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Carb ajusting 18hp onan


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#1 sandhopper2 OFFLINE  

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Posted February 09, 2016 - 09:33 AM

I just did a rebuild kit on my carb , now how do I do the adjustments ? I have both screw jets turned out 2 turns , motor runs and starts but I want to fine tune it Thanks for the help Larry

#2 jms180 ONLINE  

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Posted February 09, 2016 - 10:40 AM

There are some Onan manuals in the manual section. you may find some useful information in one of the manuals.

#3 larrybl ONLINE  

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Posted February 09, 2016 - 10:59 AM

Runs and starts is good. Once I get mine to that point I'll set the idle to where it sounds good by ear, then go to 1/2 throttle and slightly tweek if needed, then go WOT with a load (deck enguaged) and tweek if needed. The tweeks are usually just a smiggion adjustment "if needed". Then back to idle. Repeat as needed.

Points are another factor with the carb adjustment. A clean air filter is a must.


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#4 sandhopper2 OFFLINE  

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Posted February 14, 2016 - 03:43 PM

How do I adjust the float , I think mine is not correct . I ordered the brass one this morning . I only have about 1/4 inch of fuel in the bowl

#5 JiminRI OFFLINE  

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Posted February 14, 2016 - 06:09 PM

From the Onan BF and BG Service manuals:

Carburetor Float Adjustment

1. Invert float assembly and casting.

2. With the float resting lightly against the needle and seat, there should be 1/8" of clearance between the bowl cover gasket and the free end of the float.

3. If it is necessary to reset the float level, bend the float tangs near the pin to obtain 1/8" clearance (figure 6).

Attached Thumbnails

  • Float.JPG

Edited by JiminRI, February 14, 2016 - 06:11 PM.

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#6 MiCarl ONLINE  

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Posted February 14, 2016 - 06:31 PM

I'd like to emphasize: "2. With the float resting lightly against the needle".  Inverting the carburetor like the picture isn't resting lightly.  If there is a spring in the needle you may get wrong results.

 

Start with the carburetor right side up and rotate it until the needle just closes.  Measure in that position.


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#7 JiminRI OFFLINE  

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Posted February 15, 2016 - 01:54 PM

I have seen a "helper spring" on one of the forums, but the stock carb on the Onan BS/MF 16 hp in my SS-16 does not have a spring on the float so don't be surprised if your carb doesn't have one. If it does, that sounds like good advice to me.

Good luck,

JiminRI






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