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I have this annoying misfire on my 03 R1100S. It's at around 1500 - 2500 rpm, it kind of sneezes and can stall the engine

I took it to a local independant dealer and he put the balance gauges on the throttle bodies and fiddled with the cable adjuster/butterfly on the right throttle body, and for the rest of the afternoon it seemed smoother and the misfire disappeared for a while.

By the time I got home (about 20 miles) it had started farting about again, so I checked the brass air bypass screws, both were at one and a quarter turns out...

I have got to get this sorted out, it's spoiling my enjoyment of a great bike, but I just don't have the funds to go to a dealer...

Any suggestions?

When was the last time you changed the fuel filter and drained the petrol tank? You'd be amazed at how much crap manages to find it's way into the tank over time. Just a thought. The bits are cheap and it's an "interesting" job changing the filter if you've not attempted it before.

Paul

Paul wrote:When was the last time you changed the fuel filter and drained the petrol tank? You'd be amazed at how much crap manages to find it's way into the tank over time. Just a thought. The bits are cheap and it's an "interesting" job changing the filter if you've not attempted it before.

Paul

I've changed the fuel filter on the K100 a number of times (getting used to your hands smelling like unleaded is the hardest bit) but thanks for the pointer Paul.

Is it a case of removing the fuel cap surround and getting in there with a screwdriver in a James Herriot kind of way?

BTW the bike has had the original collector box and cat replaced by a Laser Y piece - would this make a difference to the smooth running?

Try new plugs as well

Bob

While it could be anything,i'd also check the air filter,cuz it doesn't take long for all the crap to settle on the top,and to be honest you could do the whole lot in one go.

Mine used to sneeze on the right side at about 2500 rpm on gentle throttle. I cured it when I set it up with the Twinmax and not had it back since.

oyster wrote:Mine used to sneeze on the right side at about 2500 rpm on gentle throttle. I cured it when I set it up with the Twinmax and not had it back since.

Just ordered a Twinmax type thingy, spoke to a really helpful guy at Motorworks, who told me to take the air bypass screws out and clean them and their sockets with carb cleaner.

It has new plugs - that was the first thing I tried, but I'm going to change the fuel filter over the weekend, clean the air filter, and just give it a good going over...

Wish me luck...

My GS was having an coughing pluttering super nightmare a few months ago... turned out to be an HT lead.

Jason

Doctor Dan wrote:

oyster wrote: Just ordered a Twinmax type thingy, spoke to a really helpful guy at Motorworks, who told me to take the air bypass screws out and clean them and their sockets with carb cleaner.

It has new plugs - that was the first thing I tried, but I'm going to change the fuel filter over the weekend, clean the air filter, and just give it a good going over...

Wish me luck...

Worth doing the valve clearances also (before balancing the throttle bodies)

Nigel B

Latest installment...

Removed the tank and after learning basic midwifery techniques changed the fuel filter, drained the tank and cleaned and re-oiled the K&N filter - which was completely filthy.

After much swearing and cursing have mostly re-assembled everything (except side panels) and put about 1.5 gallons in.

It won't start!

Turns over, no leaks anywhere, but it won't fire up and now the battery is run down.

Any tips/wisdom/clues anybody? (I can see my Bank Holiday ride fading into the ether...)

Even the misfire was better than this...

Alas! The woes and frustrations of a sunny day at last and no bike!
Back to basics. Easiest first. Is there a spark at the plug? (Check the gap while it's out!!!) Then is fuel getting to the injector? Two allen screws, same size as the fairing cover screws, secure the injector. Whip it out and watch as you crank. Should mist every rev. If either of these have failed, work backwards to trace the fault. Check throttle cables are all seated correctly in their sockets. Make sure the bike is in neutral! I've had that one. You did say it cranks o.k. so it wont be that. Good luck.

Have you got the fuel pipes the right way around.I got it wrong and I spent hours trying to sort it out. Swaped the pipes and this sorted it.

Did you reconnect power to the fuel pump?

What I've tried so far:

Checked the spark, (plugs completely dry) three pin plug from the fuel pump is connected, (also a squirt of WD40) pipes from the fuel pump back plate are connected top/top and bottom/bottom, breather pipes inside tank are connected so that the pipe with the white band on the end is on the pipe with a yellow O ring, plenty of petrol in the tank.

Pump makes the usual short whining noise when I turn the ignition on. (I assume that's the fuel pump...)

Tried getting one of the injectors out but it was stiff and I didn't want to force it. I assume as plugs are dry the juice isn't getting through.

Bike is currently on the Optimate to try to get a bit of charge back in the battery, but I'm not too optimistic of it firing up at this point...

Am guessing it must be some kind of airlock...

By the way, thatks for your help and suggestions so far guys, keep 'em coming...

Latest update...

After leaving the bike to charge over lunch, I returned and optimistically pressed the starter - it started! (with air filter in place cleaned and oiled but air intake pipe off)

Trouble is it is still misfiring! Bugger!

Would this possibly be caused by having the pipe off?

I also noticed there is a hole about two inches by three cut in the airpipe at the filter end, presumably to improve performance.

I have bought some fuel system cleaner which will be going in over the next few tankfuls.

So, to recap, I have fitted four new plugs, a new fuel filter, drained the tank, cleaned the very dirty air filter, and bought a mercury type balancer and balanced the throttles as per the instructions.

And it still misfires...

Still left to try: New plug caps, valve clearances (I'm not intelligent/brave/technical enough to do this) disconnect the oxygen sensor (it has a Laser Y piece) and somebody mentioned re-setting the electronic ignition by removing and then replacing a fuse?

Grateful for any further suggestions...

Edit - took it for a spin, filled up with petrol, still the ov=ccasional misfire but much quicker since the air filter was cleaned.

Came back and adjusted the throttle cable between the two on the gauge.

Sounds sweeter, just about to go for an evening ride...