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“unscrew both regulating screws evenly approx 3/4 turns.” “unscrew both regulating screws evenly approx 3/4 turns.”
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Old 13 May 2011
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“unscrew both regulating screws evenly approx 3/4 turns.”
R100GS

Why does everybody set the mixture screws more then is stated in the manual?

The manual clear states “unscrew both regulating screws evenly approx 3/4 turns.”

I normally set my carbs accordingly to this but I fear that running too “lean” I could damage the engine….

besides the additional power is there any reason to run richer that what is stated in the manual?

What am I missing?
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Old 13 May 2011
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I'm no bimmer expert but I know my way round an engine so I'll try and help out here until someone else jumps in.

A richer idle mixture will typically give you better throttle response off idle - open the throttle from idle and the engine will respond faster. However it'll also give you worse exhaust emissions (more carbon monoxide, more unburnt hydrocarbons) which is why the standard idle mixture is usually fairly lean, even on "pre-emissions control" engines. Additionally, a richer idle mixture will also use more fuel when you're idling (no different at all any other time).

For the record, nothing you can do to your idle mixture will result in engine damage. A lean mixture at high load (open throttle) will result in high temperatures and potentially also detonation, both of which cause problems. At idle the engine simply isn't burning enough fuel to get anything hot enough to cause a problem. Feel free to twiddle away and see what setting you prefer...
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Old 15 May 2011
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The setting indicated in the manual is the initial setting. If you delve further you will find that different models have different settings.

The proper way to address this is to lean the screws out until the engine reaches it's highest rpm...then richen it up a tad. Every bike and carb is different.
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Old 19 May 2011
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I was running with ¾ turn but last time I adjusted the carbs I set the mixture a bit richer.

Now I have 3 strange symptoms:

-sometimes at tick over one cylinder misses the ignition
-When reaching a red light the after some cruising kms the engine switches off (the tick over is higher than it was)
-at cruising speed sometime the engine momentarily losses power…

Before going back to the old settings am I missing something?
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Old 20 May 2011
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My bet is electrical...are you still running the grey OE coil?


Quote:
Originally Posted by bernardo feio lightweight View Post
I was running with ¾ turn but last time I adjusted the carbs I set the mixture a bit richer.

Now I have 3 strange symptoms:

-sometimes at tick over one cylinder misses the ignition
-When reaching a red light the after some cruising kms the engine switches off (the tick over is higher than it was)
-at cruising speed sometime the engine momentarily losses power…

Before going back to the old settings am I missing something?
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