Share Your Pilot Air Jet Experience!

[Bradley.Isaac]

I know I need to richen my pilot system but should I increase my pilot fuel jet or decrease my pilot air jet? (If needed, see #6 post by 49er in "air jet size and what it does?" explaining the reverse relationship between the pilot air jet and pilot fuel jet)

I have an 83 GS 850G with stock everything except for a 4-1 exhaust. It is very clear that I need to make my pilot system richer. I have symptoms that have been described on almost every "lean carburetor" post online. FYI, everything from the airbox (which is sealed with weather stripping) to the exhaust has been quad-cheked for air leaks.

So if I need to richen my pilot...

What are the tradoffs of changing the pilot air jet vs the pilot fuel jet?

Will a single size increment of the pilot fuel jet have the save affect on the A/F ratio as single size decrease of the pilot air jet?

Please share your experiences with pilot system adjustments. I hope to learn from the community's vast experiences before i go and buy several sets of air jets and fuel jets to experiment myself.

Cheers,

-Isaac

[hampshirehog]

If the only thing that's not original is just that 4-1 exhaust she should dial in on the mixture screws alone. If she doesn't you have an airleak.

[gearhead13]

The pilot air jets are smaller changes in air/fuel than one size of pilot jet, I used them to fine tune the mixture in between pilot jet sizes. They are also a LOT easier to change than the pilot jets.

[Bradley.Isaac]

The pilot air jets are smaller changes in air/fuel than one size of pilot jet, I used them to fine tune the mixture in between pilot jet sizes. They are also a LOT easier to change than the pilot jets.

gearhead13,

Would you say that major pilot system tuning should be done using the pilot fuel jet. Then any smaller changes for temperature or elevation change would best/easily be done using the pilot air jet?

Thanks!

-Isaac

[gearhead13]

gearhead13,

Would you say that major pilot system tuning should be done using the pilot fuel jet. Then any smaller changes for temperature or elevation change would best/easily be done using the pilot air jet?

Thanks!

-Isaac

I have never found changes for elevation or temp necessary. But if you find one step of pilot jet is too much, then fine tuning with the air jet works good.

[Who Dat?]

If you have done a proper carb cleaning and replacement of the o-rings, the stock pilot jets will work just fine.

What settings have you used for the mixture screws? You should be able to tune your pilot mix there with no problems.

The only jetting changes you should need would be to the mains, and possibly shimming the needles a bit.

You only need to re-jet because of an increase in airflow due to lower restrictions, like your header or pods. At throttle settings where the pilot jets are in play, there will be no difference in airflow, the only restriction there is the throttle, not any of the intake or exhaust plumbing.