R1200GSW Cam Timing Adjustment
Wednesday, Jul 2 2014 [12,372 miles]
When I performed the 12K service last week I found out that the cam timing wasn’t correct on the left side. Today I had time to address that issue.
I put the bike on its center stand with the front end tied down to the lift. The rear wheel needs to be off the lift to bump the engine to top dead center. To remove the valve cover I have to loosen the Hepco & Becker crash bars. I can just squeeze the valve cover out between cylinder head and crash bar with the crash bars loosened at all three connection points (4 fasteners on the '13 GS).
The plug for the TDC tool needs to come off, too. With the tool installed I bumped the rear wheel until the pin in the tool engaged the flywheel with the left hand cams pointing out. I tried the alignment jig: yup, doesn’t fit. The timing isn’t off much, but why not make it right.
The left side is slightly different from the right by the addition of the cam position sensor and sensor trigger.
The sensor trigger must be removed from the exhaust cam. Once loosened the trigger can be turned to the orientation needed to fit between the two cam gears. The second picture, above, shows the alignment mark on the trigger. More on that later.
The cam chain tensioner comes out and a tensioner tool is inserted. The tool has an inner threaded and spring loaded plunger that is tightened a specified amount to put the appropriate tension on the cam chain. To adjust the timing the two 16mm screws that attach the cam gears to the camshafts are loosened so the cams can be rotated by hand. The position is right when the jig fits over the end of the cam.
All that needs to be done is re-tighten the two 16 mm screws. But there isn’t enough room for a socket. And of course I didn’t have a 16mm crows foot. I had several other sizes, but no 16mm. Off to the store. The first store didn’t have any. The second store only had a 10mm to 19mm set, no single items. Grumble. That was an expensive 16mm crows foot.
The dealer didn’t have any of the required crush rings for the cam chain tensioner. The needed size is commonly used in Porsches. A bag of 20 from a third party seller was cheaper than what the dealer would charge for a half a dozen.
The picture shows what the cams look like when the opposite side is at TDC. I thougth it was mildly interesting.
I discovered something interesting. After removing the cam tensioner tool and re-installing the normal cam chain tensioner the alignment jig didn’t quite fit. In stead of going on and off easily, I could get it about half way on before it started to bind. I swapped tensioner and tensioner tool a few times. The difference was repeatable. Apparently the tool puts more tension on the cam chain than a standard tensioner that isn’t pumped up with oil and that extra tension ever so slightly changes the timing.
After installing the cam chain tensioner the final time while the cylinder was still locked at TDC I re-installed the cam position trigger. There is a groove in the cam position sensor. The alignment mark on the trigger should match the lower edge of the groove. I forgot to take a picture of that in my hurry to get the bike back together. It looks pretty much the same as it came off – maybe a bit better aligned.
You may have noticed in the pictures that I never removed the inner valve cover gasket. There was no need. It never fell off. I installed the outer gasket and finessed the valve cover back in place. Everything was re-connected and torqued. Lastly I removed the TDC tool re-installed the plug. Time to start the bike.
The bike was slightly noisy for about 2-3 seconds then settled down to a fine idle. Riding impressions will have to wait for another day. I do not expect much change, if any at all. The bike was already running well.
Sunday, July 6 2014 [12,441 miles]
I tried to pay attention to the engine and engine vibrations during the morning ride to breakfast and back. The ride may be smoother… or not. It’s hard to tell as overall riding vibrations change with wind, road, tire condition, and possibly ambient temperatures. Added to the equation are my expectations. The bike is a big twin. I expect big twins to vibrate some. It doesn’t bother me. If it did I wouldn’t own big twins.
Acceleration: The engine is slightly smoother accelerating between 3,000 and 4,000 RPM than it is accelerating between 4,000 and 6,000 RPM. However, it’s lots more fun between 4,000 and 6,000 RPM in dynamic mode on back road twisties. Vibration is the last thing on my mind at those times. In any case it is not enough to cause concern. It’s also pretty much the same from 4,000 RPM until I decide to shift.
Constant speed: When maintaining constant freeway speeds I tend to keep it under 4700 RPM. I do that not because of vibration, but to reduce the chance of receiving a moving violation. From a vibration point of view the bike feels just right about 4600 RPM. Too bad that is beyond local speed limits.
Deceleration: The bike generates the most vibration with throttle off deceleration, i.e. engine braking into a turn. This is most noticeable at the throttle on to throttle off transition, but the vibrations are quite noticeable until the tach falls below about 3800 RPM. I don’t know how much of that is from the engine vs other sources.
My expectations were correct: not much of a change if any at all.