Dirty return springs - K-Bikes.com - Excellence in Motion
 
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post #1 of 7 (permalink) Old Feb 20th, 2013, 6:03 pm Thread Starter
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Dirty return springs

The cause of the sticking fast idle has been found. The fast idle uses the same mechanism as the throttle to activate the throttle bodies. It activates all four, not just one as I had guessed earlier. The fast idle uses the same return springs as the throttle. These were covered in mud. Cleaned the springs and the return action on the fast idle came back to normal.


Here are some shots of the springs.







Here is shot of the arm the fast idle cable links to.




So as a mechanic once told me, you can do away with the fast idle. A throttle lock does the same thing.
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post #2 of 7 (permalink) Old Feb 22nd, 2013, 4:20 pm
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Quote:
So as a mechanic once told me, you can do away with the fast idle. A throttle lock does the same thing.
Not sure what bike you are on about, but if it is Efi controlled by an ECU your mechanic is out of touch with electronic engine management systems.

On these systems the bike has to start and run at the correct idle, usually under control of the Efi loop, in order to setup and initialise the fuel map mixture for the rest of the throttle range (which IS important)

Good find on the mud and crap, but setting idle speed with the throttle cable adjuster is not a good thing to do on an EFi bike.



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post #3 of 7 (permalink) Old Feb 22nd, 2013, 7:37 pm Thread Starter
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Quote:
Originally Posted by voxmagna
Not sure what bike you are on about, but if it is Efi controlled by an ECU your mechanic is out of touch with electronic engine management systems.

On these systems the bike has to start and run at the correct idle, usually under control of the Efi loop, in order to setup a initialize the
fuel map mixture for the rest of the throttle range (which IS important)

Good find on the mud and crap, but setting idle speed with the throttle cable adjuster is not a good thing to do on an EFi bike.
This is the 85 K100RS. I know it is LE-JETRONIC. I know little about EFI. Dont care about EFI on 2013 mcs. Do care about EFI in 1985. The only source I have is the Clymer manual. I dont see anything there about initialization. I have the second edition,1997. On p. 227, there is one paragraph about the ECU at start. The only thing mentioned is a temp sensor which adjusts the initial fuel/air mixture.

Are you telling me the the throttle grip on the handlebar must be in the closed position at idle upon start-up in order to get the correct fuel/air mixture thruout the entire range of throttle positions in the LE-Jetronic system?

I know everybody keeps telling me this a very, basic EFI system and that most consider this a plus. Does LE-Jetronic do the same kind of initial sensing that that the later systems do?
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post #4 of 7 (permalink) Old Feb 23rd, 2013, 9:29 am
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The L-Jetronic is an analog device. The only fuel "map" is the hardwiring of the circuit.

The only "initialization" it does is enrich the mixture when the starter button is pressed.

Last edited by FlyingDuck; Feb 23rd, 2013 at 9:34 am.
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post #5 of 7 (permalink) Old Feb 24th, 2013, 11:31 am Thread Starter
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Quote:
Originally Posted by FlyingDuck
The L-Jetronic is an analog device. The only fuel "map" is the hardwiring of the circuit.

The only "initialization" it does is enrich the mixture when the starter button is pressed.
Thank you. Had a talk with an old timer. Told me same thing.

The fast idle control IS a throttle lock. It opens the butterfly valves inside the throttle bodies in the same way that the handlebar grip control does. The difference is the fast idle holds them open against the return springs whereas the right grip control does not.

And the only data the ECU gets for the positions of the butterfly valves, the fast idle knob and the right hand throttle control is thru the Throttle Position Switch. The operator has to properly physically set (orient) the controls, the cables and the TPS in order to get the correct fuel/air mixture during operation. The ECU adjusts fuel/air (mostly) by two bits of data, air pressure reading and throttle position switch reading. The ECU doesnt directly "know" anything about throttle grip position, TPS initial orientation or position of butterfly valves. It only knows the TPS has rotated to a particular point. It doesnt know where the TPS began; it doesnt calculate the distance of rotation, only notes the point.

Right?

Last edited by 97tiger885; Feb 24th, 2013 at 11:49 am. Reason: Clarification
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post #6 of 7 (permalink) Old Feb 24th, 2013, 3:46 pm
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It does not measure the air pressure. It measures the volume of air passing through the airflow sensor.

FYI: for US models there's an "altitude plug" to insert for riding above 4,000 feet.

The -Jetronic also monitors:

Engine temp. (via temp sensor where coolant exits the cylinder head)

Air temp. (via sensor in the intake port of the mass airflow sensor)

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post #7 of 7 (permalink) Old Feb 24th, 2013, 9:14 pm Thread Starter
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Quote:
Originally Posted by FlyingDuck
It does not measure the airbec abuse pressure. It measures the volume of air passing through the astartingrflow sensor.

FYI: for US models there's an "altitude plug" to insert for riding above 4,000 feet.

The -Jetronic also monitors:

Engine temp. (via temp sensor where coolant exits the cylinder head)

Air temp. (via sensor in the intake port of the mass airflow sensor)

Right, volume of air...Thanks for the correction.

Is the engine temp monitored for a reason other than determining if a richer fuel mixture is needed for starting ( cold vs hot start)?

And the necessity of air temp measuring is because it roughly tracks air density?

Jetronic monitors engine RPM as well for the rev limiting function?

Very helpful. The Jetronic picture is slowly coming into focus.
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