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New SBT engine - can't keep it running
89' 650 X2 Jetski
Westcoast pipe
PJS intake
Mikuni BN Single
PJS water box
Premix and primer
The ski was sitting for several years after it stopped running. Once I got my hands on the machine I tore down the engine, realized just about every bearing was out of tolerance and thus decided on a SBT engine.
I installed the engine, rebuilt the carb, flushed the fuel tank, replaced much of the fuel line, spark plugs, and checked/replaced electrical connections as needed. Excited, I drove to the water, gave it a primer shot and .... instant start on the first few revolutions. I was thrilled to say the least until it died about 10 seconds later. Tried again, started right back up again. This process repeated several times while I tweaked the carb settings (I assumed the problem was fuel mixture). The engine ran as long as a minute but typically for about 10-30 seconds before it would die again. After about five minutes it just stopped even trying to start. Baffled I checked for spark - and found none!
Disgruntled I took the ski out of the water and back to the cabin. There I continued not to have a spark. Swapped the CDI with a spare, still no spark. Let the ski sit for about two hours,,,, boom spark was back and strong! So I messed with all the connections, double checked the wiring and headed for the water..... Same result - short engine run time followed by a sudden engine stop. Eventually it again would not start – still just felt like a carburetion problem, but, checked spark and it was sometimes present but appeared weak (difficult to tell for certain in daylight).
Any thoughts? I tested all of the ignition components (CDI, exciter coil) and everything appears inside of resistance specifications. I doubt both CDIs are faulty. Is this a spark problem or am I miss-diagnosing a fuel issue? I am thinking about just replacing the exciter coil, but advice is appreciated as I am just starting to learn about 2-strokes.
Also can anybody tell me what the "pilot" screw adjustment does on a Mikuni carb?
Westcoast pipe
PJS intake
Mikuni BN Single
PJS water box
Premix and primer
The ski was sitting for several years after it stopped running. Once I got my hands on the machine I tore down the engine, realized just about every bearing was out of tolerance and thus decided on a SBT engine.
I installed the engine, rebuilt the carb, flushed the fuel tank, replaced much of the fuel line, spark plugs, and checked/replaced electrical connections as needed. Excited, I drove to the water, gave it a primer shot and .... instant start on the first few revolutions. I was thrilled to say the least until it died about 10 seconds later. Tried again, started right back up again. This process repeated several times while I tweaked the carb settings (I assumed the problem was fuel mixture). The engine ran as long as a minute but typically for about 10-30 seconds before it would die again. After about five minutes it just stopped even trying to start. Baffled I checked for spark - and found none!
Disgruntled I took the ski out of the water and back to the cabin. There I continued not to have a spark. Swapped the CDI with a spare, still no spark. Let the ski sit for about two hours,,,, boom spark was back and strong! So I messed with all the connections, double checked the wiring and headed for the water..... Same result - short engine run time followed by a sudden engine stop. Eventually it again would not start – still just felt like a carburetion problem, but, checked spark and it was sometimes present but appeared weak (difficult to tell for certain in daylight).
Any thoughts? I tested all of the ignition components (CDI, exciter coil) and everything appears inside of resistance specifications. I doubt both CDIs are faulty. Is this a spark problem or am I miss-diagnosing a fuel issue? I am thinking about just replacing the exciter coil, but advice is appreciated as I am just starting to learn about 2-strokes.
Also can anybody tell me what the "pilot" screw adjustment does on a Mikuni carb?
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