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I have a rather strange problem with my BMW G650GS. In the morning, when the engine is cold, it starts fine with a single crank. There is no problem with riding, the engine works fine and never chokes. Then, if I ride for a while to make the engine hot, stop it, let it stay for about 5 - 10 minutes and try to start it, it won't start. It is cranking, the battery is new, the wires are checked and they are fine, the starter apparently works because there are no problems to start engine in the morning but the engine does not start no matter how long I keep the starter button pushed. I can drain the battery but it won't start.

There are two options to start it. One is to wait for 20 - 30 minutes until the engine cools down a little, then it starts with 2 - 4 cranks. Another options is to switch to the first gear press the clutch, push the motorcycle forward until it is going at least 5 miles per hour, then push the start button and start releasing the clutch, then at certain moment when the clutch is almost released the engine starts.

Sometimes it doesn't work from the first try when the speed is too low.

Has anybody experienced similar problems and how to fix it? There is problem to show this problem to a mechanic because the timing varies probably depending on the weather (how cold it is) or something else and it is not repeatable every time but in about 75%.

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  • Have you checked for spark when it is not starting? Hopefully it's not heat-related seizing in some mechanical part of the electric start system.
    – user10962
    Jun 22, 2015 at 0:56
  • I would go with the service bulletin first. It should be free work from the BMW dealer, you can mention that there is a software update at that time and they should do that for free as well. Has your issue been solved?
    – DucatiKiller
    Dec 12, 2015 at 3:18

5 Answers 5

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Your problem is caused by decompression valve problem in 650 engines prior June 2012. Only way to get rid of it permanently is to replace decompression valve, which fortunately is not a huge job.

BMW bulletin about the issue: http://www.gravesurrounds.com/bike/hotstart.pdf

Chances of having hot start problems due decompression valve are higher when your battery is not 100% charged. If bike is not starting when hot, let it cool down, drive it home and connect the battery to a trickle charger overnight. (You can access '+' terminal by taking the seat off. Right hand side below the 'fake' fuel tank cover).

With full battery bike should start even when it is hot or at least reproducing the problem should be much more difficult.

What goes wrong when bike doesn't start; ECU feeds fuel to cylinder only when revs go above certain threshold which I think in G650 is 700 rpm. Faulty decompression valve leaves compression in cylinder too high when engine is hot. This results extra load to starter motor during start and battery fails to turn starter motor fast enough to get engine to go over 700 rpm.

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In fuel-injected systems, hot-start problems indicate that the fuel line is unable to maintain pressure.

This could be due to a few things related to the fuel supply line, including:

  • a leaky fuel injector
  • minute cracks in the fuel line which leak fuel when under pressure

The reason why this happens only for hot starts is because the fuel is more likely to vaporize as temperature increases. In order to avoid vaporization problems the fuel lines are expected to be pressurized during a hot start.

I believe the reason why the rolling-start fix works is that it applies an additional load on the engine that demands extra fuel. The fuel pump would then increase fuel pressure to the point where vaporization is no longer a concern, allowing the engine to start.

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There is another problem, recognized by BMW with this motorbike when starting with hot engine, so you are not alone. Have a look to this web http://www.bmwg650gs.com/ where there is a document sent by BMW Spain with info (in spanish). Basically they told they know the problem and the solution is a new software for the ECU which nowadays is not available. So the only solution is waiting for BMW to release this new software while we try to use the motorbike as much as it allows.

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  • That sounds rather strange. It is almost 5 years old bike and there is still no software update? Plus, now I'm confused what is more probable the decompression lever or the software...
    – Alex
    Sep 15, 2015 at 22:19
  • mmm... with a 5 years old motorbike I would think it is not related with the ECU problem. Great motorbike, isn't it?
    – Barbosen
    Sep 17, 2015 at 7:16
  • Besides the problem with starting engine it is the best for short to medium rides, local commute and occasional off-road riding for one person. Riding two is rather uncomfortable.
    – Alex
    Sep 18, 2015 at 13:32
  • ohh I was being sarcastic. I regret to buy this motorbike
    – Barbosen
    Sep 21, 2015 at 11:07
  • There is a recall for that: bmw-motorrad.com.br/br/pt/index.html?content=http://…
    – Barbosen
    Sep 23, 2015 at 15:58
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Had a similar problem with my 2007 xcountry. Thought it was a couple of accessories that I put on the bike. So many issues with starting when I travelled a short distance, then stopped the bike. Put in new battery, didn't fix the problem. Changed to a lithium battery on the bike which fixed the problem or at least I am not having that issue any more. It usually occurred if I was going for a ride, decided to stop at shops, get petrol nearby, it wouldn't start. Felt like there wasn't enough charge left in the battery to start until I'd ride awhile. Lithium battery works a treat for me and my G650

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My BMW 650 has the same problem. I purchased a kit from Rusty at MAX BMW. Kit costs $54.00 plus shipping. Should not be a problem to install on the exhaust cam area.

this is the kit I was speaking about. Here is the kit that MAX BMW sent me. I hope it works.

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  • 1
    While that may be a solution, how does it fix what the OP is talking about? What does the kit actually do? How is the kit installed? Give the OP (and the rest of us) some information about what you're talking about and it might incur some positive response! I'm looking forward to reading what's going on :o)
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Feb 26, 2016 at 23:00
  • I have a kit from Max BMW. It features part # 11 31 8 540 965 it is a new decompression lever and associated hardware. If I could post an image, I can show you the parts.
    – Bill Peloquin
    Mar 4, 2016 at 20:03
  • Edit your original answer and put the image in there. Infact you can post all the information back into your answer if you'd like.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Mar 4, 2016 at 20:09

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