Hard starting, not starting and everything in between

[new2merockster]

Recently bought 2004 Rockster. My second BMer. Could not start after delivery-internet sale from private party. I put fresh fuel with Seafoam (no fuel in tank for transport) and put new OEM battery. Cranking but not starting so took it to dealer. They changed spark plugs, replaced air filter element, connected it to comp., adjusted fast idle, changed oil and filter. Checked TB sync. It started. They sad it was flooded. Runs good when runs.
The next day in the morning it started after 3 cranks. Same thing 9 hours later in the afternoon and ever since. Only exception is when started when still hot. After it cools down a little starts on the 2 crank. Suspected bad fuel so I drained tank. Fresh fuel. Started. I drove it home. In the morning it didn't start. Tried 5 or 6 cranks until rattling starter Connected to charger and left for 9 hours. I have removed, checked and cleaned spark plugs. Drained and fresh fuel again. One crank to clean cylinders. Put them back. Started.
Next morning what the dsfsaldfeorir
Side stand is ok. Kill switch works. Fuel pump ok.
Any suggestions?

[jfslater98]

How many miles on this Rockster?

My thoughts run to either bad stick coil(s) or Hall Effect Sensors...

[riceburner]

All the messing about may have shifted the right or left side throttle cable outers in their seats - so the bike is unbalanced.

[new2merockster]

That might be it- I mean stick coils. Throttle cables are in their seats. Hall Effect Sensors- I hope not. It has 20K+. I took the newly installed (@ BMW dealership) spark plugs out and checked the gaps. It should be 0.8mm or 0.03in on all four . Some of them are too big. Factory setting? Checked for spark. Only lower spark plugs give spark. Mains nothing. That would explain difficult starting, bad acceleration and MPG- 36. Stick coils look BAD. I just bought new ones- ouch!!!. Have not tested it yet. Still waiting for some parts so have time to take things apart. Took the fuel tank off the bike for fuel filter and air filter element change. I was told by the mechanic @BMW air filter havs been checked and is ok but after my inspection it was not ok. It is in one spot scorched. No idea how could have this happen in I hope normal use by previous owner
How the dual spark system works on BMW? What happens in case one coil on one spark plug fails. Does the computer shuts ignition to the other to keep thing balanced. In general aviation airplanes you can select: both (left and right magneto together), left, right. If one fails you can find which and select working one. All with a turn of one key
Will find if that helps this Friday or Saturday.

[jfslater98]

It does sound like coils to me. There's no "intelligence" that I am aware of in the motor to switch sides if the other isn't sparking. It just keeps trying to go forward, and as you are seeing, sometimes it does, sometimes it doesn't. The part number changed at some point, I believe because the originals failed so early. Good luck I hope this works out for you!

[razz]

my rockster was behaving the same, hard starting, running poorly, stalling, poor fuel economy and generaly running like a pig. one morning going to work, started the the bike, left it idling for 20 seconds, bike stalled and would not start again. flattend the battery trying to start it again.
bike went to the local dealer, told them what happened and the swapped the stick coils over. i thought they gave me a new bike the differance was that great.
i would have the stick coils looked at, could be the problem. two stick coils cost $436 aussie dollars, not cheap but worth it

[new2merockster]

I have installed new coils on Friday and what a difference. Started right away. Runs much smoother and accelerates much better. Now I will need to adjust idle speed. When the engine gets warm it idles at 1300-1400RPM. I'm not sure by how much but it is way to high. Have not received original books with the bike. What the idle speed should be and what's the procedure Decided to postpone fuel filter change until I reach 24K. Will change final drive and gear box oil since I don't know when it was done the last time. Have Mobil 1 Synthetic 75W90 ready.

[omg1010]

Hi,

idle should be at 1100 rpm. You need to get the workshop manual which does not come with the bike. Most probably your bike also needs a fresh sync!

Brgds
Oliver

[new2merockster]

Will adjust the valves, adjust idle and sync carbs. Already changed final drive and trany oil. Thanks for all help.

[new2merockster]

Valves adjusted and I think I did decent job for- first time. Run good. I also did adjust idle and sync carbs using tube manometer filled with engine coolant. Started after the job and run good. However, two days later didn't start. I checked fuel injectors by removing them and cranking the engine. Very little at the beginning to nothing at all after about one second while cranking.
I replaced fuel filter. I can hear the fuel pump. Checked for spark at the mains- looks ok. Charged the battery, also tried jump- still nothing, cranks but does not start. I'm running out of ideas. Please help.