Remove o2 sensor or pull the muffler right off and go for a ride. You will know in 50 feet.
Thanks for the idea. I checked the exhaust prior to taking it to the dealer and tried riding with O2 sensors removed, no difference.
Flat might not be the best way to describe. At 3K under full load it coughs and splutters, almost like its going to stall its actually quite violent. The only way to stop it is go back to 10-20% throttle and it smooths until over 4K but its a similar story from 4 upto the limiter albeit less violent as the speed smooths out the coughing.
Sounds to me like someone is confused by the difference between cam timing and ignition timing with no proof cam timing has been ruled out or in..
What exactly did he change or inspect to get cam timing correct if it was in fact off?
There is no such thing as mysterious machine behavior in the hands of competent mechanics and diagnosticians- a thing few are good at in this day where parts swapping substitutes for understanding and the limits of the factory-provided diagnostic tool are all the so called techs can manage...
You are unlikely to get an answer with the shotgun approach and lack of detail in your responses in this thread and will need to record more specifics if you hope to get to an accurate answer here. If you are unable to deal at that level of detail yourself, your best bet is to hunt up the most technically respected BMW mechanic within a few hundred miles of you and take the bike to him- your current dealership obviously lacks needed skill or is restricted by instructions/limitations you've placed on them.
Cam timing has been ruled out as the cause. The tech stated the camshaft sproket was not correct and adjusted it.
At present they are just going through changing not random but possible parts they think it might relate to. Next will be fuel pump and O2 sensors.
I have asked if they can jack the bike up, strap it down and go though the gears accelerating. Service department think this won't work [but will ask the Tech] as they assume there will be insufficient load to generate the problem. I did wonder if transmission resistance might be enough to cause the problem. If they can't or won't do this will suggest they try the above but instead of jacking it up put it on their brake tester and do the same [I am not sure however if the BMW computer can data log in real time]. I have asked if they use a GS911 and could connect to the bike and then ride but they don't have one.
I have no other experience of dealer within say 200 miles but I am certain if I did take to another dealer they would go through the same process thus far hence I would be no further forward.
Dealer called today having tried O2 sensors and fuel pump regulator, still the same. They are now at a loss and cannot come up with anything else.
Can anyone suggest anything the dealer might not have tried?
All your problems seem to be only under heavy load which is when a coil or spark plug would fail.
Need to see the bike. Stop by my shop
Would love to drop by! Which highway runs from Kent to NY?
The dealer has assured me its none of those things although I guess it must be. I wonder if its the signal to the coil under load which they would have no way of measuring. There next suggestion I am sure is going to be the ECU. They state the straightforward things which can be checked such as cam and igntiion timing are correct. No issues with the exhaust.
You didn't assemble the motor yourself apparently so have no direct knowledge of anything being said. The info you're relaying is minimal and insufficient for anyone to really help you.
The usual cause of stuff like this is either a problem with work done (the cylinder repair) or one of a handful of well known issues with the specific model (eg coils). Only rarely does a truly novel and tricky problem show up.
For the really tough ones, clues can sometimes be found in real time data logging (the GS-911 / computer) but be forewarned that unless the fault is very obvious, interpretation of such data can be tricky and requires a very complete understanding of sensor controlled fuel injection engines. It is unlikely such data will scream the cause to any casual user.
There is no reason this can't be found by a well trained mechanic. The guys you're using are parts swappers, apparently overly reliant on BMW diagnostic computer instead of their own understandings and skill. They may have already seen and missed the real cause or are out of ideas. I took my first auto mechanics class in the 1960s and am a retired scientist and track junkie. I can tell you 2 things for sure - about 1/3 of all so called professional work is sub standard and observational skills of most folks are marginal at best- I can't tell you how many times I have seen mechanics or scientists overlook an obvious cause readily visible simply because they did not understand what was obvious to a more observant person. You can play the game on this thread forever at this level and continue to get nowhere- but I'd suggest its past time to get this to someone better qualified. There are no mysteries in something as simple as a motorcycle to properly trained and experienced people.
One basic item you haven't mentioned except in passing (engineer who assembled it said valves looked good) is whether or not compression has been verified on each cylinder. While I don't think this is highly likely if the work was done passably well, low compression on a cylinder will often allow an engine to idle but to lose power and efficiency under load (you note now only 36 mpg which is terrible for this model) as revs climb.
Thank you Racer,
It's certainly not my intention to continue a thread which is not helpful to me or anyone else. All of the information I have listed in relation to this thread is via someone else telling me this.
The part swappers or dealers are what you would expect at the top of the food chain when it comes to repairing BMW bikes in the UK. There are other specialists but they would not have access to the part swapping element or any diagnostic equipment hence I am at a loss as to where to go with this now.
The bike remains at the dealer they have raised with BMW tech department what they call a 'puma' case which asks for suggestions from BMW tech department. If they come back with nothing then other than collecting the bike there seems to be little where else to go with this.
In the UK when you phone a main dealer you do not get to speak to the Tech they are purposefully [IMHO] isolated by the service reception who are administrators rather than able technicians so I its made worse by everything being related by an admin officer rather than the actual tech.