posted 09-15-2007 05:40 PM ET (US)        

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I can't seem to get the carburetors [on a Mercury 100-HP two-stroke in-line four-cylinder 2 + 2 configuration] adjusted to my liking for both easy starting when hot and smooth idle. Sometimes it quits while loading on trailer. The carburetors and fuel pump were rebuilt by a dealer, along with new needle and seats. [The engine has compression of] 125-PSI on all cylinders. The ignition has checked out, and the engine has new plugs. There are new check valves in the oiling system.

The Mercury 100-HP in-line four-cylinder starts fine [when] cold, and it runs strong to 5,000-RPM. But [the Mercury 100-HP in-line four-cylinder two-stroke 2+2 is] hard to start when hot after sitting--hot soak--and it idles roughly when hot in gear at 750-RPM. I heard carburetor adjustments are tricky on this motor and might be the problem. I see there is a lot of expertise on this site. Any thoughts or suggestions would be appreciated.