Rough idle when hot

mitch9

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Hi bike is 1150gs 03 that i recently bought and had a few problems. One of them being the tickover.
I have serviced it changing plugs,fuel filter etc. Ticks over great at approx 1100 rpm but when it gets warm after good run it starts missing beats to the point of stalling. I have done end float ,tappets and tbs. still no joy. Brass screws have been cleaned and fuel injectors taken out and look clean ,new battery . Can a coil be breaking up or hall sensor? Bike goes well once off tickover even warm.Thanks
 
Stick coils on their way out maybe. Have a search, lots of information about them on here.
 
Yes i was thinking its the possible the coils breaking up as its done 50,000 and look original . But under load the bike pulls great and would have thought if coils or hall sensor were suspect it would be more consistent. Thanks
 
It could be stick coils but there are other possibilities such as the O2 sensor, coding plug, Motronic needing to be reset. First, which coding plug is installed: none, yellow or another? Do you have a stock exhaust, BoosterPlug, techlusion, power commander or some other fueling device? Is your O2 sensor installed and connected (connector under tank)?

To check the stick coils try disconnecting them (carefully) one at a time when your condition occurs.
 
Is it a twin spark? I was on a trip once with a lad on a twin spark which started doing similar. It had recently been serviced but one of the plugs was faulty.
 
I remember Ash having a similar problem a few years ago. We changed the wee rubber covers on the brass spigots on the underside of the throttle bodies which were badly perished and that solved the problem.
 
It is a twin spark and i replaced all plugs. Everything is stock on the bike. New battery so did the throttle reset for motronic gizmo .Not sure about 02 sensor have fitted new air filter but need to maybe look at that as just done a run out and spark plugs colour look fine but noticed brass screw on the left hand tb side was black and sooty if this is relevant
 
Most likely one or both of your main coil caps are failing. Very very common.

Simple test. Pull off your lower secondary plug caps from each side and see if the bike runs on just the main plugs which use stick coils ...
 
weekend after posting i took plugs out again cleaned them although looked ok L/H brass screw was black and sooty so cleaned it gave them both another shot of carb cleaner for luck and assembled all back together.
Been out on it last 2 days giving it a good run over 400 miles and tickover and bike ran great with only one fault today as i got low on fuel, filled up and never missed a beat again !
Off work friday so might aswell give above method ago and see if it is the main coils didnt know about that method. Thanks for all the help lads:beerjug:
I was aware of the throttle cable thanks as i have had tank on and of loads lately .:thumb
It started out with abs lights flashing but thanks to great article on here removed the whole lot and so easy to do .
 
Went out all weekend two up no problems till last run when original fault returned and nearly dropped it pulling away it hesitated and stalled .
Did suggested test pulled one secondary plug and bike reluctantly started and was rough repeated the same on other side and it was the same !! Fu* does this mean i need two coil sticks ? i think i know the answer but thought id check before order em . Thanks again
 
mitch9 said:
Went out all weekend two up no problems till last run when original fault returned and nearly dropped it pulling away it hesitated and stalled .
Did suggested test pulled one secondary plug and bike reluctantly started and was rough repeated the same on other side and it was the same !! Fu* does this mean i need two coil sticks ? i think i know the answer but thought id check before order em . Thanks again
Click to expand...

Sounds like the coils as Steptoe said.
Pull both secondaries off and see how she runs....or not.
Put one back at a time. This will show you if they are both gone or just the one.
There is a cheaper alternative than BMW from somewhere, but the source escapes me atm.
 
yep pulled both off and woulden start at all ! if both are buggered im surprised it ran so well. I only noticed a drag when i opened it up from say 50 to 80 and thought it was the strong winter weather buffering on the bike and me so maybe it was the stick coils .
 
flatdog said:
Sounds like the coils as Steptoe said.
Pull both secondaries off and see how she runs....or not.
Put one back at a time. This will show you if they are both gone or just the one.
There is a cheaper alternative than BMW from somewhere, but the source escapes me atm.
Click to expand...

I bought a pair from here recently- good service-http://www.ebay.co.uk/itm/301790997645?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
 
Ya did indeed Mr Steptoe :rob never did listen to my dad :blast thanks again everyone for ya input ordered 2 new stick coils. Never thought it would run so well on just secondary plugs .Looking forward to feeling the difference :thumb
 
Replaced both stick coils and wow what a difference it has made a joy to ride even though it rained !after it was all warmed up the tickover was to high though about 1500 , tried to lower it on the brass screws which were at 1 1/2 turns out and have ended up at only 1/2 turn out to give it a 1100 ish tickover .
My question is do i risk running it weak like this or do i have to get the tb balanced again and turn the b/screws back out ? thanks
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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