Name: 38T HPS-415 "TORQUE-LOCK" REAR SPROCKET (THROUGH-HARDENED N22CB BORON-STEEL)
Brand: YUMINASHI
SKU: 41201-KPH-1538
Price: 284.6 SEK
Availability: InStock

Description

● YUMINASHI HPS-415 “TORQUE-LOCK” REAR SPROCKET (THROUGH-HARDENED N22CB BORON-STEEL)

• When you build a high-compression big bore or a long-stroke engine, instantaneous crank torque and violent cylinder pressure spikes are sent straight into the final drive.

• Converting to a narrow #415 racing chain and sprocket set is one of the most effective ways to cut parasitic drivetrain friction for faster throttle spool-up and higher trap speeds—but a narrower #415 tooth profile concentrates massive mechanical load onto a smaller contact patch, where lightweight aluminum sprockets rapidly hook, flex, or shear teeth.

• The YUMINASHI "HPS" High Performance Sprockets, built for engine tuners and racers who refuse to risk a thrown chain or stripped teeth, the Yuminashi HPS-415 “Torque-Lock” Rear Sprocket is CNC-machined and CAD-windowed from solid N22CB Boron-Steel, through-hardened and induction-treated to 50–56 HRC, and finished in a low-friction black oxide coat.

● Why N22CB Boron-Steel Beats Standard C45 Steel, SCM415 & 7075-T6 Aluminum on Tuned Engines:

Zero Lateral Deflection Under Load (210 GPa vs. 70 GPa): While 7075-T6 aluminum sprockets reduce spinning mass, aluminum has a modulus of elasticity of ~70 GPa compared to ~210 GPa for steel. When a long-stroke single slams the chain on a hard launch or aggressive gear shift, an aluminum sprocket micro-flexes laterally, accelerating chain misalignment and friction. Once the thin hard-anodized layer wears through, raw aluminum teeth hook or shear off completely. N22CB Boron-Steel provides nearly double the yield strength of 7075-T6 (950+ MPa vs. 500 MPa), locking the chain dead-straight in the tooth root.
Double the Lifespan of Standard C45 Steel: Standard C45 carbon steel lacks deep hardenability; under heavy load on a tuned motor, its teeth deform and "hook" rapidly, destroying your chain rollers. The trace boron inside N22CB acts as a metallurgical hardenability catalyst, allowing deep, uniform through-hardening (1,100–1,400 MPa tensile strength) that delivers nearly double the wear resistance of C45 at the exact same weight.
No Case-Cracking Like Carburized SCM415: Carburized chromoly (SCM415) relies on a brittle, ultra-hard outer skin over a softer core—great for small front countershaft sprockets, but prone to case delamination and cracking under directional shock waves (such as violent downshifts and engine braking) on large-diameter rear sprockets. N22CB absorbs extreme shock loads without chipping or snapping.
1-Tooth Increment Precision Tuning (28T to 38T): Available in every single tooth count from 28T through 38T, allowing you to dial in your exact final drive ratio for wind resistance, rider weight, track layout, and peak powerband RPM so you hit the rev limiter right at the end of the longest straight.

● Drivetrain Material Engineering Matrix:

● Technical Property	N22CB Boron-Steel (Yuminashi HPS)	C45 Carbon Steel (Standard OEM)	SCM415 Chromoly Steel	7075-T6 Ergal Aluminum
Material Classification:	Boron-Alloyed Through-Hardened Steel	Standard Medium Carbon Steel	Chromium-Molybdenum Steel	Zinc-Alloyed Aviation Aluminum
Density (g/cm³):	~7.85	7.85	7.85	2.81 (Lightweight)
Tensile Strength:	1,100 – 1,400 MPa	570 – 700 MPa	850 – 1,000 MPa (Core)	570 MPa
Yield Strength:	~950+ MPa	340 – 430 MPa	~700+ MPa	500 MPa
Tooth Surface Hardness:	50 – 56 HRC (Deep Induction)	40 – 45 HRC (Shallow)	58 – 62 HRC (Thin Case)	~15 HRC (~45 HRC Anodized Skin)
Elastic Stiffness (Modulus):	~210 GPa (Zero Micro-Flex)	~210 GPa	~210 GPa	~70 GPa (Lateral Flex on Launch)
Primary Failure Mode:	Slow, uniform abrasive wear (20,000+ km)	Rapid tooth hooking & chain stretch	Case cracking under shock load	Anodize wear & catastrophic tooth shear

● Available Gearing & Yuminashi Part Numbers (#415 & #420 Series | 58mm Center Bore):

Note: Part numbers with -15XX are #415 racing pitch (must be paired with a #415 chain and #415 front sprocket).
Part numbers with -20XX are #420 pitch.
※ Each sprocket is "3-in-1" multi-drilled for three 4-bolt hub patterns: 90mm PCD (M10 Studs) | 90mm PCD (M8 Studs) | and 78mm PCD (M8 Studs).

Teeth	#415 Pitch Part No.	#420 Pitch Part No.	Center Bore (ID)	Bolt Patterns Included
28T *	41201-KPH-1528	41201-KPH-2028	58.05 mm	90mm PCD (M8) + 78mm PCD (M8) (Not for Grom/Monkey)*
29T	41201-KPH-1529	41201-KPH-2029	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
30T	41201-KPH-1530	41201-KPH-2030	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
31T	41201-KPH-1531	41201-KPH-2031	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
32T	41201-KPH-1532	41201-KPH-2032	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
33T	41201-KPH-1533	41201-KPH-2033	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
34T	41201-KPH-1534	41201-KPH-2034	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
35T	41201-KPH-1535	41201-KPH-2035	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
36T	41201-KPH-1536	41201-KPH-2036	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
37T	41201-KPH-1537	41201-KPH-2037	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)
38T	41201-KPH-1538	41201-KPH-2038	58.05 mm	90mm PCD (M10 & M8) + 78mm PCD (M8)

● Final Drive Gear Ratio Tuning Matrix (Rear 28T–38T vs. Front 13T–18T):

• Lower Numerical Ratio (e.g., 1.56 – 2.15): Taller gearing for higher top-end speed, lower cruising RPM, or engines with long-stroke / big-bore torque curves.
• Higher Numerical Ratio (e.g., 2.40 – 2.92): Shorter gearing for harder launch acceleration, tight technical tracks, uphill pulls, or high-RPM short-stroke builds.

Rear Sprocket (#415 / #420 Part No.)	13T Front	14T Front	15T Front	16T Front	17T Front	18T Front
28T (41201-KPH-1528 / -2028)	2.15	2.00	1.87	1.75	1.65	1.56
29T (41201-KPH-1529 / -2029)	2.23	2.07	1.93	1.81	1.71	1.61
30T (41201-KPH-1530 / -2030)	2.31	2.14	2.00	1.88	1.76	1.67
31T (41201-KPH-1531 / -2031)	2.38	2.21	2.07	1.94	1.82	1.72
32T (41201-KPH-1532 / -2032)	2.46	2.29	2.13	2.00	1.88	1.78
33T (41201-KPH-1533 / -2033)	2.54	2.36	2.20	2.06	1.94	1.83
34T (41201-KPH-1534 / -2034)	2.62	2.43	2.27	2.13	2.00	1.89
35T (41201-KPH-1535 / -2035)	2.69	2.50	2.33	2.19	2.06	1.94
36T (41201-KPH-1536 / -2036)	2.77	2.57	2.40	2.25	2.12	2.00
37T (41201-KPH-1537 / -2037)	2.85	2.64	2.47	2.31	2.18	2.06
38T (41201-KPH-1538 / -2038)	2.92	2.71	2.53	2.38	2.24	2.11

*Cyan-highlighted ratios indicate common OEM baseline ratios: 2.27 (15/34T MSX125/Grom & Monkey 125), 2.50 (14/35T Innova 125), 2.57 (14/36T Supra-X 125 / C125), and 2.64 (14/37T Wave 110i / NBC110 & C110X/XJ Postie).

Important Hub Fitment Warnings (Do Not Order For These Specific Hubs):

28T Sprocket (41201-KPH-1528 / 41201-KPH-2028): Cannot be installed on the MSX125 / Grom 125 or Z125 Monkey due to chain-to-carrier hub outer diameter clearance.
Honda Wave 110i LED (2021–Present) & Wave 125i LED (2018–Present): Does NOT fit. Honda enlarged the rear sprocket hub on these LED models to a 64mm center bore.
Honda C125 Super Cub (2021+ Euro-5 / JA58 / JA71) & Cast-Wheel C110 (JA59): Does NOT fit (uses the 64mm center bore hub). Fits 2018–2020 C125 (JA48) and spoke-wheel C110 models only.
Australian Postie Bikes (NBC110 & C110X/XJ vs. CT110): Fits the fuel-injected NBC110 Postie (JA10 / 2013–2017), C110X / C110XJ Postie (JA10E / K88 / 2018–2021), and CT125 (2020+) directly. Does NOT fit the older carbureted CT110 Postie (1980–2012), which uses a 52mm, 54mm, or 70mm center bore.
Old Carburetor Wave 100 / Wave 110 / Dream 100 / Round-Light Super Cub: Does NOT fit (those hubs use a smaller 54mm center bore / 70mm bolt circle).

● Worldwide Motorcycle Fitment Guide (58mm Center Bore | Grouped by Model Family):

Brand	Model / Platform / Market	Model Years	Bolt Pattern & Required Stud Size
1. Honda Minibikes, Super Cub, Hunter Cub & Australian Postie Series
HONDA	MSX125 / Grom 125 (OG & SF 4-Speed / JC61 / JC75) (29T–38T Only)*	2013 – 2020	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	MSX125 / Grom 125 (5-Speed / JC92) (29T–38T Only)*	2021 – Present	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	Z125 Monkey (4-Speed / JB02) (29T–38T Only)*	2018 – 2020	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	Z125 Monkey (5-Speed / JB03 / JB05) (29T–38T Only)*	2021 – Present	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	ST125 Dax (JB04 / JB06)	2022 – Present	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	CT125 Hunter Cub / Trail 125 (JA55 / JA65 — Worldwide)	2020 – Present	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	NBC110 Postie Bike (Australia Post / JA10 / JA23E PGM-FI)	2013 – 2017	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	C110X / C110XJ Postie Bike (Australia Post / JA10E / K88)	2018 – 2021	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	C110 Super Cub (JA07 / JA10 / JA42 / JA44 / JA56 / K58 Spoke Wheel) & C110B Pro / MD110 Postal	2009 – Present	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	CC110 Cross Cub 110 (JA10 / JA45 Spoke Wheel) & Super Cub 50 (AA04 / AA06 / AA07 / AA09)	2012 – 2021	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	C125 Super Cub (JA48 First Gen — Does NOT fit 2021+ JA58/JA71) & CC125 Cross Cub	2018 – 2020	90mm PCD \| M8 Studs (8.75mm Holes)
2. Honda Underbone (Wave / Innova / Supra) & Sport 125–150cc Series
HONDA	Wave 110 / Wave 110i (KWW Halogen & K58 Early LED — Does NOT fit 2021+ K2E LED)	2009 – 2020	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	Wave 125 / R / S / X / Z / Wave 125i (Non-LED — Does NOT fit 2018+ LED)	1999 – 2017	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	ANF125 Innova / Innova 125i (JC37 — Europe / Greece / SE Asia)	2003 – 2014	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	Supra-X 125 / Supra-X 125 PGM-FI / Helm-In / Future 125 / XRM-125i	2005 – 2020	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	CZ-i 110 / Dream 110i (ND110M) / Dream 125 / Nice 110 / Nice 125	2000 – 2018	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	Astrea Grand 110 (Euro 3/4) / Blade 110 / Blade 125 FI / Revo 110 FI / Dash 110 & 125 FI	2011 – 2020	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	Biz 110i / Biz 125 / Biz 125i / Pop 110i (Brazil / South America)	2011 – 2020	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	Sonic 125 / Nova Sonic RS125 / Sonic 150R (K56)	2000 – Present	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	CBR125R (JC34 / JC39 / JC50)	2004 – 2017	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	CBR150R (4-Bolt Hub / Carburetor & Early PGM-FI — Not 6-Bolt LED)	2002 – 2015	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	GTR150 / Supra GTR 150 / Winner 150 / RS150R	2016 – Present	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	CB125F (GLR125 — Does NOT fit 2021+ K0N)	2015 – 2020	90mm PCD \| M10 Studs (10.75mm Holes)
3. Honda Classic Road, Trail, 2-Stroke & Cruiser Series (90mm PCD)
HONDA	CA125 Rebel / CMX250C Rebel / CB250 Nighthawk & Two-Fifty / VT125C Shadow / XL125V Varadero	1985 – 2016	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	CB100 / CB125S / CB125J / CB125N / CB125T / CB125TD / CB125RS / CB125TT / CBX125 / CL125	1970 – 1990	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	CD125T / CD185T / CD200 Benly / CM125C / CM185T / CM200T Twinstar / CB175 / CL175 / CB200	1969 – 1997	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	CG125 (Japan, Europe & Brazil Models) / H100A / H100S Super	1977 – 2005	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	CR80 RA / RB Elsinore (1980–1981) & CR80 R2F / R2G Expert (1985–1986)	1980 – 1986	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	MB5 / MB50 / MB80 / MBX50 / MBX75 / MBX80 / MCX80 / MT50 / MT80 / MTX50 / MTX75 / MTX80 / NS50F	1979 – 1990	90mm PCD \| M8 Studs (8.75mm Holes)
HONDA	MTX125 RW / MBX125 FE / NS125F / NSR125F (Early) / NX125 (1989–90 Europe)	1983 – 1994	90mm PCD \| M10 Studs (10.75mm Holes)
HONDA	ST90 Mighty Dax / EZ90 Cub / SL100 / SL125 / MT125 / TL125 / XL100 / XL125S / XL185S / XR185 / CT125 (1977–89) / CT185 / CT200AG	1970 – 1996	90mm PCD \| M10 Studs (10.75mm Holes)
4. Other Global Brands (Brixton, Daelim, GPX, Kawasaki, KTM, Kymco, Suzuki, SYM)
BRIXTON	Cromwell 125 (BX125) / Sunray 125 / Felsberg 125 / Rayburn 125 / Haycroft 125 / Crossfire 125 & XS	2018 – Present	90mm PCD \| M10 Studs (10.75mm Holes)
DAELIM	100 Altino / VC125 S / VS125 / VT125 / VJ125 & VJF125R Roadwin FI / VL125 Daystar I & II	1996 – 2016	90mm PCD \| M10 Studs (10.75mm Holes)
GPX	Demon 125	All Years	90mm PCD \| M8 Studs (8.75mm Holes)
HMZ	GS125 / HMZ125 Cruise I & II / XRX125 / 125 V2 Chopper	1996 – 2005	78mm PCD \| M8 Studs (8.75mm Holes)
HYOSUNG	110 Midas / GA125 Cruise I & II / GF125 / GV125 Aquila / RT125 Karion / RX125 / XRX125	1997 – 2015	78mm PCD \| M8 Studs (8.75mm Holes)
JINCHENG / KEEWAY	Jincheng 125 Abila / Keeway RKS 125, RKV 125, Speed 125, Strike 125 / Generic Worx 125	2007 – 2018	78mm PCD \| M8 Studs (8.75mm Holes)
KAWASAKI	KLX110 / KLX110L / KLX110R / KLX110RL & Z125 Pro (BR125)	2002 – Present	78mm PCD \| M8 Studs (8.75mm Holes)
KAWASAKI	Kaze-R 115 / Joy-R 125 / ZX130 / Max 100 / KZR100 / AR50 / AE50 / AR80 / AE80 / KC100 / KE100 / KH100 / KM100 / KV100 / KD80 / KD100 / KH125 (4-Hole)	1976 – 2015	78mm PCD \| M8 Studs (8.75mm Holes)
KREIDLER	125 Enduro DD / 125 Street DD / 125 Supermoto DD	2008 – 2014	90mm PCD \| M10 Studs (10.75mm Holes)
KTM	125 Duke (2011–2013) & 200 Duke (2012–2014) (Early 4-Bolt Non-ABS Hub Only)	2011 – 2014	90mm PCD \| M10 Studs (10.75mm Holes)
KYMCO	125 Hipster / 125 Pulsar I & II / 125 Spike / 125 Stryker / 125 Zing / 125 STR	1997 – 2012	90mm PCD \| M10 Studs (10.75mm Holes)
MODENAS	Kriss 100 / Kriss 115 / Kriss II / Kriss 125	1999 – 2015	78mm PCD \| M8 Studs (8.75mm Holes)
SUZUKI	RGV120 / RG110 / RG-Sports / Satria 120 / FX125 / Raider 125 & 150 (Early) / Shogun 110 & 125 / Address 125 / Smash 110 & 115	All Years	78mm PCD \| M8 Studs (8.75mm Holes)
SUZUKI	GP100 / GP125 / TRS 118 / TRZ / CT Siam / A100 / B120 / GT80 / GT100 / GT125 / RG80 & RG125 Gamma / GN125 / GS125 / TU125XT	1974 – 2001	78mm PCD \| M8 Studs (8.75mm Holes)
SUZUKI	DR-Z110 (2003–05) / DS80 / JR80 / RM50 / RM60 / RM80 (1977–81) / TS50 / TS80 / TS90 / FR50 / FR80 / RV50 / RV90 / RV125 (Early) / LT50	1971 – 2005	78mm PCD \| M8 Studs (8.75mm Holes)
SYM	VF125 (Greece / SE Asia)	All Years	90mm PCD \| M8 Studs (8.75mm Holes)

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