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  7. EC 263R 76mm x 58mm Rotating Assembly
EC 263R 76mm x 58mm Rotating Assembly
EC 263R Stroker Kit Assembly Exploded Diagram
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EC 263R 76mm x 58mm Rotating Assembly

Part Number: 263-SKA
Online Price: $274.99
EC 263R Rotating Assembly for 76mm Tillotson Blocks – 263cc Stroker Kit
Questions about this item? Be the first to ask here.
Availability: Out of Stock.

Description

The 263R Rotating Assembly is made for the Tillotson R-Series Blocks bored to 76mm.


The 263cc kit is made of a 76mm hypereutectic piston(same material as the 72mm Tillotson Racing Piston), EC's Pinnacle Forged Connecting Rod, and 58mm Wildcat Ductile Iron Crankshaft. The 76mm Tillotson Block is not included. 


In the world of automotive and motorcycle engine engineering, the 250cc engine is a standard benchmark for performance engines. The bore and stroke are very common among single-cylinder, 2-cylinder, 3-cylinder, and 4-cylinder motorcycles. The increased bore sizes not only add more displacement but also increase compression and vacuum, allowing for larger valves, ports, and camshafts with fewer adverse side effects, such as low-speed torque and reduced responsiveness. 


Whether in karting, motorcycle, or automotive performance, making 1 hp per cubic inch is a respectable engine, 1.5 hp per ci is often expert level, and 2 hp per ci is exceptional by few elite builders. All dynos are different and may reflect higher power per ci; however, you can divide your current power level by your displacement and then multiply by 16.06, which is the ci of the 263R kit for estimated theoretical power output. 


For comparison, we should look at the differences in displacement among other small block engines. 

212         70mm x 55mm = 211.67cc (12.92ci)  difference 51.45cc(3.13ci) 25%

223/224  70mm x 58mm = 223.21cc(13.62ci)   difference 39.91cc(2.43ci) 18%

225         72mm x 55mm = 223.93cc(13.67ci)   difference 39.19cc(2.38ci) 18%

228         72mm x 56mm = 228cc.    (13.91ci)   difference 35.12cc(2.14ci) 16%

236         72mm x 58mm = 236.15cc(14.41ci)   difference 26.97cc(1.64ci) 12%

254         76mm x 56mm = 254.04cc(15.5ci)     difference 9.085cc(0.55ci)   4%

263         76mm x 58mm = 263.12cc(16.05ci)   difference 51.45cc(3.13ci)


The 76mm piston is very lightweight, which can help with the "balance" of the rotating assembly, improved acceleration, and increased durability. The piston journal's improved strength lies in its wider diameter, which exceeds that of the Tillotson 72mm piston, and its longer 13mm wrist pin.


We measure the weight of common stock piston assemblies (piston, rings, wrist pin, and clips) and a couple of market pistons of similar sizes to see how they compare to the 76mm piston assembly. The 76mm piston assembly weighs 190g.


68mm Clone Dish Piston(Lightweight)  - 207g 

70mm Predator Hemi Flat Top Piston   - 203g

72mm Tillotson Racing Piston               - 172g

2.8335 Wiseco Single Ring Piston        - 192g

2.985 Wiseco Single Ring Piston          - 208g


The New 76mm piston is 8mm larger than the 68mm piston and 6mm larger than the typical flat-top 212/223/224 piston that comes with the 196cc clone, but the 76mm assembly weighs 13–17g less. The 2.8335 Wiseco is 4mm smaller and weighs 2g more, and the nearly equal-sized 2.985 piston weighs 18g more. 


You will also gain inc compression, which can impact what fuel you run or possibly the camshaft and cylinder head you choose.


22cc Combustion Chamber 

w/.045 Head Gasket & Zero Deck - 10.67:1

w/.035 Head Gasket & Zero Deck - 11.1:1


20cc Combustion Chamber 

w/.045 Head Gasket & Zero Deck - 11.42:1

w/.035 Head Gasket & Zero Deck - 11.92:1


18cc Combustion Chamber 

w/.045 Head Gasket & Zero Deck - 12.31:1

w/.035 Head Gasket & Zero Deck - 12.9:1


16cc Combustion Chamber 

w/.045 Head Gasket & Zero Deck - 13.35:1

w/.035 Head Gasket & Zero Deck - 14.06:1


14cc Combustion Chamber 

w/.045 Head Gasket & Zero Deck - 14.73:1

w/.035 Head Gasket & Zero Deck - 15.61


Best of all, the feature is the price. Compared to all billet assemblies that cost nearly 2.5 times as much, the 263R rotating assembly is only $275, which may not be much more than a bored Tillotson Block. 



FAQ

Q1: What engines are compatible with the EC 263R Rotating Assembly?
A1: This assembly is designed for Tillotson R-Series blocks bored to 76mm. It is not compatible with standard 212cc or 225cc engines unless they are machined for the larger bore.


Q2: What’s included in the EC 263R kit?
A2: The kit includes a 76mm hypereutectic piston, 13mm wrist pin, ring set, circlips, EC Pinnacle billet connecting rod, and 58mm Wildcat ductile iron crankshaft. The block is sold separately.


Q3: What performance benefits does the 263R kit offer?
A3: The kit increases displacement to 263cc, improving torque, throttle response, and power potential. The lightweight piston and balanced rotating mass enhance acceleration and engine durability.


Q4: What kind of fuel should I run with the increased compression?
A4: Depending on your head and gasket combo, compression ratios can exceed 13:1. High-octane race fuel is strongly recommended to prevent detonation.


Q5: Can I use this kit with a stock cam or head?
A5: While compatible, the 263R kit is best paired with a performance camshaft and CNC-ported head to fully utilize the increased displacement and compression.


Q6: How does the weight of the 76mm piston compare to others?
A6: The 76mm piston assembly weighs just 190g, making it lighter than most 68–72mm clone pistons and even some aftermarket forged options. This helps with engine speed and balance.


Q7: Is this a good budget alternative to billet stroker kits?
A7: Absolutely. The 263R rotating assembly offers exceptional performance for under $300—up to 2.5x cheaper than comparable billet options.


Q8: Do I need to modify anything else to use this rotating assembly?
A8: Yes. Your block must be bored to 76mm. You may also need to adjust your deck height, head gasket, and valve train depending on your desired compression and cam profile.

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