Carbs getting more fuel on PRI?

[bakirkwold]

Just a little thing I noticed today. While I was messing with my jetting I noticed that my plugs came out more on the rich side when I had the petcock on prime vs. ON. Any ideas why? More fuel pressure? Do I have a dirty screen? Thanks again guys!

[tom203]

Since you usually run on "ON", I'd leave it there while you mess with jets- hopefully this flows more gas than your carbs need-and more hopefully your float needle seats are in good shape.

[bakirkwold]

Right I am still going to take a look at the petcock and clean it.

[Killer2600]

PRI as well as RES draw fuel from the bottom of the tank, you could have a dirty screen in the tank or it could be the added pressure from the extra fuel weight.

If it only occurs on PRI and not the other positions then it's likely the vacuum petcock not opening as much as the PRI setting.

Not a really big deal unless the difference is big.

[sedelen]

Right I am still going to take a look at the petcock and clean it.

Proceed very carefully, especially if you intend to take it apart. I cannot overstate the fragility of those things, once you get it to the point it doesn't work, it can be very frustrating to get it working again. You may try soaking it in gasoline and blowing air through the orifices first.