Valve shims

mxrose3
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mxrose3
Edited Date/Time 4/28/2015 6:22am
Since I have had to deal with shimming valves on modern 4 strokes lately, it got me wondering why the Japanese manufacturers haven't adopted an automatically adjusting hydraulic valve lifter under the valve buckets. Like the one BMW uses in their overhead cam car engines:



Anybody know the answer?
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PTECH
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PTECH 4/23/2015 6:21pm
4/23/2015 6:21pm Edited Date/Time 4/23/2015 9:26pm
Porsche uses these as well. No clearances to check or adjust and they're incredibly reliable. I've seen 2 or 3 fail in the 12 years I've worked on cars professionally. And there are at least 24 in every car I work on!
pCp 252
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pCp 252 4/23/2015 7:24pm
4/23/2015 7:24pm Edited Date/Time 4/23/2015 8:04pm
I see an opportunity for the aftermarket parts to develop these. That would be a nice feature for sure.

EDIT >
*Quick google search shows a constant need of pressurized oil in the cylinder head for these to work. So therefore a redesigned head would be needed. I'm sure this is a much more complex and expensive design for the manufacturers to produce.
Paw Paw 271
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Paw Paw 271 4/23/2015 7:31pm
4/23/2015 7:31pm
Do you not have to have oil pressure to these for them to work? If so, the bike head would have to be redesigned to create that oil pressure to each valve, that they don't have now.

Paw Paw

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Knoby
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Knoby 4/24/2015 1:49am
4/24/2015 1:49am
But if you look at all the M series engines they are all solid lifters.
Paw Paw 271
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Paw Paw 271 4/24/2015 5:27am
4/24/2015 5:27am Edited Date/Time 4/24/2015 5:28am
When was the last time you saw any auto engine stretch an intake valve? They simply don't turn the RPMs of our bike engines.
Almost every valve adjustment needed in an auto is to reduce the valve clearance, not make wider as in bike engines. This is due to high RPM wear of the valve seats and the fact that the valves grow in length due to couping of the valve.

Paw Paw
lumpy790
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lumpy790 4/26/2015 8:35am
4/26/2015 8:35am
Why?

Probably because of the weight. With the RPM's modern race bikes turn compared to the models you described the extra weight can not rev that heigh without floating the valves..

BTW ..... had to replace a bunch of those on a Kawasaki Vulcans in warranty.

Knoby
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Knoby 4/26/2015 9:40am
4/26/2015 9:40am
Paw Paw 271 wrote:
When was the last time you saw any auto engine stretch an intake valve? They simply don't turn the RPMs of our bike engines. Almost every...
When was the last time you saw any auto engine stretch an intake valve? They simply don't turn the RPMs of our bike engines.
Almost every valve adjustment needed in an auto is to reduce the valve clearance, not make wider as in bike engines. This is due to high RPM wear of the valve seats and the fact that the valves grow in length due to couping of the valve.

Paw Paw
Sometime last week, I believe there were four or five of them that stretched. But I'm only assuming this because I had to put smaller shims in. I didn't actually see it. Or it could be the valves "couping." When was the last time you shimmed a 4, 6, 8, or 10 cylinder race engine?
Knoby
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Knoby 4/26/2015 9:41am
4/26/2015 9:41am
lumpy790 wrote:
Why? Probably because of the weight. With the RPM's modern race bikes turn compared to the models you described the extra weight can not rev that...
Why?

Probably because of the weight. With the RPM's modern race bikes turn compared to the models you described the extra weight can not rev that heigh without floating the valves..

BTW ..... had to replace a bunch of those on a Kawasaki Vulcans in warranty.

X2
ToolMaker
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ToolMaker 4/27/2015 6:58am
4/27/2015 6:58am
Also the materials they use are light and minimal to keep the mass down so the valves don't float at high RPMs.
So they just don't have the strength to maintain their original shape and size for any length of time.
mxrose3
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mxrose3 4/28/2015 6:22am
4/28/2015 6:22am Edited Date/Time 4/28/2015 6:24am
I was curious. thanks for all the insight guys...

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