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I pulled the factory caps off today to adjust the screws. When I turn them in to lightly seated, the right carb was 2 1/4 out. The left carb was 1 1/2. Is that possible, or did I just screw up counting the turns? Is there a better way to set this, or should I just turn both screws 2 1/2 turns out?

Thanks,
Rich
 
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So my power-plant is stock except for a K&N filter. What benefits would I gain from just doing a pilot screw adjustment? Also, what is a step-by-step process to do this? Thanks!
 

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smithmax said:
So my power-plant is stock except for a K&N filter. What benefits would I gain from just doing a pilot screw adjustment? Also, what is a step-by-step process to do this? Thanks!
Your looking to smooth the acceleration. with the bike fully warmed, whack the throttles wide open and listen to it rev. till about 8 grand. adjust the screws a 1/4 turn at a time till the best acceleration is achieved.

FOG
 

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FOG said:
smithmax said:
So my power-plant is stock except for a K&N filter. What benefits would I gain from just doing a pilot screw adjustment? Also, what is a step-by-step process to do this? Thanks!
Your looking to smooth the acceleration. with the bike fully warmed, whack the throttles wide open and listen to it rev. till about 8 grand. adjust the screws a 1/4 turn at a time till the best acceleration is achieved.

FOG
I was wondering... when we drill out the plug for the pilot screw mod:

For each carb, would it be worth while to count how far we turn each side in to seat the screw.
Then, if the screws are set different, say 2 turns vs 2 1/4, then add that 1/4 difference onto that same carb? So carb A starts at 2 1/2 & B gets 2 3/4?

Or, esp with the airbox hole mod evening out the pulses/flow, would it be better to keep both carbs the same?
 

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Always the teacher want to complicate things. If you worried about Symmetry. pull one plug wire and tune the other carb alone, then reverse the process. Or stop being so anally retentive and just make them both the same. 2 bits say you can't tell the difference.

FOG
 

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FOG said:
Always the teacher want to complicate things. If you worried about Symmetry. pull one plug wire and tune the other carb alone, then reverse the process. Or stop being so anally retentive and just make them both the same. 2 bits say you can't tell the difference.

FOG
My experiences with cars has shown that small changes can make signifigant differences with the idle, esp for 4 cylinders, even if fuel injected. So I figure a small twin, with 2 individual carbs, might benefit from the best individual carb settings.

If the stock airbox with the one-sided intake tube causes pulsations that mess with the engine's idle and low rpms, then it seemed possible that the factory might have compensated in part with one carb being tweaked different from the other. Even if not true, it's a reasonable speculation.

If the maestro engineer could get over his uncivil all-knowingness and practice some people skills you could choose to respond politely or just not respond. A lot of riders, new and veteran alike, benefit from the information and experience you share. Why complicate that sharing with blasts of grudges you seem to hold against teachers from decades past?
 

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FOG said:
Always the teacher want to complicate things. If you worried about Symmetry. pull one plug wire and tune the other carb alone, then reverse the process. Or stop being so anally retentive and just make them both the same. 2 bits say you can't tell the difference.

FOG
I wouldn't start the engine with only 1 cylinder. what i have heard is that the other spark will do some kind of damage, when there aren't any place where it can go to ground safely(like the spark plug has only a little space where the spark jumps). I'm not sure if this applies to these bikes but my dad kept me a lecture when i accidentally started my old bike with only one cylinder :)
 

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By danger do you mean damage to the bike's ignition system? Or do you mean that the surrounding area might be damaged by starting a fire or somthing like that?

FOG
 

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<<If the maestro engineer could get over his uncivil all-knowingness and practice some people skills you could choose to respond politely or just not respond. A lot of riders, new and veteran alike, benefit from the information and experience you share. Why complicate that sharing with blasts of grudges you seem to hold against teachers from decades past?>>

Because then he wouldn't be FOG.

;-)

My kids came home from school with a beaut that only a teacher could invent: You'll get what you get and you won't get upset.

(They LOVE quoting it to each other at the dinner table if one complains about portion sizes or the mere existence of Brussel Sprouts.)

FWIW, former & current LRRS Production Twins champ Steve Leslie (who has forgotten more than I ever care to know about a dyno) claims that removing the tubes in the airboxes universally resulted in worse power.

Anyone got a link to the airbox mod?

B.J. Worsham
 

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Tell him BJ
..FOG
 

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FOG said:
There not much chance of that. You might want to brush up on the way sparks are created. Go here: http://www.ex-500.com/index.php/topic,347.0.html.

FOG
If the cable is removed from one of the plugs and you start the engine. (i believe that there isn't any "safetyplace" where the spark could jump if the plug is not connected. i have heard only one motorcycle has ever had it and it was '69 AJS)

so if you remove the cable and dont hold it near ground(-) so the spark could jump. its most likely to screw up the coil by jumping inside it. (i know how sparks are created and confirmed this information from my father and 2 differend car mechanists. ;)
 

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I'm not going to cast aspersions at anyone's father (I'm a father of 4). I frankly can't see how a spark could jump inside a coil. If there is no proximity to ground the electrons will just not flow, IE: no spark. unscrew a lit bulb, what happens to the electrons that were heating that filament a few seconds ago. Nothing they just stopped flowing. The same for the electrons flowing down a wire to a plug. If there is no connection , no flow.
I agree that letting a wire dangle along side an engine might allow a random spark to jump to some unwanted place, but not internally within a coil. Maybe a damaged one.

We need an EE to ring in here, this one is a little off to the side of my expertise.

FOG
 

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FOG said:
I'm not going to cast aspersions at anyone's father (I'm a father of 4). I frankly can't see how a spark could jump inside a coil. If there is no proximity to ground the electrons will just not flow, IE: no spark. unscrew a lit bulb, what happens to the electrons that were heating that filament a few seconds ago. Nothing they just stopped flowing. The same for the electrons flowing down a wire to a plug. If there is no connection , no flow.
I agree that letting a wire dangle along side an engine might allow a random spark to jump to some unwanted place, but not internally within a coil. Maybe a damaged one.

We need an EE to ring in here, this one is a little off to the side of my expertise.

FOG
sorry if i continue this offtopic little bit more :)
("I agree that letting a wire dangle along side an engine might allow a random spark to jump to some unwanted place"
this is not dangerous in my mind, if you remove one of the wires, you SHOULD keep it near the engine(or some metal parts, where the spark could jump and therefore ground.))

i did some research and found from google: "the best way to break one of your coils is to start the engine with one or more of spark plug wires unattached, like they suggest to do in Guzzi's instructions when balancing the carbs. If the spark can't jump at the head of the spark plug, it definitely WILL jump somewhere else, for example burning the "non-conductor"(or insulation, I found from a dictionary :/) inside the coil."

hmph, sorry for my bad translation :)

if someone must test and tweak the carbs by one carb at a time, i suggest him to use electricians tape or something to keep the wire/plug's head near the motor, so the spark can still jump(any place will do the job as long as the spark can go to ground safely). beware of toasted coils :)
I myself don't want to touch the carbs as long as it's possible. I've had enough problems with my 125cc bike's carbs..
 

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Well in your light bulb analogy, the current is AC not DC, and the circuit is wired in parallel. When you remove the light bulb there is no flow of electrons on that leg of the circuit. Instead of flowing to the lamp, the electrons go to other circuits.
In the coil, the electrons are excited in the coil and need somewhere to go, there are no other circuits. They can't go down the secondary lead, they HAVE to go down the primary lead.
Eventually it will find a path to ground, following the path of least resistance, which will drop the impedence in the coil, taking out the ECU.
 

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OK , fair enough, Getting back to the point. It's still unnecessary to tune each pilot screw individually. The slight variance in the Idle mixture , if any, would be so slight that it would be un noticeable.

FOG
 

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Eventually it will find a path to ground, following the path of least resistance, which will drop the impedence in the coil, taking out the ECU.
This is false reasoning.

The coil builds up close to the same amount of voltage whether the spark plug is attached or not. The coil has insulation in it to prevent internal sparking. End of story.

[rant]
By this faulty reasoning, every time you unhooked leads from a battery, a huge spark would jump across the terminals until the battery was dead.

The plain and simple fact about voltage and capacitance is that the voltage must build up enough to overcome the capacitance.

The coil will only short out inside if it is damaged. AS FOG SAID. Transformers (as a coil is), are usually damaged by heat melting insulation or burning it. Heat in this coil is caused by current. So, if you want your coils to last forever, don't have any current running through them. So, unhook your coils from the spark plugs, and they will last longer.
[/rant]
 

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"The coil builds up close to the same amount of voltage whether the spark plug is attached or not. The coil has insulation in it to prevent internal sparking. End of story."

NO. lets say that if the coil had about 5kV(i know how the spark is formed, there are no 5kV all the time ;) again i'm not sure if its 5kV ) when working normally(connected to the plug).
if you remove the wire, the coil will have about 20-25kV(not sure of this, but still enough to jump INSIDE THE COIL, making a route for future jumps inside the coil) this will result to instant junk coil, or couching acceleration (when you quickly turn the throttle, the mixture will go to lean for a very little time. at that time(mixture lean) the spark will have to be stronger to jump at the tip of the plug, so it might jump inside the coil(if the insulation is damaged, here you are right, but the insulation can be damaged by running the engine without wire plugged to one of the plugs.) and therefore cause poor acceleration or stalling.

had a little discussion with a car mechanic 10 minutes ago :)

the kilovolts are so high, because the spark normally can jump when only (as said 5kV for reference, not sure of the right value) 5kV is achieved. but if the distance is more than the little space at the plugs tip, then kV:s will go high and MIGHT(usually will) jump inside the coil.

could you now believe me :D
 
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