Missfire after low speed accident

gb's

gb's

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Whitwick near Leicester, England
Some weeks ago slid off bike on low speed lefthander. Majority of parts on left hand of bike scratched leading to longish spell at dealers awaiting Insurance Ok and arrival of parts.

Got bike back yesterday, now find it suffers from a "missfire" when the engine is underload at approx 3000 revs. Problem is also very marked at 5000 revs where previously there was a marked pick up in acceleration, now engine bogs down.
Missfire not apparent revving the engine in neutral.

No obvious loose, or missdirected cables.

Intend to contact dealers (pidcocks Long eaton) as soon as poss this week but wondered if symptoms suggest anything to anyone.

Cheers
Graham
 
Had a "missfire" after an off on the 12 in December. After replacing the fuel pump controller and most of the LT leads, turned out to be a dodgy connection to the coil on the secondary sparkplug. This "missfire" was only apparent under load with the throttle at least 3/4 open.
 
I have had one like this before. It showed no fault's on the gt1 but it turned out to be the primary coils. The accident must have damaged the coil.
 
bmwlee said:
I have had one like this before. It showed no fault's on the gt1 but it turned out to be the primary coils. The accident must have damaged the coil.
Click to expand...

Each spark plug has it's won coil atop it. I suspect the one on the lower plug on the side that you went down on.
 
Emoto said:
Each spark plug has it's won coil atop it. I suspect the one on the lower plug on the side that you went down on.
Click to expand...
It was the lower one that knackered on me.
 
Had this too - lower plug coil had come off. The engine runs smoothly at low revs as it is working ok off just one plug, but at higher load the 2nd plug is expected to be operating but if it isn't the thing misfires badly.

Interestingly, the fantastic BMW diagnostic facility was unable to detect the fact that the coil was disconnected!
 
Thanks for your ideas.

Have checked the bike myself and can not see any obvious disconnections.

Have taken bike to dealers today. As in Tobers case the diagnostic device can't find anything wrong.

Have left it with them to fix, once the problem is known I will post details of it to add to our collective knowledge:)
 
In my case, an initial inspection of the bike showed nothing loose. In fact, the dealers spent about 3 hours changing all sorts of things (including the petrol tank) to eliminate the problem until they decided to change the coils on the plugs. At this point they removed the plastic spark plug covers and found the loose coil on the lower right plug.

So, even if nothing is immediately visible it's worth removing the snap on covers and having a closer look-see. Would have saved me about 6 hours to have done so. Big respect to Motorrad Central in Glasgow for sorting it for me on a Saturday morning with no appointment etc etc.
 
Problem solved.
On this ocassion the problem was tracked down to 3 small cracks in the ceramic of the No 2 spark Plug.
No more than 3mm in length they run down the plug from the HT plug end.
Almost certainly caused by the impact of the accident, with the spark plug being in such an exposed position on the underside of the cylinder.
 
gb's said:
Problem solved.
On this ocassion the problem was tracked down to 3 small cracks in the ceramic of the No 2 spark Plug.
No more than 3mm in length they run down the plug from the HT plug end.
Almost certainly caused by the impact of the accident, with the spark plug being in such an exposed position on the underside of the cylinder.
Click to expand...

So, this could be quite common for any of us who happen to tip over, eh? GB's, do you have crash bars on your bike? If so, which brand and were they on when the tip over happened?
 
Emoto.
No crash bars on the bike at the time of the accident, only the black plastic "protectors". Now have H&B bars fitted, once bitten...Looking at the design of these I think they would have prevented the damage in my case.
Greg.
I'll give you a ring.
Graham
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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