Hi

Must admit I am at a loss here after the images and earlier suggestions.

One other consideration to throw in, is have you got the correct gap between the red pick up coil and the flywheel?

Craig

Here is a video of it idling. 257 carb set were it will run= 1 3/4 on low ,1 on high.This thing looks like it is misfiring to me. Is that shaking normal? I have checked ignition system per Zenoah manual.Crank,piston and rod are new.Coil gap is set to business card spec.Thanks for your help. -Cris

Don't worry about how many turns out on the screws just how it runs all engines are different the book gives a starting point to work from go in 1/8 turn at a time check how it runs /go out 1/8 turn at a time check how it runs. Many gallons through a Hommie could not tell you where the screws were set just that it ran at it's best every time out.
Dave

It is definitely miss firing. Could be a crankcase leak? Does it have zero drag seals? I have a love/hate deal with those. They can wear and leak or damage the seal when installed. Are you seeing any oily mess or black goo at crankcase halves,seals,or cylinder?

I recently installed the zero drag seals.The boat ran exactly the same before the seals.There is no oil residue.Could it be an ignition problem because if it had false air wouldn't I be able to run it rich ?(at least to factory setting on low needle) I checked the fly wheel and key are OK.
Thanks,Cris

What plug gap are you running? I run mine about .014-.018. Have you changed your fuel pump diaphragm? Still think it is air leak/lean problem. Try putting your finger over the carb inlet slowly to see if it smoothes out. But don't forget a rich engine can cause the same problem. One more thing your pipe header looks a little long. You might try moving it up closer to the engine. Would not hurt to try??

Plug gap set at .020" .Yes I changed the carb pump and metering gaskets.I will run it tomorrow to check running with finger over carb.
Thanks