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SC 120 4-stroke

Started by metcalfeclive, January 02, 2006, 18:29:10 pm

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Hi all heres some figures from my funtana today fitted with SC120 4-stroke.

Fuel 10% Flair firestorm synthetic
Cold and damp

APC 15x8 8400 rpm
APC 16x4W 9300rpm



May 13, 2006, 00:09:46 am #1 Last Edit: June 01, 2006, 14:26:35 pm by maveric944
becra 10%  apc 16x6   8,500rpm. still a bit rich as well.
becra 5%   graupner 16x8  7,600 rpm  leaning off to normal running now
honest it was a glitch, the signal from my brain didn't make it to my thumbs!

The Model Shop

8400 rpm   APC       15x8
9000 rpm   APC       16 x 4wide
7400 rpm   APC      16 x 8   
7400 rpm   Graupner      16 x 8   

This was done using Straight fuel with 18% oil {9% synth and 9% castor} and the Std silencer


Think you guys are overproping this motor, the rpm you are seeing represents between 1.5 / 1.7 hp reckon if it was allowed to rev out a bit on something like a 15x6 or 15x4W it would make a lot more power.


warbird freak !

amb temp 5c                       engine badged as asp 120fs
als hobbies 12% fuel
os f plug

g sonic                            15x8            9100
g sonic                            14x10          8800
apc                                  14x10          8400
apc                                  16x6            8600
apc                                  16x7            8000
master classic                 16x6            8500
master k series               15x8            8400
master k series               16x8            7200
g sonic                            16x8            8200
g sonic                            15x10          8200

engine as fitted in kyosho mustang 90. All readings are peak, ritchen 200rpm for flying

regards to all


I am struggling to get any where near those sort of rev's with a APC 14x8 am only getting 7600. valves set at 0.10 using lazer 5 fuel and F type plug.What am I doing wrong????

British Victory

Probably being honest  ;)  :''  :study:
there's only one f in RCMF,


No, I used to have three 120s, all pulled well over 8k on a 15*8 APC using 5% fuel.  Will it go both lean and rich on the main needle?  If so it doesn't sound to be carb related.  Warped head or bent valve?  Sticky cam follower?  Cam timing out?  Is it really a 90 in disguise?
flying's easy - it's getting it back down in one piece that's the hard part


One two other options, sticky piston ring or it's worn out :D
flying's easy - it's getting it back down in one piece that's the hard part


Quote from: RobC on August 13, 2019, 18:06:41 pmOne two other options, sticky piston ring or it's worn out :D

Or 'it's an Sc",,, :embarassed:
Mode 2 THE only way to fly


It's OK on the top end needle, so it's not that, cam timing is OK, not that, good compression no air leaking from valves, so valve seating is OK, what does that leave? Piston liner looks OK, no sign of ware, defo not a 90.