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Old 02-14-2012, 04:38 AM   #1576
vtbob
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Quote:
Originally Posted by milo View Post
I'm not so sure about a modern boxer having a low center of gravity? I would think a V-twin with the heaviest part of the engine (the crank) positioned low would be better. The boxer has to be raised high to allow cornering clearance. Maybe I'm wrong though.
I think you are right. I would love to seen some data/graphics on this.
While the R GS have long been praised for their "low center of gravity" it seems every chance BMW get they make changes to degrade that benefit. The newer boxer engines are wider than the past and mounted in the frame, the GSA is taller raising the CofG, it has a bigger tank up very high raising the CofG, the overly upswept exhaust raises the CofG, then we all add cases and top boxes that raise the CofG more.

I guess is fine if you cruise interstates...but tipping in loose or slippery dirt puts you down quick.
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Old 02-14-2012, 04:40 AM   #1577
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Improved street handling doesn't come from a low CoG. It comes from mass centralization around the roll axis of the bike. My guess is that the progression of the GS architecture has had a relatively positive effect in that direction.
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Old 02-14-2012, 06:16 AM   #1578
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Originally Posted by dmac57 View Post
Improved street handling doesn't come from a low CoG. It comes from mass centralization around the roll axis of the bike. My guess is that the progression of the GS architecture has had a relatively positive effect in that direction.
Help me out. I don't understand "roll axis" ..amoung many other things it seems. It seems to me the "a" but likely not "the" roll axis is where the tires contacts the pavement. i.e. the bike "roll's" /tilts right or left on those points.

The Center of Gravity, which is different from the center of Mass, rotates above the tire/pavement contact points. The higher the center of gravity is from the pavement the longer it has to travel to any given lean angle. i.e. slower steering and likely more effort expended by the rider to move it thru that distance.

Standing up on the peg can help this, because the peg are below the center of gravity vs your butt which was on the seat(higher than the center of gravity) but doing so move the center of mass higher. a bit of a oxymoron..but who cares?

I just don't understand how raising CoG higher helps steering responiveness.
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Old 02-14-2012, 09:01 AM   #1579
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While the boxer twin has lower CG than a similar sized vertical or Vee twin, it doesn't improve handling appreciably as stated previously. The prime advantage over other engine layouts is reduced vibration and harshness relative to output and displacement. The lack of vibration in the Goldwing/Valk six is remarkable for the displacement. Same with the R12 engine. Compared to the other bikes in the same class, it's absolutely remarkable how smooth the bike is. Shit, it's smoother than any FJR13 I've ever ridden...

A water-cooled version is going to produce a very impressive NVH (noise, vibration, harshness) factor. Water cooling reduces all three by virtue of the ability to run closer piston/cylinder clearances and the water jacket dampens the noise and vibration. Wish I could wait for it...
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Old 02-14-2012, 09:13 AM   #1580
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What is water cooling likely to do for maintenance intervals? Are valve checks/adjustments still going to be every 6k? If so I am thinking that folks concerned with frequency or ease of maintenance (as I am) may look at other bikes like the Super Tenere with 26k valve adjustment intervals.

As much as I love my GSA, and boxer motors in general, if water cooling only gives a bit more power, a little quieter, but comes at the expense of more difficult routine maintenance at 6k intervals I don't think it will be that attractive to anyone that rides a fair amount. If the liquid cooling gets it close to the longer service intervals on competing bikes it would seem a lot more attractive.
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Old 02-14-2012, 10:03 AM   #1581
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Originally Posted by tyandresen View Post
What is water cooling likely to do for maintenance intervals? Are valve checks/adjustments still going to be every 6k? If so I am thinking that folks concerned with frequency or ease of maintenance (as I am) may look at other bikes like the Super Tenere with 26k valve adjustment intervals.

As much as I love my GSA, and boxer motors in general, if water cooling only gives a bit more power, a little quieter, but comes at the expense of more difficult routine maintenance at 6k intervals I don't think it will be that attractive to anyone that rides a fair amount. If the liquid cooling gets it close to the longer service intervals on competing bikes it would seem a lot more attractive.
I shouldn't think the maintenance would be more difficult on a boxer configuration. Other than the additional care for the coolant system, performing other regular maintenance items *should* be similar. For instance, valve adjustments should only require the removal of a valve cover and replacement of shims much like today's camhead. Oil changes and air filter replacement ditto. Hopefully, the addition of a water cooling system wouldn't make access to these items more difficult.
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Old 02-14-2012, 10:15 AM   #1582
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I shouldn't think the maintenance would be more difficult on a boxer configuration. Other than the additional care for the coolant system, performing other regular maintenance items *should* be similar. For instance, valve adjustments should only require the removal of a valve cover and replacement of shims much like today's camhead. Oil changes and air filter replacement ditto. Hopefully, the addition of a water cooling system wouldn't make access to these items more difficult.
It wasn't access that I was concerned with. The camhead design is already a more complex valve adjustment than my 07 Hexhead. I put on a lot of miles and wouldn't consider a camhead just for that reason. I know there have been other improvements but I'm just not willing to give up the ease of valve adjustment and being reliant on the ability to get the right shim when I need it. I am assuming that a liquid cooled version would retain much of the camhead design, including shim type adjustments. If liquid cooling stretches that adjustment interval to 26k or something in the range of competing bikes then I personally would be much more interested. I still don't like the idea of being at the mercy of being able to get the right shim when I need it. I am guessing that after some time it will probably be the exhaust valves that tend to tighten up a bit, and carrying a couple of likely shims may not be that big of a deal. If the adjustment interval goes up significantly in my mind it would be an okay trade-off.
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Old 02-14-2012, 10:31 AM   #1583
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Originally Posted by Florida Lime View Post
I never knew they had wooden stoves or radios with valves !


But if you have a wood stove, I'll take it !
Wooden stove ooooops, not so easy for a bloo.y foreigner
Radio with valves YES!!!!!
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Old 02-14-2012, 11:15 AM   #1584
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Originally Posted by tyandresen View Post
It wasn't access that I was concerned with. The camhead design is already a more complex valve adjustment than my 07 Hexhead. I put on a lot of miles and wouldn't consider a camhead just for that reason. I know there have been other improvements but I'm just not willing to give up the ease of valve adjustment and being reliant on the ability to get the right shim when I need it. I am assuming that a liquid cooled version would retain much of the camhead design, including shim type adjustments. If liquid cooling stretches that adjustment interval to 26k or something in the range of competing bikes then I personally would be much more interested. I still don't like the idea of being at the mercy of being able to get the right shim when I need it. I am guessing that after some time it will probably be the exhaust valves that tend to tighten up a bit, and carrying a couple of likely shims may not be that big of a deal. If the adjustment interval goes up significantly in my mind it would be an okay trade-off.
Liquid cooling on its own won't change anything regarding clearance checks. The valve train is also not the same as the twin cam as it will be pure bucket and shim with no rockers as it is now. This should stretch the checks out although to what is anybodies guess. I would also think that the water Cooling and new valve gear could shave a bit off the width but they might have done other things like increase the stroke to widen it again.
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Old 02-14-2012, 12:14 PM   #1585
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Originally Posted by Marki_GSA View Post
Liquid cooling on its own won't change anything regarding clearance checks. The valve train is also not the same as the twin cam as it will be pure bucket and shim with no rockers as it is now. This should stretch the checks out although to what is anybodies guess. I would also think that the water Cooling and new valve gear could shave a bit off the width but they might have done other things like increase the stroke to widen it again.
I thought someone may have a guess as to how much it may stretch out the valve checks.

I own some other rigs with bucket and shim type adjustments and I've spent some time waiting for a dealer to get the shims that I need. I personally don't like the idea of a traveling bike that I may have to set somewhere with waiting for the right shims. BMW dealers are sparse enough. Add in having to either plan being where there is a dealer when you do your maintenance or being willing to wait for the parts to be sent to you to finish and it just starts not being that attractive. I suppose you could drain the oil, check things, measure and calculate what shims you need, put it back together to ride and order the parts to be delivered to a future destination and do the actual valves then. Either way, it's a bit of a hassle. Progress always has some type of price, and I'm just not sure that if that ends up being the price with the new GS that I'd end up buying one. No doubt plenty of others will.

Right now I plant to take really good care of my 07 so that any decision is hopefully quite a ways down the road.
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Old 02-14-2012, 12:26 PM   #1586
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Originally Posted by tyandresen View Post
What is water cooling likely to do for maintenance intervals? Are valve checks/adjustments still going to be every 6k? If so I am thinking that folks concerned with frequency or ease of maintenance (as I am) may look at other bikes like the Super Tenere with 26k valve adjustment intervals.
Yamaha specifies 26k on all of its bikes. But note that Yamaha doesn't have some sort of super secret valve train technology that keeps valves in spec so much longer, they just think the bikes will run longer without needing a check.

Having had two yamahas (both sport bikes) that both had failed valves before 26k, I think that, were I ever to own one again, I'd check them as frequently as Honda or Suzuki would recommend for a similar machine. That's in the neighborhood of 12k
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Old 02-14-2012, 12:53 PM   #1587
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Stupid thing is that the K and F bikes have 30.000km valve intervals and the OHC boxer has 10.000km.
But the valve system is basicaly the same. Seems they kept the intervals low just becose it easyer acces.
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Old 02-14-2012, 03:23 PM   #1588
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Stupid thing is that the K and F bikes have 30.000km valve intervals and the OHC boxer has 10.000km.
But the valve system is basicaly the same. Seems they kept the intervals low just becose it easyer acces.
I don't know anything about the f and k engines do they have rockers? If not then they aren't basically the same. There are loads more friction and ware points which is why the clearance goes out so quickly on the boxer. Unless your going round the world I don't think you need to worry about valve clearance even if they just double it. 12000 miles is a long trip even longer if it's moved to 18000. Do them as part of the prep for the trip at home and your sorted.
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Old 02-14-2012, 04:29 PM   #1589
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Originally Posted by Marki_GSA View Post
I don't know anything about the f and k engines do they have rockers? If not then they aren't basically the same. There are loads more friction and ware points which is why the clearance goes out so quickly on the boxer. Unless your going round the world I don't think you need to worry about valve clearance even if they just double it. 12000 miles is a long trip even longer if it's moved to 18000. Do them as part of the prep for the trip at home and your sorted.
It would be nice if the liquid cooling and new design allows intervals of 12k or 18k. With my 07 I don't worry too much about where I will be when it's time for a service. I can easily carry the few tools needed to do it. I've done it more than once in a parking lot in a 3rd world country and it isn't a big deal. No concerns about finding the right shim or waiting for it, or finding what shim I need only to find out it isn't quickly available and having to put things back together and deal with it at a later time when the shim can be had.
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Old 02-14-2012, 05:55 PM   #1590
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Originally Posted by tyandresen View Post
It would be nice if the liquid cooling and new design allows intervals of 12k or 18k. With my 07 I don't worry too much about where I will be when it's time for a service. I can easily carry the few tools needed to do it. I've done it more than once in a parking lot in a 3rd world country and it isn't a big deal. No concerns about finding the right shim or waiting for it, or finding what shim I need only to find out it isn't quickly available and having to put things back together and deal with it at a later time when the shim can be had.
The camhead Boxer valve intervals are check at 6 K miles then every 12K miles afterward. Adjustment is rarely needed even at 18K miles, The K16's check is at 18K miles and rarely needs adjusting.

No doubt the water Boxers will easily meet or beat that.
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