Speed O.S. Engine 12TZ Spec II

O.S. (#11385) – O.S. Speed 12 TZ Spec II 2 – NEW OS ENGINE

This is the O.S. Max 12TZ Spec II (P) Pilot Crankshaft

Speed Tuned Engine for 1/10 scale racing.

Meets IFMAR specifications.

*** Due to the High Performance of the TZ Series Engines ***

*** OS does NOT provide a warranty with this engine ***

FEATURES: Silicon filled crankshaft Nine fin aluminum cooling head, black in color Two-piece turbo cylinder head with magnesium outer head Ceramic rear ball bearing 11HBS Slide Valve Carburetor (OSMG3667) Round rear exhaust

INCLUDES: One O.S. Max 12TZ Spec II Pilot Shaft Speed Tuned Engine with P7 glow plug (OSMG2695) 11HBS valve carb, decal sheet, instruction manual 5.5mm carb reducer, and rubber exhaust sealing ring

REQUIRES: Fuel: 10%-30% nitro (recommend starting w/20% changing to a higher nitro content if necessary) with at least 16% lubricant Air Cleaner DTXG2612

SPECS: Bore: 0.543″ (13.8mm) Stroke: 0.551″ (14.0mm) Displacement: 0.128 cu in (2.1cc) Practical RPM Range: 5,000-44,000 Power Output: 1.7 ps/35,000 RPM Weight: 7.336oz (208g)

Distance between mounting holes same side: 0.43″ (11mm) Distance between mounting holes opposite side: 1.2″ (31.4mm) Width not including mounting flanges: 1″ (25.4mm) Width including mounting flanges: 1.5″ (39mm) Height bottom of crankcase to top of cylinder head: 3.5″ (89mm) Height crankshaft center to top of cylinder head: 2.9″ (74.2mm) Length from front of crankcase to end of crankshaft: 1.2″ (29.5mm) Length center line of piston to front of crankcase: 1.4″ (34.8mm) Length center line of piston to front of crankshaft: 2.5″ (64.3mm) Length from backplate to end of crankshaft: 3.1″ (79.4mm) Length from backplate to front of crankcase: 1.9″ (49.9mm) Crankshaft threads: 1/4-28

COMMENTS: Some notes on slide valve and rotary carburetors: Rotary carbs offer a larger response in the middle of the power band. This works well for off-road applications when throttle response must be varied. Slide Valve carbs provide greater response at the beginning and end of the power band. This works well for on-road and racing applications for fast take-offs and high speed. Many high-performance engines have short lives, as racers constantly strive to “lean them out” for greater performance. Unfortunately, it also makes engines run hotter, which reduces their lives. Needle Valve (aka High Speed Needle): Approximately 2.5 turns from closed, page 19 in manual Mixture Control Screw (aka Low Speed Needle): Factory set where slotted head is flush with carb body, page 25 in manual Metering Needle: Factory set where slotted head is flush with ball link body, page 25 in manual Throttle Stop Screw: Approximately 0.5mm open with the reducer removed (factory set)