What octane rating?
- Thread starter jackditch
- Start date
cdiver666
Active Member
Depends on compression, and other factors to a lesser extent. My truck gets 87, the 300zx (undergoing turbo conversion) will get 93. Before it got 87. Don't have a bike ATM but my kz650 ran on 87.
A stock engine is most likely good on 87, but with higher compression pistons you may be detonating a bit and would be better off with higher octane fuel. Newer bikes might require "premium" fuel, because of compression. Lots of variables play in though.
I read somewhere that since motorcycles have less load on the engine (moving less weight) than a car, you could get away with higher compressions before you started detonating. Everyone's bike is different. I say no need to run higher octane unless you're detonating.
A stock engine is most likely good on 87, but with higher compression pistons you may be detonating a bit and would be better off with higher octane fuel. Newer bikes might require "premium" fuel, because of compression. Lots of variables play in though.
I read somewhere that since motorcycles have less load on the engine (moving less weight) than a car, you could get away with higher compressions before you started detonating. Everyone's bike is different. I say no need to run higher octane unless you're detonating.
crazypj
Split personality, I fake being smart
Most stock bikes only need 87, using higher octane when you don't need it is more likely to cause problems as fuel will quite likely still be burning when exhaust valve opens.
IF you modify motor you MAY need higher octane.
I usually run my 360 on 93 octane, but, it's had a lot of mods and isn't actually 360 anymore ;D
IF you modify motor you MAY need higher octane.
I usually run my 360 on 93 octane, but, it's had a lot of mods and isn't actually 360 anymore ;D
t71ford
Over 1,000 Posts
Remember that octane is merely the fuel's "burnablity". Hence higher octane in high compression engines, to prevent compression heat igntion similar to that of a diesel engine (detonation). But, and high compression engine at altitude may run better with lower octane fuel, since the air is thinner, and the combustion mixture is less--creating less heat at compression. This also can hold true on cold days, or also on hot days, as far as what fuel will work the best.
93 in my lexus LS400 (itll run on 87 but the computer retards the timing big time)
I'll run 90 in my 350, but it got a compression boost and a bunch of other work done. otherwise, most bikes made before 1980 are happy on regular long as its clean and fresh.
I'll run 90 in my 350, but it got a compression boost and a bunch of other work done. otherwise, most bikes made before 1980 are happy on regular long as its clean and fresh.
whataulooknat
Been Around the Block
I run BP's Gold gas in my 74 CB450. I get really bad spark knocks on the 87 and 89. The Gold is 91 Octane around here. I've got Higher Compression Pistons and I'm bored out 3mm. Before the Overbore I could run the BP Silver 89 Octane in a pinch, but it still ran better on the 91.
my-79-750-k
Therapy is expensive. Riding is cheap. You decide.
Honda says to run 93 (or whatever is highest in your area) in the 750, therefore, I run 93. It doesn't knock. I put 87 in the first tank I ever ran in it, and it sounded horrible. But then again it's got pods, 4-1, open muffler and somewhat ported intakes.
Sunoco 114 for the TZ - it's 15.5:1 CR, it only needs 110 but that gas has a faster burn speed
87 for the RZ
89 street gas for the CB160 race bikes - tried U4.2 at $15 a gallon but no difference.
As a rule, the lowest it will tolerate without detonation is the gas to use. We got 1/2 hp more out of the CB160 racers on street gas than on VP C12.
87 for the RZ
89 street gas for the CB160 race bikes - tried U4.2 at $15 a gallon but no difference.
As a rule, the lowest it will tolerate without detonation is the gas to use. We got 1/2 hp more out of the CB160 racers on street gas than on VP C12.
kopcicle
antidisestablishmentarian
teazer said:
About the same experience here . I'm able to run higher compression on 87 with careful squish/quench management . I've used as close as a .037" deck but backed off to .043 for common street use . The hint here is percentage as well as location of the quench area as well a bit of taper . Indexing plugs opening towards the intake helps more than you might think . Understanding and being able to control your advance curve counts for a few more points of compression . I'm able to run a bit richer with more and earlier advance to take advantage of occasional added octane . If I don't add advance with 110+ I pour a bunch of heat into the pipes . It should come as no surprise that with added octane and advance the engine runs a bit cooler allowing for slightly tighter valve clearances , added duration , overlap , etc ...
Just my $0.02
~kop
my-79-750-k
Therapy is expensive. Riding is cheap. You decide.
Buy an ethanol filter. They're a total of about 15$.
