Seem to have problem starting the Rockster lately

[fnfalman]

I'm at 15,000-miles with the 12,000-miles service done less than two months ago. Southern California temperature is at around 40-F at night, low humidity. The last couple of weeks, it seems like the bike cranks over quite a bit before starting. It hasn't quite drained the battery every time I cranked the bike, but it seems to keep cranking, cranking and cranking before ignition kicks in. And yes, I do use the cold start lever.

Any ideas, fellow Rockster riders?

[Mike in TX]

Think the power commander may have something to do with it?

[fnfalman]

I doubt it. It happened a few times before I installed the Power Commander.

[riceburner]

How long are your rides??

if you're only doing short journeys then the battery won't be recharging after the drain of starting the bike and might not have enough power to supply both the starter and the electricals.

Go for a good long 2 hour ride.

[leno]

Have you tried it without the cold start?

[sjbmw]

My R1150R also cranks a lot more to start in colder temps. When it gets real cold, I will need a few hours of a battery tender else I can kill the battery.

I recommend getting a battery tender and leaving it plugged into your accessory port during your cold season.

[fnfalman]

I don't know, I think that the valves may need adjusting. As far as how long are my rides, they are plenty long. 15,000-miles in 8 months.

The bike will just crank and crank and crank and crank until the battery goes weak without using the cold start lever.

Anyway, I'll bring it in and let the BMW people look at it. It's still under warranty.

[bmwfbd628u]

Hi,

Having the same prob, and found this old thread.

I am from Singapore - a tropical country. Riding a 4 year old Rocks with 25,000 km on it. Performed 20,000 km complete servicing by agent few months ago. Just changed my starter motor by agent couple of week ago and the prob came. Sent back to agent for checks - cannot detect any fault with diagnostic tests, swapping various sensors, compression pressure, fuel lines, etc. Have to crank (press start button) up to 10 times before engine fires, and rides smoothly after. Engine seems to fire quicker if I throttle just before switching off in the ride before. Noted advices from the old thread and will try them. Appreciate any more comments and advices. Thanks in advance.

Justin

[boxermania]

The Motronic in the R1150R doesn't have the smarts to enrichen the cold start fuel mixture and reverted to an inexpensive solution.....the "two position choke", which is nothing more than a hand acelerator.

What it does is mechanically (by opening the throttle butterflies) increase the TPS voltage signal to the ECU. This in essence enrichens the mixture slightly, once the engine fires, to overcome the cold engine and the added friction of the cold oil.

That being said, make sure to pull the "choke" all the way up to the #2 position and hold it there while starting, after the bike runs for a few seconds and the rpms go above 1600 rpm let go of the choke and it will slide to the #1 position. Begin your ride and push the "choke" down, to the home position, after a mile or two.

Contrary to popular belief, forgeting the "choke" in the #1 position will cause no harm to the engine other than an elevated idle. As a matter of fact, some users that have yet to master getting off the line, will find it much easier to accomplish.

Last but not least, if you ride in temps 40 F and below, it is best to change your oil to 10W40 as it will make the engine much easier to start, again, with no damage to the engine internals.

[rjh58]

Where is the choke on this bike and how do you operate the cold start lever?

[jfslater98]

Look for a lever right near the base of the left mirror. Pull it all the way back to start the bike, then let go once the motor's running. It will stay in the "high idle" position until you lightly tap on it.

[bmwfbd628u]

hi boxermania,

Thanks for your informative post. I must admit I am not much of a hands-on person, leaving the repair and maintenance to the shop. But I am keen to get to the bottom of this issue, and have been reading previous related posts.

I have a few clarifications:

1. The "choke" on the fuel injection bike is really a "hand accelerator" (borrowing a term you used previously), so engaging it in position #1 or #2 will serve the same function as throttling? Understand throttling opens the air valve, and EUC will inject the correct amount of fuel based on readings from various sensors? If so how does throttling "enrich" the fuel mixture - by "enriching" I will guess to mean higher fuel-to-air ratio?

2. Read in another thread that pressing the starter button will cause EUC to inject more fuel? If so, it seems to serve a completely opposite function to throttle, in adjusting the fuel-to-air ratio?

3. Is the stated prob due to too high or low fuel-to-air ratio? Either will require different actions - throttle when starting to add more air, OR press starter button WITHOUT throttle to add more fuel?

I have tried using the choke at both positions, throttle when pressing the start button, rest (few secs) between every crack. The last time I tried, after parking the bike for 2 days in tropical Singapore that has temp above 80 F throughout, I have to press the button about 10 times till the engine fired. Rode bike for 20 mins before stopping. Intending to try starting later, after about a day.

[boxermania]

Tbmwfbd628u

1) The TPS (black box mounted on the left TB) sends a VDC signal to the ECU. The level of the signal (range) tells the ECU if the bike is idling, begining to move and anywhere else fom minimum throttle application to WOT. That signal along with some other engine inputs essentially taylor the A/F ratio based on an algorithm to what is best for the engine under the operational conditions. Please do understand that there is some basic operational criteria, based on emmissions, fuel econimy and other parameters that need to be served as well.

So in answer to your question, enrichening, does mean an A/F ratio richer in fuel or lower in number (i.e. 14.7 vs 13 as an example0

2) First time I heard of it, it seems an odd way to go at it. I don't believe it......

3) I'm confused.....the only time that I have opened the throttle while starting one of our bikes was when I had evidence of water in the fuel and the bike would not hold idle. I managed, on several ocassions, different bikes, to keep the engine runnming and the bike moving long enough to clear the offending water.

If you have a 4 plug engine I would check the operation of your stick coils or the connector as they have been an issue as of late.

[bmwfbd628u]

just to close the loop/issue..

sent bike to another workshop, and discovered a faulty spark plug - all 4 were supposedly changed 2,000 km / 2 months prior?! anyway, changed all 4 to Iridium (from BMW OEM parts) and the shop re-sync the valves and re-set the TPS.. and the bike fires up right away since! sorry to raise the issue when such basic checks and tuning should have been done, esp when trouble-shooting..

thanks for all the advices, esp from boxermania..

[bmwfbd628u]

just to share a further development..

since last post, bike started right away, but that lasted for about 3 days, and the old problem returned.. sent back to workshop, and changed the battery after checking it did not hold charge well - voltage for various start stages were as follows: 13.5V without turning ignition, 12.7 after turning on ignition (headlight auto-on), 9.5V on pressing start button.. with new battery, voltage holds at 11+V on pressing start button.. bike has been starting well for a week now..

sent old battery (BMW OEM) to agent.. it was installed last than a year ago, ie still under warranty.. but agent claimed load test showed battery still useable.. fact is, it did not allow me to start bike right away.. any ground for me to press for it's replacement under warranty?

[boxermania]

sent old battery (BMW OEM) to agent.. it was installed last than a year ago, ie still under warranty.. but agent claimed load test showed battery still useable

Hmm....I wonder if the agent is not being thruthfull or lacks brand knowledge.The Motronic and the ABS as do not operate well at voltages below 11 VDC....and it appeared, based on your post, that the cranking voltage of the "old" battery was well below 11 volts.

Something just doesn't add up, press "the agent" for what is the load voltage on the battery when tested.