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Valve adjustment on R1200RT...can lack of adjustment cause damage or just noise?


Wildwestrider

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Wildwestrider

Have wondered for years on my various 1100s, 1150s and now my R1200RT............If I blow off a valve adjustment is there a risk of damage or is it more likely to just cause valve clatter and reduced power as the valves will be opening a mm or so less.

 

Brian in Austin

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Firefight911

Maybe delaying or missing one here and there may not cause a huge problem, but an overall neglect of the valves WILL cause permanent damage at some point. Especially when the motor is young.

 

A young motor will tend to close the valve gap due to the mating of parts and the seating of the valve seats, etc. This will be seen with tight tolerances.

 

At some point, this subsides and you may go quite a long time without even having to adjust them, just check them and button up. 30 minutes tops.

 

After a while, due to wear and tear, the valve gap can actually start to increase. This is due to the valve and tappet "mushrooming" from all the "beating" it has taken ove rits life.

 

A lack of maintenance can result in reduced performance or engine damage.

 

If the tolerance tightens to the point that there is no gap, the valve will not seat entirely. This will cause reduced compression from blowby and an exponential increase in heat retention to the valve itself. This will result in a burned valve and a big $ to fix.

 

You can also burn a piston, etc.

 

It takes such a little amount of time that it really, IMO, makes no sense to not take the time to pull the valve cover and check them.

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I'm having a brain fart here, would not the mushrooming valve that is digging into the head make the gap tighter?

 

I believe the mushrooming referred to is at the other end of the valve stem.

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Firefight911
I'm having a brain fart here, would not the mushrooming valve that is digging into the head make the gap tighter?

 

I believe the mushrooming referred to is at the other end of the valve stem.

 

Correct. The mushrooming occurs between the valve stem and the tappet.

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Arizona_oldguy

1bmwfan wrote:

 

Quote:

 

A young motor will tend to close the valve gap due to the mating of parts and the seating of the valve seats, etc. This will be seen with tight tolerances.

 

At some point, this subsides and you may go quite a long time without even having to adjust them, just check them and button up. 30 minutes tops.

 

After a while, due to wear and tear, the valve gap can actually start to increase. This is due to the valve and tappet "mushrooming" from all the "beating" it has taken ove rits life.

 

A lack of maintenance can result in reduced performance or engine damage.

 

************

 

Or to put it another way, No valve clatter is BAD, it means no gap. but noisy valves only mean lower performance but they are not burning up.

 

So If I have no valve noise I would not skip an adjustment, but if they were a tad noisy I might risk it.

 

Visualize that if there is no gap, the valve is actually not closing all the way, which means it never seats on the cooled engine head, which is the only way the valve can cool, so instead of cooling it burns, and then it can never seat again until a valve job.

 

for the opposite problem,

Visualize huge gap, so huge that the valve never opens. This never happens, but it helps you see why performance goes down. the less the valve opens the shorter time it is opened, and the less exhaust out and fuel mix in, translates into less performance.

 

In 1966 I rode my Honda fifty 750 miles from Pittsburgh Pa to Madison Wisconsin, and 750 miles back; (thirty hours each way) and I thought I would improve performance by shortening the gap, well I burned the valves and had to have them replaced in Madison. Cost me $35. back in those days, parts and labor. If I did that today on my r1200RT, it would cost a bit more.

 

Glenn

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