Rodbolt,<br /><br />Thanks for posting the following detailed carb rebuild procedure for 2-Stroke Yamaha 150 motors. I have a 175, but this looks to be about everything I would need as well. <br /><br />Anyone with a V6 Yamaha 2-stroke and thinks they may do a carb rebuild in the future should copy paste this one to a file and save for future reference. You could save a couple hundred easy $.<br /><br />Rodbolts original post:<br /><br />if you have never done yamaha carbs you will need two voodoo priests, a witch doctor, a shaman and maybe a buddist monk.<br />naaaa just kidding. <br />leave the monk alone.<br /><br />that motor has three two barrel carbs. each barrel feeds a cylinder. take careful notes when dissasembling. I usually back off the idle speed screw 3 turns before removing. then remove the carbs. its best to push the hoses off the bowl inlets rather than pull. sometimes I work a thin small screwdriver blade under the rubber to help break it free. when you get all three on the bench make careful notes as to the size of the mainjets in each bowl. sometimes they are odd sizes and if they are they must go back in the same location. now we remove all the fuel bowls. remove the main jets(12mmhex) carb drains(10MMhex) and the idle fuel jet plugs ( small brass slotted screw).<br />dont lose the metal washers under the idle fuel plugs, they dont come in the rebuild kit, however spare fuel bowl screws may . I dont try to remove the idle fuel jets unless I have to. they are small and easy to break/destroy. soak the bowls in some carb cleaner. remove the orings from the main jets and soak them to. on to the carb body. remove the floats use a piece of cardboard to lay them on in order. helps on reassembly, usually if the same float goes back in the same spot you wont have to adjust them. float height is measured with the bowl gasket in place carb upside down and from the gasket to the top of the float. .630" plus or minus.02". on the body. I remove the two small brass slotted pugs inside the throat. I usually dont remove the idle air jets. the two small jets at the upper outer edge of the throats. remove the idle fuel screws and the stainless plate. I usually dont remove the two large brass plugs at the top rear of the carb unless its been under water. I have seen many break the casting when removed after so long.now soak the bodies for 20 min or so. remove all parts and wash with water. blow out with air. then blow out with spray carb cleaner, the super tech brand works good. now blow out with air again. reassemble with new gaskets and needles. set mixture screws at 1 1/4 turns out. install the carbs. install the throttle links. loosen the carb sync screws. they are left hand thread but if you look they are marked.while holding the bottom shutter closed tignten the synch screw then do the top. I dont know which oil pump you have. follow the procedure in your manual to insure its set correctly. some of the old kien pumps set at WOT and the mikunis with the pump arm closed and the throttles fully closed. now turn the idle screw back in 3 turns exactly. now set the throttle roller inline with the mark on the cam ( sometimes the cam must be disconnected to perform the first 3 steps) now make sure all cam,throttle,choke and OIL. repeat OIL links are installed. prime the system and fire it up.<br />its imperative to identify and properly check/adjust the oil pump. the 88 originally had a pump with 6 nipples in a circle pointing up (kien). the conversion pump has 6 nipples 3 pointing fwd and 3 pointing aft (mikuni). I think the two set up differently but memory is muddy.follow the manualif any steps are different from above. like I say memory gets muddy. but thats about the low down and skinny of it.
