F650 Valve Adjustment

The BMW F650 has one cylinder with four valves and solid (non-hydraulic) lifters, two exhaust valves in the front and two intake in the rear. The clearance between the cam and the lifter is supposed to be .004″ to .006″ for all four valves with the engine cold.

On my bike the left intake was .003″ and the right exhaust was .007″ and the others .005″ and it has been that way ever since the bike had a few thousand miles on it. Now with 15K miles, I decided it was time to try adjusting them.

Checking the clearance involves removing body panels, the fuel tank, the valve cover and then positioning the engine rotation properly, and then slipping feeler gauges between the cams and the lifters. The Clymer manual covers it well, and the process is straightforward, but it is still a lot of work. Adjusting the clearance is much worse because you have to remove the overhead cams, remove the adjustment shims on the offending valves, measure them and compute what they should be, order new ones and wait for them to come in, and then reassemble everything.

The shims are about 1.125″ in diameter and come in various thicknesses in .002″ increments. They sit in a little recess in the top of the lifter, which is shaped like an inverted cup. BMW uses the metric system but my 1″ micrometer is in .001″ increments, so I had to convert to millimeters. Incidentally, it’s easy to interpolate between marks to a precision of .0005″, and that’s what I did.

The old shims were not worn and still had the original thickness.

The exhaust valve with the loose .007″ clearance measured .0985″ (2.50mm). I reasoned that I needed a thicker shim to make the clearance less so I ordered a 2.55mm shim from BMW. (.05 mm is .002″ and .002″ thicker would theoretically give me the desired .005″ clearance.)

The intake valve with the tight .003″ clearance measured .0945″ (2.4mm). I needed a .002″ thinner shim to get the .005″ clearance, so I ordered a 2.35mm shim.

I’m a “shade tree” mechanic, so I covered the open top end of the engine with a clean plastic bag and then put the tarp over the bike and waited about three days for the new shims to come in. I reassembled everything using a torque wrench, some Loctite 235 on the internal bolts and a slathering of oil on sliding surfaces, rotated the engine a few times and checked the clearance. It was .005″ on all four valves!

The two main difficulties I encountered were one, deciding not to be daunted by it and two, adding and subtracting appropriately with confidence. Maybe I should have been daunted.

The good news is the valve clearance seems to not change at all once the engine has been run in those first few thousand miles. I think it’s better to have a system that is hard to adjust but stays adjusted rather than one you have to keep adjusting all the time.

Notes:

You have to remove a spark plug in order to easily spin the engine into position, and I used my pressure washer with the 15 degree nozzle to blow the dirt out from around the base of the plugs so it wouldn’t wind up in the cylinder. But after removing the tank, I noticed there was some grit sitting on the frame and the spark plug wires. I had already put the washer away so I left the grit there, but it was sitting right above the valve cover and could have dropped into the cam area. I was careful, but I should have taken the time to clean off all the dirt above the area where the engine would be wide open. At least I covered it while waiting for the parts to come in.

Coincidentally, when I was on my way to Stowe, Vermont I stopped in Barre to check my navigation on the iPhone. A guy walked up to me and struck up a conversation about the bike. He had worked on them and knew all about adjusting the valves on an F650 and other makes as well. He said they would often leave them alone if they were only .001″ out of spec. I prefer to feel righteous about having my valves dead on spec rather than stupid at having wasted a lot of time and effort. But my instincts were right in taking my time before actually getting into the cam tear-down scenario.

A valve that is .001″ out of spec allows you to buy a shim that is .002″ different and bring the clearance right to the middle of the .004″-.006″ tolerance. I think that is the exact scenario it was designed to handle, given the spec and that the shims come in .002″ increments. And…if you are checking the clearances every 6000 miles, like you are supposed to, and at some point make the adjustment like I did, I doubt you will ever see anything more than the .001″.

Stowe, Vermont

If you are going to Stowe to attend a wedding, I recommend riding your motorcycle. I took the occasion to do just that and try out my new Saddlemen TS3200 rear bag.  I had recently adjusted the valves, changed the coolant and put in the 20W50 summer weight oil. The bike was loaded and I ran 32 psi in the front tire and 34 in the rear.

Saddlemen TS3200 bag with the bike rain cover on top of it.

The bag sits on the passenger seat and just clears my back. I can lean back onto it or not. Pretty much ideal in that respect. I have to help my leg bend enough to clear it when getting on and off. I can still open the top box enough to get at the contents pretty well. The bag hangs down over the sides of the seat, but is still well above the exhaust, and it sits just in front of the rear directional lights. It’s held securely with quick-disconnect straps, sort of pulled back against the top box, conforming to the shape of the available space.

The bike is more top heavy when loaded this way but it handles fine once you get rolling.

I was headed to the Field Guide Inn there and got Google Maps to cook up this 123 mile “back roads” route through the mountains northwest of Plymouth, NH and into Vermont. It was a sunny, 70 degree day. Perfect. I wore my Revit Wind summer weight armored jacket my wife recently bought me. Very comfortable all the way up.

Bridge over the Connecticut River between Piermont, NH and Bradford, VT

The roads typically follow small rivers flowing towards the big Connecticut River and I leaned into a lot of curves on the way to Stowe.

I arrived at almost the same time as my wife, who prefers her Infiniti G37X over anything with only two wheels.

The newlyweds

In addition to a great wedding, great food and company, we enjoyed hiking in the area, visiting Moss Pond Waterfall and Bingham Falls in Smuggler’s Notch.

Moss Pond Falls – about 60 feet top to bottom

Stowe is a wonderful place to spend some relaxing time.

On the way home, though, the iPhone radar was showing rain approaching from the west. It was 42 degrees. I layered up and wore the Sedici three-season jacket that I had squirreled away in the TS3200. Also the down mittens with wool liners. Got on I 89 for the short run from Waterbury down to Barre, but the bike felt so good with little wind that I decided to cover some quick miles by staying on the interstate down to New London and then taking NH Route 11 east. I was comfortable running 65-75 mph with an occasional unintended streak near 80 mph. The bike always runs silky smooth in 5th gear and the torque peaks by design at 70-75. I only passed a few vehicles because I was mostly just keeping up with traffic in the right lane.

Stopped for gas and then again for a quick snack. Pulled into the driveway just ahead of some heavy rain. I love radar!

2012 G650GS

I enjoyed taking a spin on a 2012 BMW G650GS, essentially the latest and final version of the F650 line that started back in the early nineties. My own bike is a 1997 F650.

The engine is pretty much the same with the notable exception of fuel injection. I looked for the enrichment lever to start the bike and didn’t find one. Give it a little gas, press the start button and it fires right up!

It has the same characteristic big-single vibration in the 4000-4300 rpm range although a bit more subdued. Nothing in the bars, a little in the pegs, nothing in the seat. I think it has slightly more power in the 3000-5000 rpm range. I rarely use anything higher than that.

The sound is different with more of a growl. The exhaust pipe feeds into what appears to be dual mufflers, but they are connected in series and the exhaust exits from the one on the right.

The geometry and dimensions of the G are identical to the old F, but it felt a bit more nimble, maybe because the fuel tank is under the seat. Or maybe the rear tire had less of a worn flat center section than my Metzler Tourance tires with almost 8000 miles on them.

The suspension is identical as far as I can tell and, by the way, having gotten used to 6.5 inches of travel front and rear, I don’t think I would be happy with the couple inches you typically get on something like a Sportster.

The gnarly headlight works for me and I like the idea of running tubeless tires on the cast rims. It was a cool day and I enjoyed the luxury of heated grips.

Overall, the G has that contemporary BMW feel of substance. It’s a great bike and could last a lifetime with the remarkable support BMW has for older bikes. But this one is essentially brand new with less than 6000 miles on it.

The G650GS got me to the local SlashBurger restaurant very nicely, but I felt like riding it further.  Say, to Deadhorse, Alaska.

A borrowed 2012 BMW G650GS and Bell helmet and my new Sedici jacket