what fuel ratio to use ?

Onion

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Feb 12, 2019
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Hi, i'm just wondering what fuel ratio should i use for my 80cc bike after the break in period ? I was using fully synthetic oil with 1:16 ratio. What ratio should i use now ?
 

Greg58

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May 1, 2011
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32/1 is a good ratio, 16/1 is what has been recommended for the Chinese kits for a long time. 24/1 is a good starting point, and will not drip out of the exhaust when you stop.
 

Jimmy Bloodmaker

Active Member
Nov 24, 2018
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i run at 24:1 with a larger jet. i have found if jetted properly, you get more power with more oil and lower temps. i have experimented from 8:1 all the way to 32:1. 24:1 is what i find gives me no spooge, good temps, and just a whisp of smoke. 16:1 ( remember jetted properly) give me best power, a tiny amount of smoke, but it drips about 3 tablespoons of oil on my basement floor when i put it away. 24:1 give me a few drips, but i can live with tht. jetting seems to be the key with more oil, which gives more power. i believe it is because it seals the rings better, and i would expect longer life from the bearings and rings as well with more oil. anything lower than 16:1 doesn't give me any more power. again, your jetting is the key with your oil ratio.
 

Jimmy Bloodmaker

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Nov 24, 2018
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i used cheap dino store brand stuff on break in. switched to syn blend after 350 miles or so. only after i felt the rings seat and everything was set in. head bolts etc haven't come loose since then. although i did sheer the grade 2 bolts on the front mount, was a pretty scary fast stop when tht happened, was next to a 4 lane busy road. i since went to grade 5 bolts and studs for my mounts. i've also compression tested this one piece jug at around 130-35 psi ( 135 in winter and slightly less during summer)
 

Larry Trotter

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Nov 26, 2017
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You should probably run as much oil as you can and still have a good running engine. Think about it and do some math. 32 to 1 is about 3% oil to fuel and 16 to 1 is about 6%. I can't imagine that a 3% change in the ratio can have much effect on the power and I am sure the engine probably appreciates any more lube that it gets. I really can't tell any difference between 16 and 32 to one.
 

Greg58

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May 1, 2011
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I run 32/1 in everything that requires mixed fuel, I have a 1983 poulan chain saw that has never been apart running on it cutting fire wood every year. I've been running my bikes for 9 years on 32/1 also, why would I run more oil?
 
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FOG

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Mar 3, 2019
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My 2 cents on fuel ratio's. The reason we put oil in the fuel is primarily to lubricate the rod bearing. Back in the day I learned that lesson when I briefly ran 50 : 1 in my CR125. OOPS! Picture dark blue needles welded to a twisted cage.

Sticking a piston is another option I suppose, as in when ya forgot to fill the auto injection tank with oil? But I still think that time the sudden 0 : 1 ratio let the piston beat the rod bearing to it. In general it's all about keeping the rod bearing alive and well.

Since small motors don't create as much stress as big ones they can live on less oil, but that being said, I'm like Greg. I put 32 to 1 in everything.
 

Larry Trotter

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2 cycle engines on vehicles have some special challenges that other engines don't. The china girl isn't forced cooled and they are subject to some fairly high RPM when going down hill with very small throttle openings which results in very little oil getting to the bearings. I am sure that 32 to one is fine most of the time, but I will guess an engine will live longer running a little more oil. Just keep leaning out the oil mix and eventually you will find out just how little is too little.
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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The oil ratio debate ended years ago when all the major 2-stroke engine manufacturers (& the 2-stroke oil manufacturers) finished spending millions of dollars on R&D & all came to the conclusion that 32:1, 40:1 & even 50:1 (when recommended) are a optimum mix for engine life & performance!!

We 'motorized bicycle guys' figured that those ratios work perfect in our engines too.

We also figured out many years ago that the Chinese probably recommend using 16:1 because they didn't have fancy 2-stroke oil back in the day, & they were just dumping used motor oil in their gas... (& who knows, they still might be)!
 
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Larry Trotter

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Guess all manufactures know what amount of oil to mix with the gas unless it is a Chinese company and then they don't know squat. Could just be they know the engines need more oil because of the cheap bearings and aluminum bore.
 

Greg58

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May 1, 2011
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A lot of the importers simply copy the instructions that have been in circulation for years, if you read them closely they state use any motor oil or 2-cycle oil. Some of the distributers are now changing their recommendations to 24/1 with good 2 cycle oil and 16/1 with motor oil.
 

xseler

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Apr 14, 2013
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I'm at 6 years on this engine at 50:1 Echo mix......same as my 14 year old Echo trimmer. This engine has a lot of miles on it --- many at 35 to 45mph. Break in was at 32:1 with Lawn Boy oil. Your results may vary.
 
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