Home › Forum › Ask A Member › Water Getting in Top Cylinder Yamaha 40hp Twin › Re: Water Getting in Top Cylinder Yamaha 40hp Twin
I checked the carbs out yesterday and the butterflies were all the way closed and snapped shut very well. I didn’t get a chance to look into the cylinders yet but hopefully will this evening when the sun isn’t so bright.
I have a yamaha 2 stroke golf cart and I had a similar problem with it and I got to thinking about that early this morning when I woke up from a dream where I was dreaming about the cart. It has 1 cylinder. It would not want to run at high rpm’s. I rebuilt the fuel pump, cleaned and fined tuned the carb like 6 times, and a new fuel filter it still wouldn’t run steady at full rpm’s. This was one of those things you pull your hair out. It had plenty of spark and compression. I noticed that the wires coming from the pulsar unit or what I call the pick-up area (under flywheel) were burn’t looking. If I remember right it had 3 wires 1 of them was a ground the other 2 went to the coil if I remember right. I decided to make a ground harness that grounded the 1 wire that was a ground from pulsar to the ignition coil ground then to battery ground then to the solenoids ground. The cart has 2 solenoids since the crankshaft turns reverse for reverse and this fixed my problem and I had never had that issue before then for like 3 years or since then for like 3 years. I think Yamaha copied the Harley Davidson golf cart concept on this. This was their 1st golf cart they produced and sold the G1 they say their bullet proof and I love mine use it daily for mail and take trash off.
I started reading the manual for the ignition. It has several grounds that may/will need cleaning. I have the ignition with one pulsar coil some yamahas have 2 pulsar coils one for low speed and one for high speed mine is just the one pulsar coil and one igintion coil one cdi unit and one charge coil.
Best I can tell is 1 coil fires 2 cylinders. Both cylinders fire at the same time and this is called wasted energy since one piston is in the non-compression stroke. It says one plug may not fire correctly due to low coil voltage output and coil leads can be reversed to spark plugs to easily see if this is the issue switches to other spark plug. What happens is the spark goes to the first plug through the plug wire then it goes through the cylinder head itself to the other plug and returns to coil through other coil wire this takes 30 percent more energy to do and do it right. I will attach the pdf of this look in the 2 cylinder part. I am good at checking electronics so I won’t bore anyone but I intend to check the pulsar coil, cdi, charge coil, ignition coil and clean grounds, check connections etc. I due have an old school meter that will check the strength of fire being produced so I will need to leave one spark connected when checking the other lead to see if I have a low output on one the top cylinder wire first before cleaning grounds and checking connections and doing ohm tests etc.
This is the model of my motor 1995 C40PLRT Yamaha Outboard 592cc 2 cylinder 2 stroke
Thanks for the help,
Joe
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