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How to choose the right Octane Fuel For Motorcycle

here are recommended octane ratings for other motorcycles

Honda cd70 old model 

Honda cd70 2022 or new model

Honda pridor 

Honda cg125 

Suzuki gd110 

Yamaha ybr 125

Honda cb150f 

Suzuki gds150 

Suzuki gr150 

87 to 92

87 to 96 

87 to 96 

87 to 96 

87 to 96

92 to 100 

87 to 96 

87 to 96

87 to 96 

87 to 96 

how to find the right octane for your motorcycle: the easiest way of choosing the right fuel octane is to consult owner's manual. and there you will find the recommended fuel octane. and also check for other fuel related recommendations such as if your motorcycle engine can run on leaded or unleaded fuel .

before 2015  the year when yamaha ybr125 released, every motorcycle in pakistan used low compression engine that doesn't require high octane fuel. but now even honda cd70 have 9.5:1 compression ratio in 2022 or newer models. and because higher octane fuel is available in pakistan. so more motorcycles will make use of that. but weather or not your motorcycle required the high octane fuel depends on its specs . and it is necessary to know what is the right octane for your motorcycle.

the first spec to look for is the compression ratio of an engine.

compression ratio:

                                 there are 4 strokes in a 4stroke engine.

                                 1: intake.

                                 2: compression

                                 3: power.

                                 4: exchaust.

after the fuel and air mixture is fed into the cylinder. it is compressed before the spark ignites it.

compressing it brings the air and fuel molecules close together and raises its temperature for an efficient burn.

compression ratio is written as 10:1 or 9.5:1. the ratio sign ": " determines the compression ratio between the 2 values.

fuels are rated in octane and ron . and the higher the octane the better it resists the combustion.

but why do we need to resist combustion when we are trying to combust the fuel mixture.

the answer is when we are trying to compress the air-fuel mixture it raises its temperature if the fuel is not the right octane range. then due to compression, the fuel will reach the temperature where it ignites without the spark. that causes knock and that damages the engine.

and if you put high octane fuel into a low compression engine. then because the high octane. the fuel resists combustion. that results unburn fuel and exhaust gases that choke the catalytic converter foul spark plug and reduce power.

when the engine is operating we want combustion to occur at the right time and the right octane fuel helps to achieve that.

so the right type of fuel is required for proper combustion. here is the list of recommended octane ratings related to the compression ratio of an engine.

Note: octane rating does not denotes the power that fuel can make.

Compression ratio to octain chart

Compression ratio |

Recommended octane

5:1

6:1

7:1

8:1

9:1

10:1

11:1

12:1

72

81

87

87-92

89-96

92-100

96-104

100-108

let's see what is the right octane fuel for honda CG125. to find out open the owner's manual and find the page where atlasHonda mentioned compression ratio of the engine. in case of honda Cg125 it is 9:1 now compare that to the chart above and we have the right octane and it is 89 to 96 ron. we can use any octane fuel in that range. 

atlashonda cg125 specification chart

in case of Yamaha ybr125 it has 10:1 compression ratio engine. you can use 92 to 100 octane fuel. 95 to 100 octane fuel is recommended.

yamaha ybr125 specs chart
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