I text today with a well respected tuner about what octane to run in our Gen 1’s
He said all he has ever run in any of his stock motor bikes was regular 87 octane.
Little background on my riding style if it matters. 99.9% of my riding is curvy roads so im not full throttle often but i do have the occasional roll-on contest with riding buddies.
The can of worms is now open for your thoughts.

* Last updated by: morgstang on 7/30/2024 @ 2:56 PM *

Regular and mid-grade gasoline caused my Gen1 to pop more on deceleration. If it's burning more readily in the exhaust, I thought it might do that in the engine too. Preignition was the concern. The ZX-14 seemed to run just fine on regular but I could feel no performance increase from lower octane. I saw no reason to use regular gasoline except the lower cost. I don't use my bikes as daily drivers so I don't mind spending more for gas. For my bikes, I always use Premium 91 octane here in Michigan. It's also ethanol-free.

So im lost on what ron and mon mean. Does this pic mean 90 octane US?

US, yes.

* Last updated by: piken on 7/30/2024 @ 9:12 PM *

So im lost on what ron and mon mean. Does this pic mean 90 octane US?

I assume the pic means 90 octane Japan. I do not think the US averages RON and MON. read on!

I googled it and it appears that US gas is rated 4-6 numbers lower than the exact same fuel in other countries and the reason is that other countries average the RON and the MON. I guess the US just uses MON? If so, you should be able to use 87 octane safely. I'd rather play it safe and go with the higher octane.

Since you asked, RON + MON is the average of the Research Octane Number and the Motor Octane Number. I googled "anti-knock index" to find that.

The MON is "The motor octane number (MON) describes the behavior of the fuel in the engine at high temperatures and speeds."

The RON is "The research octane number (RON) is defined as the percentage by volume of iso-octane in a mixture of iso-octane and n-heptane that knocks with some intensity as the fuel is being tested."

I googled those too.

What does that all mean? I'd have to google more to give an answer but my assumption is that the RON and the MON are two reliable forms of data that are used together by Kaw to determine the minimum octane fuel that is safe for their engine. I'm guessing the RON is a test that yields very conservative results and they use it to provide a margin of error. Google on if you like. For this one, I just follow the crowd. Too many "maybes, I thinks and probablys" from a guy looking up things on google. I don't spend enough on gas for my bike to justify deeper research. This is a welcome relief from oil threads though.

I assume the pic means 90 octane Japan. I do not think the US averages RON and MON.

Thought it was apparent in the image I posted above.

Yes, this is what the US uses.... (R+M)/2 = "RON + MON / 2"

I don't see any debate here. I'll use what the manufacture that built and tuned the motor recommends.

I run Chevron 89 octane year round in my 14R and occasionally 90 octane ethanol free.

Run 87 with all 4 of the 14's I've owned. Hot days it will knock. Has to be under the right conditions >> Heavy loads. Winter months >> ~Quiet.

Thanks Hub. I live in Texas and its hot…lol

This was how it was explained by a respected engine guy

Lower octane gas actually provides more horsepower up to the point it starts pinging. The pinging is detonation caused by the fuel igniting before the piston is in the right place. Higher octane fuel just burns SLOWER to prevent this. Made sense to me. I've always used 87 in my 06 ZX14 and that includes track days

Mad

^^^^This has always been my understanding also. Plus since Kawi recommends 90 Octane (US) I’m pretty sure they played it safe with a small margin when deciding which Octane to “recommend”. I live in the blistering Texas heat and haven’t experienced any detonation or issues running 89 in my 2017 ZX10R, 2012 ZX14R and my newly acquired 2023 ZX14R. I can definitely feel the difference when I’ve accidentally filled up with 93 and go back to 89. It pulls harder throughout the entire rev range.

It my sport bikes I use the highest rating until I get a new exhaust and tune. I had a tuner out of Arizona explain it to me several years back. He tuned my CBR1000RR and he also tuned the sidecar bikes that race in the TT, so I'd like to believe he was relevant. Basically said that a bike with all its emissions in tact will run hotter. Remove the emissions and tune for the fuel to cool as well, and the highest octane isn't needed because our bikes don't have high enough compression if only running basic boltons. My liquid cooled inline street bikes have run awesome on 87. Now, my V-Twins on the other hand? I have 100% gotten some pre-det running lower octane fuel but there were usually other issues and conditions that accompanied that.

ZX14s have over 12:1 static compression. That's far beyond any limitation of low octane fuel.s. As Hub says, he gets detonation when it's really hot. Anyone that runs 87 (US) is going to get detonation. You might not hear it, you might not tell, but it's there. Also I'm sure there's knock sensors and the ECU will pull timing to try to reduce any detonation.

Run what you want, I don't think we've seen anyone who we've blamed on detonation for a blown engine or catastrophic failure, but it's definitely preferable under any conditions not to have it. It's literally the result of the pistons rattling around in the bore. There's no way anyone can tell me that's preferred.

The pinging is detonation caused by the fuel igniting before the piston is in the right place.

Right place is at peak compression or at TDC. Empirical evidence for me is having a bore scope, saw a V divot in the piston crown for lathe work. Felt a heavy knock under load. Pulled the plug, ran the bore scope down to see the piston dome.

Now the V was gone and looked more like a crater with balls of melted aluminum. Therefor, when reading a plug, you can see the gray spots on the nose of the porcelain burned or melted into the surface.

Kind of see it has to be at TDC to be near enough for the aluminum to hit the plug that close?

Damnit, I should have come over here before I wrote a small novel on the 14r side.

For those who don't want to read my blather there, im having some ping under load @ low RPM and I think its due to the summer fuel mix - and it seems that maybe I'm on the right track.

If anyone of yall feel bored and want to entertain my post, cool, but I think now I'm going to experiment with using a lower oct non ethanol summer blend and see if THAT is the remedy.

Heck, that's not a novel, it's very concise if you ask me. I hope you get some advice on your problem.

https://zx14ninjaforum.com/messages.cfm?threadid=9D93B5A4-0D8D-ECCD-954B6E6A921753EB