03 GSA engine unstable

[dubweiser]

hei all,

i have some problem here:
when riding in 1, 2, 3 gear in around 3000 rpm, i feel like my bike is throwing itself very very little front and back. when i was riding yesterday with my friend 1100 (new sparks, valves- throttles balanced), he have the exact same symptom.

it seems like the fuel injectors does not give the fuel normally
cannot belive it can caused sparks, etc, because if the spark is unstable, the bike will run totally unstable. but with our bikes it is very little, possible to feel only when riding in smooth surface with unchanging throttle.
i have read here a lot about "surging", but dont understand properly, is it the same thing. or is this surging just the engine vibration in around 3000rpm.


thanx ahead,
Joel

 

[Spout]

i have read here a lot about "surging", but dont understand properly, is it the same thing.

Yes.

Basically the engine management system (EMS) isn't good enough and can't decide how much fuel to provide accurately (on a steady throttle opening). So gives too much for a while, realises it's too much, then gives too little, then too much, then too little etc. Sort of cycles between the two.
You wont feel it accelerating or decelerating (the EMS knows what you're doing).

Accurately setting up valve clearances, balancing throttle bodies and TPS setting can reduce the effect. And a bad sensor can aggravate it.

Do a search on here or Advrider for lots of info on how to reduce it,

Hope this helps.

 

[Canuck]

SOunds like surging to me... but I'm no expert. I'd make sure my valves were spot on and throttle bodies balanced. Hopefully that will make it better and it doesn't take long to do.

 

[dubweiser]

TPS setting can reduce the effect. And a bad sensor can aggravate it.

thanx Spout for the info.

what sensor do u mean, TPS?

vcan also faulty lambda sensor cause surging?


Joel

 

[Canuck]

Maybe the o2 sensor... otherwise referred to as the lambda probe that you should see sticking out of your catalytic converter under the bike. If you do a search on here I'm sure you can find a thread that tells you how to check so see if it is working... but you will need a voltmeter.

 

[The smudger]

Is it twin spark? i had this, it was a stick coil. Does your bike have coil on plug? sounds like it could be that. Mine started just like yours, very slight jerk at mid-high range under load. I renewed both coils, superb, what a difference!

 

[dubweiser]

Is it twin spark? i had this, it was a stick coil. Does your bike have coil on plug? sounds like it could be that. Mine started just like yours, very slight jerk at mid-high range under load. I renewed both coils, superb, what a difference!

twin spark

Smudger, how u realised, it was stick coil? by just replacing them?





and like i read, taking up the slack in the throttle cable helped the most. has anyone tried it here with good result?



Joel

 

[Steptoe]

twin spark

Smudger, how u realised, it was stick coil? by just replacing them?





l

To test...
Pull the caps off the lower secondary plugs and see if it runs on only the two stick coils/main plugs.

 

[Spout]

cannot belive it can caused sparks, etc, because if the spark is unstable, the bike will run totally unstable. but with our bikes it is very little, possible to feel only when riding in smooth surface with unchanging throttle.

Joel

A faulty ignition (coil/plugs) will usually be felt under load. So I doubt it's your coils.

Edit: But maybe not if it's a twin spark

 

[Steptoe]

Joel

A faulty ignition (coil/plugs) will usually be felt under load. So I doubt it's your coils.

Not necessarily so on a twin spark.........

 

[The smudger]

As Steptoe says, mine felt wrong all the way up from idle to full load.