20 Most Recent 2003 Yamaha YZ 125 Questions & Answers


you should try cleaning your carb i dont know how often you clean your air filter but if you havn't done that you should do it also.after you do that turn the gas on lean it over till gas runs out the over flow and give it choke no gas and try kicking it over.you should be able to just loosen up the clamps on each side of the carb and twist it so you can get to the float bowl,unscrew the four screws and blow it out with a air nossle you can try that before you go through the troubles of taking it off to clean it.

2003 Yamaha YZ... • Answered on Jul 08, 2020


ALWAYS have a fire extinguisher on hand when working on carburetors.
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 large plug on the bottom of the carb float bowl. Remove the plug then replace it after the fuel drains. Turn the gas back on and wait a minute for the carb to fill with gas. If the bike doesn't start and run properly then shut off the gas and 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. Remove the idle screw and the air screw on the outside throat of the
carb and spray into the screw holes as well.
< < READ CLOSELY > >
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. Post a comment to get back to me if it doesn't.

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2003 Yamaha YZ... • Answered on Jul 08, 2020


you need to clean or replace the float valve in the carburator.

2003 Yamaha YZ... • Answered on Sep 14, 2018


32:1--40:1 Any less than a 32:1 mix and she will smoke and foul plugs(not to mention wasting money on mix) Any more than a 40:1 mix and your top end ect. is not being lubed enough which will lead to costly top end and engine repair..... 40:1 is good for a synthetic mix...And 32:1 for a non synthetic mix.... hope this helps ya....

2003 Yamaha YZ... • Answered on Apr 18, 2018


Remove the throttle stop adjuster and the air screw adjuster and spray carb cleaner in the holes.
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. Turn the pilot screw 1/4 turn counter clockwise. Check the float level. Before putting the slide back in the throat of the carb, move the clip on the jet needle one notch lower.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. Adjust the idle speed with the Throttle stop screw. This process should get you back on the road. A “very helpful” rating for this answer? Thanks!


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2003 Yamaha YZ... • Answered on Feb 07, 2018

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