Accurate 'phasing' of left/right cams to crankshaft (R259 platform)

[jozefschumann]

Hello.

This is my first post on this forum, so here goes. As per title:

Over the decades the opportunity to sample many derivatives of the venerable 259, i.e. R1100S, 1150 , RT, GS, etc. - have led me to conclude some, within the same model range, primarilly R11S, exhibit superior all around performance to their identically equipped counterpart. This being the case regardless of mileage, exhaust, tire diameter, etc. add on fueling dupers, proms, rocket sprockets, etc. Personally, I feel tolerance stacking is the denominator - (all, or most tolerances are favourably closer to one another in the acceptable +/- specification). Particularly, in reference to camshaft timing.  This, I empirically determined by fitting a degree wheel to the crankshaft as well as individual dial indicators to both banks thereby validating timing events. Of course, I also eliminated cam chain slack from the equation by appropriately modifying both tensioners to manual duty.

 

I have scoured all possible sources in search of any corroborating findings only to come across one - posted many years ago by an mechanically competent owner who machined aluminum cam sprocket carriers allowing adjustment. His result was favourable in every opertaional dynamic save for one. Vibration or a frequency oscillation. This dynamic being exacerabted by an out of balance rotational mass hanging a considerable distance from the motors centerline is unedrstandable and expected. This, then gave me reason to pause as I was curious about the factory or privateer campaigned bikes back in  the day. I briefly spoke with Chris Hodgson (SJ BMW) who agreed this is a fundamental flaw and issue with the platform though did not elaborate further than verfying my mechanical musings.

 

My interest being piqued, and coupled to opinions from reputable sources, I have conceptually devised a very plausible, fundemental fix to this issue which addresses the as per factory engineered compromise.

 

Being this platform is now quite long in the tooth. I am reaching out in hopes somebody, somewhere, has also tinkered with this un-BMW-like production malady. I eagerly await await you collective comments.

 

regards,

J.S. 

[dirtrider]

47 minutes ago, jozefschumann said:

Hello.

This is my first post on this forum, so here goes. As per title:

Over the decades the opportunity to sample many derivatives of the venerable 259, i.e. R1100S, 1150 , RT, GS, etc. - have led me to conclude some, within the same model range, primarilly R11S, exhibit superior all around performance to their identically equipped counterpart. This being the case regardless of mileage, exhaust, tire diameter, etc. add on fueling dupers, proms, rocket sprockets, etc. Personally, I feel tolerance stacking is the denominator - (all, or most tolerances are favourably closer to one another in the acceptable +/- specification). Particularly, in reference to camshaft timing.  This, I empirically determined by fitting a degree wheel to the crankshaft as well as individual dial indicators to both banks thereby validating timing events. Of course, I also eliminated cam chain slack from the equation by appropriately modifying both tensioners to manual duty.

 

I have scoured all possible sources in search of any corroborating findings only to come across one - posted many years ago by an mechanically competent owner who machined aluminum cam sprocket carriers allowing adjustment. His result was favourable in every opertaional dynamic save for one. Vibration or a frequency oscillation. This dynamic being exacerabted by an out of balance rotational mass hanging a considerable distance from the motors centerline is unedrstandable and expected. This, then gave me reason to pause as I was curious about the factory or privateer campaigned bikes back in  the day. I briefly spoke with Chris Hodgson (SJ BMW) who agreed this is a fundamental flaw and issue with the platform though did not elaborate further than verfying my mechanical musings.

 

My interest being piqued, and coupled to opinions from reputable sources, I have conceptually devised a very plausible, fundemental fix to this issue which addresses the as per factory engineered compromise.

 

Being this platform is now quite long in the tooth. I am reaching out in hopes somebody, somewhere, has also tinkered with this un-BMW-like production malady. I eagerly await await you collective comments.

 

regards,

J.S. 

Afternoon J.S.

 

It has been years since I looked at BMW 1100/1150 cam phasing, way back I did check a couple of 1100 engines to see how close they were side to side (both low mileage engines). Neither were off far enough to be much of  a problem. 

 

I have installed Lennies sprockets on a few 1100 bikes years ago, that made a difference in the midrange feel but I kind of lost interest when the 1150 Ma 2.4 systems came out as those had  better midrange power right from the factory. 

 

With the 1100 & 1150 being sort of  outdated now I can't see much market for any type of commercial cam phasing devices due to expense, checking/setup time & tools,  plus probably not much market for that type of device. 

 

Probably on an individual level anybody that really wants to tweak their cams to be exact (I can't imagine a lot of gain for the work involved)  it is as easy as determining the cam phasing difference, then determining what side you want to use as the correct side (ie do you want to use the most advanced cam or the most retarded cam?). Then a little grinding on the other side cam sprocket alignment key to get the correct cam phasing, then a little TIG welding on the other side of that cam sprocket key to regain the key width  back & preserve the phasing position. 

 

Most 1100/1150 riders that want a little more from their engine will probably not want to  mess with cam phasing just to gain a little,  probably something they probably won't even feel. 

 

On the 1100/1150 my guess is that adding an XiED Fuel Enrichment device & going to better (later design) fuel injectors will do way more for performance than a long (difficult for most) cam re-timing ordeal.