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Discussion Starter #1
Hi guys. I hoping someone can point me in the right direction. In the last couple of days, my K9 650 has developed an irritating fault. It runs fine on the highway, but stop/go in suburban streets is a bit hairy.

Intermittently, it decides to not idle when I cruise to a stop at a set of lights. The engine will die. I can twist the throttle a bit to control this, but when I go to take off, the engine bogs down. When I try to increase the revs to get more power, it stuggles up to about 3000 rpm, running quite roughly, but still bogs down when I start releasing the clutch. Generally, this clears after about 2 to 5 seconds, and the engine suddenly roars back to normal life. I then continue to ride normally until the next time it happens. That might be the next set of lights, or it might not happen for 5 minutes.

I also notice it sometimes on a steady or trailing throttle around 3-4000rpm, and it will stumble when I try to accelerate. It's only a quick stumble, maybe about a second, then the power is back on. So far, anything over 4000rpm is completely normal - no loss of power, excess vibration, or anything else I can notice.

My first inkling was last week when I went to start it at 0300 on a cold morning (5 degrees C / 40 F ). It didn't immediatly start like it usually does. After a couple of quick jabs on the starter with no luck, I held the starter button down for maybe 5 or 6 seconds, and it fired up. I've never had that happen before. It was probably the coldest its (ever?) been when I've started the bike, but it's still not that cold, and shouldn't cause any issues. But maybe cold enough to show up any underlying dodgy electrical connections? Anyway, after it eventually started, it ran fine, and I rode it for an hour to the airport. When I got back to the bike a couple of days ago, I was a bit dubious about how it would start, but it started fine. About 5 minutes in to the ride home, as I slowed for a set of lights that turned green as I approached them, the engine seemed to lose power. No warning lights, just felt like it had no power, and ran real rough as I tried to accelerate. I was just heading to the side of the road to pull over, and it came to life. I continued on to the motorway for an hour, then when I pulled in to my local streets, it did it once more. I rode it again yesterday, and it is getting worse.

Battery is a couple of years old, and reads 13.8v with anything above 1500rpm. Spark plugs are NGK Iridiums, about 40,000km old. Bike has done 80,000km. I pulled the plugs out, and they all look pretty normal - no black deposits or white burning. I'm wondering if a corroded connection might be affecting the FI? Why does it only happen at low revs? Fuel should be ok. I had 98 RON in it at the airport, and I filled it up on the way home with more 98 RON - no difference in performance. Annoyingly, it runs fine in the driveway at home - idling sweetly, and reving smoothly.

Can anyone offer some suggestions on where I should be looking?

Cheers
Dean
 

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A check list of things that could possibly be causing these symptoms:
1) a shorted out clutch switch or clutch switch not releasing
2) a TPS could be busy failing
3) a fuel pump not always providing enough fuel
4) evaporative canister issues (if installed)
5) a bad electrical connector or earth connection

For info on the TPS internals, https://www.sportbikes.net/forums/fz6-fz6r/7320-throttle-position-sensor-issues-you-experiencing-poor-idle-mileage-stalls-25.html#post2105110
For a fuel flow test, http://www.vstrom.info/Smf/index.php/topic,3981.0.html
 

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Discussion Starter #3
Thanks for the response Gert. I've had a little time today, so checked the TPS. Seems it was a little out, as the readout in Dealer Mode showed the dash before C00 in the upper position at idle, and the idle speed was a bit low, sitting around 800rpm. A slight adjustment put the dash in the centre, and upped the idle speed to about 1300rpm. Only had time for a short test ride, but all seemed well. Since it was an intermittent fault, I'll go for another, longer, ride tomorrow, to see if the fault returns. I'll leave it in Dealer Mode during the ride, so I can see what is happenning.

Cheers
Dean
 

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With your mileage the TPS could well be the cause, especially since the symptoms are at low throttle opening.

Gerts list is excellent. I would verify #1 is working properly, #5 making sure that battery and ground contacts (at both ends) are clean and tight. #3 symptoms of a failing fuel pump are typically at high fuel demand (going uphill not revving up normally), so less likely unless you have an intermittent fuel pump failure issue (would be non typical).
 

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Discussion Starter #6
Went for a longer ride today, to ensure everything was definitely warmed up. All went well. Engine runs cleanly at idle and low revs, and still revs to redline cleanly.

The only thing in your list that I have checked, Gert, is the TPS. I wanted to adjust one thing at a time to try to isolate what the fault was. It seems that might have been the issue. I had already gone over the bike to check all wiring connections and rubber hoses etc in detail, and hadn't noticed anything amiss. If the problem recurrs, I'll go further down the list.

This is the first time I've posted in the forum with a query on my bike - generally I've been able to search and find someone else has already had the same issue. Great forum. Thankyou to Gert, and all those other members that help others every day.

Cheers
Dean
 

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My TPS passed the resistance, volt, & sweep test. I took an educated guess & replaced it anyway. Fixed.
Point being, I found that the test was inconclusive, for me. Maybe you'll get lucky & it will fail the test. But like Gert said, "could be."
 

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Discussion Starter #9
Went for a much longer ride today - 3 hrs, including an hour of busy city traffic, and it didn't miss a beat. I'm now of the opinion the original problem was dirty contacts in the TPS, and my moving it around as I adjusted it has temporarily cleaned it enough to work for now. I'm going to buy a new one, and replace the original one before it dies again. I saw a post about cleaning the internals of the TPS, but I will just bite the bullet and get a new one.
 

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When was the last time your throttle body were synchronized?

A friend had intermittent stalling issues on his 2006 650.

Changed the TPS, didn't fix the problem. He swapped the whole throttle body assembly and CPU, but it still stalled.

Finally he did a throttle body sync and the bike has been working fine ever since.

Maybe it's worth a try before you buy a new TPS.

Sent from my Redmi 4 using Tapatalk
 
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