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westygas270

TRRs mixture screw

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Hi all just wondering what people have there mixture screw roughly set at, think mines 3/4 turn out but been told by people 1 and half ? It’s a 250 2018 rr 

also has anyone altered suspension from standard settings? 

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I wouldn’t think most owners would have the mixture screw ‘roughly’ set, more like as close to perfect as possible. You need to have everything nicely warmed up and the air filter clean and the throttle checked for free action, better the  bike is ridden to get it to normal heat. With bike held upright, not leaning on side stand or against a wall and the engine idling move the mixture screw a tiny amount in ( imagine the screw as a watch face so a tiny amount would be from say 12.00 to 12.05) now listen to the engine and next move the screw the same amount but out. Do all adjustments in slow precise movements, no wild twiddling ...you’ll get lost and upset the engine. Note the engine idle and sound, using this method together with the idle screw you should be aiming to achieve the smoothest, slowest and consistent engine idle. Once you have this it is a matter of personal preference if you want to have the engine idling a little faster, in which case adjust the idle screw only to increase the idling...do not alter the mixture screw. When you blip the throttle you want smooth transition from the idle jet through to the main jet ...clean carburration in other words...as most trials bikes are ridden at slow speeds in sections apart from climbs and jumps etc you want the engine to be as jerk free as possible. Just setting the carb to someone’s “mines on 3/4 turns” is not necessarily what your carb may need it might be close but not perfect?I have assumed your bike has a Keihin carb...although most carbs are adjusted in the same manner. These bikes are good and have plenty of urge right across the rev range.?

Edited by section swept

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Thanks for the reply yes the carbs a keihn, so is it best to set the mixture screw at a certain point to be able to do it that way like a ful turn out ? as if try setting it fully in you would be able to turn it to come out but won’t be able to turn it in if that makes sense ? 

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You tune from rich to weak.  Set a tickover with the throttle stop screw. Turn the mixture screw in (out if it is an air screw, I'm not familiar with the Keihin).  As you weaken the mixture the tickover speeds up.  Turn very slowly until you reach the fastest it will go then turn the throttle stop screw out to reach the tickover speed you want.  You can fine tune from there.  I would start at 1/2 turn out on the air screw if you have no approximate figure.

The general principle is outlined here http://www.amr-of-tucson.com/idle_adj.html

There is a good Amal pdf that can be downloaded showing the various stages of the operation of a carb - can be applied to any similar carb.

 

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3/4 of a turn out sounds about right for stock settings (if its revving cleanly off the bottom leave it alone). As you wind it out from there you will probably find the bike will get a bit 'poppy' on over run...

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It's in for rich on a Keihin and it's a very sensitive adjuster,half a turn is a lot.I find mine needs slight adjustment according to the weather to keep it how I like it

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