Fuel Mixture Oil to Gas Ratio Help!!!!!

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Apr 29, 2016
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#61
Ok so i have a question on gas/oil ratios regarding performance parts
1st off does the gas/oil ratio matter when running performance parts on your build? I run 32/1 before i added flex fit poo poo exhaust with an Xport manifold
I have also purchased the GT-80 reed valve and carby intake manifold running on a 36 thooth sproket

Before parts where added was able to get up to 32.8 MPH with just a dual boost bottle kit now with everything listed minus the boost bottle i only get about 21 MPH and the engine at time seems bogish if im asking this question in wrong area please just let me know where i can get the proper information
 


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#62
What I always recommend is do one modification at a time, when you try too many things at once it hard to tell what works and what doesn't. What rear sprocket were you running when you reached 32? It sounds like it could be geared too high, but that depends on the terrane and the weight of the rider. My 48cc bike with a custom pipe performs better using a 44t sprocket than it does with a 41t. It gets in the pipes power band better with the 44t.
 
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#63
Was running a 36 thooth sproket with a dual boost bottle kit was able to reach 32.8 at WOT

With new setup still running 36 thooth sproket no boost bottle running gt80 reed valve carburetor intake with XPort intake and flex fit poo poo exhaust only able to get about 21
 
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#64
If you run a reed valve the carb sometimes needs a bigger jet, you'll have to experiment to find what you need. To answer the first part of your question you do not need to change fuel ratio when you add a reed valve, 32/1 with a good oil for air cooled engines should lubricate the engine well. Most upgrades are not a bolt on and go situation, on a 2-stroke you have to tune to every modification.
 
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#66
The reed valve came with the carburetor its the gt80 reed and carb assembly they seel ut at gasbike.net should i have the c clip in the highest position on the needle meaning the needle goes furthest into the float bowl thats what ive read from a couple of people
 

Big G

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#67
Your two stroke motor will run fine on just about any branded 2 stroke oil. The big enemy of any 2 stroke is heat. Get a big finned head and replace the muffler with one that will let the motor breath. Reed carbs, boosters and the like don't really let you gain much. Here is an example. 66 cc Grubee, stock will run you down the road at about 30 to 35 mph. Add a ported cylinder and high compression head with a expansion chamber type exaust and you're going 40 to 45. Add a good after market carb and you are going a solid 45mph. It's that simple and a mixture of 4 oz. to one gal. of reg gas is fine.
 
S

sully1617

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#70
Hey everyone! I'm still new to the motor bike world but I have completed my first build! I love riding my motor bike. The only question I have now is after the first 2 tanks of gas what's the oil:gas ratio? The first 2 tanks I mixed 16:1. Now that the motor is broken in what oil:gas ratio should I be using? I'm wondering if there are better ratios that make the motor faster or more quiet? I don't need speed because you can only go 30mph on a motor bike here in Wisconsin. Any ratios I can use to make the motor running smoother and more quiet? Anyway, can anyone give me some insight on which ratios work better after the first 2 tanks of 16:1????? Thanks!


WickedWheelz
GO GREEN
Get yourself a 1 gallon gas can and some better quality oil such as Lucas oil or amsoil and put 4 oz of oil in the plastic jug the go to the gas station and put in exactly 1 gallon of gasoline. problem solved. if you can't figure out 4 oz you can borrow your mothers or chicks measuring cup and put 4 oz of water in it the pour that into a glass jar or glass and mark it with tape. (Marker rubs off quik don't bother) then dump the water out of the jar and dry it out good and now you have your own measuring glass for oil. i use a small canning jar with a lid to keep the dirt and bugs out when not in use and keep it filled to the line so when i run out of fuel it is already to go for the next trip to the gas station. But Don't take the glass jar with you to the gas station pour the oil in your gallon jug and take that to the station. also you can purchase little 5oz oil bottles at any hardware store that has lawnmowers. the problem with that is you need to figure out what size tank you have and carry just the right amount on your ride to do a fill up and most of the tanks out there are rather small so that little bottle will be too much for your tank which is why i said go buy a 1 gallon gas can. your gonna get a lot of people with good intentions telling you all kinds of confusing things... just do what i just said and you'll be just fine. i've been doing exactly that for 4 1/2 years on mine and not a single problem with mine
 
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deadboy@216

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#72
I do not believe there is a correct "ratio". It is relative to where you live. I am running 30/1,bike runs smooth and quiet in the morning when it is cool and damp. But on the way home when it is 85 degrees out it is extremely noisy. That is the nature of the cheap "china girl". Been riding mine for two years on the south shore of lake Erie
,summer and winter with no problems. So over all a fun experience,eats up brake pads and tires though.
 

45u

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#73
I do not believe there is a correct "ratio". It is relative to where you live. I am running 30/1,bike runs smooth and quiet in the morning when it is cool and damp. But on the way home when it is 85 degrees out it is extremely noisy. That is the nature of the cheap "china girl". Been riding mine for two years on the south shore of lake Erie
,summer and winter with no problems. So over all a fun experience,eats up brake pads and tires though.

My tires and brake pads wear out quickly about every 150 to 200 miles. My first build is a 27.5 and hard to find street tries for it.
 
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#74
Dead boy what you described is a air/fuel mixture problem not a oil/fuel mixture problem. A 30/1 mixture ratio is good for lubrication, it sounds like your jetting is too lean. I like to jet mine so its a little rich when cold, then when its hot it runs like it should.
 
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ShelbyCobraSS

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#75
This is a GREAT read on the subject of premix ratios.

Fly
Ok, I now am a participant in the motorized bike world. Builder I bought the bike from ran 2-3 tanks through the bike and told me to run 20/1. I did and when the bike sits I have to put a paper plate under the pipe to catch all the blowby. The last time I rode it there was at least a teaspoon if not more of ooze that poured out while sitting overnight. I used to race Open Class two strokes in the So. Cal desert, District 37, Hare and Hounds. The last bike I raced was a KTM 540 DXC, an absolute beast of a bike. What I don't understand from the threads here is why I/we (and friends) always ran 50/1 with absolutely no problem whatsoever. Anything less was too much oil. And these threads talk about loosing hp with less oil and not running the bike to hard? WHAT ARE YOU GUYS SMOKING? And what is this garbage about the smaller the engine the higher the rpms? Did I read that right? What malarky.
 
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#76
Ok, I now am a participant in the motorized bike world. Builder I bought the bike from ran 2-3 tanks through the bike and told me to run 20/1. I did and when the bike sits I have to put a paper plate under the pipe to catch all the blowby. The last time I rode it there was at least a teaspoon if not more of ooze that poured out while sitting overnight. I used to race Open Class two strokes in the So. Cal desert, District 37, Hare and Hounds. The last bike I raced was a KTM 540 DXC, an absolute beast of a bike. What I don't understand from the threads here is why I/we (and friends) always ran 50/1 with absolutely no problem whatsoever. Anything less was too much oil. And these threads talk about loosing hp with less oil and not running the bike to hard? WHAT ARE YOU GUYS SMOKING? And what is this garbage about the smaller the engine the higher the rpms? Did I read that right? What malarky.
What we are running are not as well made as a KTM, Yamaha, Kawasaki etc, our clearances are much wider and the quality control at some of the manufacturing plants is non exsistant. If you have a well balanced and machined engine you can run a leaner fuel/oil ratio, I have as well owned many 2 stroke dirt bikes and ran a lot leaner ratios, but the wear that some of these engines show indicates more oil is needed. I have found that 32/1 with a synthetic smokeless oil works best for me.
 
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#77
I just take a standard 16 oz water bottle and fill the bottom 1/20 section with oil, and then shake and pour as needed. Simple, and effective for mixing and storage.
 
D

Dashz

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#78
when i first bought my grubee gt5 i ran it at 16:1 like the manual said and thought that is way to lean and too much oil it will carbon up in a second. sure enough lol using the suplied oil and the recomended mix of 16:1 after i rode about 150 miles i took the motor apart for inspection ............ lolol lol lol 16:1 my but ! the whole top of the piston had a thick (for 150miles) layer of carbon and the cumbustion chamber on the head was crudded up and the cheap 3 prong spark plug was black as a cat and fould !!!! i knew i could get way more power from this thing if i modded it my own way.

i have no money but i have lots of tools so time for the...
FREE MODS !

so i took the cilynder and heaad off and gave the cilynder a good heavy port and polish, raised the exhaust about 3/16 and lowered the intake about 3/16 and widend bolth by 1/16 each side then decked it down a little with sandpaper and glass... then the piston i rounded the edges of it and made ramps for all the ports even the transfer ports effectively changing the timing ( if you look at the top of the piston now it has a 4 leaf clover pattern ground in it) and i cut a full 5/16 off the entire intake side of the piston skirt ! man its way lighter than before WAY lighter ! allowing for quicker rev's. along with the port time changes i made with the dremel i estimated it would be a lot better for mid to high rpm power.

the head i had to take a lot off because i ground a lot off the piston witch lowered the compression so i took .100 off the head and dremeled a new squish band in by hand then polished the chamber to a mirror finninsh and put in a nkg b5hs plug and made shure it did not hit the piston and it was in line with the intake port.

i also port matched the exhaust and intake by the way i am using the long intake ... the z one with a 2.5 in extention hose for addeed tourqe .

i installed a new set of rings after a slight honing of the cilynder (slight i said as i was scared the cheap chrome would flake just enough to put some honing marke back on there at 45s or so) and reasembled the motor. it has a lot of compression now way more than stock ! it tested at an average of 138psi !!!

i cut off the cheap crappy plug boot and just crimped a simple loop conector strait onto the plug wire and screw it onto the tip of the plug directly ( mutch better conection )

and since then i have been running my oil gas mix at 40:1 full synthetic ... i use promix at lowes or true fuel 40:1 premix

good god man after those FREE MODSmy motor feels like a whole new beast !!!! it is literaly 3 times more powerfull !!!! i can cruse comfortably at 30mph !!!!

after about 100 miles i tore down the top end to inspect its condition and wow is all i have to say ! running 40:1 full sythetic and 93 oct the combustion chamber looked spotless like a mirror still and the cilyender was spotless no signs of scratches or wear the piston was perfectly clean aside from the small brown spot where the spark plug was fireing and the plug looked like chocolate color but slightly darker than usual (probably because i was riding low rpms and going slow for a lil bit before shutting it off and tear down) the plug on normal inspection ... WOT then cut off looks perfect !!!

so my theroy is that these motor can run at 16:1 or 20:1 or 25:1 with regular oil but you will carbon the heck out of it and foul plugs like a mad man. also you wil never get the full potential out of the motor with so little gas in the mix and natural oil.
even in a bone stock motor i would recomend you run 32:1 to 40:1 and use full synthetic right out the box! even for break in that is how i broke in my new rings at 40:1 full synthetic and my engine has rediculous amounts of power compared to when it was stock and at 16:1.

so i tell everyone who ask me what i run ... 40:1 full synthetic 93 oct. i recomend that mix also to all who have a grubee gt5 if your stock compresion then use 87oct 40:1 if your high comp the 93oct 40:1
some higher grade better more well designed oils for motor crross race bike can be run at 50:1 to 75:1 but i personaly would never go over 50:1 on this type of engine as it does need significant lubrication ! the parts are cheaply made and tolerances are not to spec so pushing the limit of how little oil you can use... it is very stupid for sutch a tiny insignificant gain if there even is any .... i would rather run 40:1 full syn and know i am safley lubed and getting the proper amount of air fuel mix than run 16:1 and be lean and foul up my engine or 75:1 and be to rich and stressing all my bearings and every moving part with unnessasary heat and preasure

i also tried running it at 50:1 full syn with lucas oil upper cilynder lube added to the gas and the differance was neglegable i hardly noticed a thing and my plug looked like it was getting lighter in color and straying off from the good coco color i want so i swapped back to 40:1 and add a little (1oz) of lucas oil upper cilyender lube every other tank.

Some years have passed, and they still recommend the crazy 16:1 ratio... I readed your whole post, thanks, you really helped me.
 
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#80
I have only used Valvoline Multi-Purpose 2 cycle oil mixed 32:1 in all my 2 strokes for over 10 years with no problems. I find the oil at Auto Zone
 

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