R1250GS Valve Clearance Check

R1250GS VALVE CLEARANCE CHECK PROCEDURE
Note:
This procedure was written for the author for his own service notes and general interest. It should not be relied upon as being factually correct. When performing DIY maintenance, it is essential to follow manufacturer service manuals and guidance.
1. Remove Coil Cover
a. 1 x T25 (5Nm)
2. Disconnect Coil & Removed Spark Plug
a. Unclip electrical Connector from Coil
b. Slide Coil electrical supply cable from Rubber Grommet
c. Remove Coil (Specialist Tool)
d. Remove Spark Plug (14mm) & (12Nm)
3. Remove Rocker Box Cover
a. 3 x T50 (10Nm)
b. Tray to Catch Oil (~ 200mil)
c. Remove Gasket and inspect (No need to replace if OK)
d. Remove and inspect the Spark Plug Gasket (No need to replace if OK)
4. Remove Top Dead Centre (TDC) Inspection Bolt
a. 1 x T50 (New Washer Required) - (30Nm)
b. Washer: Int diameter ~ 16.5mm, Ext diameter ~ 22mm
5. Acquire TDC Alignment
a. TDC Check 1 (8mm notch appears concentrically, in the middle of the inspection Hole)
b. TDC Check 2 {The Cam end should be positioned with L & R vertical sides & labelling at bottom}
c. TDC Check 3 (Piston all the up at TDC. I use an old chop stick to pop in as additional check)
6. Select 6th Gear and use wheel to rotate CCW to turn Engine
a. It’s possible to gently rock the rear wheel gently CCW (normal travel direction) whilst observing the TDC Inspection Hole
7. Measure Valve Clearance (Always with COLD Engine)
a. 4 Valves in each cylinder (2 Inlet Valves & 2 Exhaust Valves)
b. INLET Valve Clearance: 0.10mm to 0.17mm
c. EXHAUST Valve Clearance: 0.34mm to 0.41mm
d. Be careful of sticking feeler blades!
e. You want a nice drag with two fingers pushing/pulling on the feeler gauge.
f. Measure each of the four clearances and record on work sheet
8. Measure & Replace (if necessary) Valve Shims
a. Remove Black Solenoid
i. 3 x T30 (10Nm)
ii. Unclip electrical supply cable (same mechanism type as Coil)
b. Remove Axial Fixation Pin (looks like a C clamp) - 2 x T30 (10Nm)
c. Mark (paint dots) selected cog teeth for post re-installation (wipe clean first)
d. Remove Cast Bracket - 10 x T30 (10Nm)
e. Remove, inspect and replace the rubber spark plug seal.
9. Measure Valve Shims
a. Each Shim is partially held in place by the black follower arm. The Inlet ones are hinged at the top. The Exhaust ones are hinged at the bottom and fall back when the cast bracket is removed.
b. Using a magnetic tool, remove each shim and measure and replace until the new shim is inserted.
c. When inserting a new shim, apply a film of oil to both sides.
10. Calculate new required shim
a. Use a good quality micrometer
b. The Valve Clearance and the Shim Thickness are in Series. So, if the clearance is too large, the shim thickness needs to increase and vice versa.
c. New Shim Thickness = Current Shim Thickness + Current Clearance - Target Clearance
d. Example: 2.16mm+0.40mm-0.34mm = 2.22mm (From one of my Exhaust measurements)
e. You will probably have to nudge slight up or down for your new shim size. This is because the shims are normally only available in multiples of 0.02mm
11. Move to the other Cylinder
a. Prior to moving to the other cylinder, complete the one you’re working on. Its absolutely necessary to fit the new shims, replace the cast bracket, axial fixation pin and solenoid and torque up (slowly and evenly).
12. Re-Installation (Reverse order with special attention to)
a. Lubricate the exposed components with a small brush (shim holders, cam lopes, cam chain etc)
b. Refit the cams locating the teeth with the ID paint dots and carefully hold both whilst fitting the cast bracket. (make sure the 2 black exhaust followers are swung back up first and the black rubber spark plug seal is fitted)
c. Remember all the bolts are 10Nm. Don’t over torque.
d. When fitting the Rocker Box Cover, check the spark plug gasket is fitted
e. Don’t forget to fit the rubber pad at the bottom. Fits into a square recess and hinges on each side.
f. 10Nm for the bolts. Don’t over torque.
g. Insert Spark Plugs and reconnect Ignition Coils.
h. Each cylinder will lose approximately 200mil of oil. So, add 300-400 mil of new oil prior to restarting engine.
i. Start Engine, let idle for a while whilst checking.

[@marcelodc8801]

Very good. It help me a lot. Thanks.

[@CLLUK]

Update: 24/01/2024. Since resetting the Exhaust Valves, the starting is still not completely normal. Sometimes it starts okay, sometimes not. So, I decided to open up again and look at the Auto Decompressions Mechanisms which are positioned next to the Exhaust Valve (Front) on both cylinders. (I should of done this the first time!) The Auto Decompression Mechanism only operates on the Front Exhaust Valve.
Comparing both sides, it was clear that the RHS was OK and the LHS defective. This just flops around and doesn't return to the 'Start' position (ie, with the rounded profile protruding slightly above the cam lobe surface. So, this is indeed Good News and makes sense why sometimes starting is OK and others not so. I now need to look into a change out.
I will upload a video on what I found later today or tomorrow.

[@MrCruiser666]

Great instructions for the clearance check, thank You!
But the adjustment needed :
1: Timing Chain Tensioner Assembly - BMW part # 83300444292; (tension for chain like in working mode)
2: Cam Alignment Jig - BMW part # 83302467268 (OK, you marked the gears, but the shaft alignment is also adjustable - right side 65 Nm )
I wonder how can you fix the decompressor!
btw. I have the same starting issues. 2021-1250GS 27000km for a few months
My bike has warranty, but I read everywhere dealers can't solve this problem.

[@CLLUK]

Thanks. Waiting for the replacement cam shaft and specialist tools. Will need to redo valve clearances checks of course and also cam alignment. I hope to start when everything is here ( ~ 2 weeks )
Will upload another video with all the information. Looks like you've been doing your own research too! 👍
I would love to know why it failed in the first place?

[@CLLUK]

Forgot to mention. The auto decompressor is integral to the exhaust cam shaft :( It comes as one part ( auto decompressor and cam shaft.) Minus the Gear Wheel and reluctor which I have to remove from the defective cam shaft and fit onto the new one. Yes, you're spot on 65Nm for the 16mm hex bots at the end and 8Nm for the Reluctor ( That's what BMW call it - the plastic composition component at the end and is part of the positional feedback system to the ECU. )

[@yetiiti7631]

Thank you for the movie, the procedure was nicely and succinctly presented. I don't entirely understand the purpose of this tool "Cam Alignment Jig" - is it used to set the cams before checking valve clearances, or is it for setting during basket assembly? Or other purpose? Thanks in advance for clarifying.

[@CLLUK]

Thanks. The purpose of the Jig as I understand it is to lock the inlet and exhaust cams in their correct position at TDC whilst tightening up the end bolts to their correct torque. You raised a good point. I think it makes sense to do the cam alignment (that's if it need doing) prior to doing the valve checks/adjustment.

[@wacksalad3110]

How did it go then ? This is a big issue. I think it would be great to hear how you got on. Very much appreciated.

[@CLLUK]

Hi, yes, I think you're absolutely right. I was really sure that the Auto Decompression Mechanism was defective on the LHS. Now, after comparing in more detail with the RHS and others I don't think it is. I still need to complete a few further checks. What I see, though, is that the cam alignment looks out. So I shall be very soon carrying out a Cam Alignment. I've got the specialist tools for this apart from the "Cam Chain Alignment Tool" which after days of searching seems impossible to obtain. ( I did find a German retailer and ordered it, but the next day they informed me it was discontinued and refunded me :(
But, good news is that I will hopefully have one on loan soon from the BMW Motor Club UK ( Southern Section )
So I will then do the Cam Alignment and put everything back together again and fingers crossed, test and ride.
So, regardless what happens, I will upload a video on this bmw auto decompressor as it's different from what I am used to on other non bmw bikes. The 2nd video will be on the CAM Alignment procedure. I'm just hoping after all this, it resolved this starting issue. If it does, then it will be two things I've done. (1) Adjust valve clearances. (2) Adjust Cam Alignment. If it doesn't, then back to the drawing board.