95 RT plugs

From left to right; left bottom-left top-right bottom-right top.

Left bottom-left top

Right bottom-right top

Plugs are Iridium. Used for 3500 miles. Bike runs fine, milage 47-49 mpg - single rider with only the topbox.
Pictures not that good. Right side always a bit ?oilier?, although I?ve learned not to have too much oil in the engine.
Do they look about right? I feel I could run leaner. Ignition is Silent Hektik.
Sincerely
Hans
Norway

Gap? Looks huge.

"Bike runs fine, milage 47-49 MPG"

Nothing wrong with that.

The color looks O.K. to me, the insulator on right/bottom plug looks funny.
I agree with Kurt about the gaps.
Too lean is a bad thing, you are not there yet.
I like to run the NGK, BP6ES plugs, But I have not had any problems with other brands.

Tanks for comments! I've never paid attention to gap, know nothing about it. Will have to look into that.
Insulator on the right bottom looks "dirty". Is it burnt oil? It seems to me that right hand plug(s) always are "dirtier" than the left side, on my bike. I thought that was normal, something to do with the oil circuit?
I wish you all a nice Thanksgiving!
Hans

We use those Iridiums on our Hexheads

Those pics are not sharp enough to me to see the tiny electrode the Iridiums have...may be a reason it looks odd.

If all the parts are still there and connected, remember that any crankcase blowby is sent through the carbs. This the the most likely source of oil on plugs for a bike this new.

lkchris said:

If all the parts are still there and connected, remember that any crankcase blowby is sent through the carbs. This the the most likely source of oil on plugs for a bike this new.

Click to expand...

Do you really mean "blow-by? Because the term has to do with piston rings worn or seized enough from carbon to allow some of the compression mix to "blow-by" into the crankcase. Has nothing to do with the carbs.

I think you are referring to the "breather" air from the crankcase with some oil mist in it, being directed back through the engine via the intake system - thus going through the carbs.

Breather air. Any theory why it would affect right side more than left, if that is the cause.
My 95RT got less than 30K miles, meter says 42598 km to be exact.
I would claim right plug was messier before, until I started keeping the oil level on the low side.
Hans

Earlier models sent mist to right carb only...they diverted to both later on...probably your situation. Worth a check on the routing under the top cover. One side could be plugged.

That I'll check!
Hans

Kent, once again is totally correct.

Enter "Engine Blowby" into Wikepedia and one gets:

Crankcase ventilation system
escape in a controlled manner from the crankcase of an internal combustion engine . but continual amount of blow-by, which occurs when some ... 14 KB (2,268 words) - 16:32, 16 November 2013

or

Crankcase (redirect from Blowby)
In an internal combustion engine of the reciprocating type , the crankcase is the ... blow-by than the crankcase ventilation system can handle. ... 9 KB (1,249 words) - 17:58, 28 October 2013


on and on.....................God bless........Dennis

jimmylee said:

Do you really mean "blow-by? Because the term has to do with piston rings worn or seized enough from carbon to allow some of the compression mix to "blow-by" into the crankcase. Has nothing to do with the carbs.

I think you are referring to the "breather" air from the crankcase with some oil mist in it, being directed back through the engine via the intake system - thus going through the carbs.

Click to expand...

Indeed I was.

Ran across this post on the Hex/Camheads:

http://forums.bmwmoa.org/showthread...park-Plug-Cost&p=718305&viewfull=1#post718305

So, the gap should be around 0.8mm (~0.032")...somewhere else I read the gap as 1.1mm (~0.043"). Hard to judge from the pictures, but they really appear to be gapped pretty wide??

DennisDarrow said:

Kent, once again is totally correct.

Enter "Engine Blowby" into Wikepedia and one gets:

Crankcase ventilation system
escape in a controlled manner from the crankcase of an internal combustion engine . but continual amount of blow-by, which occurs when some ... 14 KB (2,268 words) - 16:32, 16 November 2013

or

Crankcase (redirect from Blowby)
In an internal combustion engine of the reciprocating type , the crankcase is the ... blow-by than the crankcase ventilation system can handle. ... 9 KB (1,249 words) - 17:58, 28 October 2013


on and on.....................God bless........Dennis

Click to expand...

From:Bot-the-oil-guy: http://www.bobistheoilguy.com/blowby.html, and every other person I have met who races motorcycles and autos!

WHAT IS BLOW-BY?

What is Blow-by? Blow-by occurs when the explosion that occurs in your engine's combustion chamber causes fuel, air and moisture to be forced past the rings into the crankcase. Your engine's rings must maintain an excellent fit in order to contain the pressure. The causes of blow-by: wear, soot and deposits As rings and cylinder liners wear away they are less capable of maintaining this seal. Consequently as a car ages the amount of blow-by that occurs can increase. Soot and deposits left over from incomplete combustion that collect on the rings can also inhibit their seal worsening blow-by. The effects of blow-by: loss of horsepower and oil contamination and dilution Blow-by inhibits performance because it results in a loss of compression. When the expanding gases slip past the rings they cannot as effectively push the piston down and make the vehicle go. As a result the car will have less horsepower. This also results in a loss of fuel economy. When the fuel, air and moisture slip into the crankcase they contaminate and dilute the oil in the crankcase. Among the many gasses in your compression chamber are unburned fuel, moisture, sulfur dioxide and soot. Once these gasses slip into your crankcase they can dilute into your engine causing great damage. The detergents and Molybdenum Disulfide work together to clean the soot and deposits off of your rings allowing them to better seal the combustion chamber. The Moly fills the crevices in the cylinder walls providing a better seal:

He also has accompanying pics to illustrate.

I have never heard anyone ever refer to crankcase ventilation systems using the word "blow-by."

I am sure it has been said above in some form, but we need to differentiate between crankcase pressure due to the piston downstroke and "blow-by" commonly known as combustion pressure finding its way past the rings.
The former is a common problem on many engines and resulting oil coming out of the crankcase breather. For some reason, this is more pronounced in dry sump engine designs, where either oil rings are worn or a check valve in the pump is not properly working and makes oil accumulate in the crankcase after the engine is shut off. Upon re-start, this oil is forced out through the breather and into wherever this connects to. Mostly the carbs.
Many Harley owners who change their carbs to some aftermarket design, which does away with the breather connection and routs this to the outside, will have an oil spot under their bike. Not a sign of a leaking engine, but rather the result of a breather spewing oil.

Irrespective of the technical distinction I often use the term blowby referring to crankcase pressure because I believe that even in a brand new engine, combustion pressures past the rings is a component of crankcase pressure except when the engine is being cranked by the starter and not firing. I think it is a matter of degree.

Certainly the process of pistons retreating to bottom dead center adds to crankcase pressure. This is particularly true of two cylinder boxer style engines where both pistons are retreating from TDC together. In a V8, for example, some pistons are retreating and others are advancing at the same time - which is not true of BMW boxers.

But, even as small as they are, the rings have end gaps, and some combustion pressures excape through the labyrinth of the three rings and enter the crankcase. This happens at peak combustion chamber pressures including as the piston is retreating after firing just before TDC. So the crankcase is getting both the pressure of the displacement from retreating pistons and anything escaping from the combustion chamber past the end gaps.

Obviously, the more worn an engine is, the more escapes past the rings. So a sound, just broken-in engine gets just a little blowby and a well worn engine gets a lot. Strictly speaking, my view may not be semantically correct in the mainstream, but I hold it nonetheless.

PGlaves said:

Irrespective of the technical distinction I often use the term blowby referring to crankcase pressure because I believe that even in a brand new engine, combustion pressures past the rings is a component of crankcase pressure except when the engine is being cranked by the starter and not firing. . .

my view may not be semantically correct in the mainstream, but I hold it nonetheless.

Click to expand...

I don't mean to beat this to death, but (for me), I like to try to keep things technically correct and use explanations that way. I think, here as well, the more technically correct notion of "blow-by" as to do with compression gasses that "blow by" the piston due to wear, or carboned-up rings, and not the normal sort of pressure lost by the simple fact of ring gap, etc. as you have used it. I don't mind your using it, but I think that an explanation is also due as you did.

However, in this case, the boxer engine on these BMW's (my familiarity only with the /5 - /7's) as the original poster asks - the problem seems to be due NOT to blow-by as normally thought of, but by simple crankcase pressure. Almost to a person in my acquaintance who has had one of these /'s has had this problem and has seen oil usage beyond normal - at least until enough volume of air gets into the crankcase that doesn't allow the oil mist to reach out the breather and into the intake tubes.

jimmylee said:

I don't mean to beat this to death, but (for me), I like to try to keep things technically correct and use explanations that way. I think, here as well, the more technically correct notion of "blow-by" as to do with compression gasses that "blow by" the piston due to wear, or carboned-up rings, and not the normal sort of pressure lost by the simple fact of ring gap, etc. as you have used it. I don't mind your using it, but I think that an explanation is also due as you did.

However, in this case, the boxer engine on these BMW's (my familiarity only with the /5 - /7's) as the original poster asks - the problem seems to be due NOT to blow-by as normally thought of, but by simple crankcase pressure. Almost to a person in my acquaintance who has had one of these /'s has had this problem and has seen oil usage beyond normal - at least until enough volume of air gets into the crankcase that doesn't allow the oil mist to reach out the breather and into the intake tubes.

Click to expand...

I agree.