Backfiring on full throttle

[millard]

A couple of days ago my 2004 42k mile 1200 started occasionally backfiring when giving it a handful. Now almost every time I open the throttle from low revs (2-3k ish) it splutters then mostly it'll give a couple of loud cracks before it picks up. If I open the throttle gently it doesn't happen.
I ditched the factory exhaust for a remus and straight through Y peice but that was some months ago now and it's been fine up to now.
It's been dealer serviced up to now by previous owners but since buying it at 36k I did another 6k on it before doing my own first major service the other week - oil/filter change, checked valve clearances etc.

Can't think of anything else relevant.

It's been trouble free up to know, any ideas please?

thanks
Millard

 

[Wapping]

If it's banging on acceleration, as opposed to overrun, it may be an air leak in the exhaust somewhere.

 

[TomiH]

A couple of days ago my 2004 42k mile 1200 started occasionally backfiring when giving it a handful. Now almost every time I open the throttle from low revs (2-3k ish) it splutters then mostly it'll give a couple of loud cracks before it picks up. If I open the throttle gently it doesn't happen.
I ditched the factory exhaust for a remus and straight through Y peice but that was some months ago now and it's been fine up to now.
It's been dealer serviced up to now by previous owners but since buying it at 36k I did another 6k on it before doing my own first major service the other week - oil/filter change, checked valve clearances etc.

Can't think of anything else relevant.

It's been trouble free up to know, any ideas please?

thanks
Millard

Same mods and problem here. When I open the throttle more than half it is like hitting against rev limiter.
Is there a online shop where I coud order stick coils? I did find one but it doesn´t deliver to EU!
http://www.ascycles.com/Illustrated_catalog/R1200GS(04-up)/catalog_frameset.html

R1200GS 2004 41000km

 

[millard]

If it's banging on acceleration, as opposed to overrun, it may be an air leak in the exhaust somewhere.

That was my first thought Wapping, but I checked the joints and all good.
If it was one of my carb bikes I'd be looking at mixture strengths, but with an injection bike I'm a bit lost.

 

[TomiH]

Okay I made simple test. Warm bike idling and I just loosen the secondary stick coil. On the right side when removing the coil idling changes for worse. Then I removed the coil from the left side and idling didn´t changed at all.
So my left side coil is bad! Now I just have to find a new one! But where???

 

[millard]

Tomi, are you getting the same symptoms as me? If so can you please let me know if a new coil cures it?
thanks
Millard

 

[TomiH]

Tomi, are you getting the same symptoms as me? If so can you please let me know if a new coil cures it?
thanks
Millard

Almost the same symptoms. All revs,low or high, when I open the throttle more than half it sputters and looses power. It´s like hitting against rev limiter! And it doesn´t pick up like Yours.
When opening the throttle gently and it doesn't happen.
Did you already try that coil test?

 

[TomiH]

More testing. I swapped the secondary coils between side to side and make same idling test. Result was just like earlier. When removing the right side coil idling changes for worse, and left side there was no effekt.
Next I check the left side sparkplug. It was light brown, so it fires good.
So both coils are good, but bike still dont work properly.

 

[DrFarkoff]

Tomi check the wires where they go into the stick coil ?? There was a warning when we were doing the first bikes with twin spark not to pull the wires but to ease the coil out completely then undo the connector

Try a new plug ?

Maybe a Plug gone duff??? (i.e not functioning correctly)

 

[TomiH]

Tomi check the wires where they go into the stick coil ?? There was a warning when we were doing the first bikes with twin spark not to pull the wires but to ease the coil out completely then undo the connector

Try a new plug ?

Maybe a Plug gone duff??? (i.e not functioning correctly)

Yes I did try new plug. What do you meen by checking where the wires go?

 

[DrFarkoff]

Yes I did try new plug. What do you meen by checking where the wires go?

The wires go into the connector sometimes if they're bent badly they break inside the insulation

 

[TomiH]

I disconnected secondary coils and measured them! Between left and right pin 1,2 ohm. There was no result for middle pin. Exactly the same result in both coils.
Does anyone know what is the purpose of the middle pin?? Should there be some short of reading(middle pin to left/right pin)?

 

[mark71]

Hi there

I had exactly the same problem when I was running a full Akro race system it endedup being the plugs that burnt out, so I changed back to the original BM headers and de-cated it and Ive never had the problem since and I ve now done 12,000miles so all good here.

Hope that this helps.

 

[Lugs]

I cam almost, almost guarantee you that it is the side stand cut out switch.

You might think thats crazy, but the symptoms are identical.

If you search on here there is a great thread giving instructions on what to do. It'll take 5 minutes.

Ian

 

[TomiH]

Hi there

I had exactly the same problem when I was running a full Akro race system it endedup being the plugs that burnt out, so I changed back to the original BM headers and de-cated it and Ive never had the problem since and I ve now done 12,000miles so all good here.

Hope that this helps.

Thanks! That helped a lot!

 

[TomiH]

I cam almost, almost guarantee you that it is the side stand cut out switch.

You might think thats crazy, but the symptoms are identical.

If you search on here there is a great thread giving instructions on what to do. It'll take 5 minutes.

Ian

Okay now I am very confused again But I will test that tomorrow! Thanks!

 

[TomiH]

I cam almost, almost guarantee you that it is the side stand cut out switch.

You might think thats crazy, but the symptoms are identical.

If you search on here there is a great thread giving instructions on what to do. It'll take 5 minutes.

Ian

It´s been tested now and it doesn´t work!

 

[millard]

Thanks LUGs, but it dodn't work for me either.

I found the thread you refered to

( http://www.ukgser.com/forums/showthread.php?t=112515&highlight=side+stand+switch )

and shorted out the white and brown wires, leaving the red disconnected as I removed the switch anyway - planning on replacing it, but it's still the same. In fact if anything it's getting slowly worse I'd say. If I wind the throttle on gently it's ok-ish, but open it up and it spits and bangs like buggery.
I'm gonna try Jaythro's ideas and have a good look at the coil leads, but any other suggestions please?

Thanks
millard

 

[millard]

I just checked out the plugs and leads etc and all look good, battery terminals are nice and tight and clean.

I'm stumped

 

[bumpy]

My guess is that this is an electrical problem on the ignition side, the symptoms are typical of something breaking down under load.

At the moment you dont have an idea if the problem is in one cylinder or both.

I dont know if this little experiment is practical:

Disconnect the plugs from each cylinder in turn and either drive the bike on one cylinder or rev it (under load with the clutch being engaged). This should at least tell you which cylinder is failing and we can progress from there.

Good luck