Just thought I'd post some feedback about my progress in dialing in the jetting for my RB-modified carb.
Motor: 225cc big bore kit, w/light porting.
Air-box mods
FMF torque pipe
power core silencer
plug: BR7ES
Boyesen power reeds (#607)
Fuel: pump gas (Mobil unleaded premium)
Altitude: 1000ft
Temp: 65-70 deg F
Ron's original recommendations were: 155 main, 45 pilot, needle (AEG) on the fourth clip. Air screw 0.5 to 1 turn out. I started with 3/4 turn. With these settings the bike ran ridiculously rich off idle to around 1/4 throttle. Massive burbling and gurgling. Fiddling with the air screw made a big difference. I opened it up in half-turn increments. At 2.5 turns, things got dramatically better. At that point, I stopped screwing around with the jetting and just went riding.
This last weekend, I dropped the pilot to a 42. The air screw for this pilot size seems happiest about 1.5 turns out (though I'm still experimenting). This pilot/air screw combo brought another big improvement. The bike now has a clean, linear pull right off idle.
I'm really pleased at the way the low end power deliver has improved. :cool:
I'm trying to decide what my next move should be. My main jet run was cursory - just to be sure that I was not too lean. I'm considering dropping it to 152 and check the effect. I can't remember how this works: is the high speed circuit affected by the low speed, or is it the other way around? I thought I remembered a post by MX Tuner that changing the low speed affects high speed, but not vice-versa, so tune the low speed first; but I may have that confused.
The other thing I might try is to lean the needle once clip to see what happens, but I'm on the fence about that because the 1/4 to 3/4 range feels pretty good right now.
Where I'm at right now:
Jet Needle: "AEG", 4th position
Slide cut: #7
Air Screw 1.5
Main: 155
Pilot: 42
Motor: 225cc big bore kit, w/light porting.
Air-box mods
FMF torque pipe
power core silencer
plug: BR7ES
Boyesen power reeds (#607)
Fuel: pump gas (Mobil unleaded premium)
Altitude: 1000ft
Temp: 65-70 deg F
Ron's original recommendations were: 155 main, 45 pilot, needle (AEG) on the fourth clip. Air screw 0.5 to 1 turn out. I started with 3/4 turn. With these settings the bike ran ridiculously rich off idle to around 1/4 throttle. Massive burbling and gurgling. Fiddling with the air screw made a big difference. I opened it up in half-turn increments. At 2.5 turns, things got dramatically better. At that point, I stopped screwing around with the jetting and just went riding.
This last weekend, I dropped the pilot to a 42. The air screw for this pilot size seems happiest about 1.5 turns out (though I'm still experimenting). This pilot/air screw combo brought another big improvement. The bike now has a clean, linear pull right off idle.
I'm really pleased at the way the low end power deliver has improved. :cool:
I'm trying to decide what my next move should be. My main jet run was cursory - just to be sure that I was not too lean. I'm considering dropping it to 152 and check the effect. I can't remember how this works: is the high speed circuit affected by the low speed, or is it the other way around? I thought I remembered a post by MX Tuner that changing the low speed affects high speed, but not vice-versa, so tune the low speed first; but I may have that confused.
The other thing I might try is to lean the needle once clip to see what happens, but I'm on the fence about that because the 1/4 to 3/4 range feels pretty good right now.
Where I'm at right now:
Jet Needle: "AEG", 4th position
Slide cut: #7
Air Screw 1.5
Main: 155
Pilot: 42