Originally posted by bbntc3
My murnan ran great with little bottom and ballistic top for about 6 tanks of fuel, after leaning after breakin, Now it won't run over 2 mins on the track acts as if its leaning out or something......................................... ..... What's all your buds setting even the mid jet???. If you don't care, I've tried everything I know and I think I can tune pretty good, and have never seen temps over 240 on 30%......................
Hope these help. I've been following them with success for two years on my Sirio's , and had no problems so far.
AFM
SIRIO ENGINE BULLETINS
Bulletin #1
When tuning your Sirio carb DO NOT adjust the mid-range needle. This is set from the factory on a flow meter to help calibrate the other two needles and should not be touched unless you really have a grasp on carburetor tuning. The mid-range needle can be found underneath the high-speed needle on the end of the carb opposite the low-speed needle.
Bulletin #3
Sirio .12 (General Base Carburetor Settings)
High Speed - 5.5 turns out
Low Speed - 3-1/2 turns out (Generally this should be flush with the end of the slide)
Mid Range - Flush then one turn out. (if you have moved it)
Bulletin #5
When using a Plastic tie wrap to lock the piston to install a flywheel, make sure the tie wrap is thick so it will not be cut. Make sure there is no plastic remaining in the engine as it will cause damage. We do not recommend the use of a piston locking tool as it can damage the piston.
Bulletin #6
We recommend the use of the following plugs
- Sirio .12: (standard plug) Novarossi C7S or C8S
- Sirio .12 (turbo plug) Sirio S001720127 or Nova C7TGF
Bulletin #7
Crank pin on a new stock .12 engine has 4.428mm.
The right play between crank pin and conrod bushing is 0,04 - 0,05 mm. if you're not able to check it, I suggest you change the conrod every 2-3 hours running.
The life of the conrod depends mainly on the fuel you use, as the lubrication and the right carburation keeps your engine running well for long time.
Bulletin #8
This is the correct Break-In procedure for the Sirio S12 Evo2
1.- One (1) 125cc tank in the bench at WOT with very rich setting of HSN, avoiding it to go on 4 stroke.
COOL DOWN
2.- Three (3) tanks on the track at WOT on the main straight with very rich setting of HSN, as if the engine wants to die, and tuning the HSN at the end of third tank to get almost full power.
COOL DOWN AFTER EVERY TANK
3.- For 20% Nitro, use .20 head shim and N° 7 Glow plug.
After that, the engine will give more power every new tank.
Which means that Breaking-In Sirios, should be done with more or less 300 to 500cc of fuel
ANDREA ROSSI
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