What is the minimum octane rating for a motorcycle with 11.3:1 engine compression ratio ?

Question

I heard that the bigger the compression ratio, a better octane rating is needed ? Or am I wrong ?

Answer 1

Compression is just one aspect. Generally, the higher the compression the higher the octane you will need. But, there are so many exceptions to that rule. The Yamaha Zuma 2016 takes 87 octane. But, has a compression ration of 12.0 to one. However a Honda Rebel with a compression ratio of 9.2 to one may knock at higher tempuratures with 87 octane and be fine at lower tempuratures with 85 octane. Elevation also affects your octane need. Almost every engine will drop two octane levels going from sea level to Denver. That is why you see 85 octane prevalent there and not at sea level. The best guide to go by is the owners manual. Whatever it calls for that is what I would use. If you don't know, just pay attention to the engine. If you hear any knocking go up one level of octane untill it stops. Knocking can wreak havok on any engine except diesels. So, If it knocks under normal exceleration or use then you need a change right away.

Answer 2

Minimum Octane Rating

Answer 3

Depends on actual motorcycle engine, combustion chamber design, size. Small bore cylinder have less detonation problems than bigger bore cylinder, Herret head combustion chambers with flat head surface and depression in piston for the actual combustion chamber like on Moronis from Italy had 12:1 compression and ran on the 87/89 octane for American market, some of the new fuel injection engines are running 11:1 compression ratios and regular fuels. The old dual spark plug heads conversions for Harley, BMW before the fuel injections used to get away with regular fuels with the 'stock' high compression heads that had required high lead premium fuels. Late hot spark ignitions in small combustion chamber with rapid swirl patterns a good quence area surface can take high compression with lower octane fuels- especially if direct fuel injection or a Ricardo spherical precombustion chamber. Some of the newer motorcycle engines are using these proven methods to meet emissions standards, fuel requirements and maintain decent power levels without detonation. .

Answer 4

It has to do with a number of variables - just look the bike specs up online - see what the minium RON is and use that - higher doesn't buy you anything if the engine doesn't need it. My 2005 DL-1000 has 11.3 to 1 ratio and runs just fine on 87 octane AND it is the recommended fuel for the bike.

Answer 5

If you are looking for simple rules.... forget it!



Shape, size, ignition method, injection / carbureted, and how cooled will change the engine requirements.



If you are in doubt and want to save money, a few pennies especially on motorcycle fuel will not save you much; buying a new replacement engine is very expensive! ...Buy the next fuel grade up!



If you fear the mechanical devastation examine your spark plugs often, that is where the damage MAY show up first... and as you throw the old damaged spark plugs away.... entertain the thought that the money you saved buying a lower grade of fuel....has now been spent on a new plugs AND would not come up to the difference in what you saved on low grade fuel.

Answer 6

The only correct answer is what the manufacturer recommended for that bike/ engine. Otherwise spend the extra 20 cents and run premium so you won't have to worry about harming anything.

Answer 7

The higher compression ratio the higher grade the fuel this is true you either need unleaded or the next one up I forget the name at the moment

Answer 8

i would say most bikes are designed for premium fuel ... low octane fuel ignites easier so is more prone to detonation, which is probably the #1 killer of bike engines .. i wouldnt risk it to save a few cents ..

Answer 9

91/93

Answer 10

You heard wrong. Use whatever rating the manufacturer recommends.

Answer 11

Look up the proper fuel for your bike....which you failed to give any details about.

Answer 12

just use the best premium octane

Answer 13

I would be using premium unleaded