Predator 430 carb jet

[wwbragg]

I put a Predator 420 (13 HP - brand new out of the box) in my Simplicity 725.  It only runs well with the choke half way closed.  I am about 700 feet above sea level and the original jet is still installed.  Do I need to re-jet the carb or adjust the governor?  Do I need a larger jet or a smaller one?  

[PhanDad]

22 minutes ago, wwbragg said:

Do I need to re-jet the carb or adjust the governor?  Do I need a larger jet or a smaller one?  

I don't think 700' above sea level is enough to have to re-jet; if you're in Denver (5000+') that's a different story.  The jet would be smaller at higher altitudes to decrease the fuel flow since there's not as much oxygen in a CF of air at altitude.  

And I thought, having to have the choke out to run cuts down the air flow which enriches the mixture - so you need more fuel, not less.   I might have this backwards, but I don't think so.  

 

[wwbragg]

1 hour ago, PhanDad said:

I might have this backwards

Thanks, Bill.  Yeah, I've been over thinking it and getting all confused but your logic makes sense.  I just found the mixture screw and will try that first - then drill out the jet.

[LMichaels]

See if there is both an idle and high speed mixture screw. They may be hidden under plugs to satisfy the clean air nazis. There should be no need to take a drill to anything. You may also have a restriction causing not enough fuel to get to the carb. Look for simple things before doing drastic things

[wwbragg]

1 hour ago, LMichaels said:

simple things before doing drastic things

Copy that, Red Ryder.  

[Gerg]

I have the same problem with my 670 Predator, I ran all year on partial choke with no problems or lack of power. I am sure that the main jets are to small, someday I will tear the carb apart and drill them out. I did remove the plugs over the idle mixture adjusting screws, that adjustment mainly effects idle mixture and some mid-range, it didn't help high speed mixture (maybe slightly). If the engine is running lean, partial choke will not harm anything, all it will do is reduce your HP, sort of like Nascar restrictor plates, with the restrictor above the throttle plate instead of below.

Greg    

[wwbragg]

I found a set of jet cleaners/files on Amazon for $8.00.  Cover me, I'm goin' in.