Yamaha 115 2 stroke. The other day I was running along and the top and bottom cylinder on the left side ran out of fuel. plugs were dry. Today,same thing only on the right side, top and bottom.

Does it have spark when it cuts off?

Hey Alex, No, I would get a new bulb..check for leaks in the fuel system.

Make sure that the fuel lines and filter are clean and unobstructed

Thermostat faulty or blockage in block not allowing water to flow thru block.remove cylinder head and side water jacket

Could be too much idling,4 strokes like a good run to get rid of fuel in oil,too much pitch on prop can also not allow motor to rev enough

The carbs on 2 strokes are always needing a little adjusting, either your plugs are somewhat foulded, carbs gummed up from setting, restriction in fuel delivery, linkage could also be biding slightly. These are the general issues, any more would require a tech to get hands on and test them. But if your savy enough to adjust the carbs, just bump the idle up a tad after you check everything out. I am guessing that this may clear up on its own, but may need a bump.

have you checked the fuel plate thats in the bottom of carb? they tend to dry up and because rubber the 2 stroke fuel makes it dry and shrink, then it no longer pumps fuen into cylinder

First make certain the fuel is fresh ,and drain any old fuel out of the carb ,small screw at the bottom of the float bowl.when dry turn fuel on ,if flow starts again no blockage .start bike now,if no fix, remove spark plug if it is dry the carb is blocked . touch plug to cylinder head and start be carefull not to shock yourself use pliers . If no bright blue spark check side stand cut out switch ,kill switch . if the battery has been left uncharged for more than 2-3 months replace as wont work well. to check for seizure remove plug and push bike in first gear you should hear and feel the engine turn.

is it carbureted or fuel injected? are your warning horns working? if it iscarbureted then a few easy test can be done to find out. if its fuel injected then its a little harder but not impossible.(1) check compression. without the year model I'm giving you a average numbers. all cylinders need to be over 100 lbs and equal each other within 5 lbs.(2) check spark. use a spark gap tester all cylinders should jump a half inch gap. if you have good compression and good spark fuel is the problem nine times out of ten. clean fuel lines replace primer bulb and replace all fuel filters. Yamaha has a gravity filter under the engine coul. take it to the lake if no improvement. clean carbs. same test to be and fuel system service used of fuel injected engines. if no improvement in engine preformance then you will have to take it to a dealer to test with computer.