problem has been a topic for discussion long before my five years here.

A former member, regularly added Seafoam to his gas to prevent the carbon. I used it also, but can't say that I did on a regular basis.

Once the carbon buildup becomes so thick, I have read that the cylinder heads shoud be removed to scape it off. More than once, Cyclerob has warned about loose bits of hard carbon in the combustion chamber causing damage.

Certainly there are many thousands of boxer engines in use that don't become damaged by carbon buildup. So far, I haven't heard a difinitive explanation about the cause or prevention.

jb

[boxermania]

Samiam

I really want you to visualize the diferences between your Sporty and he BMW boxer.

A) Both are air cooled, air cooled engines have a temperature differential between the part of the cylinder facing the air and the part away from it. This diferential could allow the roundness of the cylinder to be affected and allow a little more oil to get past the oil control rings. However, this is not the major contributor.

B) The Nykasil coating on the BMW's is very hard and long wearing. So during the greak in period as the rings seat o the cylinder wall there is also added oil consumption. Im sure you have heard on this board those owners that at 20K miles and 30K miles are still using significant amounts of oil.....what do you think their piston tops and combustion chambers look like.

C) The BMW is a horizontal cylinder, the Sporty is a vertical, the gravity is on your side on the Spoty, not so on the Boxer....hence the more possibility to pass oil by the rings.

B) and C) are the primary reason for carbon build up and the one way to mitigate that effect is to heat cycle the engine (on the gas, off the gas) by riding it hard....in the upper rpm ranges......

[Samiam]

Boxermania - I get the picture and I suppose I'm trying to be overly simplistic and looking for easy answers. At my somewhat advanceed age, I tend to be a rather laid back rider and not nearly as aggressive as I was back in my forties. I don't mind going into the upper end of the rev band and I'll just have to spend more time there. If it has to be done, then I'll do it and not argue. After all, I bought a BMW due to my mindset instead of another Harley.

Let me just pause here a minute and recap recent events for my own benefit and put them down for the record. Lessee; one doctor, back in November, says I need to have more sex for prostate health. Another doctor, last month, says to drink more wine for cardiac health. And, now, you're telling me to ride harder for motorcycle health. GAD! Getting older really isn't for slackers!!!!

[Beemeridian]

99

[Samiam]

Is this a great country or what?

[allanj255]

Here is a 1150R piston from a British site's Black museum