Ideas ?

[Steve V]

I was travelling down the motorway on my 05 1200 GS at a decent rate of knots and the bike suddenly made a strange noise and wouldn't accelerate, almost like a kind of limp mode. I backed of the throttle and everything was fine, when I introduced more throttle at anything other than gradual the load seemed to make the engine go into a type of limp mode. i was able to finish the journey no problem but the issue appears to be when I want to rev anything above gradual.
Does anyone have any ideas where I can begin looking? Cheers Steve

 

[Bobbin-Man]

Have you lost the cable connection to one throttle body?

 

[Alan R]

Fuel starvation? Partially Blocked vent hose creating a partial vacuum in the fuel tank? Insulation on a coil stick breaking down rendering a spark plug ineffective? Dirt in the tank clogging the entrance to the fuel lines? Really dirty air filter? And so on.
Alan R

 

[Rocketman]

What bobin said ,don't ask me how I know but I have got some bloody big
Clumsy plates of meat,

 

[mikeyboy]

Primary coil failure

 

[Rich C]

Primary coil failure

Ditto. Had very similar symptoms on my 1150 a few years back.

 

[Steve V]

Thanks, I'm leaning toward the coil I'll have a look tomorrow and see what damage I can do

 

[Bendy toy]

Check which exhaust is cold. Swap coils left & right. If cold side swaps you have a failed coil.
Are they black or stainless finish?

 

[Pukmeister]

Steptoe put advice on here about coils a while ago stating to unplug secondaries then actually start and ride the thing to put coils under load. If okay, swap over to secondaries and repeat. The only sure fire way to find a coil that breaks down under load.

 

[Bendy toy]

Steptoe put advice on here about coils a while ago stating to unplug secondaries then actually start and ride the thing to put coils under load. If okay, swap over to secondaries and repeat. The only sure fire way to find a coil that breaks down under load.

The ideas work you have the original old type coils. Mine both began to break down at the same time and eventually failed within a few miles of each other. Swapping them left/right didd nothing useful because they were both bad. I was chasing my tail for weeks with that lot.

The symptom I ignored was that both coils had that hot winding smell. I put it down to them running inside a hot cylinder head. But they really were burning out. If a coil smells hot it's likely to be packing up.

 

[Alan R]

Check which exhaust is cold. Swap coils left & right. If cold side swaps you have a failed coil.
Are they black or stainless finish?

The symptoms reported on the Op's first post are unlikely to result in a 'cold' side. An intermittently failing coil will probably heat up the pot enough to be unable to determine which side is not firing correctly. Substitution seems to be the tried and tested method.
Alan R

 

[Steve V]

It appears to be intermittent, but I'm confident its one of the coils. Perhaps replacing them both might be a worthwhile exercise on a 10 yr old bike.

 

[Bendy toy]

The symptoms reported on the Op's first post are unlikely to result in a 'cold' side. An intermittently failing coil will probably heat up the pot enough to be unable to determine which side is not firing correctly. Substitution seems to be the tried and tested method.
Alan R

Makes sense and indeed mine were similar temperature but when one coil did finally fail the cold side was obvious.
On the other hand if the OP has black painted coils and they smell of electrical shellac they are failing. Replacements are stainless sheathed.
North Oxford BMW told me they tend to fail in pairs. I bought just the one and on the way home the other coil cut out. So they were bang on with that advice.

 

[Steve V]

Well its doesn't appear to be the coils