Adjusting idle speed on an old moped.

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Adjusting idle speed on an old moped.

Postby simmisj » Wed Oct 24, 2012 3:06 am

Hi.
My moped is running at a high rev when idle. I googled it and there are supposed to be two screws to adjust both the idle speed and the high speed.
How can I know which screw is the idle one? Can I just keep it running and try one of the screws to see if the idle speed changes?
Also, this is a very old moped. Is there a high chance that I will "jinx" it so that it stoppes working all together?

Thanks for your input
Simmi
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re: Adjusting idle speed on an old moped.

Postby John » Wed Oct 24, 2012 4:44 am

Simmi, what moped is it and what engine does it have. Any identifying number/name on the carb. A picture of the bike and carb would help.

Found you and see what you have, have you checked the manual found here:
http://www.mopedriders.org/html/manuals ... iosism.htm
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re: Adjusting idle speed on an old moped.

Postby John » Wed Oct 24, 2012 5:12 am

It appears that it is a delLorto SHA12/12. Main jet is a 49 . Only one adjustment at the carb side for idle where the spring encased screw is that adjusts the slide. You also may have a throttle cable hang up and may need adjusting at the bar or the nipple at the top of the carb. Pull the cable and lubricate it and don't have any sharp bends in the sheaf.
Page 57 in the manual gives you a good picture of the carb. Hope this helps you.
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re: Adjusting idle speed on an old moped.

Postby simmisj » Wed Oct 24, 2012 5:22 am

Yes. Your answers are helping.
So on page 57, the screw that is labeled 3 on the picture "Throttle slide set screw" is the one I should try to adjust?
As for the lubrication. I have WD40. Will that do the job of lubricating the whole thing? Can I jut spray it over the area where the throttle is?
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re: Adjusting idle speed on an old moped.

Postby John » Wed Oct 24, 2012 6:44 am

WD40 may free it up but cable probably should be lubed with white lithium grease or a proper cable dressing. To do it properly the cable should be pulled from the sheaf. #3 is adjustment for the idle.
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re: Adjusting idle speed on an old moped.

Postby simmisj » Wed Oct 24, 2012 2:30 pm

Okay. I will try it tomorrow morning. To dark outside to do anything.
Thanks.
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re: Adjusting idle speed on an old moped.

Postby cfg500 » Thu Oct 25, 2012 7:35 am

On this same note, what does it mean when the idle screw is tightened all the way? Loosen it and it idles too low, tighten it all the way and it is fine.
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re: Adjusting idle speed on an old moped.

Postby John » Thu Oct 25, 2012 5:39 pm

Adjust the cable so slide is slightly open when the idle screw is about 1 1/2 - 2 turns out from the bottom.
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re: Adjusting idle speed on an old moped.

Postby cfg500 » Thu Oct 25, 2012 7:21 pm

Thanks John.
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