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Bad Idle (Read 3325 times)
Kiwi Roy
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Bad Idle
05/22/11 at 13:36:32
 
My V11 Sport has always been a bad idler (with the original ECU too), it idles nicely for a while about 1000 rpm then all of a sudden it comes to an abrupt halt like it is trying to reverse direction. I opened up the valve clearance and it seemed to help a bit. If I set the idle higher about 1200 it never misses a beat. The problem with this is the engine braking isn't as good.
I have a theory that since the ECU calculates the engine position from counting the number of teeth on the cam sprocket if it were to get a few extra pulses every now and then this would cause it to fire early.

How would it get extra pulses?
1)   Perhaps the sprocket bounces a little giving two pulses at the tooth edge.
2)   Perhaps the gap is incorrect on the sensor, too far away perhaps
3)   Loose timing chain ( I pulled the cover and it seems to be ok, spring loaded shoe takes up any slack)

Question
a)  Would it be possible to change the map so it ignores pulses too close together at low speed
b)  If I were to delay the spark at idle say TDC would that help?

Any thoughts would be most welcome
Regards
Roy
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Rat Patrol
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Re: Bad Idle
Reply #1 - 05/22/11 at 20:59:51
 
As I recall, motors are very sensitive to any noise on the engine position circuit.

Can you follow the wiring from the sensor? Look to see that it doesn't run near the coils, and that it isn't damaged.

I'm sure Cliff will have some other ideas.

pete
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Luhbo
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Re: Bad Idle
Reply #2 - 05/22/11 at 22:57:51
 
Check the mechanical components. Valve guides, seats, things like that. Also make sure the plugs are (still) ok.
I mounted good heads to my bike this winter and this improved nearly everything (not that things before were bad).

hubert
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Re: Bad Idle
Reply #3 - 05/23/11 at 06:17:00
 
I'll think 1000RPM is too slow for a sport. You should aim for 1200RPM for a bike that is thoroughly warmed up.

You should be able to improve engine breaking through the map.

You might be able to increase idle by advancing the spark at (0,1) and ( 0,2) without changing anything else on the bike.
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