Potentially stupid question, but... What is Octane booster and should I be using it in any of my bikes? (fantic 200, Yamaha ty250 mono and 1954 tiger cub)

Thanks

Sam

No

It does what it says

It boosts the Octane rating a little of the fuel, I'd have thought it isn't needed in a trials bike as there not in a high state of tune.

The higher the octane number the slower the fuel burns (explodes). raw petrol would burn too fast and make a knocking / pinking sound (called detonation). This destroys motors (basically the petrol is exploding before the piston has got to the top and  tries to push it back the wrong way, while momentum is moving it forward, over loading bearings, conrods etc). 

Higher octane fuels burn slower thus the spark lights the fire before top dead center ( modern engine designs) and the piston is over the top and starting to descend when the explosion starts pushing its hardest. Also the explosion of the higher octane fuel will take longer, pushing on the piston all the way through the power stroke.

Higher octane is needed for higher compression ratios. By squeezing the gasses together more they react more violently (bigger bang) creating more push on the piston (more power). With low octane fuel this compression can cause "dieseling" (compression ignition like a diesel engine, very bad, difficult to stop, kill switch wont work on motors doing this, use high gear and stand on the back break HARD).

If your motors made a loud sharp knocking noise when hot and under load this might be ocuring, if so use a higher octane fuel. The other alternative is to lower the compression by adding an extra base gasket. Also note that riding around at low engine speeds and loads, can on two strokes carbon them up and then under load conditions make them detonate. To stop this without lifting a spanner, when you have a long hill go flat out in a mid to high gear, make the motor work hard and it will burn this buildup out.Note; It will smoke a Lot if there is buildup, sometimes even when you turn it off!

It can make some not nice noises if buildup is bad during this as it blows the crap out. Have a cool down ride after. Your bike will run smoother after, 

I doubt your motors need octane booster. Compression ratios above 10:1 will need 98 or higher octane if pushed hard.

 

Hope this helps

 

In general on a trials bike octane booster is not needed, may even reduce power. TY250 monos were known for pinking so if best quality pump fuel such as BP ultimate does not prevent pinking try octane booster.

I would read up on pinking / detonation / pre ignition to try to make yourself aware of its symptoms so you can tell if your bike is pinking. Then you can decide if octane booster or another remedy is appropriate.

Road racing 2 strokes used to be fitted with pinking detectors / counters and some 4 strokes use knock detectors to give engine management information.

The higher the octane number the slower the fuel burns (explodes). raw petrol would burn too fast and make a knocking / pinking sound (called detonation). This destroys motors (basically the petrol is exploding before the piston has got to the top and  tries to push it back the wrong way, while momentum is moving it forward, over loading bearings, conrods etc). 

Higher octane fuels burn slower thus the spark lights the fire before top dead center ( modern engine designs) and the piston is over the top and starting to descend when the explosion starts pushing its hardest. Also the explosion of the higher octane fuel will take longer, pushing on the piston all the way through the power stroke.

Higher octane is needed for higher compression ratios. By squeezing the gasses together more they react more violently (bigger bang) creating more push on the piston (more power). With low octane fuel this compression can cause "dieseling" (compression ignition like a diesel engine, very bad, difficult to stop, kill switch wont work on motors doing this, use high gear and stand on the back break HARD).

If your motors made a loud sharp knocking noise when hot and under load this might be ocuring, if so use a higher octane fuel. The other alternative is to lower the compression by adding an extra base gasket. Also note that riding around at low engine speeds and loads, can on two strokes carbon them up and then under load conditions make them detonate. To stop this without lifting a spanner, when you have a long hill go flat out in a mid to high gear, make the motor work hard and it will burn this buildup out.Note; It will smoke a Lot if there is buildup, sometimes even when you turn it off!

It can make some not nice noises if buildup is bad during this as it blows the crap out. Have a cool down ride after. Your bike will run smoother after, 

I doubt your motors need octane booster. Compression ratios above 10:1 will need 98 or higher octane if pushed hard.

 

Hope this helps

 

Thanks, thats a great reply and taught me a lot!

 

In general on a trials bike octane booster is not needed, may even reduce power. TY250 monos were known for pinking so if best quality pump fuel such as BP ultimate does not prevent pinking try octane booster.

I would read up on pinking / detonation / pre ignition to try to make yourself aware of its symptoms so you can tell if your bike is pinking. Then you can decide if octane booster or another remedy is appropriate.

Road racing 2 strokes used to be fitted with pinking detectors / counters and some 4 strokes use knock detectors to give engine management information.

 

My TY does actually knocksometimes. Some people have suggested piston slap, some have suggested pinking, others say they always knocked even from new. IT may be worth trying a little octane booster to see if it cures anything. Thanks

you could also retard the ignition a fly **** too, as it may be over advanced.

you could also retard the ignition a fly **** too, as it may be over advanced.

 

Good thinking, definitely worth a try. Thanks

I had the same problem from time to time with my B model ( std Mikuni carb. ), I tried playing with the needle eight, main jet etc. . I change the pilot jet to a #40 and it did made it a lot better.

 

Guy