Kawasaki Z125 Forum banner

1 - 20 of 24 Posts

·
Registered
Joined
·
106 Posts
Discussion Starter #1
How's it going everyone. I just wanted to know what do you put on your z.

I use 93 octane on mine since filling up this bike is cheap.

How about you? :)
 

·
Registered
Joined
·
143 Posts
I work in the fuels career field for the Air Force and take an interest in fuel outside of that. You are likely just costing yourself a few extra pennies for nothing running premium. Our simple little Z125 engines just aren't designed for it. The only way I would run higher octane would be if I did upgrades that I felt needed it such as higher compression. A couple months ago I went to a station and mid-grade was a penny cheaper a gallon, and I still got 87 in my Jeep. Even going 86 or 85 wouldn't bother me much, but I would certainly be listening for knocking.

There are a lot of discussions on this over the years on the internet. Here is a pretty good one: https://www.reddit.com/r/askscience/comments/p97jk/does_using_a_higher_grade_gasoline_give_me_better/
 

·
Registered
Joined
·
22 Posts
I use 87 as recommended. Higher octane is for higher compression ratios. Since the Z is air cooled, I feel that it's best to run the recommended 87 in it.
 

·
Registered
Joined
·
106 Posts
Discussion Starter #8
I use 87 as recommended. Higher octane is for higher compression ratios. Since the Z is air cooled, I feel that it's best to run the recommended 87 in it.

That makes sense since 93 octane burns hotter than 87.

I forgot to take into consideration that our motor is air cooled and not water cooled. :)
 

·
Registered
Joined
·
3 Posts
Until you add more compression or advance the timing, you will not see any advantage in running 91/93 octane fuel over regular 87.

Also, 93 octane doesn't burn any hotter than 87. The octane rating is simply a fuels resistance to detonation under pressure. All other qualities, such as energy potential, heat production, burn rate, etc.. have nothing to do with the octane rating.
 

·
Registered
Joined
·
3 Posts
Oh ok. I always thought they burn hotter. I have a lot to learn. :)
No worries. Fuels can get very tricky once you start throwing around additives, leaded, oxygenated and ethyl (alcohol) based fuels.
 

·
Registered
Joined
·
67 Posts
I run 87 as it is a low compression engine. I tried once to use 93 and I burned through it so much faster. Never again till I start heavily modding this engine.
 

·
Registered
Joined
·
16 Posts
Ive been using ethanol free 87 and seems to do best with it. I used premium once and noticed the heat didn't put it together in my head it was hotter fuel. I had some MS98L VP for a Legend car air cooled fj1200 yamaha motors but I couldnt bring myself to use it in the z becuase it was leaded
 

·
Registered
Joined
·
275 Posts
Older thread I know but curious if anyone runs 89? Everyone says use what is recommended in the manual but the manual just states do not use under 87 but it also doesn't say not to use anything else so?
 

·
Registered
Joined
·
326 Posts
Run 87. Run 89 if you wish. Wont make much of a difference at all. Ive been down this road so many times. If you get a fuel controller and it states use 93, then use it. I dont think the stock ecu has a way to advance the timing enough, (especially with no knock sensor) to make 93 useful.
 

·
Registered
Joined
·
42 Posts
Run 87. Run 89 if you wish. Wont make much of a difference at all. Ive been down this road so many times. If you get a fuel controller and it states use 93, then use it. I dont think the stock ecu has a way to advance the timing enough, (especially with no knock sensor) to make 93 useful.
So any advice as far as advancing the timing to effectively run 93. I can with the PCV and can map the timing out.
 
1 - 20 of 24 Posts
Top