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Discussion Starter · #1 ·
have removed the restrictor plate from air box, want to make sure my jetting is at least close to what it should be, running a 790 motor, 130 main jets, stock needle with 1 shim, two turns out, 42 pilot jets, enlarged filter plate hole, tors exhaust, unifilter, with a 18 tooth sprocket. thanks for the help. on a 300 mile run today it averaged 47mpg.
 

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IMHO, you may be too large on the main jets. How does it respond if you are riding in 5th gear at 5000 rpm and suddenly open the throttle? It should accelerate rapidly--if it bogs some, you may be too big on the mains.

I think you should go back to 40 pilot jets. I am running 42 pilot jets and the pilot screws are adjusted out less than one turn. If I ever get into the carbs again, I will probably put the 40's back. The only time I really needed larger than 40 pilot jets was when I was running headers without the crossover pipe--then I needed 45 pilot jets.

I would recommend pulling the shims on the needles until you get the main jets where you think they should be. Then test your mid-range for flat spots, etc. If you feel the mid-range is lacking, then try shims or Thruxton needles. Once you get the mains and mid-range where you want it, set the pilot circuitry for best idle and low speed operation.

For my 790, the mid-range is a little rich with stock needles and no shims; however, others run shims or Thrux needles. I had a lot of trouble sorting the mid-range, so I took it to the dyno.:D Best money I have ever spent on the bike. I haven't touched the carbs in over 21000 miles.
 

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Discussion Starter · #3 ·
thanks redbird, will do a little run today and see.
 
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