F650GS Twin Stalling

Inspired by CycleRob, this section is devoted to all flavors of the F800.

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Boxer
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F650GS Twin Stalling

Post by Boxer »

Last week I had my Lil Chubb in a local motorcycle repair shop to have valves adjusted/shimmed and when I picked it up on the ride home it stalled about 6 times when I slowed in traffic or at a light. Yesterday I took her out again to check it and I was able to make a stall happeb at a stop sign and once Just decelerating as I approached a stop sign. The tach has a little "bump" in it on the way back to idle, when decelerating rapidly. It will move quickly to about 1500, then bump, then move on down to about 1100 which is idle. I noticed that when the tach hits that little bump is when the engine shuts off. I can immediately hit the starter and it fires right back up.
My question is this: when the battery is disconnected for maintenance and the computer has to reset, could this be causing the stalling, until the fuel mapping has reset, adjusted, then reset again, etc.?
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Re: F650GS Twin Stalling

Post by sweatmark »

Boxer, did you have the infamous early-F800 stalling behavior previously? Or did it just start after service?
My F800S had a bad case of the stalls, which was "fixed" by BMW remap upgrade in response to the widespread problem. I've only experienced a couple of decel/stop sign stalls in the past 5 years.
I'm due to install Af-XIED on the F800, and have been very pleased with the results of same install on my Rockster. Wondering if doing the mod might address the stalls because of the change to richer mixture.
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Re: F650GS Twin Stalling

Post by Boxer »

Yeas it has happened before. When the bike was relatively brand new, it did it a few times then no more. Last year it stalled inexplicably after making a turn and accelerating, in the rain. That was, more than likely, a different issue, same symtom. But it has not stalled repeatedly like this for a long time. I have always gone through the initiation procedure with the computer after the times I've done maintenance requiring a battery disconnect. I haven't yet mastered Rob's technique of keeping the battery hooked up while removing it from the bike, so I just let the computer zero out and re-initiate it upon reinstall. I wonder if the mechanic bothered to do that this time. That's the first time someone else besides me has done maintenance on it.
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Re: F650GS Twin Stalling

Post by sweatmark »

Boxer wrote:Yeas it has happened before. When the bike was relatively brand new, it did it a few times then no more. Last year it stalled inexplicably after making a turn and accelerating, in the rain. That was, more than likely, a different issue, same symtom. But it has not stalled repeatedly like this for a long time. I have always gone through the initiation procedure with the computer after the times I've done maintenance requiring a battery disconnect. I haven't yet mastered Rob's technique of keeping the battery hooked up while removing it from the bike, so I just let the computer zero out and re-initiate it upon reinstall. I wonder if the mechanic bothered to do that this time. That's the first time someone else besides me has done maintenance on it.
Hope it gets back into the groove.

I'm concerned about long-term effects of the 10% ethanol on fuel systems: wetted parts not designed to withstand effects of the mandated fuel mix. For Rockster, the fixed speed fuel pump and fuel supply system is easier to work with; for F800/700/650 bikes, variable speed pump and associated logic system is simpler (parts count) but more abstract for diagnosis. For my new S bike, BMW dealer has already told me to add fuel system conditioner regularly because of the ethanol. And all this is before we talk fuel mapping and ECU.
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Re: F650GS Twin Stalling

Post by CycleRob »

Boxer,
I'm surprised you did not tackle the cam removal yourself, use BMW-Atlanta or myself . . . although the delay in getting the shims needed would require practically a full day house-call. Then again, your schedule and obviously happily married life figure into the decision.

The stalling sounds like either a loose battery connection (even though the starter works) -or- one of the connectors is not fully plugged-in. The bobbing tach needle sure does indicate a circuit interruption. Strange that it did not set the orange/red/yellow warning/fault triangle indicator.

I have seen loose battery terminals be able to start the bike while causing a flickering headlight, stalling, etc. The high current draw of the starter temporarily "spot welds" a small area of the the poor connection while the lower, sustained current from the alternator and intermittent connection break to the battery raises hell with the bike's ECU (CAN-bus) system. There is even the possibility of a pinched/crushed component wire during the reassembly.

So . . . how many shims did it take and did you get the old shims?
.
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Re: F650GS Twin Stalling

Post by Boxer »

I took it to Paul's Garage in Dallas. Nice guy with a family and a daughter who is undergoing cancer treatments at Egleston. He has a good reputation and used to work for BMW Atlanta as one of their techs. When they let him go he opened his own shop. I just didn't feel confident to tackle the camshaft removal, etc. myself and I kind of thought at least one would need changing out.
I totally did not even think about asking for the shims taken out, but Looking at the sheet he gave me, he changed out 4. They all were still within tolerance but I told him to change them if they were close to the tight end of the tolerance range.
I'll open up the cover tomorrow and check the wiring connections. That new Yuasa battery had some funky nut/bolt connections that were tricky to tighten when I installed it, so that may be part of the problem.
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Re: F650GS Twin Stalling

Post by CycleRob »

Boxer,

I'm glad you clarified everything, and I must say you made the right timely choices and for a really good cause. =D>

Removing/Replacing both camshafts seems difficult and it can be if you have not been walked thru it to learn what is important and how the unaware can do expen$ive damage before and/or after the engine is started. :shock: :oops: #-o [-(

It requires patience and a complete understanding of the need to coordinate:
-- an exact, locked-down crankshaft TDC
-- the correct cam timing after the cam bearing plate is in place (it changes as the bearing plate is lowered in place by the stud nuts)
-- the bearing plate removal loosening and tighten-down parallel evenness, so you do not bend or crack the casting or damage/dent the end-play surfaces
-- cam and bearing surface cleanliness and lube oil on reassembly
-- shim rocker cup location data recording errors, clearance needed math errors, feeler gauge measurement errors and shim storage mix-ups
-- dropping a shim down inside the engine
-- under or over tightening nuts, bolts and screws

Every experienced Honda/Yamaha/Suzuki/Kawasaki dealer mechanic (originally me) should be able to breeze thru the F800 valve adjustment with ease because similar designs and the same parameters apply. Of course the BMW guys have top billing, the parts to do it all and will update the service reminder . . . . While-U-Wait (if necessary).
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Re: F650GS Twin Stalling

Post by Boxer »

Update on the stalling issue.
I took everything back off the bike to remove and inspect the air box reassembly that the mechanic's inept helper attempted to put together. He had left off a couple of parts and really mixed up the oem screws and such. I had to replace the o-ring in the crankcase vent hose adapter in order to seal that opening. While I had it apart I replaced the air filter and drained/replaced the coolant. After buttoning it back up carefully replacing the air box onto the throttle bodies and making sure all connectors were tight, it runs much better.
I rode about 1000 miles this past weekend, in all kinds of weather, and it stalled a couple of times upon rapid deceleration and/or hard braking scenarios. Once or twice it just inexplicably stops! Then restarts with no problems. This may be attributable to the ethanol fuel issue or just a weakening seal along the air intake somewhere. Much more tolerable now than before though. I haven't had a diagnostic done on it yet, but that may reveal something when I do that.
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Re: F650GS Twin Stalling

Post by CycleRob »

Boxer,
In your first post you said: "The tach has a little "bump" in it on the way back to idle, when decelerating rapidly. It will move quickly to about 1500, then bump, then move on down to about 1100 which is idle. I noticed that when the tach hits that little bump is when the engine shuts off. I can immediately hit the starter and it fires right back up."

My best guess involves 3 components. The TPS (ThrottlePositionSensor), CPS (CamshaftPositionSensor) and the ICM (IdleControlMotor).
That TPS is extremely active in normal riding, so some wear of the stationary resistance strip or movable slider contact is normal. When the TPS internal wear goes deep, an open circuit will occur, usually just off idle at the normal cruise throttle setting. That'll cause the ECU to react and that disruption can stall the engine. The TPS appears to be high quality and well sealed, but the seal around its' rotating shaft has to wear over time, especially with all the "every-type-of-weather" sometimes interstate riding you do. That'll let in dirt/water that'll raise hell with the lifespan. The same type of component on cars/trucks with EFI seems to last forever. With all the riding you have done, it seems possible the TPS is near the end of its' lifespan -or- BMW has redefined what that lifespan is for them.

The CPS component is usually damaged/killed by excess engine heat and/or engine vibration. Since it is expensive, it should be the last replacement suspect, and hopefully we can monitor an intermittent data running misfire with my GS-911.

The ICM also is also extremely active in normal riding, subject to wear that can cause it to bind and be slow to respond, stalling the engine. It does not however cause the tach needle to "hit a little bump" during a sweeping movement. Anyway, I would inspect/clean/re-grease it just because the bike will be apart and I found it does get gunked up slightly over time.

We can get together (Gimme a call) and hook up my GS-911 to it for an error code check and TPS/ICM/CPS component real-time readings and setting/recalibration -after- we take it apart for wire/connector inspection and TPS Ohmmeter tests to look for a dead spot from Idle-to-Full throttle. BTW, There are excellent pizza houses near either of our places.
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Re: F650GS Twin Stalling

Post by Boxer »

I haven't been riding much since I made my move to south Alabama, but I DID make a long ride a couple months ago up to Kickstand lodge with a few friends. I believe it was actually over that total eclipse weekend. Put about a thousand miles on over the weekend. Anyway, the unknown stalling issue persists under certain circumstances. It seems to be more prone to do it when very low on fuel. So I'm wondering if it might just be the charcoal canister being in need of replacing.Any ideas on that.

I now have 52K miles on her and have kind of lost that "loving feeling" for Lil Chubb of late. Possibly time to think about switching. I'm looking at Triumph and Honda as possible alternatives to BMW. Although I DO have a secret lust for the R1200RT touring bike.
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