My rs 125 keeps cutting out after a few miles, it starts again after a few minutes and rides again for a few more miles then does the same thing. all i know is it has a performance exhaust. could it be running too rich?

SOURCE: I HAVE AN OLD YAMAHA SR 125 ITS REVS GO UP AND

Remove the water trap bowl at the bottom of the petcock, (gas valve). Any water or trash in the bowl? Drain a cup of gas from the tank. 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. Turn the gas back on and wait a minute for the carb to fill with gas. Install a new stock NGK spark plug and try to start the engine. 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 two screws on the outside throat of the carb and spray into the screw holes as well.
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Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw 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. Set the idle speed with the idle screw. This process should get you back on the road.

Since you mentioned uneven idle revs, be sure the carb and manifold are on tight and also tighten the cylinder and head. Air leaks can screw up the idle.

Please rate this solution. Thanks speedfreak41

SOURCE: aprilia cut out couldn't get it started

if it's trying to start, but taking ages, could be two things really, one it's a fuel problem, check out all your fuel pipes and breather pipes and clean your carb, of the other is the compression is ****, may need new rings, but i would go down the route of fuel first, sounds like it's the fuel

SOURCE: 125 twin recent rebore 1000 miles ago one exhaust

Its a little hard to tell without seeing the exhaust color.Black is oil.brown is fuel.If the bad cyl. still has a good plug it may not be oil.Check the smoky exhaust carby.It may be you do not have complete firing on the bad cyl.MAYBE.Does the bike run well once you get the revs up under load?Check for inlet leaks that may change the fuel mixture on the suss. cyl.There is a few more things but start at these things 1st.After a complete rebuild,these problems do start.I hope this helps

SOURCE: aprilia rs 125 wont idle and sputters and sperts

ok buddy on carb will be a screw try fiddling with this screw till it runs ok also try changing the spark plug underneith the tank you can access this screw from the right side just on carb next to the idle screw black big one with a long flat head screw driver get back to me if no difference

SOURCE: aprilllia rs 125 wont idle

some things to try,
adjust the idle using the black knob on the carb,
check air filter is clean,
remove and clean carb