I am getting frustrated, before it would run on one cylinder, but now it won't even sputter. Carb rebuilds are normal maintenance. Looks like a small Boston Whaler with handelbars. Threads need to be reorganized and it's taking a long time to rebuild. Sometimes you can get away with a plug wire splicer and aftermarket plug wire and not go into the box I'm presuming Jet-N-Cat supplied a single square body Mikuni carb. I tested the thermo switch and it seams to be fine.
Does choking it help when running? No, if I leave the choke on it will die when it gets warm. The spark plug wires looked ok and the ohms reading on them was close, but I trimmed the end of the spark plug wires off anyway. I replaced the spark plugs and it ran great for 5 minutes and then it blew up. Be very careful if you are running fuel starved lean as that will put a hole in a piston in a hurry. I removed the filters for a test, and there was no change. The first question that I have is about the kill switch.
Here is a breif recap; I replaced the ignition coil and retested the secondary coil tests at 4120 ohms, but I can not get a clear reading on the primary with my meter Replaced the stator and rechecked: Charge coil had 36V and 380ohms. The boats length and width was designed so you could pick it up and put it in the bed of a pick- up truck. Can this cause my weak spark issuse? There is only 1 coil, which fires both plugs simultaneously. Fairly straightforward job for Mikuni carbs. You can start by replacing the inline fuel filter as they get clogged. I did not find any gunk in the carb. It has the Coast Guard certification placard on the hull certified for 3 adults.
Now I have weak inconsistent spark. The forums are open but you may see old threads while the processing is running. I have replaced the engine with a used engine. Set up to tow behind a boat and serve as a tender as well. Built by one of the glass men actually making them at the factory , he traded a months pay and built his own, beefed up the glass work, and strenthened the forward bulkhead. For the high, set it at 2 turns out. You can test the firing on the rear cylinder using the front wire to see if it stays running.
I will have to check to see if I have an inline filter tomorrow. Sometimes cutting back the plug end of the wire cures it, but there's little excess. It sound almost like it is blowing up when it cuts out, but there was no aluminum on plugs and the compression is 125 or so in both cylinders. Is there a common mistake or something that I could have missed? Database work was done to update the forums. I don't have the service manual in front of me. For the high, set it at 2 turns out.
At the bottom of each forum section select Thread Display Options. Does choking it help when running? The front cylinder ran smooth by it's self but the rear would die instantly as soon as I pulled the front wire. Just as I was about to recheck the compression I decided to switch the spark plugs, and there it was. The guy who built it said he loaned it out and the guy left the key in on position for 50 hours. I found a mistake that I made in the carb and corrected it, but now I am back to a spark issue.
Running the motor at lower rpm is very convenient for docking, etc. The boats about 10' 2' long , I would say about 4 foot wide. The lighting coil is 2. Yes we know about the old posts in forums. You can start by replacing the inline fuel filter as they get clogged. The length of the boat on the trailer from the ball to the back of the boat is about 12 and a half feet.
Now I am waiting for a new kill switch that I ordered. I never would have guessed that a plug that looked good and had a spark that I could clearly see could cause a severe misfire. The way he designed the boat was simple. For example, the foward storage hatch is designed to hold one six pack of beer. Just an fyi - Jet-n-cat can have different specs for the motors from Yamaha, although often times the specs are same.