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Carburetor adjustment Suzuki RM50


Posted by Anonymous on


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Hi, Anonymous it should be noted that the "AIR FUEL" mixture screw adjustment "ONLY" manages your idle and has no effect on any other circuit also any intake leaks must be repaired before the A/F adjustment procedure can be performed otherwise you will never obtain a proper idle and you will waste a lot of time chasing the impossible. The A/F mixture screw's purpose is to fine tune the fuel charge entering the combustion chamber. The following applies to both 2 and 4 stroke engines:
1. The mixture screw may be sealed at the factory with a Welch Plug please review the following video for removal.
2. The mixture screw manages a range of 3 complete 360-degree counterclockwise turns from the bottom/closed position.
3. The mixture screw should have a spring and o-ring for tension and sealing integrity.
4. Turn the mixture screw clockwise until it gently bottoms out, this makes the fuel charge very lean and the engine should not idle if it does then the pilot/idle jet is too big and needs to be replaced with the next size smaller.
5. Turn the mixture screw 1 and 1/2 turns counterclockwise to establish a baseline for starting the engine.
6. To fine-tune the idle circuit, adjust the mixture screw 1/4 turn in or out to achieve maximum idle RPM, wait 15 seconds between each adjustment for the idle to settle.
7. Never go past 3 full turns out this will make the fuel charge rich, foul plugs, and produce black smoke out of the exhaust, if the engine RPM keeps increasing past 3 turns the pilot/idle jet is too small and needs to be replaced with the next size larger.
8. After achieving maximum idle back out the mixture screw another 1/8 of a turn then adjust the throttle cable idle stop screw to 950-1050 RPM.
9. This procedure works great on 99% of all engines, for the 1% that demand a more robust throttle response on aftermarket monster fuel delivery systems additional tweaking outside the box may be necessary.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
How to adjust idle on 2 stroke dirt bike air screw adjustment 2 stroke
2 stroke Carb Tuning Idle Adjustment Fix Your Dirt Bike com

Posted on May 03, 2019


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Posted on Jan 02, 2017



  • 3567 Answers

SOURCE: Hyosun Scooter Carb Adjustments

Very good thought process on the adjustments. The throttle screw sets the idle speed and the air screw sets the fuel mix at idle speed. The stock setting is 1.5 turns outward. IMPORTANT > do not tighten these two adjusters down. Only screw these in until they LIGHTLY seat. Now turn each adjuster one and one half turns outward.

From this point you adjust the idle speed then adjust the air screw for fastest idle speed at that throttle screw setting. If the idle speed becomes faster than desired after adjustment, just reset the throttle screw and then reset the air screw.

A “very helpful” rating for this answer? Thanks!

Posted on Jun 27, 2009



  • 267 Answers

SOURCE: wheres the idle adjustment screw on my carb.. i

There is a small knurled knob to the rear base at centre of carbies, this turns a worm screw, actuating a bar for all 4 carbs. The site below provides an exploded view and name of carby parts.

Here's a tip...if the knurled knob (designed to turn by hand) is too hard to turn, a multi facet (not hexagon facet) socket or ring spanner is far easier than pliers or grippers.


Posted on May 15, 2010

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