What kind of gas wont hurt my 70cc engine and works best?

What type of gas do you mix your oil with?


  • Total voters
    157
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sherryc8641

Guest
#1
I want to know what gas to mix my oil with. When I say that I mean, what should I use and shouldn't use for a healthy 70cc engine.TYPES OF GAS: regular, premium, ect.

Please give me any facts or opinion's you have or know on how to maintain a healthy engine :)
 


S

sideshowsideswipe

Guest
#2
I use synthetic oil now, but I may switch back to the regular stuff... I have always used 89 octane and it works great.
 
E

etheric

Guest
#3
I have heard a few good arguments that most small two stroke engines aren't designed to very high specifications and physically can't take advantage of higher octane fuel. I have used different octanes in multiple engines and consistently not noticed any difference.
What I have noticed is fuel from different companies perform differently (I acquired a good/bad station list when I first started driving.)
Speedway consistantly sucks (but their diesel seems okay)
Amoco/BP is good
Shell has always treated the car really well.
Sunoco is always good too (plus they've got lot-o-options on the octane levels)
Marathon has teetered on the fence.

I do practice using, exclusively, either high end or low end though, in hopes of getting fresher fuel. The middle isn't used as often I think (given the stations location) and I've heard it is common practice to mix the 87 with the middle tank (generally 89) if the station mis-estimated how much fuel they would need and ran out of tank space.

That being said I feel better sometimes getting the fancy fuel and even though I know it may not matter at all, I like to be happy, and I like my engine to be happy. Then we ride off into fields of blueberries and stuff outselves silly till we fall asleep in eachothers arms.
 
G

gone_fishin

Guest
#6
well...i'm pretty sure i know what sherryc8641's trying to get at. i think the real question might be "is there anything i shouldn't be using?"

i answered "premium" because ya didn't give me a mid-grade choice...i know gettin a few points of octane is worth it, but i won't pay the premium price for a barely noticeable leap in quality.

personally, i've always wondered...would there be a problem using octane boost w/lead substitute in these things? wouldn't that maybe be a benefit?

nobody better make fun of my stoopid question. that's not what we do here 8)

at MBc, we explain why it's stoopid :LOL:
 
E

etheric

Guest
#7
I voted for diesel in the name of Equality!
don't anyone be dumb enough and actually use it though.

by the way, what is synthetic gas?
 
G

gone_fishin

Guest
#8
hey, etheric, you got here fast...i didn't even finish my edit :eek:

so, you got any "racey" pics of you and the bike frollicing in the blueberry patch? :LOL:
 
G

Guest

Guest
#9
The 70cc/80cc engine has a compression ratio of 6.6:1. You can run as low as 70 octane in it with no problem.

Use as low octane as you can: Reason
1. Cheaper
2. More energy content (BTU) per gallon. Higher octane fuel has less energy content
3. Easier starting due to higher volatility. Higher octane fuel is harder to start in cool temps or first start of day. I had run100LL octane fuel in a engine and it was impossible to start when cold. It was a very high compression ratio engine (modified) and needed this fuel. I used starter fluid a lot in this engine.

The only time you need higher octane fuel in any engine (to include cars) is when you experience detonation or preignition and/or you engine is higher in compression (or runs hotter) and is specified in owners manual.
Older engines typically have carbon build on on piston tops and this caused increased compression and hot spots that can cause fuel to ignite prematurely. This is why older cars may run better with higher octane fuel.

If you use high octane fuel for any other reason, you are wasting your money and are being foolish.

Drew
Some of my qualifications: Engineer (lots of thermodynamics), maintenance test pilot, 20 years of wrenching on almost any kind of machinery.
 
G

Guest

Guest
#10
As for oil, any TCW-III rated 2 stroke oil should suffice. Type of oil isn't that important, what is important for these engines is the rather high concentration ration of oil to fuel.

With that said, I use the cheap walmart stuff in all of my 2 stroke engines and also in my 4 stroke 1.3L Mazda Rotary engine.
 
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