[BBRMotosports]

A guy on here asked for the valve timing on a crf250R. If anyone wants to compair here ya go.

Valve timing.
Intake opens 15Degrees BTDC
Closes at 50 Degrees ATDC

Exhaust opens 50 Degrees BBDC
Closes at 15 Degrees ATDC

Cam specs
Lobe hight intake 36.00-36.240
Exhaust 25.502-25.741

Spring free length
Intake 39.47 (1.554)
Exhaust 43.07 (1.696)

This bike is a uni cam motor

 

[sendler]

Diameter

Valve diameter? Can you type in the specs of the CBR250R? It is interesting that Honda is using the CRF engine and not the CBR250R engine in their new $13000 spec racer.
.

A guy on here asked for the valve timing on a crf250R. If anyone wants to compair here ya go.

Valve timing.
Intake opens 15Degrees BTDC
Closes at 50 Degrees ATDC

Exhaust opens 50 Degrees BBDC
Closes at 15 Degrees ATDC

Cam specs
Lobe hight intake 36.00-36.240
Exhaust 25.502-25.741

Spring free length
Intake 39.47 (1.554)
Exhaust 43.07 (1.696)

This bike is a uni cam motor

 

[BBRMotosports]

That will be next because if the valve sizes are the same when I do my head work i'll use kibble white valves, springs and keepers if they are the same as the CRF. I don't know what the cbr specs are because i don't have a real book on it. Maybe someone else can help us out here?

 

[AJ250r]

Intake valve
opens at 1.0 mm (0 .04 in) lift 20° BTDC
closes at 1.0 mm (0.04 in) lift 35° ABDC

Exhaust valve
opens at 1.0 mm (0 .04 in) lift 40° BBDC
closes at 1.0 mm (0.04 in) lift oo TDC

Cam lobe height
IN 30.931 - 31.171 (1.2178- 1.2272)
EX 30.839-31.079 (1.2163- 1.2236)

Valve spring Free length
Inner 34.58 (1.361)
Outer 40.37 (1.589)

Straight from the service manual. Not sure what they mean by inner/outer for the Valve spring free length

 

[sendler]

Overlap

The CRF has more overlap and lift. The CBR250R cams are more for fuel economy.

 

[Kurlon]

Straight from the service manual. Not sure what they mean by inner/outer for the Valve spring free length

Two springs per valve, one nestled inside the other. Dual springs are easier and cheaper to produce than more expensive but lighter single spring beehive setups.

 

[BBRMotosports]

Stock the CRF has one spring per valve, when you switch to kibble white valve witch I did on my CRF's then they come with dual springs

 

[BBRMotosports]

Or should I say my 07 does anyways

 

[BBRMotosports]

Intake valve
opens at 1.0 mm (0 .04 in) lift 20° BTDC
closes at 1.0 mm (0.04 in) lift 35° ABDC

Exhaust valve
opens at 1.0 mm (0 .04 in) lift 40° BBDC
closes at 1.0 mm (0.04 in) lift oo TDC

Cam lobe height
IN 30.931 - 31.171 (1.2178- 1.2272)
EX 30.839-31.079 (1.2163- 1.2236)

Valve spring Free length
Inner 34.58 (1.361)
Outer 40.37 (1.589)

Straight from the service manual. Not sure what they mean by inner/outer for the Valve spring free length

We must be looking at two different books here because our numbers are completely different. I got mine out of the cylmer master book for my 07.

 

[saikamaldoss]

We must be looking at two different books here because our numbers are completely different. I got mine out of the cylmer master book for my 07.

this is the timing of CBR250R not CRF that u posted and BBRMotosports can u post ignition timing as well for CRF ? for CBR it is 10°BTDC at Idling