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Lycoming 200 problem


Well-known member
last year my son and I put together another boat sled with 0360 200 recently we just put first run cylinders and rings ,because it was using a lot of oil. before we did this she ran pretty good but now for some reason it does not want to idol. the new cylinders have thicker head where the spark plug goes maybe quarter inch thicker , we put the same plugs back in it couldn't figure out a replacement plug for the champion D16 . Any idea why she wont idol would be appreciated this our first AC motor and so far its been a pain THANKS
2 things to check, be sure that the injector ports are plugged, also be sure that the intake gaskets are installed correctly. The long reach plug bosses will not affect idle.
did you do anything to the cylinders or run them as is?

that was my first motor it had a bendix servo had a little trouble with it. sent it to southeast fuel systems. the original owner passed but i think his son inlaw runs it now. if a bendix it will have to be bench flowed.
John's input is spot on, unless the carb/injection was dinked with, the most likely cause of poor idle on anything is unmetered air after the throttle. Vacuum is highest when the throttle is closed, so the motor runs the leanest. At WOT it might run like a you know what ape, that's cause it's lean and burning up.

Get a can or 2 of ether and find where your intake system is leaking.
Thanks John, wink57 we left the cylinders as they were they were missing a few plugs that we took off the old cylinders and put on. we put all the gaskets and everything back on the intake. Sliden Gator we took it to the local airboat mechanic in Naples he is well know ,but also very busy he has not got back with us as of yet. But for some reason if I have to go get it I will try the either trick right now where our camp is its dry . thanks every one
It ended up being the the short hoses for the intake tubes and a couple gaskets I ordered the hose in blue to match the boat I guess they were junk ,but while he had the boat he noticed that the ground was run wrong so he corrected that for us .we were having trouble with it not wanting to start after you ran it for a little bit .you would have to sit there and like cool it down or something then she would start. Hopefully that will not happen now