Hard to cruise

[junaidi]

At low rpm my engine is good but when i push the throttle fully forward for high rpm,the engine is still at low rpm and i wait for several minute the engine sound struggle and shaking and then itself go for high rpm and start to cruise perfectly.No prob at start and idle and i have change all the fuel related thing from tank hose until the filter which is all brand new. I have service the carb by removing all it,using the high pressure blower and soaked it in a chemical carb cleaner but th prob is still there.what do i have to do?pls help me .mine is yamaha 2 stroke 85hp,year 1992

[boats.net]

Run a compression test, check timer base and throttle linkage advances freely without sticking or binding. Do a spark test.

[junaidi]

Compression cx have done and psi show good reading.Throtlle linkage is good and move freely.How to cx timer base and where to locate it and how to run spark test instead of pulling out the plug and put it near the engine body(ground) and crank the engine?pls help me cos i was novice outboard mechanic