AMA Sports Youth 51cc Stock Class
approved 2003 models

	YAMAHA	SUZUKI	KTM	KTM	KTM	KTM
YEAR	2003	2003	2003	2003	2003	2003
MODEL	PW50 Oil Injected	JR-50K3 Oil injected	50 Mini Adventure O.I.	50 SR Adventure	SX PRO JR LC	SX PRO SR LC
BORE	40mm	41mm	39.5mm	39.5mm	39.5mm	39.5mm
STROKE	39.2mm	37.8mm	40.0mm	40.0mm	40.0mm	40mm
DISPLACEMENT	49cc	49cc	49cc	49cc	49cc	49cc
CYLINDER LINER MATERIAL	STEEL	IRON	Cast Iron	Cast Iron	PLATED	PLATED
CARBURETION	YM12 MIKUNI	VM 12SC MIKUNI	Dell'Orto 12mm	Dell'Orto 14mm	Dell'Orto 14mm	Dell'Orto 19mm
SUSPENSION FT.	60mm Telescopic	70mm/2.8 inches Telescopic-coil, w/2 way adjust	4.5 inches Conventional	6.9 inches Conventional	5.3 inches Conventional	6.9 inches Conventional
SUSPENSION R.	50mm Unit swing	52mm/2 inches swingarm, twin shock, coil spring, w/2-way adjust	7.3 inches Single	7.5 inches Single	7.9 inches Single	7.3 inches Single
WHEELBASE	33.7 inches	33.9 inches	35.8 inches	40.0 inches	36.0 inches	40.0 inches
WHEEL SIZE F	10 inches	10 inches	10 inches	10 inches	10 inches	12 inches
WHEEL SIZE R	10 inches	10 inches	10 inches	10 inches	10 inches	10 inches
OVERALL LENGTH	49 inches	50.6 inches	51 inches	54.5 inches	51 inches	54.75 inches
SEAT HEIGHT	19.1 inches	18.9 inches	21.8 inches	26.5 inches	24 inches	26.6 inches
Class 1 Stock 4-6	YES	YES	YES	NO	YES	NO
Class 2 Stock 7-8	YES	YES	YES	YES	YES	YES
Class 3 Stock 4-8	YES	YES	YES	NO	NO	NO
Class 4 Stock 4-8	YES	YES	YES	NO	NO	NO

	COBRA	COBRA	COBRA	COBRA	LEM	LEM
YEAR	2003	2003	2003	2003	2003	2003
MODEL	King	PW3 O. I.	CH2	CM	R2	R3
BORE	39mm	39mm	39mm	39mm	39mm	39mm
STROKE	41.7mm	41.7mm	41.7mm	41.7mm	41.7mm	41.7mm
DISPLACEMENT	49.8cc	49.8cc	49.8cc	49.8cc	49.8cc	49.8cc
CYLINDER LINER MATERIAL	Nikasil	Plated	Plated	Nikasil	Chromium	Chromium
CARBURETION	DEL 19mm	Dell'Orto 12mm	Dell'Orto 19mm	Dell'Orto 14mm	Dell'Orto PHBN14M 14mm	Dell'Orto PHBG19BS 19mm
SUSPENSION FT.	Inverted Cobra 8 3/4 inches	4.75 inches Conventional	6.75 inches Conventional	4.75 inches Conventional	140mm Hydraulic Marzocchi	170mm Hydraulic Marzocchi
SUSPENSION R.	Ohlins w/Reservoir 9 3/4	8.5" Cobra Hydraulic	8.5" Hydraulic	8.5" Cobra Hydraulic	140mm Hydraulic Paioli	190mm Hydraulic Paioli
WHEELBASE	39 inches	35.75 inches	40.0 inches	35.75 inches	35.83 inches	38.78 inches
WHEEL SIZE F	12 inches	10 inches	12 inches	10 inches	10 inches	12 inches
WHEEL SIZE R	10 inches	10 inches	10 inches	10 inches	10 inches	10 inches
OVERALL LENGTH	55 inches	51 inches	56 inches	51 inches	51.18 inches	53.54 inches
SEAT HEIGHT	26 inches	22 inches	26 inches	23.88 inches	23.82 inches	26.57 inches
Class 1 Stock 4-6	NO	Yes	No	Yes	YES	NO
Class 2 Stock 7-8	YES	Yes	Yes	Yes	YES	YES
Class 3 Stock 4-8	NO	Yes	No	No	NO	NO
Class 4 Stock 4-8	NO	Yes	No	No	NO	NO

	Honda	Kawasaki	WASP	POLINI	POLINI
YEAR	2003	2003	2003	2003	2003
MODEL	XR50R3	KDX50	SR	X1 Works	X3 Works
BORE	39mm	41mm	39mm	40.2mm	40.2mm
STROKE	41.4mm	37.8mm	41.8mm	39.3mm	39.3mm
DISPLACEMENT	49cc	49cc	49.9cc	49cc	49cc
CYLINDER LINER MATERIAL	Steel	Electrofusion	PLATED	Alloy	Alloy
CARBURATION	VM 12SC MIKUNI	VM 12SC MIKUNI	Dell'Orto 19mm	Dell'Orto 14mm	Dell'Orto 19mm
SUSPENSION FT.	Inverted Telescopic Fork 3.8 inches	70mm/2.8inches Telescopic-coil, w/2 way adjust	EBR 6.3 inches	Hydraulic 5 inches	Hydraulic 5 inches
SUSPENSION R.	Single Hydraculic Shock 2.8 inches	52mm/2 inches. Swingarm, twin shock, coil spring, w/2-way adjust	IMCA ADJ 6 inches	Hydraulic 5 inches	Hydraulic 7 inches
WHEELBASE	36.00 inches	33.9 inches	39.25 inches	35.5 inches	40.6 inches
WHEEL SIZE F	10 inches	10 inches	10 inches	10 inches	12 inches
WHEEL SIZE R	10 inches	10 inches	10 inches	10 inches	10 inches
OVERALL LENGTH	51.4 inches	50.6 inches	55 inches	51.5 inches	54.8 inches
SEAT HEIGHT	21.7 inches	18.9 inches	26.25 inches	24 inches	28 inches
Class 1 Stock 4-6	NO	YES	No	Yes	No
Class 2 Stock 7-8	NO	YES	Yes	Yes	Yes
Class 3 Stock 4-8	NO	YES	No	No	No
Class 4 Stock 4-8	YES	YES	No	No	No