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[Merlin]

Hello all,
first post here, hope this is not a FAQ.

Bike:
2014 Classic 500, EFI with a bit over 12000km on it.
I've had it a couple of months now, and it's been great - until...

Symptoms:
* uneven idle

* hesitating/surging when riding in traffic at 60km/hr [~20% throttle]

* engine coughs/dies, sometimes backfires when "blipping" the throttle on down shifts.

* once it has revs [say, over 1500 or so] if you give it a hand full of throttle it performs as it should. Seems to have normal power as it did before, but only when you get up it. Power fluctuates at around 20% - 40% throttle position.



Troubleshooting steps taken so far:
* replaced spark plug. Old plug was fairly black, but not as bad as some I've seen. I'm told these EFI bikes are tuned to run a bit rich.

* replaced air filter. It was quite dirty.

* drained the fuel, removed the tank, pulled the fuel pump off and cleaned the filter. There was a bit of crud in there but again, I've seen worse.

* Refilled with new fuel and gone for a test ride, no change.



BTW dealer I bought it from said they gave it a full service - about 1500km ago. It has a new battery.



Any help will be very much appreciated.
What do you suggest as next step?
Have you seen this kind of problem before?
Has it been discussed on this board before and I didn't see it?

Cheers!!!

[Merlin]

eeewwwww
just saw my post, seems all the line feeds have gone.
Is there some kind of markup/formatting language on this board?

[hagis]

[hagis]

[Haggis]

Try disconnecting the lambda sensor? Your problem seems to be occuring in typical closed loop running. You could also check the voltage of the TPS?

[hagis]

Contrary to your post the EFI engines are set to run on the lean side not on the rich side this is to keep emissions as low as possible, with this type of problem, check - is the battery fully charged, EFI bikes need a very good battery to run, if your battery is more than two years old or been standing for a few months without use then replace battery, - try new spark plug and replace plug cap with a new NGK resistor type cap, if still playing up then you have a sensor problem, check all sensor connections and relay connections by taking apart and reconnecting, if still playing up then, what is the MIL light doing on off flashing?, then you may have to do a sensor test to check sensors ect.

[Merlin]

Hi Haggis/Hagis,
thanks for your replies.

What's a lambda sensor? I've just done a search through the service manual and it's not mentioned at all.

The battery is new, and was reading 12.8V after sitting all week not started.

[Merlin]

oh btw the MIL light is not coming on at all.
Maybe the globe has blown, again it's not mentioned in the service manual how to get it out to test/replace it. Does it just pull out? Twist out?

[Rattlebattle]

Lambda sensor is aka the O2 sensor, the carbuncle on the exhaust header pipe. It senses the amount of oxygen in the exhaust gasses and corrects the fuelling accordingly. This happens at part open throttle onwards and is known as closed loop running. Whilst these EFI bikes run at stoichmetric if there is an issue they often run rich. If there is an air leak in the induction side this will cause rich running (not lean as with a carb) because the MAP sensor will cause the ECU to add more fuel to compensate for the increased air caused by the air leak. Have a look at all the joints behind the throttle body. Try spraying them with WD40 or similar with the engine running to see if the speed changes. Also check the connection to the tp sensor. I had a poor connection here that caused intermittent missing and a rich mixture. Have a look also at the battery leads, in particular the thin wire to the -ve terminal. These have been known to break, particularly on the C5 where they are under tension. You need to strip back the sheathing to be sure. It could also be a loose fuse. See if the ECU has any stored faults. Earth the little spare wire attached to the ECU, turn on the ignition but don't start the engine. Make a note of the series of short and long flashes on the MIL. There may be more than one series, in which case the first is the latest. If you don't have a workshop manual I'd advise you to buy one - it's quite helpful on fault finding. Our forum host sells them.

[hagis]

MIL bulb is rubber mounted and pulls down for access, check the bulb or replace with known good bulb, if still does not light then it will be hard to do a blink test, reasons for mil bulb not lighting -engine stop switch is off -battery discharged -side stand switch faulty - fuse blown-. Check all fuses, Check all sensor and wiring harness connections for proper connectivity.