Raptor Forum banner
1 - 1 of 1 Posts

·
Registered
Joined
·
3,611 Posts
There isn't a one size fits all jet set up.
Any time you change the intake or exhaust, or your altitude changes significantly(the higher you go the less oxygen is in the air), then you are changing the ratio of air to fuel.
Too much fuel, and it runs rich, fouls plugs, bogs, performs bad.
Too much air, and it's lean, and then runs hot, which is bad for several reasons.
Air/fuel ratio needs to stay around 13-1 ballpark.
Fuel injection can and does constantly change the a/f based off of what it's programming and an O2 sensor is telling it.
Carburetors do this by different hole sizes in pilot and main jets, and the heigth/depth of the needle, so when you change engine parts, or go up or down significantly in elavation, you have to manually change jet sizes or needle positions to get the a/f back in spec.

If you are having idling or bogging issues, did you change something, or did it just start?
Because if it just started, then you have a very dirty air filter, or, more likely a jet is becoming clogged, probably by a small piece of whatever that made it through the filter, which effectively has changed your a/f ratio.
Or, sitting long term can cause gas to gum things up.
If you changed intake or engine parts(exhaust), then you are lean, and need to go up jet sizes, and/or change the needle position.
There are alot of variables, but these are basics as to why.
Most newer machines are factory lean for emmisions, and through jetting (or a fuel injection controller) can be improved by adding a small amount of fuel(bigger jets), but it's not just throw in X and you get the right result.
There is also no magic jet kit that you just install and get a big power gain.
All you are doing is making adjustments to keep the a/f ratio where it needs to be, regardless of how mild or wild the mechanical engine is.
 
1 - 1 of 1 Posts
Top