I have a 2002 Yamaha YZ 125, yesterday this is the first time my bike ever behave like this it starts first kick and I warm it good n ride it good n one of my water pump seal is damage n it leaks not a lot but after a few rides I starts to drip a lot n every lap or two my coolant finishes n my bike we u rev to high rpm it starts to misses idk wats the prob can somebody help me?? :(

SOURCE: while riding my yz 125 it just died and won,t kick up again

• If a hole in the piston then install new piston and rings. Next, clean the carbon off the head and install a new head gasket.
• If cylinder wall is scared the piston has seized up. Pull the cylinder off and take it to the dealer. Have them bore the cylinder and return it along with a new oversize piston and rings.
• While at the parts counter, get a new stock spark plug and a supply of Yamalube Two Stroke Motor Oil. You need to add 4 ounces per gallon when filling up. This will be a 32/1 gas to oil ratio. NEVER ride the bike without at least the needed 32/1 mix.

SOURCE: water leak

The small hole under the water pump is the weep hole and is designed to start dripping water when your pump has a problem. You should remove the pump and find out what the problem is before it quits and leaves you stranded. Could be simply the seal, or the shaft may have become pitted.

With the brakes, I assume you have looked at the brake pads and they are good so bleeding is definitely the first option. If that does not fix it remove the calipers and check that the pistons move when you squeeze the lever and that you can easily push them back into the caliper (after you disconnect the brake line). Then rebuild them if required and reinstall.

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: Where can I find a power valve assembly diagram?

http://cgi.ebay.com/ebaymotors/1984-YAMAHA-Riva-XC180ZL-Scooter-Carburetor-Assembly_W0QQcmdZViewItemQQ_trkparmsZ72Q3a543Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318QQ_trksid

SOURCE: yamaha yz 125 1994

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