Required fuel for GPz900R / Ninja 900? - Kawasaki Motorcycle Forums
 
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post #1 of 10 (permalink) Old 06-12-2018, 01:49 AM Thread Starter
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Required fuel for GPz900R / Ninja 900?

What's the minimum fuel octane rating for an 85 GPz900R / Ninja 900 / Zx900R? I have a the factory service manual, but it doesn't say. No owner's manual. The 89 owner's manual that I found online doesn't seem to show this either.

I see some mentions of "91" but that's usually in RON. 91 RON is only 87 in the US (R+M/2). Does anyone have an actual manual that specifies RON or R+M/2?
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post #2 of 10 (permalink) Old 06-17-2018, 10:30 PM
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Regular should be fine but see if you can find non ethanol gasoline.

This should help in your search for that if you do not know of a station nearby that sells it.
https://www.pure-gas.org/

1986 LTD 454
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post #3 of 10 (permalink) Old 06-18-2018, 11:00 AM
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The owner's manual should have the info or there might be an info label on the motorcycle somewhere under the seat or behind a side cover. I didn't see the fuel octane info in the 83-85 1100 manual.

From the 1981 KZ650-CSR owner's manual: it says to use 87 [(R+M)/2] or 91 [RON] >>> or a higher octane with either method.

The pumps around here are labeled [(R+M)/2] and ethanol-free isn't available.
Most of the time I use at least 89 octane, but I kind of alternate between 87, 89, 91 & 93.

....

1981 KZ650-CSR. Competition, Sports & Road.
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post #4 of 10 (permalink) Old 06-22-2018, 04:07 PM Thread Starter
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Quote:
Originally Posted by kawpaul View Post
Regular should be fine but see if you can find non ethanol gasoline.

This should help in your search for that if you do not know of a station nearby that sells it.
https://www.pure-gas.org/

Oh, ethanol again? Thanks for the link, but I think I'll stick with the E10. It actually helps draw water out, protects brass and particularly aluminum, it's no more "corrosive" (misnomer) than the toluene added to gas, and it's not bad for anything else. In fact, it has a higher octane rating and burns cleaner. The vapor pressure in the fuel tank (PV=nRT) also water being collected from the air. I can dig up scientific studies on all of that if anyone's interested, but that's for another thread.


Quote:
Originally Posted by martin-csr View Post
The owner's manual should have the info or there might be an info label on the motorcycle somewhere under the seat or behind a side cover. I didn't see the fuel octane info in the 83-85 1100 manual.

From the 1981 KZ650-CSR owner's manual: it says to use 87 [(R+M)/2] or 91 [RON] >>> or a higher octane with either method.

The pumps around here are labeled [(R+M)/2] and ethanol-free isn't available.
Most of the time I use at least 89 octane, but I kind of alternate between 87, 89, 91 & 93.

....
No sticker on this bike. Maybe someone removed it. Thanks for the data, but that 650 looks a 9.5:1 static compression ratio and the GPz900R was 11:1 from what I'm reading. I'm running on 91 (R+M/2) until I find out for sure. Lower power and more carbon than 87/89 if it can use that, but safer until I know for sure.
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post #5 of 10 (permalink) Old 06-23-2018, 07:05 PM
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I have an owners manual for my 84 Ninja 900 and it lists the octane requirement as 91 RON, or 87 AKI ((RON+MON)/2), so regular unleaded is fine. I've been using regular unleaded for many years with no problems. I do try to use non-ethanol though because I have found that when I use E10 for long periods I get greenish colored deposits in the carb float bowls, and these end up blocking the pilot jets. The carbs are a real pain to remove from the Ninja so going out of my way to get non-ethanol fuel is worth it to me.

Tod

'84 Kawasaki ZX900A1 Ninja
'75 Yamaha RD350B
'84 Yamaha RZ350L
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post #6 of 10 (permalink) Old 07-05-2018, 11:52 AM
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I am looking for an original air box for my 84 900. Thanks
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post #7 of 10 (permalink) Old 07-06-2018, 02:16 AM
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There's a 15 year old tank sticker. Less than 90 octane can result in severe engine damage. And they could only say 90 plus because all you could get was 91. I think the actual knock tests resulted in something like 96 octane in these 13.1 compression engines. I think ethanol fuel also delivers less power per gallon and rapidly degrades.

For an extra 20 cents per gallon i would go for the highest pump octane you have. Also against popular belief the slower and more controlled burn of higher octane actually has a cooling affect on the engine.

You could use vp motor sport 103 octane. It would be a waste of money but you wont do any damage. If you run crazy high octane like 108/110 in a 4 stroke you can get valve recession. By slowing the burn down so much the fuel mixture is still burning when the exhaust valves open.

You can also kind of mimic higher octane gas with fuel stabilizers. Like red line complete fuel system treatment.And not the ones for fuel storage.

To chose regular over premium to save 1.50 on a fill up just doesn't make sense. But to each there own
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post #8 of 10 (permalink) Old 07-06-2018, 02:47 AM
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Well online says your compression ratio is 11.1. you might be able to get away with 87. Low compression is considered 10.1.

10.1 is like the older ford flex fuels where it states in the owner manual that you can run your engine on high proof drinking alcohol in a pinch.

That tank sticker is off 13.1
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post #9 of 10 (permalink) Old 08-26-2018, 12:09 PM
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Hexa, ethanol is crap for older bikes and older automobiles as well. It is true it draws water but from the atmosphere which is them added to your fuel. The higher octane rating is funny seeing as how both fuels are regulated and marked on the pumps. The thing is ethanol degrades over a much shorter time so is not ideal for any engine that is not ran frequently.

A few years back I switched from a 10% ethanol fuel to a pure gasoline in my GPz 750. The first thing I had to do was idle it down as having the idle speed set at 1100 rpms for ethanol the bike was not idling at 1500 rpms which indicated a lot more power from the fuel. Also my mileage went from 50 to 55 mpg just by that simple switch. The bike ran much better and carbureted smoother as well. Having had to pull those carbs a few time before due to gumming up of the pilot jets from that corn fuel I decided even if it cost a little more I would run good gas like the bikes of yesteryear were designed for.

So while you can bring your propaganda here and try to sell it I am not sure you will have many takers. Most understand these older bikes need fuel that was in vogue when the bikes were designed.

1986 LTD 454
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post #10 of 10 (permalink) Old 08-26-2018, 12:41 PM
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While it is true the 650 has a lower compression ratio compared to the ninja there are other factors to consider. Namely cylinder head design. The 650 has a two valve head sitting atop a bore of 62mm. The spark plug is offset to one side so in reality the flame has a longer travel path across the piston to reach the other side of the chamber. The Ninja being a 4 valve head design has its spark plug centrally located in the head and the bore is 72.5mm so in reality the flame only has to travel half that distance or 36 mm whereas the 650's flame has to travel further and in my guess about 50mm across the piston and combustion chamber. By design the 4 valve head can handle a higher compression ratio from the same octane rated fuel than a two valve head due the spark plug location in relation to the cylinder wall.

My bike is a 454 LTD and is basically a half of the 908 ninja engine. Look it up if you don't believe me.
It runs fine on regular gas and has since the day I got it running after cleaning the carbs that the previous owner had said he cleaned them so I did not have to. I am glad I did not listen to him and checked them anyway. Maybe it was the so convenient fuel he was using but those carbs were a mess and gunked up badly.

1986 LTD 454
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