How many cylinders in a f25 four stroke yamaha

SOURCE: four wheeler back fires

If the motor has two carbs then balance the carbs. Balancing the carbs basically means being certain the slides on both carbs open up simultaneously. If one carb opens sooner than the other then it 'drives' the other carb and can cause the backfire. Other things can can cause a backfire but lets start here first.

SOURCE: explain the four stroke cycleof a three cylinder

It is the same as any other engine no matter how many cylinders there are. . A 4 stroke engine has the intake stroke then compression then ignition then exhaust.(piston goes down for intake stroke,then up for compression then it fires the fuel air mixture from the intake stroke and that pushes the piston back down and on its way back up the exhaust valve opens for the exhaust stroke)

SOURCE: yamaha 225 four stroke overheating

If the engine wasn't overheating before the thermostat was replaced it could be a problem with the installation or possibly the coolant levels weren't refilled enough or at all, also if the leg was rebuilt their may be a problem with the way it was done and the engine is now working too hard to turn the prop although I think that this is unlikely. First thing is to check the coolant levels and if they are fine then you need to ensure that the water pump is circulating the coolant. If both of those check out fine then I would think that the thermostat installation is suspect and should be checked.

SOURCE: wont start

also check the jetting is set properly for weather ect, check for flooding, as mentioned check vavle clearance, also fiddle with the idle knob and fuel mixture screw(this is annoying to get to as its under the carb) and im asuming you already know the starting procedure for the 426.

SOURCE: could anyone tell me how to build a two stroke

this may sound like i'm a smart head ,,but a muffler is a muffler,, the pipe with a slip on is fine