Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

wwbragg

Predator 430 carb jet

Recommended Posts

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?  

Share this post


Link to post
Share on other sites
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.  

 

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites
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

  • Like 1

Share this post


Link to post
Share on other sites
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    

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Who's Online (See full list)

    • steve-wis
    • mike_sdak
    • thom
    • smalljob
  • Today's Birthdays

    1. Mustangsvo
      Mustangsvo
      (37 years old)
    2. RenegadeJ
      RenegadeJ
      (82 years old)
    3. srwven
      srwven
      (50 years old)
  • Recent Status Updates

    • Paul M.Murphy

      Paul M.Murphy

      Hello glad I got on this site. I hope to upload a couple of photos of my Simplicity Broadmoor 
      Model 707 Tractor. I have replaced all the belts on it and installed a new ignition switch.
      Have a mower deck which was in poor shape , repaced a couple of bushings and welded the
      deck where there was some holes. The tractor and mower deck came from a friend and the 
      mower deck metal was getting pretty thin. Some new metal was put in it and we also undercoated the underside of the deck. This was done by my friend Greg Toulman.
      I have not put the mower deck on the tractor yet, waiting for Greg to come home and give me a hand. Can you please tell me if there is a manual for the mower deck and where I could get one.
      I would also like to get some moon wheel discs as well.
      I will try and down load some photos of the tractor when my wife shows me how to. 
      I really love driving this tractor and also how well it is made compare today's tractors, especially the flexible rear end and the rollers.
      Tell the next time 
      Paul
       
      · 9 replies
    • jbrooks

      jbrooks  »  Talntedmrgreen

      Josh
       
      folowing  this from a link at the downloads.  I just rescued an AC 920 with the lambodini diesel. I can' t download  yet .  Where did you find the PDF copy you posted. . I would like to figure out how to adjust the injection pump. 
      I assume it's a bosche, correct
      · 0 replies
  • Adverts

×