20 hp onan plug gap

[bigplow1 26]

does anybody know the plug gap for a 20hp onan on a 520h its is not running good after it gets warm up starts to sputter and lose power put new coil in last year so just starting with the plugs and going from there I hate this onan cant wait to get th money to put a vangard or honda on it

[JackC 617]

Spark plug gap is .025.  

 

The biggest problem we run into that causes the ONAN engines to not run properly is a dirty carburetor.

The ethanol absorbs moisture and separates from the fuel and leaves a powder in the carburetor that causes problems.

 

You might want to start with a thorough carburetor cleaning and replacement of gaskets and float needle.

 

On the spec G engines (1994 ? and newer) I believe the service manual recommends replacing the carburetor.

[bigplow1 26]

thanks for the response I will look into the carb also it is a newer model 520 just dont know exactly the year it has the swept font axle and dash controls for travel and lift it does not like cold weather either was going to use it for snow duties but it dont like to run below 50 and it is finiky at 50 to 60 but I know the motor will be for sale hopefully this winter

 

thanks todd

[ericj 1,579]

change the oil and filter on the trans. i had a 520 that did the same problem and was very pleased to find a major improvement after just a filter and oil change. i've been told to use mobil 1 synthic  oil in the trans which i will try on the next one. you get the bugs out of your onan you will find it's worth it, but it can be very frustrating to get to that point

 

 

eric j   

[bigplow1 26]

well I got the 520 going good again changed the plugs fuel filter and added a good does of seafoam runs good mowed just fine will change oil and trans fluid this weekend

 

thanks for the help Todd