Ramva, Bought a new carb last year. Yes its a Bocar for a 1600 with the air by press screw and mixture screw. I lost the adjustments because of another problem....long story. If I seat the adjustments all the way in (gently) how many turns out for the mixture screw and how many turns out for the air by pass? Help Eric
Initial carb setting
Jun 14, 2004
6 Replies
No guarantee this will be even close on yours, but on 34-PICT carbs I found 11 turns out on the small mixture screw and
2-3 turns on the bypass. The bypass is easy; the idle speed should respond nicely to the setting. Be sure the throttle plate closes all the way (but doesn't bind).Speedy Jim
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Thanks Jim as usual....Eric
2 and a half for both, to get the engine started. THEN you start adjusting the carb to that spesific engine's needs. NOBODY can tell you exact settings. They are individuals, too many variables in the game.
Jan
WOW!
That to me says your idle passages are dirty or you have a too small idle jet for YOUR engine.
The ideal mixture screw setting is close to 2.5 turns out, and if yours takes 11 turns to run right, I say you should get a bigger idle jet so you can arrive at 2.5 turns out for it to run.
It has to do with how well the jet (whole idle passage) flows through it's whole operating area. That is, up to 3000rpms, not just at idle. If you were adjusting only the *idle* mixture with that screw/jet, it wouldn't matter. But you aren't. It affects the operation of the engine in more ways than that.
Jan
Thanks, Jan. I meant 11 turns *inward*. I try never to screw those needles all the way to the seat and the 11 turns was quite consistent over many 34-PICT Carbs.
BTW, lube the tiny O-ring with silicone grease so the needle doesn't jam up.
Speedy Jim
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Ah, now it makes sense. Inward.
Good idea.
Jan
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