ASP 55 S52 factory low speed needle setting

by Larry
(Irvington New Jersey)

I screwed up factory low speed needle setting. Can anyone tell me at what point to set the screw to begin trying to set the low end?

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Some Tips
by: rcdude07

Open it some ...not as much as possible but 3-4 turns from fully in. But if you want to open it fully, that's Ok too. Then listen to how the engine sounds when you give full throttle!!!
It should respond to full throttle imidiately without hessitation! If not turn the low speed needle in some! Keep on doing this test with long idleing and full throttle for some minutes and you will get your engine set!-If you hessitate ...get help from a friend !


Set the barrel, so you just see a sliver of opening. Put a short piece of fuel line on the inlet barb, then close the lo-spd needle while blowing on the short piece of fuel line. When air passage stops, adjust the needle back out 'til you can just get an airflow. This will put you close. The rest is fine tuning. Good luck, red

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Low Speed Needle setting
by: Anonymous

G'day

Most four strokes (other than OS) come with the LSN set quite rich. Saito certainly do but ASP can be a lottery.

One simple way to get close is as follows.

You need a length of fuel tube.

Set the throttle so it is open by about the thickness of a pin. This is approximately the idle position.

Now put your piece of fuel tube onto the carby inlet fitting. Try to blow through it. If you cannot, then the LSN is far too far in (too lean). Your engine will not start like this. Now screw it out until you can just blow through it. You are now close. Best to open it about another full turn. It should now be moderately rich. The engine should run like this but be rich and may not idle all that well.

Now with the engine running, go to full throttle and set for peak revs.

Now down to the best idle you can get. Adjust the LSN for a better idle. As you get closer, the revs should rise.

Repeat the peak test and re adjust the peak revs.

Repeat the LSN adjustment.

It may take several goes to get right.

Choose a setting that gives a good sharp transition not the smoothest idle (ie slightly rich).

The two needles interact which is why you need to repeat the two steps.

If you find the engine will simply not start, or that it is impossible to make it run rich with the main needle valve, than you have gone too lean with the LSN. Open it about a turn and start again.

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