fireman5140
Recruit
- Joined
- Jun 12, 2013
- Messages
- 3
Hello,
I have a 1996 sport jet 120xr in a 18 foot bass tracker. Last summer i began having issues with fuel flowing from the lower carb. After numerous attempts to resolve this on my own, I took it to a marine mechanic this spring. He replaced all fuel lines, fuel filter, cleaned and checked carbs, and replaced the pick up tube gasket in the tank. He then informed me i had lost 20 pounds of compression in #2 cylinder and that he could see melting on the crown of the piston with a video scope. He quoted me 1800$ for repair. (I barely have that in the whole boat) OK, I pulled the powerhead, disassembled it,and took it to a machine shop were i once worked. We checked all the measurments and decided to replace that piston after a 20 over bore. We also determined the reason for the burnt piston was a broken reed valve. The engine was re-assembled with 1 new piston (Vertex Brand from Pro Marine) re-ring and hone the other cylinders, complete gasket set, oil seals and boyseen power reeds. Engine started with very litttle effort. Timing was rechecked and fuel ratio screws were backed out one turn per Boyseen lititure. oil was added to the fuel tank for break in. Went to the water for a test run. start up was great idel was good, take off great, my boat hasent run this good since i purchased it. Returnin up river to my trailer, runninf half throttle and it died. I mean shut off dead. i kind of expected i had fouled the plugs with the double oil. When i pulled the #2 plug and knew immediatly it was bad, completly covered in aluminum. #2 is burnt again. The block is back at the machine shop and hope to reassemble it this weekend. The big Question ??? where do i start to ensure i dont repeat. I have stock jets in the carb and saw no dirt upon inspection. I know it went lean just not why? Any help is appreatiated. i am open to any suggestion.
I have a 1996 sport jet 120xr in a 18 foot bass tracker. Last summer i began having issues with fuel flowing from the lower carb. After numerous attempts to resolve this on my own, I took it to a marine mechanic this spring. He replaced all fuel lines, fuel filter, cleaned and checked carbs, and replaced the pick up tube gasket in the tank. He then informed me i had lost 20 pounds of compression in #2 cylinder and that he could see melting on the crown of the piston with a video scope. He quoted me 1800$ for repair. (I barely have that in the whole boat) OK, I pulled the powerhead, disassembled it,and took it to a machine shop were i once worked. We checked all the measurments and decided to replace that piston after a 20 over bore. We also determined the reason for the burnt piston was a broken reed valve. The engine was re-assembled with 1 new piston (Vertex Brand from Pro Marine) re-ring and hone the other cylinders, complete gasket set, oil seals and boyseen power reeds. Engine started with very litttle effort. Timing was rechecked and fuel ratio screws were backed out one turn per Boyseen lititure. oil was added to the fuel tank for break in. Went to the water for a test run. start up was great idel was good, take off great, my boat hasent run this good since i purchased it. Returnin up river to my trailer, runninf half throttle and it died. I mean shut off dead. i kind of expected i had fouled the plugs with the double oil. When i pulled the #2 plug and knew immediatly it was bad, completly covered in aluminum. #2 is burnt again. The block is back at the machine shop and hope to reassemble it this weekend. The big Question ??? where do i start to ensure i dont repeat. I have stock jets in the carb and saw no dirt upon inspection. I know it went lean just not why? Any help is appreatiated. i am open to any suggestion.
