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Henry Martin spends his nights writing fiction and poetry, which predominately deals with the often-overlooked aspects of humanity. He is the author of three novels: Escaping Barcelona, Finding Eivissa, and Eluding Reality; a short story collection, Coffee, Cigarettes, and Murderous Thoughts; and a poetry collection, The Silence Before Dawn. His most recent published project is a collection of Photostories in five volumes under the KSHM Project umbrella, for which he collaborated with Australian photographer Karl Strand, combining one of a kind images with short stories and vignettes. He is currently working on his next novel narrated in two opposing points of view. He lives with his family in the Northeast.

Tuesday, March 12, 2013

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.
 Done.
 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. 

 

3 comments:

Unknown said...

Looks like you did a lot of work on it but it sure paid off. Handling a BMW motocycle surely isn't easy since it requires one to know the mechanics which is quite different from most bikes.
- Non-FerrousFastener.com

Dan said...

Sorry to bother you with a question on here, but you seem to know quite a bit. I've got an 05 dual spark f650. I just adjusted the valve clearance (ex was tight), but it still has trouble starting and runs poorly (stalls when I give it too much gas, or open full throttle). Do you know how to check for a burnt valve, and how to replace it if I do need to? Or know of links? I've searched the internet but can't seem to find out how to test/replace valves themselves. the F650 FAQ page is helpful, but I can't seem to find anything there. Thanks for any help you may be able to offer.
Fellow F650 fan,
Dan

Henry Martin said...

Dan,

Thanks for the vote of confidence, albeit I may not be much help after all.

Two things to try - a compression test and a leakdown test.

The compression test will let you know whether the cylinder has good compression, and whether it holds. If it drops, it is either going though the rings or the valves.

Leakdown, with valves closed, would let you know where there is a leak.

Let's assume that you can pump air/smoke into the cylinder at TDC with valves closed. If any of it is coming out from the exhaust, you have a valve that does not seat. Either burnt of not shimmed properly.

Valve replacement is not easy as you need spring compressor, new valve seals, lap the valve seat, et cetera.

The head would have to come off the bike.

See if you can do the test first, before you do anything.

Any car shop should have a compression tester, and a spark plug adapter so you can pump air in and see where it is coming from.

Hope this helps.

And yes, valves can easily burn at the 6k interval if they are too tight.