This motor fires up first time every time and idles well even if clicked into gear. Open the throttle and she doesn't rev under load but will peak if run out the water. She stood for a year and picked up dirt from a corroded fuel pick up. Work completed:The tank and fuel line was cleaned and flushed with new fuel.Carbs cleaned.New plugs fitted.New fuel pump fitted.Also tried electrical fuel pump.All electrical connections cleaned and checked.New choke seals fitted.All small rubber pipes between carbs and engine cleaned.Float levels adjusted.Cylinder drop test. All cyl. OK.I have performed most of this work and it has just all been redone by mechanic. He is now battling as well.Any other suggestions / possible solutions?Glenn.
Ahoy, Scrubber.You have certainly done a lot to eliminate possible causes.It sounds like you have 1 or 2 cylinders down on power.With the engine idling, pull each plug wire and confirm that there is a hot, blue spark to the block. Note what happens to the idle speed in each case.If idle speed drops that cylinder is making power. If idle does not drop, that cylinder is either not making power or is making very little.A weak or dead cylinder with good spark is not getting adequate fuel/air mix. Try spraying some fuel mix (NOT "Starter Fluid") into the carb throat for that cylinder and see if the idle picks up.A weak cylinder that is getting good spark and doesn't pick up with extra fuel has probably lost scavenging pressure. Broken or leaking reeds, failed bypass cover gasket or even a badly failed crank seal can cause that.Let us know what you find and perhaps we can take you forward from there.Good luck.
The mechanic got back to me today. He beleives the needle and seat of the top carb was sticking almost closed, preventing fuel from entering. He just received carb kit and will fit and let me know ASAP.Cheers.