How to adjust the idle speed on carburettor! - 2006 Honda Varadero 125

This will all depend on whether your bike is fitted with carburettors or a direct fuel injection system. Is this idle speed change a new problem? Sudden idle changes could be a sign of another issue. When was it last serviced? A dirty air or fuel filter can cause idle issues.
Engines that use a carburettor, (Carb), usually have an idle adjustment screw on the carb itself. I would recommend getting an expert to do this as adjusting carbs can be a tricky job. Direct injection systems are usually not adjustable without using specialist equipment.

The user manual usually describes the adjustment process fairly well and usually it works well on a new or nearly new machine but not so well on older machines. The typical carburettor has three screws being the throttle stop adjustment for the idle speed, a mixture screw for low speed and one for high speed - by the time a machine has aged enough to need adjustment, getting it right is nearly impossible and getting it near enough to do the work is the main aim.

From the position the screws were in when the machine last run well it is important to note 1/8th of a turn at a time is the sort of adjustment needed. Adjust the low speed screw for a reasonable idle and then up to working speed to adjust the other for smooth running, or at least that is the theory.
The trouble is adjustment of one screw has an effect on the other which means a deal of patience toing and froing between the screws until a balance is reached...

oe screw is for idle and the other is for rpms
hold the throttle at the point it starts to sop and adjust the high speed screw until you can keep increasing the throttle
won't be much off the setting it is now

Check this video for idle speed adjustment. Backfiring can be caused by incorrect mixing in the carburettor or bad timing settings.


Check this link for backfire issues:

. What would cause Ford 390 to backfire through carb Yahoo Answers

Setting Curb Idle Speed of Carburetor Video Holley Carb DVD

Hi williamsc32...
Before you remove or try to adjust your low and high speed jets you should always count the number of turns it takes to lightly seat the idle mixture screw and high speed needle adjusting screws.
Be sure to write the number of turns down on a piece of paper so you will know how many turns from the seated position to open the jets when you go to reinstall them, or if you remove them for cleaning or replacement.
If you have aready tried to adjust them then the adjustments below should get it running for you for final adjustment when warm.
Normally you will adjust your idle jet to 1/2-3/4 turn open from the bottom seated position.
Then you will re-adjust the low speed of the engine when the engine is warm by turning the idle screw in or out till the engine runs smoothly at idle speed, around 1200 RPM.
The high speed jet is adjusted to 1 1/2- 1 3/4 open from the bottom seated position, after the engine is warm.
Then re-adjusted by turning the High Speed jet adjustment screw in or out till the motor runs smoothly at high speed.
Alway use the "lightly seated" method if you have not changed the screw settings.
Please take time to rate me
Bud

The manual is available here:

http://safemanuals.com/user-guide-instructions-owner-manual/ECHO/CS-400-_E

The idle speed of the negine may be too high.
Page 26 of the manual gives instructions for adjusting the speed with the "T" screw on the carburettor.

Some ATCO carburettors have more than one hole for attaching the throttle cable to the governor pivot, which will allow some variation of the speed setting by moving to a different hole.
Just before the throttle cable reaches the governor pivot it passes through a metal lug (separated from the pivot by a spring) here there is threaded screw on the throttle cable - loosen or tighten this to adjust running speed.
There is also a throttle stop adjusting screw which on the side of the carburettor which you can adjust to set the idle speed.

The Hi screw is for High speed adjustment and Lo screw is for low speed or idle adjustment.

Check the air cleaner and muffler for plugging. One screw adjusts the idle stop (idle speed) position and the H and L jet screws set fuel mixture for high speed and idle speed mixture respectively. Turn both jet screws CW to stops (lightly) then back each out CCW 1-1/2 turns. This is a basic setting and should allow the engine to start and run. Start the engine and allow to warm up. Pull the throttle full on and adjust H CW until the engine starts to speed up, but 4-strokes. Correct adjustment is when the engine 4--strokes running free, but immediately 2-strokes when cutting. Release the throttle and adjust L needle CW until the engine idles fairly well, but allows the engine to 'follow the throttle'. Adjust the idle speed screw so that the chain stops turning, but the engine will continue to run. Hope this helps!

Hey June, the correct assembly. cleaning. setting, and adjustments of the carburetor are CRITICAL....Please take the carb to a qualified professional to get it cleaned and set. Ask him which screw sets the idle speed..and you can set it when you reassemble it.. (ONLY adjust the idle speed screw!!)
IF this machine has oil injection, and its been working fine.. do not adjust it...AND .. if the oil is injected into the carb (i've seen one or two bikes with this set-up)..its working fine..the fuel/air will be taken care of when the carb is fixed! Make sure your air filter is clean!!.. and a new spark plug will help!!