Valves and feeler gauges

mpgscott

mpgscott

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Hi All,

Sorry for asking but i really want to do as much maintenance on my bike as i can for two reasons one its miles to the nearest decent garage and two i want to do it.

So i have bought a set of feeler gauges and plan on attempting the valves myself when its due in a couple of thousand miles. So i have used the feeler gauges in the past but im still a little unsure as to how to properly use them, i mean how do you know if the pull on them is too little or too much. So has anyone any good instructions on their operation??

Also if you have the correct size gauges so 0.15 and 0.3 then how do you know what size of shim to use to make the change if necessary??

Any help as normal much appretiated.
 
If you've never even used feeler gauges before I'd be wary of setting your valves on your own.

I'd get a friendly mechanic show you how first and let you get a feel - then crack on :thumb

Edit - just seen you have used em before but my suggestion remains.
 
As you're talking shims I'm assuming you have the twin cam, the single cam has old fashioned lock nuts etc. Feeler gauges should be snug.
 
Stepped feeler gauges are the best bet (go-no-go). Makes the job of checking easier.
Once you have the gaps written down you need to strip down the rocker and remove the shims to identify the size. One you have all the sizes it is just a matter of doing the maths and obtaining/swoping the shims to give you the gap within the specifications. Recently checked mine at 12000 mile service. All within tollerence.

Mark
 
Thanks Victor out of interest which feeler gauge set do you use? And so if it's a firm tug when sniffing the gauge that's what you want?
 
Blue Point from Snapon. You can order them off their UK website. There should just be light friction on the blade when inserted. The tollerence is quite generous, so would not worry about being too critical of actual gap. If you have not already removed the spark plugs, i would recommend using a thin wall plug socket. A standard one has the potential to jam in the hole.
 
Can you use a metric micrometer? You'll need one to measure the existing shim thickness ( if the valve clearances need adjusting) in order to calculate the new shim required.

The feeler gauges should be a sliding fit with a steady resistance felt eg not sloppy but not tight either.

Be sure to set the piston at TDC with both valves closed (compression stroke) when checking, IIRC the twin cam has marks on the cam lobes to show this so easier than the earlier pushrod engine design.
 
Cheers us for a micrometer so ok there. It was mainly regards the feel to expect in the feeler gauges. Before when I used them it was difficult having never used them to work out it should be like if this makes sense.
 
You're looking for a light drag as you pull the feeler gauge through the gap. If the gap is larger than the gauge, there will be no drag at all - But if the gap is smaller than the gauge it will be apparent that it is "pinching" the blade as you pull on it. The shims (BMW call them "semispheres") are marked with their nominal thickness, but if you need to change one to get the correct clearance you should measure it anyway just in case it has worn a bit.
 
Ideal, is there a kit of shims available as i dont really want to have the head covers off for ages whilst i wait for some to arrive. Planning doing it when the bike is laid up at the worst part of the year xmas time.
 
TTBOMK BMW don't list a shim kit as such. The full range of sizes is 22 shims total, and you can buy them for £4.60 each from Motorworks. Bear in mind that, in theory at least, you might need several shims of one thickness, so you might need multiple sets...

But in practice, the specified clearances have a range of 0.1mm - as the shims are sized in 0.05mm steps, there will be at least two sizes that will be 'correct' for each valve. So you may find you only need to swap the existing shims around to get all eight within tolerance.

Also bear in mind that in normal circumstances, they don't go out of tolerance very often.
 
Just to add that if anyone is doing this job then our friend (cant recommend buying his DVD's enough) then Jim has created a spreadsheet to make determining which shim you require so much easier just either search google for 'r1200gs valve shim calculator' http://www.jimvonbaden.com/Links.html or check his link and scroll down then download the excel spreadsheet. What a good man he is and this helps a treat.

The only difficult thing is when you need to swap a shim from left head to right head so thankfully i have a few spares if needed or want a swap.
 
You can learn the feel for shims by setting the micrometer and then check the feel with a feeler gauge.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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