1150 missing under acceleration

[(RIP) Johno23]

Dan my son has an 1150, which has started missing under reasonably hard acceleration.Its ok if you just accelerate normally through the gears, but if you open it up for a quick overtake it hesitates / misses badly. Any thoughts, bike has new plugs It’s a 99 model GS. Cheers

 

[Carefulkev]

I had similar symptoms on my 99 model 1150 GS (a good few years ago). It turned out to be one of the fuel injectors which are quick and easy to change. You only need to buy one (think I got a used one from Motorworks) as it fits both sides. Just try it on one side then the other side if problem still there...

 

[Timolgra]

Don't overlook the basics, I had one a long time ago that did that and it was the plug leads.

 

[Colin]

miss

I had plug lead shorting against the head. I've also had Hall sensor failure they get cooked with the heat from the engine. and vibration.

 

[sykospain]

Yes, HT voltage leaking to earth, ( plug leads ) HES Hall Effect Sensor beneath the big plastic cover behind the front wheel - just the wiring, which collapses in time, not the actual sensor itself; then try the fuel pump - check delivery pressure, which shd be almost 3bar, enough to knock your wig off - and remember BMW Motorrad only guarantees the rubber hoses on these vehicles for a paltry 5 years. The inside diameter of a pipe can clog up even tho' the outside view seems OK.
Rarely something heart-breaking, just thorough, logical step-by-step diagnosis and it'll be sort-able.
Then take it out on-road and wind that throttle open.

 

[Steptoe]

I had similar symptoms on my 99 model 1150 GS (a good few years ago). It turned out to be one of the fuel injectors which are quick and easy to change. You only need to buy one (think I got a used one from Motorworks) as it fits both sides. Just try it on one side then the other side if problem still there...

Check the resistance across the two injector terminals.. should be around 16 ohms.

 

[albatross]

I have a set of injectors spare in case you need some
Albatross

 

[gog]

I have a set of injectors spare in case you need some

as do i... and probably about 30 others of this parish

 

[Ajay]

Stick coil on its way out gave similar symptoms on my 1150

 

[metropolis2k]

Stick coil on its way out gave similar symptoms on my 1150

That's only twin-spark. This is a 1999 model so single spark

 

[(RIP) Johno23]

Thank you Gents, He is investigating as we speak.Thanks albatross for the offer, if still stuck I may take you up on that cheers

 

[Roger 04 RT]

Dan my son has an 1150, which has started missing under reasonably hard acceleration.Its ok if you just accelerate normally through the gears, but if you open it up for a quick overtake it hesitates / misses badly. Any thoughts, bike has new plugs It’s a 99 model GS. Cheers

If one of your in-tank hoses are starting to leak you could have those symptoms. Check the return flow from the fuel distributor going back to the tank. It should be about 2 liters per minute at idle. If it is, you're good, if it isn't, look inside the tank.

Note, checking the fuel pressure is not the same thing. Fuel pressure will be fine until the leak is so large that the bike will barely run.

 

[Danny88]

Thanks for all the replies guys. I took the bike out last Friday with the mrs on the back and it was faultless, no miss under acceleration and performed perfectly.

I had this issue before but assumed it was a battery which had a dodgy cell and never held charge, thought the ignition system maybe effected? Perhaps I was wrong.

Changed the battery and had that issue initially but seems to have disappeared?

Can a degrading coil cause this issue intermittently?