F650GS Spark Plugs
I replaced the 2 spark plugs on my F650GS (2004 Dakar) and since then I have a bad dead spot on low revs.
It's not completely dead, but just has almost no torque until about 5000. Only then does it wake up.
What could have gone wrong?
Plugs from Donford. I must admit, I never checked the gap before fitting it.
Also, I lost my plug spanner. Does a normal tube spanner work, or must I get a plug spanner from BMW?
Thanks,
Philip.
I think what happened is that you could have swopped the two coils around.The grey rubber sleeved coil goes on the outside, ie on the R if you would have been sitting on the bike and facing forwards.If you unplugged the wires going into the coil this could also be inserted incorrectly by accident.The connectors are interchangeable.
The secondary coil(mentioned above that goes on the outside(R side) has n white material tag on it.These tags do come off over time.If this is the case with you we will have to look up on our wiring diagram to see which colour wires correspond with which.
Thanks Jandré. I will have al look over the weekend. I was under the impression that the coils were keyed with one narrow and one wide metal tab that slides into the rubber slot of each coil, but I might be mistaken.
Will give an update after the weekend.
(rear hub is running sweet:)
Update: Its still not resolved. Checked that they were not swapped. Fitted another 2 brand new plugs. Still no joy.
When I open the throttle at low revs to accelerate, its as if it first loses some power before slowly accelerating.
Also noticed that I'm getting about 30-40km less on a tank.
What I have not mentioned was that, when I started the bike for the first time after the plug change, it made a tapping/clinging noise for a few seconds which then faded away.
If some sand fell into the cylinder when I removed the plug, would it explain what's going on here?
Thanks,
I don't think sand in the cylinder would have that effect. What I do think is that the manipulation of the spark-plug cables may have caused one of them to fail. Either the cable has become disconnected inside the insulation, or the insulation has broken down and it is arcing to the chassis instead of make a good spark.
You can try diagnose this by checking for a spark on each plug while cranking the engine.
I don't think sand in the cylinder would have that effect. What I do think is that the manipulation of the spark-plug cables may have caused one of them to fail. Either the cable has become disconnected inside the insulation, or the insulation has broken down and it is arcing to the chassis instead of make a good spark.
You can try diagnose this by checking for a spark on each plug while cranking the engine.
Thanks Charles
Silly question but there is a lead connected to the O2 sensor in the intake snorkel, has that perhaps worked loose or not re-fitted after service.
Silly question but there is a lead connected to the O2 sensor in the intake snorkel, has that perhaps worked loose or not re-fitted after service.
Genius! Its exactly that. Fire the mechanic! Removed the cover last night and there it was... All back to normal this morning 
About a week before the plug change, the air filter was changed. I probably never rode the bike in that week.
Owe you a beer, Max 
Great, glad I could help.
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