- Location
- Genoa City, Wisconsin
Hello everyone, thanks in advance for the help. I will make this as brief as possible w/ details. So i recently rebuilt my buddies 90 650sx after it failed a leak down test. It resulted in a full rebuild as water was in crank and the cylinders were destroyed so i gathered all the parts mostly used from various sources except pistons and gaskets. I was able to obtain a mariner head, new good used cylinders, used crank with good bearings, new bendix and a top end kit. Took all critical measurements and reassembled the engine with all new gaskets sprayed with cooper coat. Performed a leak down test and did loose pressure but it took 15 mins for every .5psi. Installed the engine and ran 32:1 premix for first tank at half throttle with lots of varying. Next tank 40:1 no full throttle but 1/4- 3/4 all varying. Next tank game on. Well now the 4th tank of gas and it started running bad, hard to get started once going its ok but seems kinda underpowered and recently quit pissing out the pisser. My buddy noticed a change in tone and no water out the pisser so he shut it down and swam to shore. I took a look all hoses intact nothing obvious figured blown head gasket, Get back to the trailer and bring it home. Once home tear into it test compression 175 each hole, blow out all hoses no obstructions but do hear some air in cylinders, leak down test fails losing pressure after 2 mins take the head off and gasket blown right into water jacket. I would like your opinion on piston wash I know looks rich, using a fiber gasket rather then steel since the head isnt in perfect shape, and also my cooling routing. I am going to switch the port on the head to the other side. But dont want this to happen again. The mods were done the start of last season and include the stock exhaust mod, bore intake hole to accept bigger carb, 38mm carb, flame arrestor, drill spark plug wires and install msd.
