Engine not running smoothy on light throttle pick-up

[Bendy toy]

Feeding in throttle e.g. exiting a bend, I get a stutter before it picks up smoothly. Its never a driving issue but causes some transmissions snatch. Power is good and fuel consumption is about 45mph as normal for for me.

Any ideas before I start digging about.

R120GS Adventure 2008 68,000 miles.
Odyssey battery
GS alternator (the smaller one)
Primary coils replaced in 2013 with the later stainless sleeved type
Original secondary coils
Fuel pump replaced last year.
Later type fuel pump controller.
Power Commander 5


I need to check the throttle balance but in all my ownership its never been out more than a touch.

I'm thinking secondary coils (maybe) but when I ran the bike with them disconnected they made no difference I could detect. Back then I had no light throttle pick up issues.

Any ideas?

 

[Tractors are go]

Easy to diagnose:

The owner is too sensitive !



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[Tractors are go]

What about cleaning the injectors ?

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[Kersidan]

I had a similar problem on my '06 GS that lasted over a year. Manifested as slight misfire on throttle loading/acceleration, didn't happen all the time. Traced to a faulty secondary plug, it had a hair line crack almost invisible in the ceramic insulator. A set of new plugs cured the problem immediately and it has never recurred.

Mark

 

[Bendy toy]

I had a similar problem on my '06 GS that lasted over a year. Manifested as slight misfire on throttle loading/acceleration, didn't happen all the time. Traced to a faulty secondary plug, it had a hair line crack almost invisible in the ceramic insulator. A set of new plugs cured the problem immediately and it has never recurred.

Mark

Thanks for that. Apart from checking the throttle balance that was my next place to look. I'll do it first and see if it helps.

 

[Bendy toy]

Easy to diagnose:

The owner is too sensitive !



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Could be but this is a 1200 with all the designed in transmission issues.

 

[Tractors are go]

I know it so well; built in obsolescence.

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[Magwych]

Feeding in throttle e.g. exiting a bend, I get a stutter before it picks up smoothly. Its never a driving issue but causes some transmissions snatch. Power is good and fuel consumption is about 45mph as normal for for me.

Any ideas before I start digging about.

R120GS Adventure 2008 68,000 miles.
Odyssey battery
GS alternator (the smaller one)
Primary coils replaced in 2013 with the later stainless sleeved type
Original secondary coils
Fuel pump replaced last year.
Later type fuel pump controller.
Power Commander 5


I need to check the throttle balance but in all my ownership its never been out more than a touch.

I'm thinking secondary coils (maybe) but when I ran the bike with them disconnected they made no difference I could detect. Back then I had no light throttle pick up issues.

Any ideas?

Secondary coils is my guess. Those are the symptoms. When you disconnected them it was the same? Surely that hints that it is the coils failing, rather than prove they are good?

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[Bendy toy]

Secondary coils is my guess. Those are the symptoms. When you disconnected them it was the same? Surely that hints that it is the coils failing, rather than prove they are good?

Sent from my SM-G388F using Tapatalk

Thanks for this. They are the originals but not wanting to replace on a suspicion.

The last time I disconnected the secondaries the plugs were all looking good and there was no stuttering misfire at low throttle. The main coils failed gradually so were only diagnosed when they stopped altogether.

Thanks for the tip on symptoms.

 

[The bigun]

Mine has done exactly the same last week whilst riding around the picos it would misfire at 2750 rpm to 2900 rpm whilst under load 2 up luggage etc but would be fine any where else in rev range I'm hoping a plug change will cure it

 

[Bendy toy]

Mine has no misfire at those revs. It will pull smoothly from under 2000 (with care - its a big twin) to the red line. But coming on throttle in traffic or feeding into a bend it stutters and snatches when it never used to.

The mid revs issue just might be primary coils. Changing the plugs seems to help but it will go off again quite quickly.

But before I cause a stress rush, the later stainless jackets coils are reliable. The older black painted coils will fail between 30K and 50K miles. If the coils smell burnt its likely to be the issue. Pop off the wiring cover and take a sniff. I thought it was normal until I bought new coils and the slight smell was gone.

PS
If it is a coil issue - buy a pair. When one fails the other will soon follow.

 

[The bigun]

I suppose I could describe mine as a stuttering as well I'll check it out next week and see if my GS-911 will show anything but I did have a similar problem years ago on a kawa that was plugs

 

[Bendy toy]

The 911 wont directly diagnose a coil problem. That's done by looking for symptoms caused by coil problems.

The engine should run on secondaries only (though pretty badly) so that will be where I start.

 

[Bendy toy]

The plot thickens. It stuttered to a stop this afternoon with all the symptoms of fuel starvation. Next step - a pump controller by pass adapter wire (never carried one).

 

[KP100]

Would an ACCELERATOR Module sort it?

 

[Mistacat]

As you run a power commander and they say do not alter the fuel table in that area,try adding / subtracting a little fuel in those cells.
Without the lambda sensors connected the BMSK cannot correct any fueling errors.
Ideally need to see what the AFR is doing at the point of stutter to ascertain if it is fuel or ignition.

 

[Bendy toy]

As you run a power commander and they say do not alter the fuel table in that area,try adding / subtracting a little fuel in those cells.
Without the lambda sensors connected the BMSK cannot correct any fueling errors.
Ideally need to see what the AFR is doing at the point of stutter to ascertain if it is fuel or ignition.

The Power Commander is an engineered bodge (fully agree) but its done 20,000 at least with no problems. The stutter only began a week or two ago.

Now that it's stopped we will see if the fuel pump controller was the culprit. Going out now with some wire and pliers. This time I'll have phone call the breakdown recovery service.

 

[Bendy toy]

Bike recovered. Spare pump controller didn't work.
At home, a controller bypass also didn't work. Also the starter has finally let go. It's been lazy when hot for a while now. Trying to get a hot bike going again - it's now lazy all the time. So an expensive day ordering a new fuel pump and service exchange starter motor.

 

[GreatScot]

Bike recovered. Spare pump controller didn't work.
At home, a controller bypass also didn't work. Also the starter has finally let go. It's been lazy when hot for a while now. Trying to get a hot bike going again - it's now lazy all the time. So an expensive day ordering a new fuel pump and service exchange starter motor.

Could be worse - you could be allergic to spanners and rely on recovery to a main dealer. I enjoy working on the bike almost as much as riding it. Mine's only 4 years old though and I've only serviced it and taken a few things apart so i could put them together again! Good luck getting back on the road quickly.

 

[Bendy toy]

Could be worse - you could be allergic to spanners and rely on recovery to a main dealer. I enjoy working on the bike almost as much as riding it. Mine's only 4 years old though and I've only serviced it and taken a few things apart so i could put them together again! Good luck getting back on the road quickly.

There is that!!!

I really could do without it right now. My commute mileage has rocketed recently. Thankfully a mate lent me his car for the cost of adding me to his insurance.

Motorworks came through. Fuel pump cheaper than eBlag and remanufactured Bosch starter only slightly more cost than a new yobbo brand starter.