Misfiring and Rough Running

[Deleted account 210609001]

Yes, another "Diagnose my bike's problem via the internet, please" thread.

I have a 2000-ish F650GS single spark. It runs very well nearly all the time. Today, however, it has been a complete pig. Cutting out when idling, misfiring all over the rev range, won't pull on full throttle, coughs and splutters on small throttle openings (e.g. when just going steady at 40 or 50).

I haven't done anything to it to explain this. When i last used it (maybe 10 days ago) it was right as rain.

Is there an obvious place to look for a problem?

Thanks!

 

[JayC]

Sounds like carbs.

My t/spark 650 left us stranded in Italy due to carb float/needle valve (kit) being required. She rode perfectly from the UK to Andermatt but then started behavioural symptons similar to you description.

 

[Giles]

Yeah .... the rider ...

 

[Dansin]

Check the battery terminals are clean and tight. Loose terminals can cause all sorts of odd issues on these bikes. Then carbs as above. Can you drain the float bowls to check for water?

 

[Padowan]

How many miles has it done? Could be fuel filter.

Check plug, remove and clean idle valve, reset ECU, follow bmw 'no throttle' startup procedure.

Did those on the wife's Dakar, plus a dose of Redex and it sorted a few rough running and startup probs I had.

 

[Beemerboff]

If it is an injected bike check the rubber intake manifold - it can spring a leak where the rubber is bonded to the steel flange at the head - DAHIK.

And the pins on the relays under the cover behind the steering head can corrode - pull them all and have a look.

 

[Deleted account 210609001]

Thanks for suggestions. Will have a look at those suspects tomorrow.

It is fuel injected. I didn't think they made carb models, certainly not as late as twin spark (although mine is single spark). I have never delved into fuel injection systems before.

Fuel filter should be easily changed. Disconnecting battery to reset ECU and resetting the throttle sensor is also well within my capability. FFS, even Giles could do that.

Thanks again.

 

[Giles]

Oi ...

 

[deaninkl]

A while back I had a rough running 1200, only on start up from cold, wouldn't pull a leg off a knatt until fully warm..... Changed to plugs and it was like a new bike again.

 

[Dansin]

Thanks for suggestions. Will have a look at those suspects tomorrow.

It is fuel injected. I didn't think they made carb models, certainly not as late as twin spark (although mine is single spark). I have never delved into fuel injection systems before.

Fuel filter should be easily changed. Disconnecting battery to reset ECU and resetting the throttle sensor is also well within my capability. FFS, even Giles could do that.

Thanks again.

Brace yourself for when you see the cost of the fuel filter. I'd try everything else first.

 

[DrFarkoff]

Brace yourself for when you see the cost of the fuel filter. I'd try everything else first.

My thoughts exactly I mean the fuel filter replacing ! last seen at £80 ish!! Another smart move from BMW

 

[Deleted account 210609001]

Brace yourself for when you see the cost of the fuel filter. I'd try everything else first.

I've just looked on Motorworks. I don't like to swear or blaspheme, but Jesus Fucking Christ!

I will certainly look for other quick fixes first. From the look of the filter, it isn't something than can be cleaned and reused.

It has a new-ish spark plug in it - a super-duper platinum double pronged stealth lightweight one. I will whip it out and see if it looks ok, and maybe bung an old one back in and see if that makes any difference.

Failing that, it looks like there will be a trip to my local independent. It needs some things doing I wouldn't be confident doing anyway - valve clearances, and bleeding ABS system. I think I'll be flogging it soon (not through choice ), so someone will get a nicely fettled bargain.

 

[Padowan]

Yeah, the fuel filter is a rip off as some bright spark at BMW decided to incorporate £50 worth of pressure regulator into a tenners worth of fuel filter and sell the whole thing as a proprietory part for even more profit.

Some people insert a high pressure billet filter in the line to the original filter/regulator to prevent any muck blocking the expensive part, a good option to negate the need to replace it again in the future, but doesn't help your situation if the filter is the culprit.

On the service schedule its supposed to be replaced at 24k miles/ 40k km. for me it was the last resort to get smoother idling and easier startup, but it did seen to work.

 

[Fanum]

No idea what this specific filter is, but you can get generic replacement filters with pressure regulators cheaply from any chav saxo tuning type ebay shop

 

[Timolgra]

If it were Giles asking I'd suggest you put some petrol in the tank

When you disconnect the battery or ECU leave it a few hours before reconnecting , turn ignition on, wait for dash light to go out and NO throttle.

 

[Giles]

It needs some things doing I wouldn't be confident doing anyway - valve clearances, and bleeding ABS system.

Wahey ... that sounds a piece of piss.

I'm a comin' over with me spanners Robin ..

 

[Giles]

If it were Giles asking I'd suggest you put some petrol in the tank

Yeah ... but not diesel ....

 

[Deleted account 210609001]

Well a morning in a cold, cold garage. New spark plug, new throttle cable (because I noticed it was frayed and I had a new one), battery off all morning, cleaned every little connection, made sur eair filter and airbox all connected.

The problem has almost gone away. In fact it may have goen away completely but because I've been looking for every tiny little hiccup and hesitation, maybe I'm sensing things that aren't there.

I'll use a couple of tankfuls of petrol with Redex in and see what happens.

 

[Timolgra]

Or maybe it was because you've had the battery disconnected.