650 GS Problem

[cunny]

Hi
I Have a problem with my single spark 2001 650 gs.
when i slow down for a roundabout then open the throtle it just grunts for a few seconds then picks up.I Have changed the air filter and spark plug. its only done 19,400 miles.can any one help please.

 

[wa0990]

Did you fill up at recently?

Sounds like it might be dirty fuel, the filter needs doing every 24k though so your a bit early. Does it have an in line fuel filter too? People sometimes put them in cos the BMW one cost over £70!

Of course it might be something else, some more info would help mate.

PS Does it have carbs or Fi? (cant remember for 2001)

 

[(RIP) The Wilbur]

If it's a GS, it'll be Fuel Injected.

I would suspect that you are just letting the revs drop too low. With the earlier, pre twin spark, GSs, letting the revs fall below 3k put you in the flattest of flat spots & the quickest way out is to change down a gear & increase the revs.

Just because it's a 650 single, don't expect it to pull out tree stumps from 500 rpm, cos it wont!

Best performance is between 3k - 7k rpm. Change down BEFORE the roundabout & accelerate through.

 

[Mouse]

When you changed the air filter, did you remember to reconnect the sensor in the inlet snorkel?

 

[cunny]

650gs problem

Its only got the bmw inline filter. Yes I have put the sensor back in when i changed the air filter.Just come home from work and its fine up through the gears but when as you say drops below 3000 revs its very hesitant (lumpy)but the revs dont drop off even on a straight road and when you open up it sort of dies then picks it self up then its ok.I Think its either the fuel filter or the single point injection???? I Only use BP Fuel.I Think possibly on high revs its pulling the fuel through and on low revs its strugling to pull the fuel. Any more thought guys.
Thanks
Cunny.

 

[andy]

Battery terminals loose possibly

 

[Smelly Biker]

Second that for battery terminals, or maybe the battery is just knackered. Check for loose connections or signs of corrosion on the contacts.

With the battery disconnected for a while it'll also reset the 'brain', so it'll forget the throttle closed position etc. When you start it up leave the throttle closed so it can learn that again.

 

[cunny]

650 gs problem

Thanks for that it's a new battery But the old one the terminals were loose. How long do I have to disconnect for to reset the brain.
Thanks
Cunny.

 

[Spout]

Re you poor running:

As SB says, when you start the bike leave the throttle well alone. On initial start up the "brain" decides where throttle off is - so if you've got it partly open on start up then it thinks this is no throttle. If you see what I mean.

Happened to me numerous times. Cure - stop bike, and then restart without any throttle.

 

[dotcaf]

If you've just disconnected and reconnected the battery, you could also try setting the TPS (throttle position sensor) as follows:

1) Turn key to on position (don't start bike)
2) Turn throttle slowly to maximum, then back to minimum (repeat 2 further times)
3) Turn key to off position.
4) Key to on and start bike as normal by holding down starter button (no throttle)

C

 

[cunny]

poor running

I Will try that guys. I Always open throttle when I start the bike up.
Thanks
Cunny

 

[Smelly Biker]

Thanks for that it's a new battery But the old one the terminals were loose. How long do I have to disconnect for to reset the brain.
Thanks
Cunny.

10-20 minutes should do the trick, enough time for a cuppa and smoke.

You dont have to teach the 'brain' the throttle range, just crank it over with the throttle fully closed so it gets the zero position and it'll sort out the rest.

If you've fiddled with the TPS sensor you'll need to do a brain reset anyway so it picks up the new value.

 

[cunny]

Thanks Lads for all your help. Disconnecting battery done the trick.
Thanks
Cunny.

 

[komatias]

At the risk of sounding patronizing, most people complain about the single spark at low revs because they are simply in the wrong gear. The bike should behave perfectly if you stay in the 2500-4000 rpm range and in the correct gear.

Of course if there is a delay in the response from the throttle, it might be the throttle potentiometer. Give the air intake sensor a good clean too, it pops out of the throat to reveal a thermocouple. When I washed mine it made a hell of a difference.


Good luck sourcing the probs

 

[Marks adventure]

the first time i rode my sons dakar i thought it was lumpy and somthing was wrong.

I took it out for another run and rode it like i had nicked it.....BLODDY HELL it was FUN!!!!

I made the mistake of being in the wrong gear for the revs.

My advise is RIDE IT LIKE YOU HAVE NICKED IT and you will have hours of fun.