HONDA CR750 kortekaas engine analysis cr7509

THE INLET SYSTEM

Inlet valve dia	32	mm	Inlet valve area	804	mm²
Inlet valve seat angle	45	°
Flow coefficient	0.48		Effective valve area	386	mm2

Number of inlet valves	1		Total valve area	804	mm2
			Total effective valve area	386	mm2
Velocity of sound	330	m/s	Velocity in valve throat	169	m/s
			Mach index	0.47	(Max.=0.5)
			Req'd min. inlet valve dia.	32	mm
			Max. attainable rpm with
			present inlet valve diameter	10,211	rev/min

Carburettor diameter	31	mm	Carburettor area	755	mm2
Number of carburettors per cyl.	1		Total carburettor area	755	mm2
			Air velocity in carburettor	79	m/s
			Optimum carburettor dia. 4)	31	mm
			Max. carburettor diameter 5)	32	mm

4) Based on 81 m/s air velocity.
5) Based on inlet valve area






INLET LENGTH FOR MAXIMUM INERTIA EFFECT

	Valve lift when valve area A_{mes becomes 0.5 cm2}			1.47	mm
Inlet closing angle qcs for this valve lift	40	°

Inertia factor Z	1.029		Optimum length 6)	232	mm

6) Actual length of inlet system from bellmouth to valve.


INLET LENGTH FOR MAXIMUM PULSATION EFFECT

Order of pulsation qs	3
Inlet closing angle ABDC	49	°	Optimum length	224	mm


Motor: HONDA CB750R

DATA			CALCULATED RESULTS

Bore	61.5	mm	Piston area of one piston	2,970.58		mm²
Stroke	63	mm	Total piston area	11,882.32		mm2
			Capacity of one cylinder	187.1		cm3
Number of cylinders	4		Total capacity	748.6		cm3
Max. piston speed	22	m/s	Engine speed	10,476		rpm
			Corr. piston speed 1)	21.7		m/s
Engine speed for max. power	9,600	rpm	Allowable engine speed 2)	10,600		rpm
			Piston speed for max. power	20.2		m/s
Inlet opens 3)	20	°BTDC
Inlet closes 3)	47	°ABDC	Inlet duration	247.0		°
Exhaust opens 3)	48	°BBDC	exhaust duration	248.0		°
Exhaust closes 3)	20	°ATDC	Overlap duration	40.0		°
			Lobe centre inlet cam	103.5		° ATDC
Inlet valve lift	9	mm	Lobe centre exhaust cam	104.0		° BTDC
Exhaust valve lift	9	mm

Running clearance inlet	0.15	mm
Running clearance exhaust	0.15	mm

1) Based on piston speed times square root of bore over stroke ratio.
2) Using the corrected piston speed.
3) Valve timing is based on 1 mm clearance

Volume of combustion chamber	19.7	cm3	Compression ratio	10.5	:	1