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Taipan 06-25-2012 05:44 AM

ANy F800 experts about as I've broke my F800S
Hi All

My new (to me) 2006 F800S cuts out when ever you stop. You have to hold some throttle or it just dies. Its a known issue on these bikes and apparently can be down to kinked idle actuator valve hoses or a sticking idle actuator valve. So I took my airbox off to clean the actuator valve and check the hose weren't kinking as my bike keeps stalling. Cleaned the gunky residue that was on the collar of the actuator valve and put some reinforced hoses on to prevent any kinking. Put it all back together and took it for a ride. I needed fuel so rode to the garage to fill up. As I slowed to run into the garage it cut out. Sigh, looks like I made a good job of that then. Ho hum.

Anyway I fill up and leave the garage. About 2 miles down the road the bike splutters a bit. It slowly gets worse and is just dying on me like I've run out of fuel! Hold the throttle open and it pulls through it. Let the revs drop and it was just cut out.

I head for home. Bike is really dying and then lurching forward. I have to hold it at over 3k revs at junctions to stop it dying. It has hardly any power when trying to pull away and i really have to hold the revs up and slip the clutch to get it going and stop it cutting out.

I get home and remove the airbox. Everything looks fine but I put the original hoses back on. I check the actuator valve and add a light smear of grease to the white collar bit. Off out I go again.

It feels down on power and starts to surge, so I turn round and come back in. Search the archives on the F800 forums and find the bit about resetting the tps;

1. Turn on ignition but do not start the bike
2. Turn the twist grip from zero to fully open and hold fully open for 5 seconds
3. Wait 5 seconds and repeat step 2. another 4 times (do 5 times in total)
4. Then turn off the ignition and wait at least 15 seconds before turning the ignition back on.
5. Ride and try

I do this and go out again. Bike doesn't feel as bad so I think maybe a ride will let it re-learn all its settings and I head into work in London. On the motorway at 80mph for about 10 miles all feels well. Then I roll the throttle off and reopen it and the bike jumps about again sort of dying then lurching forward. I struggle to keep it running in traffic and have to again hold the revs and slip the clutch to prevent it dying. Then it clears again. It still cuts out when I stop and now has this added problem.

I've checked and rechecked all the things I disconnected are reconnected and the are. Its all back to exactly how it was before I looked at it. Could disconnecting the battery have upset something? I topped the fuel tank right up. Can overfilling cause a problem? Any ideas on what I've done or what can be causing this? Help!

ericrat 06-25-2012 11:50 AM

Is the engine light on?
It the engine light on? You might check over in Bilkes/GSpot/paralell universe, lots of f800 folks there.

Problem is, many things can cause what you describe. A cracked hose, throttle body boot, breather hose etc. can do the same thing. Basically anything that is letting unmetered air in. My wifes K75 had similiar symptoms and it was diagnosed here (quite quickly I might add) as a cracked crankcase breather hose.

Good luck,


Taipan 06-26-2012 01:00 AM

Thanks Eric, that's a good idea. I have a more info on the fault now too. I'll post up a thread.

casperghst42 06-26-2012 10:36 AM

Sounds like fuelpump issues.

Read this thread:


Taipan 06-26-2012 11:31 AM

It was better still on the way home tonight! It did cut out a couple of times but ran okay in-between. Seems having given it a few full throttle blasts its settled down. I can only think its had to relearn all its settings after my disconnecting the battery several times in a row?

sorebutt 06-26-2012 09:43 PM

I had something similar on another bike and it turned out to be the CDI. I had a friend with the same problem. I would think if it was something electrical it would show up in the codes. Have you checked the codes?

Taipan 06-27-2012 01:34 AM

No, I dont have a code reader. I think I'm going to have to get it to a dealer and get it read though. Played up a bit again this morning, its not as bad as it was, in fact its much better but still not right and its getting annoying now.

Bayner 06-30-2012 10:02 AM

Run some fuel injection cleaner through it if you haven't done that already.

Taipan 07-01-2012 05:04 AM

I havent but I will. :thumb

Taipan 07-03-2012 01:44 AM

Well I've fixed it. But I don't really know how and I don't really know if its permanently fixed, as it seems often what is initially fixed undoes it self a few miles later.[err] So the Jury is still out on whether its a permanent fix or not![lol]

Anyway, here's what I did. I refitted the reinforced idle actuator valve pipes. This is just reinforced fuel line hose but has more structural integrity than the OEM one. I tried this before as mentioned in the opening post, but along with cleaning the actuator valve it was where things got real bad, so I refitted the standard ones. But convinced these must be better than the OEM ones I refitted them last night. Before fitting them I bent them in an arc and put the ends down into a cup and softened the hose ends by adding boiling water. This allowed them to slide over the actuator and TB inlets easily and actually form around them as they hardened again.

After some odd rich running last night, I tried to think what could make it run rich. o2 sensor? Maybe but I cant really do anything about that now. So what else is there, the air temp sensor in the air box? Hmm, supposing its dirty and not sensing air temp correctly, would it then richen the fuelling? No real idea but lets have a look at it. So I pull it from the airbox. Kind of reminds me of a MAF sensor! On diesel cars I've had some real good results with cleaning MAFs with brake cleaner or even WD40. I cant see that teh temp sensor is actually dirty, but I'll give it a quick shot of cleaner (never touching it with anything other than spray!). So that's done and the sensor refitted to the airbox.

Can I think of anything else? What about this TPS reset. Never sure about this 5 second procedure which sounds odd, especially compared to a motronic 1150GSset up where you just open the throttle fully once or twice and ride off, but hey who am I to question it. So before I replace the battery I touch the battery leads together to hopefully drain down any memory of any settings. Reconnect battery and do the hold open for 5 seconds and then hold closed for 5 seconds and repeat 5 times in total. Then switch off the ignition. I gather you're supposed to wait 15 seconds before starting but I leave it over night.

This morning I come out and start the bike up and its a nice even idle around 15rpms. I ride off and the bike appears to have more bottom end grunt? I keep riding and pull out onto the motorway and as I open teh throttle I get no 3-4k splutter! 15 miles later I pull into London traffic and here's the acid test, will it idle? It does! Eureka! Not only that it idles every time I pull the clutch in and cut the throttle.[:0] First time its done this since I've had it. I've never been able to really take my hands off the bars as I need to try and catch it as it inevitably stalls, but no more! Down side is listening to it idle with the clutch out it sounds like a toolbox falling down the stairs, but hey ho, an idling bike is more important![lol]

So for now at least I have a bike which is smoother, has seemingly more bottom end grunt and will actually idle of its own accord. I'm happy. :)

Taipan 07-03-2012 10:37 AM

Well that was short lived! Started the 3-4k lurching about again on the way home and then cut out at a junction! Jeez, what is it with these bikes!

docsherlock 07-03-2012 07:24 PM


Originally Posted by Taipan (Post 19048263)
Well that was short lived! Started the 3-4k lurching about again on the way home and then cut out at a junction! Jeez, what is it with these bikes!

Mate, fuck it off and get a Wee-strom. You know it makes sense.:wink:

Taipan 07-04-2012 01:07 AM


Originally Posted by docsherlock (Post 19052109)
Mate, fuck it off and get a Wee-strom. You know it makes sense.:wink:

Lol!, possibly. But its like its thrown the gauntlet down challenging me and laughing at my determination to get it running right. We must rise against the machines!:D Ran abit better this morning. Only cut out once. I think I've got it on teh backfoot now....:rofl

EndoAgain 07-04-2012 11:50 AM

An F800S? I had one of those from 2007. Got it used and had all kinds of issues one of which was like yours. It ran great for a while but as soon as the weather warmed up, and the bike warmed up, it routinely died. Some rides it would cut out only once and on others it would cut every time I cut the throttle. The local BMW shop had multiple calls into BMWNA, couldn't find fault codes, etc. Finally they replaced the standard vent lines with a new molded unit. Can't tell you more than that because I did not do the work but apparently the older model units had soft hoses that did not maintain their integrity so they created a unit that had several molded together. Problem fixed. Read the F800S/ST pages and you will find many similar stories and their fixes. I loved that bike more than any other but had too many problems with it. Good luck.

Taipan 07-31-2012 05:51 AM

I think I've finally sussed it all out. When I collected the bike from the previous owner we had to reset the clock as he had removed the battery at some point. He did tell me why but I cant remember. Anyway, disconnecting the battery causes the ECU to lose its TPS settings, so it basically had to re-learn them as I didn't do the reset TPS procedure.

Further to this it turns out the bike had a faulty IACV (Idle actuator Control Valve). In case anyone wants to see a working IACV in situ and working I took a video of it inside the airbox. Not great quality as I had to stick a led torch in the airbox for lighting and my video camera is only a Lumix camera.

You can see it travels downwards when you put the ignition on. When you switch the ignition off it rises and then lowers to its starting point.

As I said the first one is the original one and is actually faulty. If you listen you can hear it struggle slightly and the movement slows down. Its subtle but its enough to make the bike stall on occasion and generally run rough at lower revs.

This is a replacement one. You can hear the motor noise is constant and the movement is constant too. Not much in it to look at but its a world of difference on the bike. Its smoother and picks up better at lower revs and of course doesn't stall! :clap

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