Onan Carb adjustments

[twainharteartis]

On The Onan Generators carburetors there are three adjustments. There is one that sets the governor and the other is the ideal speed jets.Then there is the one in the back with the big wheel. How do I adjust this one? What doe's it control? I am trying to stop the surging. Thanks

[twainharteartis]

wildmanbaker wrote:
Greg, are you one of the former "Wildman" too? Your reference to a Sprinter, hero or zero!!!

No I have been involved with racing most of my 69 years. I have built dirt cars (for other people) been crew chief on Dirt cars Sprinters supermodified I was the crew chief on an F modified (now called B sportsracing) back in high school we raced out here in the west. So I now have a RX 7 that I built up from Pro 7 to a E production. I have built and crewed on Dirt stockcars,road racing cars, Winston West cars, Sprinters, Supers and I do oil paintings of race cars and other things. Other than that not much with racing. LOL

[wildmanbaker]

Greg, are you one of the former "Wildman" too? Your reference to a Sprinter, hero or zero!!!

[twainharteartis]

dougrainer wrote:

twainharteartist wrote:

dougrainer wrote:

Chris Bryant wrote:
It has idle jets and main jets.

The "big" wheel is the MAIN jet adjustment. The Idle is on the side. Doug

Thanks So do I turn the Main jet (in) till the engine starts to run rough then back it out till it starts running smoother?Do I do the adjustment under a load or no load?

The Onan at Idle. You adjust the BIG wheel in until the engine runs rough and RPM's change. You then back out until it runs smooth at 1800 RPM's. The GOVERNOR is what keeps the engine at 1800 SMOOTH RPM's under any type load. NEVER touch the Idle adjustment. A LOT of inexperienced people do that. The engine surges under load or not under load and they move the Idle screw IN and this causes the RPM's to increase and will stop the surging or rough idle. Problem is, now you have changed the RPM of the Onan and your Voltage will go UP to a unsafe too high voltage. Usually, it is BEST to have these adjustments performed by a qualified Onan Service center. Paying 1 hour service is cheap piece of mind instead of a crapshoot. Doug

If it was an alcohol burning sprinter or or my RX7 road racer no problem. Stupid little engine and it is different enough that I ask. I have a voltmeter plugged in to keep an eye on the out put. Thanks again for taking your time to help.

[twainharteartis]

AJR wrote:
When I purchased my camper the Onan started to surge after warm up and with no load. On my unit the wheel is marked for altitude. I turned it to sea level and it has been running fine. It is a 4KW Microquiet NOT unit.

Thanks If it was an alcohol burning sprinter or or my RX7 road racer no problem. Stupid little engine and it is different enough that I ask. I have a voltmeter plugged in to keep an eye on the out put. Thanks again for taking your time to help.

[AJR]

When I purchased my camper the Onan started to surge after warm up and with no load. On my unit the wheel is marked for altitude. I turned it to sea level and it has been running fine. It is a 4KW Microquiet NOT unit.

[dougrainer]

twainharteartist wrote:

dougrainer wrote:

Chris Bryant wrote:
It has idle jets and main jets.

The "big" wheel is the MAIN jet adjustment. The Idle is on the side. Doug

Thanks So do I turn the Main jet (in) till the engine starts to run rough then back it out till it starts running smoother?Do I do the adjustment under a load or no load?

The Onan at Idle. You adjust the BIG wheel in until the engine runs rough and RPM's change. You then back out until it runs smooth at 1800 RPM's. The GOVERNOR is what keeps the engine at 1800 SMOOTH RPM's under any type load. NEVER touch the Idle adjustment. A LOT of inexperienced people do that. The engine surges under load or not under load and they move the Idle screw IN and this causes the RPM's to increase and will stop the surging or rough idle. Problem is, now you have changed the RPM of the Onan and your Voltage will go UP to a unsafe too high voltage. Usually, it is BEST to have these adjustments performed by a qualified Onan Service center. Paying 1 hour service is cheap piece of mind instead of a crapshoot. Doug

[twainharteartis]

dougrainer wrote:

Chris Bryant wrote:
It has idle jets and main jets.

The "big" wheel is the MAIN jet adjustment. The Idle is on the side. Doug

Thanks So do I turn the Main jet (in) till the engine starts to run rough then back it out till it starts running smoother?Do I do the adjustment under a load or no load?

[dougrainer]

Chris Bryant wrote:
It has idle jets and main jets.

The "big" wheel is the MAIN jet adjustment. The Idle is on the side. Doug

[Chris_Bryant]

It has idle jets and main jets.

[twainharteartis]

darsben1 wrote:
Surging is usually caused a dirty carburetor. The first thing to do is clean the carb before trying to adjust anything. If it was running well in the past but now surges then it is most likely gummed up carb.
Model number would help so that someone with a Repair manual for your model can advise you.

THE ENGINE SURGED ALL THE TIME NO LOAD OR HEAVY LOAD. I REMOVED THE CARB CLEANED IT NOW IT RUNS GREAT WITH NO LOAD AND WITH LIGHT LOAD (RUNNING A FAN OR THE TWO FANS ON THE A/C). Try to run the the A/C or a vacuum cleaner and it starts surging.

[DennisVR]

I have been trying to stop the surging on my Onan for a year now. Removed the carb and cleaned the main jet to no avail. Finely broke down and found a new carb on ebay for $230 free shipping and installed it. Runs great now with no surging. Now if I can only remember to run the thing every month so it doesn't clog up again is another question.

[darsben1]

Surging is usually caused a dirty carburetor. The first thing to do is clean the carb before trying to adjust anything. If it was running well in the past but now surges then it is most likely gummed up carb.
Model number would help so that someone with a Repair manual for your model can advise you.