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Sticking rings on 2011 RT?


kiddo480

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Hi gang. I am just looking for some feedback on an issue I am having on my 2011 R1200RT. I bought the bike about a year ago with 2900 miles on it. I have put about 6000 miles on it in the past year, and it now sits at about 8800 miles. A couple of weeks ago, I went to start it and it failed to start the first crank, which is very unusual. After cranking a while, it finally started and there was a very noticeable "clacking" noise coming out of the left head. The local BMW shop did a teardown and could not find anything significant other than some evidence that the left side piston ring(s) had been sticking. There was also a considerable amount of carbon buildup in both cylinders. The mechanic's analysis: the carbon was responsible for the rings sticking. That, and the fact that the cylinder still showed a lot of crosshatching indicating that it was hardly broken in. So, he seems to think that I am not riding the bike hard enough to keep the carbon burnt off. What? I definitely don't do burnouts, but still, I don't ride like an old lady either. I ride to work several days a week, and most times, that involves a 10 mile run down the interstate at 75-80 mph. Any experiences that you guys can relate would be most helpful.

Much appreciated

Keith

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Afternoon Keith

 

On a modern emission era electronically fuel injected motorcycles you shouldn't be getting carbon buildup no matter how you ride it.

 

I would venture a guess that your carbon buildup is from oil-burning in the bike's earlier life. 2900 miles on a 2011 bike tells me that it didn't get ridden very far in it's early life.

 

BMW boxers have very hard cylinder walls so if not broken-in properly can burn a LOT of oil for a good many miles.

 

As to the crosshatch still showing-- that will be normal well into the 100,000 mark as those very hard cylinder walls will retain a factory new look for just about ever.

 

Very seldom do you encounter sticking rings on a BMW 1200 engine so my first guess would be that yours weren't sticking, but if by chance they were sticking, then it is probably more do to gummy fuel remnants in the ring area than carbon.

 

If the first owner didn't break it in properly then your riding style now won't have much effect for many miles into the future.

 

If it's apart now they will probably deglaze the cylinder walls (at least I would) & hopefully re-ring it.

 

Added: have them look at the backs of the exhaust valves & if a lot of coaking present then it was probably an oil burner in it's early life.

 

 

 

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Thanks dirtrider for the words of wisdom. I have been in disbelief since I was told that and don't buy into the "not riding hard enough" analysis. What you say makes more sense to me. I do remember the service guy saying at one point that the intake valves were more carbon'ed up than the exhaust valves. At least I think that is what he told me - he stated that one of the valve sets looked different than the other and I remember being surprised that it would be the intake valves. I will be getting the bike back next week, and am torn about what the long term consequences are going to be after this episode.

Thanks,

Keith

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Thanks dirtrider for the words of wisdom. I have been in disbelief since I was told that and don't buy into the "not riding hard enough" analysis. What you say makes more sense to me. I do remember the service guy saying at one point that the intake valves were more carbon'ed up than the exhaust valves. At least I think that is what he told me - he stated that one of the valve sets looked different than the other and I remember being surprised that it would be the intake valves. I will be getting the bike back next week, and am torn about what the long term consequences are going to be after this episode.

 

Evening Keith

 

As a rule- coke or carbon buildup on the back side of the intake valves (especially one valve more than the others) points to leaking intake valve stem seals allowing oil to get sucked down the valve stem.

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DR...I know this a completely different animal, but thought I would ask. I know it has virtually no relationship to a motorcycle engine except that it is air cooled.

 

It is not unusual on general aviation 4 & 6 cylinder horizontally opposed air-cooled engines to get carbon build up and lead on valves.

 

There are three things we usually do before we tear them down. Start with a borescope and see if carbon really there. If so we normally add a proper amount of Marvel and go run it really hard and hot as we can without overheating. That usually clears it. If not we might stake the valves. Not sure you can do that on a boxer. Then if that doesn't work we will do rope a dope valve grinding without removing the heads.

 

Of course these engines don't have cats or o2 sensors so might be damaging on a boxer.

 

As far as the carbon....there is the possibility with such low miles the previous owner thought he might be doing something good by starting it ever so often for 5 minutes without bringing it to proper heat.

 

As DR said...while they have it down, hone and replace rings is what I would do.

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I appreciate the responses, gents. Yes, the service guy did ask about the gas I use. Unless I can't find a station, I almost always use Shell gasoline; no Kroger gas for that baby! 2 more days before it is supposed to be done. I hope to have a long fruitful discussion with the service people when I go to pick it up! The burning question I have is - is this going to continue to be a problem, and if so, should I get rid of it now?

Keith

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DR...I know this a completely different animal, but thought I would ask. I know it has virtually no relationship to a motorcycle engine except that it is air cooled.

 

It is not unusual on general aviation 4 & 6 cylinder horizontally opposed air-cooled engines to get carbon build up and lead on valves.

 

There are three things we usually do before we tear them down. Start with a borescope and see if carbon really there. If so we normally add a proper amount of Marvel and go run it really hard and hot as we can without overheating. That usually clears it. If not we might stake the valves. Not sure you can do that on a boxer. Then if that doesn't work we will do rope a dope valve grinding without removing the heads.

 

Of course these engines don't have cats or o2 sensors so might be damaging on a boxer.

 

As far as the carbon....there is the possibility with such low miles the previous owner thought he might be doing something good by starting it ever so often for 5 minutes without bringing it to proper heat.

 

As DR said...while they have it down, hone and replace rings is what I would do.

 

Morning David

 

There is a lot of lead in aviation gasoline as the engines run under sustained loading for hours on end. That lead can cause build up on the back side of valve heads, piston tops, & spark plugs.

 

On the BMW boxer-- using unleaded gasoline & unleaded E-10 you can still get a slight coating of carbon on the back sides of the valves but that is usually a very light even coating & not harmful.

 

That thick rock-hard carbon on the backs of the valves usually comes from oil burning (exhaust valves) or leaking intake valve stem seals (intake valves). Once that heavy carbon build-up is layered on the valve heads about the only way to remove it is to take the heads off, remove the valves, & use a rotary wire brush to dig the deposits off the valve heads.

 

Audi_RS4_Carbon_buildup_Avalon_Motorsports_zps923e4948.jpg

 

 

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David (Skywagon) wrote:

There are three things we usually do before we tear them down. Start with a borescope and see if carbon really there. If so we normally add a proper amount of Marvel and go run it really hard and hot as we can without overheating. That usually clears it. If not we might stake the valves. Not sure you can do that on a boxer. Then if that doesn't work we will do rope a dope valve grinding without removing the heads.

 

Could you say more about Marvel (Marvel Mystery Oil?) use please?

 

Also would like to know more about "staking" the valves and "rope a dope".

 

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Sure...but again this likely doesn't apply to our motorbikes. I use MMO in my airplane engine with every fill up. It does three things really well. It keeps the top end very clean e.g. plugs have less lead, valves have less carbon, and if you have tank bladders it keeps them really pliable. If you have no bladder tanks, it helps keep wet wing tanks fuel proofing material pliable as well. Tanks will probably never leak.

 

Staking....as you know a key measure on airplane engine is differential pressure. If you find yourself with a leaking valve, especially exhaust, before you tear it down to investigate ($$$$) stake the valves. Remove the valve cover, make sure the valve you are staking is in closed position. Place a 2x4 of proper length over the valve while cold and hit it pretty hard with a hammer. It causes the valve to open and shut pretty violently If the leak is due to carbon or other deposits, 9 times out of 10 it will knock it off and leak is gone.

 

Rope a dope.....a way of grinding the valves without removing the head or the valves by threading a small rope through the valve train while under air pressure. YOu use the rope to wrap around the valve, remove the keepers, apply grinding paste, and resurface the valve without tear down. The compressed air makes sure the valve doesn't fall down requiring cylinder removal The key then once you've done this, is really flushing the engine clean as you don't want valve grinding material circulating. I've don't it many times Takes about an hour per cylinder. For example on a Continental O470 Engine, if you took it to a shop, they charge about $400 cylinder to remove and resurface. You can do it this way for nearly free. I suspect Google could lead you to a video or two.

 

It all sounds kind of elementary, but both staking and rope a dope can usually clear most valve deposits and provide a decent grind if required while saving thousands of dollars.

 

I would not recommend doing this on a relatively new bike though. In fact would recommend that you don't.

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Resolution from the mechanic: "Left cylinder had so much carbon buildup that valves were touching carbon. Leak down test failed past rings. Left oil rings were completely stuck. R&R Cylinders, clean piston crowns, rings, and combustion chambers in heads."

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