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Old 03-12-2013, 08:38 PM   #1
henrymartin OP
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Joined: Sep 2010
Location: South of the Great North Woods
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BMW 650 GS single valve check (step by step)

Mods, there are too many threads for bikes with this engine, so I figured this would be a good place to post. Feel free to move it if necessary.

G650GS (F650GS single) valve check

This is one of those maintenance items that has to be done, yet, for some strange reason, I've been really dreading to do it. Normally, I do all my engine work on my bikes, but I've been reluctant to dive into the BMW. Why? I'm not sure. After all, it is a machine and like all machines it can be serviced. So, here I was at 12k miles, thinking about paying the dealer $300 for valve check and whatnot, and then I decided to do it myself.
At first look, the layout of the BMW is a little intimidating, I'll admit that. Unlike all my previous bikes, this one has way too many electronic gizmos, hoses, tubes, and things are rather inaccessible. So, I took my time and started slowly, taking pics along the way. This will be a two-post series dealing with valve check on a BMW 650GS single cylinder, two spark motor. IIRC, this is the same for 04-07 F650GS and 09 G650GS, along with a few other models using the same motor.

First step in doing almost anything maintenance related on this bike is to remove the plastic covers. A few torx bolts and it's done, so there is no need for pics.

Next, remove the oil tank by unscrewing one Torx bolt and removing two clips. At the same time, remove air intake snorkel. The snorkel has a clipped in temp sensor (leave it in place or remove, the choice is yours), and the oil tank has a couple of hoses going in. I prefer not to disconnect any hoses I don't have to, so I left everything hanging off the side.

Remove the battery and then remove the two large bolts that hold the air intake in place. Once removed, gently pull the entire unit upwards so it pops off the throttle body. There are hoses attached, so just move it to the side and let it hang on the hoses.
Next, disconnect the throttle cable from the throttle body. You will remove it completely later on. There are two possible locations for the cable, so I marked the right one with a marker.
Next, remove the battery tray (two torx bolts) and slide it away.

Then you'll have to remove the throttle cable completely in order to remove the plastic shield that is in front of the frame.
Once gone, you can see most of the vale cover.
Disconnect the coolant overflow reservoir (one torx) and slide it outwards. I hung mine off the handlebars with a ziptie.
Cover your throttle body (a nitrile glove works rather well). Then disconnect two hoses (lower one is just pushed on, upper has a hose clamp) and three electric connectors. Unscrew two torx bolts on the manifold, and lift the throttle body off the bike.
Now you have complete access to the valve cover. All that is left is to remove the two spark plugs. Each one has a specific coil, so mark which one goes where, if you are not sure that you'll remember.
Next, grab your 10mm socket and some extensions, and undo the valve cover bolts. I like to put the same bolts to the holes they came from, so I marked the heads with a sharpie, and marked the corresponding numbers on a piece of masking tape. This way, if a thread was slightly damaged or a bolt was bent by someone in the past, the same bolt will go in the same place, minimizing future damage. (dealt with that a lot on old bikes)

Voila, ready for checkup.
I'll handle valve checking and reassembly next time.
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Old 03-12-2013, 09:34 PM   #2
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Thanks for taking the time to do this.
I've paid the dealer for two valve checks now and each time they were fine.
I'd like to do the next one myself and will be following along.
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Old 03-13-2013, 06:30 AM   #3
henrymartin OP
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Originally Posted by guavadude View Post
Thanks for taking the time to do this.
I've paid the dealer for two valve checks now and each time they were fine.
I'd like to do the next one myself and will be following along.
That's the idea. I paid for one, the 6k service, and almost paid for the 12k. Then I talked to a buddy about it, and he questioned why I didn't do it myself. Heck, I rebuilt motors before, but the BMW made me have some doubts. Anyway, I bought the CD manual just to have the right torque specs.
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Old 03-13-2013, 07:24 PM   #4
henrymartin OP
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Valve check, part II

This is just a short post. Easy...easy...

Part II of valve check, which is just how to check the valve clearance.

You'll need feeler gauges, patience, and decent light source.

Once you have the valve cover off, rotate the crank so you have the piston in TDC (Top dead center). There are two ways to do this. One way is to remove a plastic plug in side cover and use a large allen wrench. Some models have the plastic plug. Mine, for some reason does not. (First bike I own that doesn't). So, option number two is to kick it in a gear (I went with 4th) and rock the rear wheel in the direction of travel (NEVER otherwise) until your piston reaches TDC. You'll have to remove at least one spark plug to be able to move the piston, otherwise you'd be fighting compression. You'll know that you reached TDC when the valves compress and release, and your camshaft sprocket marks line up. There are four marks, two on each sprocket. It's kinda hard to get the camera in there, but here is the best pic I could get. The marks have to be in line and parallel to the cylinder head. This pics is only for illustration purposes. The bores in the sprockets have to point up.

BMW calls for a special bolt to lock the crank at TDC, but being in gear, I did not feel this was necessary for checking the valves. If I were replacing shims, it would make me feel better to have the crank locked.

Next grab your feeler gauges. You'll need metric feelers. The range spec calls for 0.25-0.33mm on exhaust, and 0.03-0.11mm on intake. THESE SPECS ARE FOR THE TWINSPARK, SINGLE CYLINDER. Try the thickest feeler first, and go down from that until one slides in freely, with a little drag, but no binding.
Gauges insert easily from the inside, like this:

My valve clearances at 12k measured:
Exhaust: Left 0.28mm and Right 0.30mm
Intake: Left 0.06mm and Right 0.08mm

This is well within spec, so I'm leaving it alone.

Now I just have to put everything back together, pop in some new sparkplugs, change the oil, and be set for the next few thousand miles.

I will probably do a post on reassembly, with torque specs.
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Old 03-15-2013, 03:37 AM   #5
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Thanks for sharing!
Diego, a proud 650GS single rida...
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Old 03-15-2013, 08:03 PM   #6
henrymartin OP
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Before I begin with reassembly, this is the CORRECT sprocket position when piston is at TDC. You want your sprockets to look like this when you check your valves - note the marks parallel to head, and the bore in sprockets on top.


After you clean your valve cover gasket and valve cover, slide the gasket into the slot in valve cover, put a little bit of oil over the seating area, and hold it in place with your fingers as you maneuver the cover back in place. Once there, reinstall your valve cover bolts. Make sure the gasket on the bolts and the seating area are clean. These bolts are torqued to 10nM. I use crisscross pattern when tightening, but I hand-tight all bolts first to prevent gasket from twisting.

Next, install you sparkplug coil leads. Note that there are two different leads, each one with its own voltage. Put them exactly where they came from. I marked mine, just in case I forget. Push on it until it snaps in place.

Next, install your air box stubble. I call it throttle body, but hey, whatever it is. Again, clean, put a little oil on the gasket (manifold) and insert the two torx bolts that fasten it in place. Just start the bolts, don't tighten them. With a pair of pliers (unless you have small enough hands to get in there), slide the hose on the chrome-plated pipe. No clamp goes on this one.

Next, insert the connector pictured here. Do it first, before you attach the fuel line. If you don't, you will have to take it apart again (don't ask me how I know). With the connector in place, slide the fuel line on and push it in place as you press the whole unit down. The hose will seat, and you can now hand-tighten the two bolts. These are torqued at 25nM.
Make sure you reinstall and tighten the hose clamp on the fuel line. This is a pressurized line, so it is important. Next, connect the other two electrical connectors, insert your heat shield routing the throttle cable through the hole in it, install you battery tray, and your airbox. The rest is easy.

A note: I found some oil/gas residue on the stubble, right where the rubber manifold attaches. This was due to a loose hose clamp, allowing the engine to "breathe" in the wrong spot. I took the rubber part off, cleaned everything, and reassembled.

Also, while I was doing the valves, I changed my spark plugs. It's much easier to do when the bike is apart. Mine were still good, but last year I swamped my bike, so this was something I wanted to do anyway. Sparkplugs are easy to do, but if you are really into torque specs, the recommended one is 20nM.

If I left anything out, PM me.
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Old 03-17-2013, 04:43 PM   #7
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Great information.. Keep at it..
12' BMW Sertao For everything
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Old 03-17-2013, 06:42 PM   #8
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you just helped about 1 million people learn something important (including myself).

many thanks sir!
Enduro Earth

off the grid and deep in the woods
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Old 03-21-2014, 09:48 PM   #9
Joined: Jul 2013
Location: Truckee-Tahoe Int.
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Thanks so much for documenting the process and posting it up! I just did my first valve check on my Sertao and appreciated the bejesus out of your blog write up and the guesswork it took out of the picture.

Originally Posted by swamp View Post
you just helped about 1 million people learn something important (including myself).

many thanks sir!
and also that.

Cheers guy!
BMW 650gs- A bike named Douglas.
The Fool's Progress: Onward-Upwards-Global on a 650gs
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