It's amazing how many threads there are (some VERY scientific, some not so much) on octane and the engine performance of older bikes, specifically the f2, which I have. I have read most of them. I was having trouble starting my f2 after it set for a couple weeks, so I put some premium in and then some STP octane booster which is supposed to be very good stuff. I always wanted to see a noticeable difference in performance between a tank of premium vs. regular (no ethanol). Some say there is and others definitely not. My mechanic, who knows bikes inside and out for decades, says absolutely higher octane gives better performance in older bikes. I could never really see a noticeable difference. Well, after that octane booster, I am 99% sure the octane boost increased performance. I notice a significant "kick" in performance. Accelerates a lot better, especially off the line. It almost feels like a different bike, maybe a 636, lol. It even sounds, meaner, exhaust "pops" more while decelerating at high rpm. Sounds real nice. Now this may all have some to do with the fact that my bike MAY have a jet kit and some kind of carb adjustment, which i'm not sure about. There's my 2 cents regarding this issue.

 

Back in the day our "fast boys" used to put naphthalene (mothballs) in their fuel to improve the octane rating. The octane boosters in use today add a percentage of highly volatile spirits like ether or something with similar octane improver.
I used 105 octane in my racing mini Cooper S and there was a real improvement in engine performance and smoothness.
Our fuel here is all 95 octane, some with lead, some without.
Honda engines are able to run on fuel with a really low octane like 83, due to the poor fuel available in some Asian countries. Just for info

 

Thanks Shadow!!

 

Homebrew Octane Boosters

I never made it myself, but I have known guys that have.
Xylene can be found in many hardware stores.
The stuff you buy, like STP octane boost, will only raise octane levels by a couple of points. Very small...
But that's done for legal reasons. Both to stay with-in emissions levels and to keep from damaging engines.

Either way, you can MAKE the octane booster, with a mild boost, for a lot less than buying the pre-made stuff if you ever wanted to.
Posting this because he drives the same car I did, and has some decent explanation.


I have no knowledge or experience on it's effect for motorcycles, just car's.
Even then, my turbo car ran on e85 :P

 

I just read that higher octane will not increase performance unless your carbs are jetted (not sure what jetted means). So I wonder if my carbs have been jetted or have had some kind of mod done to them. The original owner had the bike's nuts and bolts wired all the way around for the race track (I had to cut the wire on the radiator cap to add new coolant after draining the old), so i'm assuming the carbs have been adjusted/modified somehow.

 

Did you read this on the internet somewhere? Cause we all know they can't put something on the internet if it isn't true.

I vote we lock this thread right now and prevent what's coming next.

 

...and here we go!

Unless you have jetted and adjusted the timing for the higher octane, you won't see any advantage regardless than a slower bike. Higher octane only means a lower flashpoint to ignite the fuel to lower the risk of detonation(or pinging). All combustion engines are nothing more than an air compressor that uses gasoline to expand the air in the combustion chamber to rotate the pistons round and round for suck,squish, bang, blow(insert perverted joke here).
Higher the fuel octane, faster it ignites at the flash point, less power the combustion chamber will make. But lower the octane, the more power the engine will make, but sacrifice for a greater chance of detonation(pinging) and destroying the engine at higher revolutions.
The only reason why race cars use the higher octane fuel over the street cars is because they are tuned and built that way for hanging at the higher revs longer. Their compression rating is higher, timing and computer mapping utilizes the lower flashpoint to not cause detonation and grenade the motor on the race track.
For any bike out there; must be tuned to use Higher octane to make any sort of difference. On the F2's/F3's your bike will actually be slower unless you tune it by carb jetting and timing to see any sort of difference at the earliest. But it would be very stupid to get the bike to run on test fuel just because you thought you wanted to go faster. Oh, higher the octane, more likely it will eat the **** out of your seals. Sorry but the truth!

 

like a freakin moth to a flame...

 

I don't think this thread needs to be locked. With every inquiry or sharing of experience, we get just a little more valuable information that will help someone or prevent having to create another thread unnecessarily. We're adults, we can share our knowledge as such. Someone may see this thread one day and go AH HA!!! Believe me, I searched through COUNTLESS threads, reading for hours about octane rating and F2 performance. The only thing I learned is that there is no answer to whether higher octane increases performance. Even I didn't have any noticeable difference when using different fuels. If I did, it was so subtle, it may as well have been wishful thinking, my mood, the day of the week......or month lol. Then I poured a bit of octane booster in the tank, just to raise the octane a bit since it had been sitting a while. The difference was night and day. Pulls a LOT more, growls a LOT more, sounds meaner, runs smoother. It's like a new bike. If I were to go to the dragstrip, guess what I would pour into the tank? Now whether all that extra force in the engine is bad and not worth it, I don't know. I'm not that knowledgeable when it comes to the F2. But considering the reputation the engine has for downright abuse, i'd say a few times shouldn't hurt. I've learned a lot of stuff from this forum since getting my F2. And iv'e learned a lot by word of mouth, youtube, etc. But some things lacked a definite answer no matter how much internet searching I did. Nine year old threads with pages and pages of information, debate, experiences and even quotes from company techs and still no definite answer. Now I know.

 

This thread will not be closed as long as everyone respects each other, just like every other thread.

With that said, octane increase does not increase performance. Not directly anyway.
Low octane fuel will detonate prematurely at higher compression. Higher octane fuel can be compressed more before predetonation occurs. Its the high compression motor that increases the performance...

If your bike has been sitting for a while, the fuel will lose its octane stability and predetonate. Adding the booster will stabilize it so it will fire normally, thus giving the feeling of more power when compared running on old fuel.

In fact, the less volatile higher octane fuel could reduce performance in a lower compression motor due to it not being at its ideal compression state for optimal burn.