Yamaha 1998 two stroke 200HP

[sevcairo2k]

Engine started misfiring and stopping at idle speed. in higher RPM it seems to run better, however, when pulling the spark plug cable of each cylinder, I was surprised to find that three of the cylinders seem to have no effect when the spark plug cable was disconnected from engine. Some friends recommend to replace the spark plugs to start, but, what next if that does not do it. Please advise which troubleshooting steps should be done.
Thanks for replying,
Sev Cairo, Miami, Fl

[rodbolt17]

could ya kinda post a model number?
its bad enough when you have no clue but don't ask us to have a clue.
in 1998 there were at least 4 models of a 200 HP Yamaha.
a model number will aid in what fuel and ign system we are discussing.

[sevcairo2k]

Sev

Thanks for your come back. It is a Saltwater Series two. Model # s200txrw, serial 6g6x504219v. You are right no clue and little cash. Paying a professional is out of the question. Great appreciation for any help you can provide.
Regards,
Sev

[rodbolt17]

ok
first with the basics.
test spark and compression.
google home made spark tester.
you can make a tester that will check all 6 cyl at once for less than 10 bucks.

once compression and spark are verified good test the fuel pumps for leakage.
usually you can use the fuel primer bulb for that.
if all the above pass clean the carbs.

[sevcairo2k]

1998 Yamaha 200hp Saltwater series

Thanks for your reply, I will test this coming Saturday.
Regards,
Sev

[sevcairo2k]

FYI:
Found problem to be a worped reed valve cover plate which is a piece about 3/4 inch diameter wich seats between carburators and cylinder head. Even with new gaskets still air would leak in making carburators imposible to adjust in low. It could have been a result of overheating the engine.
Thanks for everyone contribution.
Sev