96 octane or not.

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Should be. Standard in the UK is 95 with premium at 98 & Im sure some have run the 98 with no problems. The higher octane makes for a more balanced fuel but apparently only gives performance enhancement on performance engines.
 
keep an eye on the temp. 98 will generate more heat but wont give you any more performance, mainly designed for injected engines designed for higher RON.

Im using 98 octane in my zen 26cc but will be change to a 95 once I finish the current mix ive got. Its never overheated but I have been told they run hotter with the higher RON fuel with no performance gains.
 
Straight out of the Zen G230 manual

Mix high-octane (over 95) gasoline and high grade 2 cycle oil (JASO FC Grade oil or ISO EGC grade) in the ratio of 25 : 1.
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that said, i've allways run mine on bog standard, i'm too tight to pay for a can of super unleaded :clown:
 
'Fifth gear' in the UK did a test using 95ron & 98ron fuel on a standard sort of car, a VW Golf Gti & an Impreza Sti. If I remember correctly the bhp for the town car did not change, the Golf was 5bhp up using 98ron but the more performance enhanced Impreza was 20bhp up using 98ron.
Based on that I would imagine the difference in performance, if any, for a 26cc 2 stroke would be very minimal. Thats my theory anyway :blush:
 
Don't bother. Not worth the extra cash. :no:
Put your money into your 2 stroke oil.
There are many subjects on the matter if you do a search here. Most come down to personal preference.

Not sure if Germany uses ROn or Octane but that would be why 95 is recommended, it's the equivalent of US 89-90.
 
If you are trying to gain performance then a performance plug would be better otherwise stick with what you have got imo.
 
keep the same plug for sure.

with regards to an earlier post about the improvements made on GTi and STi those are injected high compression motors, our 2 strokers are not, there will be no performance gain with 98 RON vs 95 besides maybe a fraction longer run time (and I mean a fraction) but I don't think its worth the higher running temps.

but def. don't change the spec of the plug, maybe performance one but u want it with same heat range as the 7H
 
it ll be fine. wont run any better/worse (as long as its not ethanol, lol) than with 93 or even 87.
 
what you need to remember is why you need to run higher octane fuel in a car, and thats to prevent detonation. detonation, or pre-ignition is when the combustion chamber temps get too hot, the fuel will start to compression ignite. when that happens, you get a one flamfront in the combustion chamber, however when the spark plug fires you get another flame front, and what happens is the 2 flame front collide. when that happens you get a knocking noise, however the results are huge amounts of stress to the piston and connecting rod, rod bearings and crankshaft and prolonged driving with detonation can lead to some rather serious damage. one way to help eliminate the condition is to run higher octane fuel. the higher the octane the harder it is for the fuel to ignite. this also has negative effects, as running fuel with too high an octane rating will cause poor fuel economy and loss of power.

now in rc stuff, its hard to say whats really needed. with a modded high compression motor, definetly need high octane, i see some engine builders recomending race fuel (110 octane, or alcohol). as for a stock cy or zenoah, they say to run minimum 87-92, or 95-98 depending were you are. for the cost of gasoline, its better to run higher grade imo.
 
thats great info for sure. one thing to consider is RPM. these motors are turning 18k to 20k rpm. thing is, can pre detonation been presant, and if so, is there enough time for it to cause any real ill effect via performance loss, or even damage.

i don't think i have seen a case of motor issues, atleast on the zen/cy type motors we use (and others like them) where predetonation is apparent, let alone causing damage. the theory is, there just isnt enough time at 16k or so up rpm for it to occur. again just a theory, but considering finding a predetonation issue is hard to find with these motors. if one were using an adjustable timeing cover or ecu ect. then i can forsee some predet probs, but not on the stock fixed timeing i don't think its there, or a problem if it is, unless its just a bit of lost performance.

But Predetination can have Adverse effects on performance and even durability.

i can maybe see some of the cracked heads ive seen could for all purposed be predetination related, but finding and proving it is the perverbial needle in the haystack.

so with all that said, higher octain will likely yield no advantage over a lower octain fuel where our motors are concerned. atleast in my opinion.

now if your talking 110 race fuel or aviation fuel, well now your talking a different fuel base than standard 87 or 96 even. this fuel is a much more pure and cleaner burning fuel, and is capable of higher power due to its faster burn rate. here the octaine is used in the same method for the same reason, to slow the fuel burn down, but not so much to control predetination, as more to control the length of the burn to utilize the power potential of the fuel for engine use. basically so it don't blow it up from too much power. again just some of my limited understandings of these fuels.
 
I have a solution to detecting predetonation... all you need is some Acoustic Emission monitoring kit from Holroyd instruments, it only costs £2k for the basic set up.

I have the kit at work which I use to diagnose bearing problems, it should pick up the double flamefront in the combustion chamber too. I'll give it a go later this week :)
 
BrawnFG said:
I have a solution to detecting predetonation... all you need is some Acoustic Emission monitoring kit from Holroyd instruments, it only costs £2k for the basic set up.

I have the kit at work which I use to diagnose bearing problems, it should pick up the double flamefront in the combustion chamber too. I'll give it a go later this week :)
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You are 1 clever bloke. Are you a professor by any chance :clown::clown::clown:
 
that would be cool to see if it happens.


i would also try Naptha (white Gas) as alot of people use it, but the octaine rating on it is around 55. so if any fuel is likely to predetonate, i would think Naptha would be the one it would happen to regularly, which may be easier to detect.

i can see some happening from 12,000 rpm and down, but afterwards, 12000 plus, seems like the cycle would just happen too quick.

Please be sure to post back your findings and any pertinant info you can find.
 
i've just been having a google, and found the following tidbits.

http://www.thumpertalk.com/forum/archive/index.php/t-749087.html
Remember that mixing oil with the gas (like on a two stroke) lowers the octane rating of the fuel significantly, so even though they may be lower compression than a four stroke, they often require around the same octane of fuel.
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You need the oil to provide the compression in a 2 stroke(It provides the seals around th piston rings as well as lubricates the engine) The amount of oil you run will be the determing factor on this. The more oil you run the higher the compression to a maximum that the engine is capable of. That is why you see usually two values on compression for a two stroke, it is harder to create that seal at high rpm's therefore the comprssion goes down. If you run too much oil then you decrease your octane level so greatly that you then limit the power making capability(potential energy in the fuel) of the gasoline, so there is a bit of a balance there. If you run oil rich mix say 25:1 to 30:1 then I would run 93 octane. If you were running somewhere around say 35:1 to 40:1 I would try to run 91 octane. It is always good practice to start with the manuals reccomendations, but it has no gaurantee that it is going to be the best setup for you, you may have different air density, fuel quality, oil quality than they do in giving you those numbers. A little trial and error will set you in the right direction, part of the fun in dirtbikes is finding the best setup so you can beat the next guy with the same bike...lol:banana:
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Seems to make sense that the 2 stroke oil may reduce the octane number, so you may need higher octane to compensate. Our engines definately fall into the high RPM catagory so need a stronger oil mix than bigger 2 strokes.

Starting to wish I'd paid more attention in class and taken the IC engines module....
 
BrawnFG said:
i've just been having a google, and found the following tidbits.

http://www.thumpertalk.com/forum/archive/index.php/t-749087.html




Seems to make sense that the 2 stroke oil may reduce the octane number, so you may need higher octane to compensate. Our engines definately fall into the high RPM catagory so need a stronger oil mix than bigger 2 strokes.

Starting to wish I'd paid more attention in class and taken the IC engines module....
Click to expand...

Some good info there mate, thanks for sharing. I think based on this 95RON would probablly be the best safe allround fuel to use.
 
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