Egg shapped cylinders

Bigtrucknuts

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Ok so this should be in the air-head section but iv got a LC so it's here.

I was out on a ride today and one of the riders has an R1200R air-head. She said it tends to drink oil. Fair enough it's a few years old. But the reason given seems a bit far fetched but here it is.

An air head receives most of its cooling from the front because of air flow. Therefore the front of the cylinder expands less than the back when hot. So the cylinder forms a slight egg shape. This causes a loss of oil past the cylinder rings which remain round.

Iv never heard of this sort of thin before. When I had an air head it didn't use any oil at all.

So is this a know thing or a load of bo...x? :nenau
 
My air head uses oil, no idea why but the dealer told me it would and he is right.
 
All my early R1150s and R100s drank oil. Could be for the reasons given. Only problem with the argument is my R1200GS did not use any oil at all.
 
First of all this is the wrong section and as it is a load of bollox it is right to post in the LC section. The R1200R is what is known as a hexhead and uses part oil cooling.

The cooling fins are more than enough to take care of the cooling plus there is an oil cooler. The piston design does allow for the expansion due to heat. It is therefore manufactured with the piston in a taper shape when viewed from the side, meaning that the top has a smaller diameter than the bottom. Also given that the combustion will be fairly universal with in the cylinder and that metal expand equally in all direction when uniformly heated it can be said that the cylinder will keep it shape, round that is, the top will expand a bit more than the bottom. But as in ovens where a constant heat source is present there will be cool and hot spots present. This will differ by only a few degrees and will change with each combustion stroke. As for radiation the cooling fins will take care of that. The head has smaller cooling fins than the cylinder because it runs cooler whereas when you examine the cylinder cooling fins you'll find it spaced a bit further apart and much bigger to enable it to radiate the heat to the surrounding air.
 
Ok so this should be in the air-head section but iv got a LC so it's here.

I was out on a ride today and one of the riders has an R1200R air-head. She said it tends to drink oil. Fair enough it's a few years old. But the reason given seems a bit far fetched but here it is.

An air head receives most of its cooling from the front because of air flow. Therefore the front of the cylinder expands less than the back when hot. So the cylinder forms a slight egg shape. This causes a loss of oil past the cylinder rings which remain round.

Iv never heard of this sort of thin before. When I had an air head it didn't use any oil at all.

So is this a know thing or a load of bo...x? :nenau

Are you on drugs?
 
I feel I should point out that the GS "WC" has air cooled cylinders.
 
It doesn't matter what you ride, this has nothing to do with the LC, so I've moved it.:rob
 
The cooling fins are more than enough to take care of the cooling plus there is an oil cooler. The piston design does allow for the expansion due to heat. It is therefore manufactured with the piston in a taper shape when viewed from the side, meaning that the top has a smaller diameter than the bottom. Also given that the combustion will be fairly universal with in the cylinder and that metal expand equally in all direction when uniformly heated it can be said that the cylinder will keep it shape, round that is, the top will expand a bit more than the bottom. But as in ovens where a constant heat source is present there will be cool and hot spots present. This will differ by only a few degrees and will change with each combustion stroke. As for radiation the cooling fins will take care of that. The head has smaller cooling fins than the cylinder because it runs cooler whereas when you examine the cylinder cooling fins you'll find it spaced a bit further apart and much bigger to enable it to radiate the heat to the surrounding air.

All very true but a cylinder will still wear oval due to the thrust from the crank/con rod, nothing to do with heat.
 
All very true but a cylinder will still wear oval due to the thrust from the crank/con rod, nothing to do with heat.

That generally doesn't happen any more, due to the coating on the cylinders, it's actually harder than the piston rings, if anything is going to wear oval it will be the pistons!
 
They are more likely to use oil when run in too gently. All sorts of complicated reasons why, but the upshot is don't be too gentle.
These bikes are big boys and like to be treated accordingly.
Mine was thrashed now shows 48 k and uses no oil
Brothers was mollycoddled now shows 25k, uses oil and still feels tight.


Sent from a widget that can't spell.
 
Having been employed for the last 40 years+ riding a fleet of Boxers & K's from 1976 onwards - some do, & some don't.

I think it's fair to say the 1100's & 1150's tended to use more than the 1200's ( my last, a TC used no measurable amount between 6,000 miles services) but I agree that some riders bedded the bike in better than others, & those that were "baby'd" tended to use more oil & generally were not such nice bikes.
 
Thanks for all the replies :thumby:

I thought it was a load of rubbish as I said in the opening post, so no I'm not on drugs but thank you for your concern.

I thought 'air-heads' was accurate? What's the problem :bounce1 it's better than WC or 'toilets'
 


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