my surging cured ? - Kawasaki Versys Forum
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post #1 of 4 (permalink) Old 04-17-2010, 12:26 PM Thread Starter
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my surging cured ?

after many many hours of searching the internet, on both versys and other bike forums.
Having examined and reviewed their fixes for FI leaning out the mix caused by the closed loop, o2 sensor etc.
looked at reviews and reports on memjet modules, PCs, others
I decided I wasn't going to have another British summer haunted by this annoying trait.
After reading up on resistors, potentiometers, checking the versys manual for allowable voltages etc
I purchased a couple of potentiometers and a mulitmeter and decided I was going to fix this one way or another.

Anyway Today disconnected O2 sensor plug at side of engine, and just for to see started it up.
No major disasters, yes FI light was on as expected.
Having read about it, tried the starting the engine before the FI boots up completely, yes that worked, engine running no FI light.
So again just to see I took her for a half hour spin, completely different bike,
I'm a lot happier
No surging, engine running very smoothly, when caught in traffic burbled along at 4k revs nicely, no snatching at throttle. Less engine braking as expected with more fuel in the mix.
Seemless transition from low to high revs.
No strong smell of fuel when i got off, or coming from exhaust at idle.

yes i expect fuel consumption to rise a bit
Not counting any chickens just yet, but i'm hoping perhaps ?
what do you think ? potential disasters ?
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post #2 of 4 (permalink) Old 04-17-2010, 03:05 PM
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I am just curious as I don't seem to have your problem but what were you going to use the potentiometers for? Some insight would be nice especially for any others that might be suffering from this same condition.
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post #3 of 4 (permalink) Old 04-17-2010, 03:36 PM
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The science of O2 sensors as I understand it FWIW.

From what I have gleaned on this subject from my car tuning days is that on our European specification bikes, is that a 'closed loop clean air' system is used to read the Oxygen sensor (lambda) located in the exhaust pipe, and under certain conditions, temporarily change the air/fuel ratio to the “stoichiometric” value of 14.7:1. This is to provide a chemically efficient burn for low rpm cruising and to aid emissions.

The closed loop circuit has a very limited operating range, which is only in effect while holding a steady speed at certain rpm and throttle positions. This ratio, while good for the environment, creates flat spots and a lack of torque that is required in certain instances, even in the low rpm area.

The Oxygen sensor can be disconnected but this will trip the F.I. warning light on the bikes dash.

You can either, by using the Dynojet Oxygen sensor eliminator ~ 20.00 or make your own Oxygen sensor eliminators by installing 330 ohm - Watt resister across the heater leads to the OEM sensor to stop the FI warning light illuminating / giving an error.

Unfortunately some Ecu's aren't fooled by the O2-eliminator mod and when it enters closed loop mode, it tries to adjust the air/fuel ratio. Unfortunately, any adjustments the ECU makes won't register because the O2-eliminators are sending a constant signal to the computer. So the ECU continues to adjust the air/fuel mixture in a vain attempt to reach the stoichiometric ratio and it eventually leans out the air/fuel mixture so much that the engine loses a ton of power. Then when you twist the throttle a bit, the ECU leaves closed loop mode and goes back to the default map. The engine suddenly makes power again and the bike lurches violently forward.

Ironically, the O2-eliminators are suppose to make the ECU think everything as just fine when it enters closed loop mode, but it instead has cause some bikes to surge severely.

The trick around this is to prevent the bike from entering closed loop mode. On some bikes you can fool the ECU not to go into closed loop mode by starting the bike before it has completed its FI / ECU boot up process

If you start the bike before the ECU finishes its boot up cycle, then it won't go into closed loop later. My guess is that by starting the bike before the ECU boots up causes an error in the ECU. To protect the bike, the ECU loads the default map and sticks with it. So, once you turn the ignition on, start your bike immediately and you shouldn't have any more surging issues. (Likewise, there's no reason this wouldn't work for bikes without O2-eliminators either).

This is a suggested start up procedure that could work:

1) Turn ignition on.
2) Put the bike into neutral.
3) Wait for the fuel pump to prime the fuel system.
4) Once FI system is primed, then in quick secession: turn ignition off, push the starter button, turn ignition on, release starter once bike starts.


Last edited by TowerMan; 04-17-2010 at 04:27 PM.
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post #4 of 4 (permalink) Old 04-17-2010, 07:06 PM Thread Starter
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I understood most of what you said Towerman
Before I tried the simple option, unplugging sensor and starting before bootup complete.(which hopefully seems to be working)
I had thoughts of doing a little creative wiring with a potentiometer/resistor to add resistance to o2 sensor output voltage, this hopefully would have told the ECU it was running too lean and added a little fuel, up to what it thought was the correct ratio, but would have been actually a little bit richer.
Further reading on an Audiworld web site suggested that a rectifier diode would be the correct item to use (not a resistor). I'm not an electronic expert, I have to research everything.
Hopefully I won't have to try either. (jury will be out for a few weeks)
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