peak output/engine speed YS 91ST

[newbie]

Hi all,

i have a YS 91 ST,and i'm trying to find the right headspeed and the right engine speed.

Manufacturer's peak output is unlisted
My gear ratio is 11/88=8.1 (JR AS 90)
engine runs from 2.000 rpm/17.000 rpm.
if my headspeed is 1850 x 8.1 =14985 and 1950x8.1= 15795 and so on...
Is it enough for this engine(too low/too quick)?
Should i change my gera ratio 11/84 = 7.63? (optionnal gear ration from JR)

need your advise please

regards
lionel

[DavidH]

Bore 27.7mm
Stroke 24.8mm
Displacement 14.95cc
Weight 540g
Practical rpm 2,000 ~17,000

From what I have seen and experienced. The power band is in the 15,500 to 16,200 rpm range.
That is the range you motor to turn at wide open throttle.

David

[newbie]

thanks david :)

Do i have to take the head speed on the ground Idle-up 2 0° pitch or in a hover with a tachometer?

thanks
regards
lionel

[DavidH]

thanks david :)

Do i have to take the head speed on the ground Idle-up 2 0° pitch or in a hover with a tachometer?

thanks
regards
lionel

No you have to tach the headspeed while the model is flying and doing aerobatics. Or if you have a speed control device, you set it for the RPM's the engine needs to turn.

David