4 stroke advice please

Just been trying to set up a new SC120 4 stroke for my son in a P51.
Had a few tanks through it now and it seems OK but I'm a bit worried
about the needle valve setting? It will only run OK with the needle
about 1 turn open. Is this right? I always thought it should be about
2 to 2.5 turns. We ran it in at about a 5 turn setting and have slowly
closed this down as it ran in. Idle is fine and it seems to go to full
throttle fine but changing the needle valve doesn't seem to do much at
all. I've only ever set up 2 strokes before and I know on them that
setting the needle valve changes the engine speed quite a bit.
Reply to
Len Cuff
Loading thread data ...
It is OK to run the engine at the setting where the engine runs the best. The number of turns out is completely irrelavent unless it changes drastically.
-- Paul McIntosh
Reply to
Paul McIntosh
Paul, Thanks for the info. I've just put another tank of fuel through it and it runs perfectly, tickover, full bore with the neddle vale about 3/4 out!
Gonna leave it like that as it seems to run just fine.
cheers, Len
Reply to
Len Cuff
Wouldn't suprise me in the least - about normal for them ~(but whatever you do make SURE you are running rich).
Reply to
ray fisher
I agree competely. you should see a nice smoke trail- at least I do down here in South Florida. Recommend that you set your RPMs with a tach or temp gun, not your ear. Good luck with it. Andy
We can make a box of wood.....FLY!!
Reply to

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.