The method of turning the engine over on these bikes - via the valvegear - is rather odd because it is opposite to what happens when the engine is actually running and doing it this way will potentially move any slack in the camchain to the top run/un-tensioned side....
Normally the crankshaft `pulls` the camshafts round by the camchain (keeping the top run tight) but the factory way of setting the camshaft timing `pulls` the crankshaft round via the valvegear putting all the load on the bottom run including the tensioner blade..
I suppose it has to be done this way as there is no facility built in to turn the crankshaft directly.
As you have noted it could be possible for the top run of the camchain to have some slack imparted in it (affecting cam timing) and i expect the special tool is primarily to ensure any slack is taken up on the bottom run ensuring the top run is tight.
I was aware of this possibility when i did my 1250 timing earlier this year but the reality was that there was no additional slack in the top run and a moderate pull on the turning tool in the opposite direction (once the engine was locked) to ensure it was tight resulted in no movement.
I didn`t use the tensioning setting tool when doing the cam timing as - if i have read it correctly - there is no requirement to do so when checking valve clearances or camshaft timing according to the factory manual.
The only times the tensioning setting tool is mentioned is when the camshafts are to be removed or for when adjusting valve gap when a new shim is required.
Did you get a copy of the factory manual, what is your interpretation?
Hi,
thanks for your very interesting reply. I thought I was out on a limb somewhat but was convinced I had it clear in my head. You very obviously thought it through too.
I haven't yet done the job and so my understanding is based largely through watching videos and reading various manuals etc in order to work out what is going on.
I had realised that cranking the engine via the cam gear effectively loads everything in reverse and potentially exerts significant forces on the tensioner blade which it isn't designed to take. For this reason, I had already decided that I would most likely remove both spark plugs, engage top gear and simply bump the engine around until the TDC lock engaged - either it works or it doesn't.
My confusion stemmed from the fact that BoxFlyer has always maintained it is important the tensioner tool exerts a precise amount of force on the camchain but at the same time, I believe his tool is spring-loaded and free to compress when subjected to additional force; I can see how this could theoretically result in potential errors, as mentioned above.
I am a little confused by your last paragraph . . . .
1. I can't see any reason why there would be a need to use the chain tensioner tool and/or reset the timing when adjusting valve clearances - I may be wrong of course. . . . . .
The valve timing is surely a function of the relationship between the various driven gears and the crankshaft - this will only change if either of the cam gearwheels are altered via their securing bolts or if the camchain/guide wears significantly? After shim replacement it is clearly a prerequisite to return both cam gears to the same position as prior to removal and this can be checked either by marking the gears to ensure the same teeth mesh as before or by ensuring the flat base on the end of each cam is parallel with the top of the cylinder head.
The OEM manuals were never basic PDF manuals and indeed, I possess one for the 2017 R1200R. It is a very sophisticated piece of software that takes account of the build status of each individual bike, either by entering the VIN into the software or by selecting the various optional extras or accessories fitted so the manual is tailored to the bike. Thereafter, you enter the bikes first registration, date and mileage of last service, today's date and mileage and the manual generates a schedule with every required service item listed. You merely click on each one and it takes you to the relevant section in the manual. All the preparatory work required is hyperlinked and it is just a superb piece of software BUT . . . . BMW won't play ball with us any longer
Whilst 90% of my OEM Manual is still relevant, there is a certain amount which is out of date and in particular, the introduction of the shift cam and for that, I am relying on a PDF for the 1250R which I purchased off eBay - it's better than nothing but only just.
It seems evident that somewhere along the line, someone with access to the OEM interactive software , has used this to compile a pdf manual but nothing is hyperlinked and there are significant sections where information is simply missing.
For example . . . you state "the only times the tensioning setting tool is mentioned is when the chamshafts are to be removed for for when adjusting valve gam when a new shim is required." . . . . this is because the sections which do mention it, along with all the preparatory work have been omitted by the person who compiled the PDF.
It would seem that a number of manuals were created in this way and then subsequently sold on by any number of folks on eBay who having acquired a manual for themselves were then looking to make a quick buck. I wouldn't mind betting that all the manuals available on eBay are fundamentally the same. Indeed, one kind gentleman on the 1250R forum forwarded me his manual and whilst it had been slightly altered, it was in essence the same pdf document that I already had.
Anyway . . .my interpretation -
The engine tdc lock tool and chain tensioner tool are theoretically required when adjusting the cam timing but I think the latter is to all intents and purposes redundant. My suspicion is that it would be more than acceptable to lock the engine at tdc, loosen off both cam bolts and attach the alignment jigs and then retighten both cam bolts while having someone apply a rotational force onto the intermediate gearwheel in order to keep the upper chain run under tension whilst the bolts are tightened. . . Whatever is going on in the lower run and whether or not the factory tensioner tool is used matters not one jot - just my thoughts.
For checking valve clearances, rotate engine until it is at tdc, confirmed by the crank locking tool but again, no requirement to use alignment jigs or tensioner tools at all
For changing shims, both cams need to be removed and so I would expect the engine to be locked at tdc, the various ancilliaries removed such as the shiftcam solenoid, axial fixation bracket etc before removing the cam caps and simply lifting out the camshafts. Again and as far as I can see, no need to use jigs or tensioner tool if only the clearances are being adjusted but clearly vital to return cams to the same relationship with their driven gears.
For now at least, I'm just hoping that someone releases the interactive software so that we have all the information we need to work on our bikes. It seems that BMW are just choosing to alienate their customer base :-(
