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How do I adjust the pilot jet screws on a yamaha xv920 model 1982? How many turns should I turn open the pilot jet adjustment screw?

I cleaned the carbs on my bike but did not pay attention when I took out the pilot jet adjustment screws. Now I don't know for how many turns to turn open the adjustment screws. I tried many possibilities between 1.5 and all the way to 5 turns but is either to rich or to lean. In any case it starts a couple of times than it doesn't and I have to start all over again cleaning the spark plugs and draining the floater bowls. It's either too dry or it's flooding. Somebody please tell me what I do wrong and how to do it right. Thank you!

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  • Motorcycles Master
  • 8,404 Answers

Carb work is for the pros. This may or may not be your trouble. Before you damage your very expensive carbs, take your bike to the pros. They have the special tools and expertise to set your carbs for maximum efficiency, safety and performance.

Posted on Nov 30, 2012

6 Suggested Answers

6ya6ya
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Posted on Jan 02, 2017

  • 126 Answers

SOURCE: klx 110 2006 stalls when choke is pushed in

i'd say the carb is gummed up especially the pilot jet (#16158) in this pic of the USA carb. may have to remove the carb & bowl and then remove the pilot jet (w/ flat head screw driver) and clean out the tiny holes.

http://partsfinder.onlinemicrofiche.com/atlanticcycleandpower/Kawasaki_OEM/KawasakiDB.asp?Type=18&A=39&B=17&Action=O

-OR-

the carb slide is installed backwards (turned 180 degrees). its #16025 in the pic. i've done this before on my daughter's XR70 and Z50. you'll know if its this when you move the choke lever, RPMs increase and decrease.

hope this worked for you and was fast enough.

Posted on Feb 06, 2009

  • 9 Answers

SOURCE: 2005 yamaha yzf 250-unstable idle

I had the same problem, Turns out that my shims were finished, replace the chims and check clearences.

Posted on Mar 12, 2009

  • 190 Answers

SOURCE: Cleaning Carb Jets

not to a trained ear also go by rpm and spark plug color

NOTE: use copper wire to clean jets, sync is just thottles are same position as all carb's just leave them adjustments alone will be fine if are out use a 1/8 drill an place in between piston/butterfly to carb bore to sync/calibrate

better use a manometer for adjusting screws

depends on condition of org parts

worn = richer running

new = lean an clean

also if changed the exhaust system need to
re-calibrate carbs for max performance

Posted on May 09, 2009

  • 200 Answers

SOURCE: Bought a 2000 yamaha yzf600r

You can fail emissions on a bike in arizona ? Wow i thought california was bad....anyhoo let's get to your concerns....All those srews should be very close to the same setting....rule of thumb is start at 1and1/2 turns out on each screw, almost any gasoline engine will run at these setting then you can fine tune from there.....no wonder you had bad idling problems...Good luck to you friend....Tim

Posted on May 12, 2009

  • 311 Answers

SOURCE: 81 xj650lh midnight maxim black exhaust, sooty plugs keep fouling

hi,fairly common problem with modified exhaust,start with the pilot screws,turn right in untill the screws are firm then back out 1 and 3/4 turns,this is a fairly standard rule of thumb that will get most things going,as far as the jets go,the original size would be a good starting point,but you should only need to go up 10-15 sizes to compensate for the exhaust mods(ie stock might be 127 may need to go to138 or 140 etc),the other thing that i would recommend is getting hold of a set of damped carb balancers these will enable you to get the mixtures and carb balance dead right,they are relitively cheap and easy to use and will have paid for themselves the first time you use them.(i regularly get 4-8 sometimes 10-11 extra hp over stock by tuning the carbs up properly).hope this helps

Posted on Jul 06, 2009

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1 Answer

How to adjust pilot jet on 2005 yamaha 125


There is no adjustment. It's a fixed jet and must be cleared with a cleaner or replaced if it doesn't clear. It's a very tiny jet. If you mean the idle mixture screw, just warm up the bike and adjust to the smoothest setting.

Dec 31, 2014 | 2005 Yamaha TT-R 125 L

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Carburetor adjustments


The only thing that can be adjusted is the pilot screws (idle mixture) and those are capped from the factory for a reason. If it is not runing right the pilot jets are clogged or restricted. You need to pull the set clean them and apply black RTV silicone to the bots to get rid of vacuum leaks.

Carburetor Cleaning Part I http://youtu.be/w4vW4zh8g0Q

Carburetor Cleaning Part II http://youtu.be/ig0qHhdxJFE

Carburetor Cleaning Part III http://youtu.be/EjCmiZ5xoeU


Mar 03, 2014 | Garden

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2003 yz450f too lean backfiring on deacceleration


clockwise is rich & cc is lean which way are you adjusting?
clean the small air port in carb with adjustment screw removed.
Screw should be set 1 1/2 turns fron light seated position.

Nov 21, 2013 | Yamaha 2003 Yz450f Yz450 Yz Wr 450 Stator...

1 Answer

How do you adjust the high speed, low speed jets on a 2002 Yamaha Road Star carburator.


The jets are not adjustable. Well - the pilot jet is adjustable a little by turning the air screw, but this is for fine tuning, not for correcting an incorrectly sized jet. If the air screw is screwed out more than about 2.5 turns, the pilot jet is too large and if it is turned in less than 1 turn, your pilot jets are too small.

Adjust the air screw out until you get the highest, smooth idle and then turn back in about 1/4 turn or less.

It is a good idea to check or just change your air filter prior to making any mixture or carb adjustments - make sure the intake tract is not restricted and make sure the spark plugs are in decent shape.

To 'adjust' the jets, they must be replaced. I know this is not what you were hoping to hear, but to adjust the jetting, the carbs have to come off and you have to get into the float bowls to physically change the jets.

Sep 14, 2011 | 2002 Yamaha Road Star Silverado

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I have a primary jet and secondary jet in the carburator of the 500 gl silverwing . and the jets I have is 75 and 125 which goes where . and what should be the setting on the air jet ?


The secondary main jet (125) goes into the jet needle holder in the center of the carb (needle). The primary main jet (75) is between the secondary main jet and the pilot screw (this one is slightly off center) . The start setting for your air screw should be 1 3/4 turns. Warm up your engine and drive for ten minutes. Adjust your idle speed to 1100 + or - 100 rpm. Now turn pilot screw in or out to get highest idle speed. Readjust idle to 1100 rpm. Now turn pilot screw in till idle speed drops 100 rpm. If pilot screw seats go to next step. Adjust the pilot screw out 1 full turn from 100 rpm drop point. Now reset Idle to 1100 rpm. That is how Honda says to set your air screw. Standard setting is probably sea level and going through the procedure will set you up for the altitude where you ride. Do the adjustment during good weather at the altitude you plan to do the most riding.

Aug 27, 2010 | Honda CX 500 B Motorcycles

1 Answer

2003 Yamaha TW 125 A/F mixture adjustment


Hi, Revasns2001 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.
https://www.youtube.com/watch?v=wAXcksgvDkM
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.
7. 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.
8. 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 please click on the blue links below. Good luck and have a wonderful day.
Life On 2 Wheels
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Yamaha TW125 1999 Service Manual
OEM parts for Yamaha
YAMAHA TW125 Owner Manual

Aug 23, 2010 | 2003 Yamaha TW 125

1 Answer

1990 Yamaha PW 80 air/fuel adjustment


Hi, Stevewright3 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.
https://www.youtube.com/watch?v=wAXcksgvDkM
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.
7. 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.
8. 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 please click on the blue links below. Good luck and have a wonderful day.
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YAMAHA PW80 Owner Manual Adjusting The Carburetor Adjusting The Engine...
YAMAHA PW80 Owner Service Manual
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Aug 15, 2010 | 2004 Yamaha PW 80

1 Answer

1997 Yamaha XVS 650 Dragstar air/fuel mixture adjustment


Hi, The4gunners 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.
https://www.youtube.com/watch?v=wAXcksgvDkM
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.
7. 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.
8. 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 please click on the blue links below. Good luck and have a wonderful day.
Pilot Mixture Screws Star 1100 Wiki Knowledge Base
Life On 2 Wheels
Yamaha XVS650 Service Manual
OEM parts for Yamaha
YAMAHA XVS650 Owner Manual

Sep 23, 2009 | 1997 Yamaha XVS 650 Dragstar

2 Answers

Cleaning Carb Jets


You shouldn't have to adjust anything as long as you don't increase the jet size and put everything back the same way it is removed.

May 09, 2009 | 2000 Yamaha YZF-R6

1 Answer

Stalls out when choke off and reverse light blinks


The pilot jet is plugged up. Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ).

Drain the carburetor. There should be a screw on the lower side of the carb float bowl. Remove the screw then replace it after the fuel drains. remove the carburetor from the engine.

Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. About 3/8" from the main jet you will see a small brass screw. This is the pilot jet adjuster. Turn the adjuster 1/2 turn counter clockwise. Make a scratch on the casing around the adjuster so that the scrach lines up with the slot on the screw. From this point, carefully count the number of turns until the adjuster can be removed. Spray carb cleaner into the jet then replace the adjuster using the same number of turns such that the screw slot lines up with the scratch mark.

< < READ CLOSELY > >
Remove the idle screw and the air screw on the outside throat of the carb and spray into the screw holes as well. Be sure to put these two screws back in the same hole they came out of. 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. Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. This process should get you back on the road.

Please rate this solution. Thanks!

Apr 29, 2009 | Yamaha YZ 450 F Motorcycles

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