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Are my valve clearances ok?

Friz Freleng

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During my 30k mile maintenance I decided to measure the valve clearances on my '13 camhead. As you can see, the my exact clearances are somewhat of a guess because they all fall between the sizes of the feeler leafs that are in my rather basic feeler gauge set.

BMW specs

Exhaust .3--.4mm
Intake .13--.23mm

My clearances fall somewhere between these feeler leaf sizes:

Left Exhaust Intake
upper .381--.406 .203--.229
lower .381--.406 .178--.203


Right Exhaust Intake
upper .381--.406 .190--.216
lower .381--.406 .216--.229

As you can see, my exhaust valves clearances are toward the maximum end of the BMW spec range, and in fact could be higher than the BMW max of .4mm since my nearest feeler leaf was .406.

So, a few questions: Should I be concerned about any of this? Is it shim time? With regard to feeler gauges, can anyone suggest a high quality precision set? Amazon sells the usual suspects but I've read where the cheap gauges can be woefully inaccurate.
 

John Macdonald

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Machinist here

Whenever I use feeler gages, I check them with a micrometer (not caliper)

I have many sets of feeler gages, also many which are not sets

When it matters, the only way to know the thickness of the feeler gage is to measure it

Also if the gage is bent or wrinkled or dented, replace it

I just note this as you asked about the accuracy of feeler gages
They wear, they get damaged, etc

There are numerous bike-specific feelers that are handy and good.

These are nice

 

Friz Freleng

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SF Bay Area
Machinist here

Whenever I use feeler gages, I check them with a micrometer (not caliper)

I have many sets of feeler gages, also many which are not sets

When it matters, the only way to know the thickness of the feeler gage is to measure it

Also if the gage is bent or wrinkled or dented, replace it

I just note this as you asked about the accuracy of feeler gages
They wear, they get damaged, etc

There are numerous bike-specific feelers that are handy and good.

These are nice

Thanks. Great suggestion...I hadn't thought about actually measuring the buggers but at least one of them is bent. Mine is an old set that probably dates back to when my dad was moonlighting as a diesel truck mechanic. And I had no idea BMW shops sold feeler gauges!
 

John Macdonald

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Sierra BMW is a good outfit, I just referenced their website because I knew those were there.

Call them on the phone before you order if you're going to order from them. They'll set you straight.

I'd comment on your actual settings, but the most current BMW twins I've owned are the 1100/1150 oilheads.
Top ends are a little different, so I don't want to speak on something that I haven't run myself.
 

Friz Freleng

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Sierra BMW is a good outfit, I just referenced their website because I knew those were there.

Call them on the phone before you order if you're going to order from them. They'll set you straight.

I'd comment on your actual settings, but the most current BMW twins I've owned are the 1100/1150 oilheads.
Top ends are a little different, so I don't want to speak on something that I haven't run myself.
Thanks! I'll give them a call and see what they recommend. The auto parts stores around me only carry the same imperial measurement gauges that I already have.
 

JimVonBaden

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The specs are pretty clear:
BMW-Motorrad
Inlet valve clearanceEngine cold max 35 °C0.13...0.23 mm
Exhaust valve clearanceEngine cold max 35 °C0.30...0.40 mm

If your feeler gages are not close enough to tell, get new ones. Autozone has them for $8.
 

Friz Freleng

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Arrghs, yeah, you guys are right, I gotta get some new gauges and start over. The last time I checked my valves, the clearances were well within the range. I was a little surprised to see the exhaust clearances toward the end of the range this time. I'll nail this down and report back. At least they're on the loose side.
 

eri

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not sure of your bike but with the wetheads be careful not to try and push the feeler gauge under the decompression lever on the forward exhaust cam

not a problem if you are at top dead centre but not far off TDC you can get a '0.01mm' clearance reading by mistakenly getting a gauge under the decompression sub-lobe, which you won't see as is on the 'other' side of the main lobe
decomp3.jpg
 
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Friz Freleng

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not sure of your bike but with the wetheads be careful not to try and push the feeler gauge under the decompression lever on the forward exhaust cam

not a problem if you are at top dead centre but not far off TDC you can get a '0.01mm' clearance reading by mistakenly getting a gauge under the decompression sub-lobe, which you won't see as is on the 'other' side of the main lobe
Thank. So far as I know the camhead design doesn't incorporate a decompression lever, but I do try to line up the cam marks as precisely as I can.
 
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Friz Freleng

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SF Bay Area
Here's an update: I re-measured my valve clearances using a new set of metric feeler gauges. The survey says...

Untitled-1.jpg


Since the right exhaust valves are at their limit, I'll check everything again at the next 6k mile service with the expectation that they'll need new shims. I tried to be as precise as I could in rotating and aligning the cam shaft marks to their correct locations.

I was careful to measure the gap produced from where the followers came to rest after the cam lobes pushed them to their spots. Interestingly, I noticed that I could actually push all the followers wider, toward the valves, with my finger. They'd snap and then move wider, almost as if the followers rotated out of a little detent on the rocker arm shaft. I'm probably not explaining this very clearly. But, as it stands, there is a gap on both sides of the follower--between the follower and the cam and a gap between the follower and the valve. Weird. Cam lobes look fine.
 

Friz Freleng

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SF Bay Area
"Slappy valves are Happy valves"
And the funny thing about mine is the valves don't make much noise. The usual cam chain slap at cold start up but other than that the bike sounds fine. I attribute it to goat sacrifices.
 

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