What type of gas do you use?

denskies · Post by **denskies** » Mon Jun 29, 2009 4:49 am

What octane grade do you put in your buck-ten? My dealer told me premium, so thats what I use. Any input on the matter?

Keys · Post by **Keys** » Mon Jun 29, 2009 8:05 am

Octane is simply a measurement of the amount of heat created during detonation. The more octane, the more heat. If your scooter is running lean in even the least amount, avoid anything that will increase heat. There are only 2 things in your control to regulate engine heat; spark plug "heat range" and the amount of gas, since prior to detonation, gas is quite cool. If you go with a bigger (higher number) main jet, it will be no issue. If you use a cooler plug it will be no issue.

Too much heat will destroy a 2 stroke engine...that's what melts rings and holes pistons. Any time you increase the heat, through octane or plug range or summer temps or anything, you will want to jet it up to keep things cooler.

If you listen to the guys racing their high powered trucks in off road races, you will notice that when they hit the long flat areas, they will rev the engine up and down, making it sound as thought the engne is backfiring, etc. What they are doing is feeding too much gasoline into the cylinders to help keep the engine cooler, thereby preventing an expensive seizure.

Short answer: if you live in a cooler climate you are probably okay with premium. If you are in a hotter climate and wish to run premium for the performance assistance, I would recommend a larger main-jet.

--Keys

Major Redneck · Post by **Major Redneck** » Mon Jun 29, 2009 2:05 pm

Low octane burns slower, produce more heat,,, Higher octane burns faster,,, Octane ratings in engines are based on compression ratio,,, gen. the higher the compression the higher the octane requirement... If the engine has enough compression and the right octane (lower)(with the right engine timing) you dont even need a spark to keep it running,,, thus the spark knock,,, and tis the diesel engine... the compression alone is enough to heat the fuel to point of ignition... An engine running on diesel compresses the air inside the cylinder to high pressures and temperatures (compression ratios from 15:1 to 21:1 are common) now we are getting into Cetane... Too high an octane is not going to hurt your engine,,, its not going to run well ether... higher octane will run cooler in a cylinder the higher the octane the cooler the cylinder,,, no need to get into the octane debate at this time.

Most 2strokes have low compression and octane is not much of a factor. But cylinder temp. is.

I use PB/Ammco Prem. 93 octane... not for the octane rating... Its clear/white gas,,, causes much less buildup of varnish in the fuel system.

Also with the heat the way it is here in NC I am adding about an oz. of 2T oil with a tank of gas gas to help with keeping the rings lubed,,, its not going to hurt the engine, might have to change your plug sooner... ITS HOT HERE!!!

brimstone · Post by **brimstone** » Mon Jun 29, 2009 3:27 pm

i just use 87 here in southeast alaska, the pan handle part point down towards washington.

Keys · Post by **Keys** » Tue Jun 30, 2009 4:04 pm

Major Redneck wrote:Low octane burns slower, produce more heat,,, Higher octane burns faster,,, ... higher octane will run cooler in a cylinder the higher the octane the cooler the cylinder,,, no need to get into the octane debate at this time!!!

You are HALF right. It is correct that higher octane burns faster. This is caused by the molecules moving faster. This, then, creates more friction which creates MORE heat. This is where you are wrong...higher octane creates MORE heat as a result of faster moving molecules...NOT LESS!!! Anybody who has been through high school physics will know this.

This truth has been supported to me by several motorcycle mechanics who tune racing dirtbikes. Their comments were that they use very high octane gas in their racing machines BECAUSE they create more heat. More heat equals more power and efficiency. The unfortunate fact is that although the engine might, in theory, be running more efficiently, the materials and technologies we have are still unable to withstand that level of heat for sustained periods without engine failure. That is why they rebuild the engine's top end after every race.

For your own engine's well-being, please consult your mechanic before you begin making ANY alterations to the operation of your engine. You have here on this forum any number of shade-tree mechanics who may have anecdotal evidence to support their theories, but very little actual scientific evidence. That includes yours truly, but you may notice I tend to err on the side of caution. I honestly don't want to see you hurt your scooter because of something I may have posted, and if I see something posted that I have reason to suspect, I will advise you to be cautious.

I have over 40 years of experience including roadracing 2 strokes in the 70's and have owned over 60 motorcycles and 20 motorscooters. I am offering you the benefit of my mistakes and the benefit of dozens of mechanics. I have experience and training as a mechanical engineer and the saddest sight to me is a damaged engine that was caused by following unsound practises.

Always research any advice first and consult a professional before you do anything beyond your own understanding. You'll ride happier and longer if you do.

--Keys

Major Redneck · Post by **Major Redneck** » Tue Jun 30, 2009 5:20 pm

like i said im not going to debate

dmwarren · Post by **dmwarren** » Tue Jun 30, 2009 6:31 pm

What I ask is "Does my Rattler have a High compression, high performance engine?" then I buy fuel accordingly.
"The octane rating is a measure of the resistance of gasoline and other fuels to detonation (engine knocking) in spark-ignition internal combustion engines."
"Octane rating does not relate to the energy content of the fuel. It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner" http://en.wikipedia.org/wiki/Octane_rating
High compression, get high Octane to prevent premature ignition, and knocking.
There are a bunch of threads here on this topic. Check out the wikipedia article, also lookup heating value or heat of combustion.

Ray Knobs · Post by **Ray Knobs** » Tue Jun 30, 2009 6:48 pm

Does anyone know what the stock compression is? It's kinda low right?

Major Redneck · Post by **Major Redneck** » Tue Jun 30, 2009 7:20 pm

6.6 to one on the 106cc

MacJac · Post by **MacJac** » Tue Jun 30, 2009 8:29 pm

Nitrotane

B02S4 · Post by **B02S4** » Tue Jun 30, 2009 11:42 pm

Running 91 or 93 octane in a low compression Rat engine is a waste of money from my perspective. And as a practical matter IMO 91 or 93 octane gas won't make a Rat motor run any hotter as compared to 87 octane, but it will empty your wallet faster. That said, I run 89 octane in mine simply because that is what I run in my motorcycle & my motorcycle is the fill source for my Rat. Otherwise I would run 87.

Major Redneck · Post by **Major Redneck** » Wed Jul 22, 2009 4:46 pm

Octane Rating on the sticker is located in the cooterhull/petcarrier... the one on my Rattler has "OR 92 or above unleaded fuel...

CitizenX · Post by **CitizenX** » Wed Jul 22, 2009 5:15 pm

Higher octane retards the ignition of the fuel allowing it to reach full compression before detonation. Use the fuel recomended by the manufacturer.