The Hodaka Club Forum

What's the word on using 100 octane AV gas in our old hodakas? I have a model 99 toad i am curious to know if I can avoid ethanol by using the local airports gas pump? Thanks, sorry if this has been touched on before.

One problem with AV gas is that it still contains lead. The second problem is that it burns slower. The third problem as I understand it, is that the octane is rated differently than automotive fuel and is only about 96 octane. I'm sure AV gas has changed since since my experimenting with it the early Hodaka days but it just didn't work in the race engine. Under racing loads the engine would just die. When it cooled down it would restart. I suspected slow burn was causing it and returning to regular pump gas, our problems went away. Racing automobiles used AV gas in the day successfully but it just didn't work in the era 2-stroke engines. I think that the slow burn was dumping unburned fuel out the exhaust creating a lean condition.

Just my dated experiences and opinion but after that I decided it was designed for aircraft. Didn't work for us.

The gang will probably have more updated info and some more modern ideas.

Max

I try to run ethanol-free gasoline in my bikes. The BMW /5 model because I _prefer_ to run non-alky gas, the Hodie because the old 2-troke engines don;t like to be run on alky-gas.

A website named Pure-Gas has listings of the Ethanol-free in the US and Canada, reported by users. I update my "local list" yearly, and if I am traveling I note the stations in "fill-up" zone I'll be needing. And something I've not tried yet, they also have a Smartphone app for their service. I addition to my paper lists of good-gas stations, I'll also input these stations into my GPS so I can locate them in unfamiliar areas.

http://pure-gas.org/

With the Hodie, advice is DO NOT use ethanol in the engine, and use a 100 octane ("Premium") grade of gas.I have a semi-local station about 20 miles away that has Premium no-ethanol, and I have a dedicated 5 gallon gas can that I fill up periodically for my "supply gas" and another 2 gallon gas can that I mix up a couple of gallons of pre-mix when needed. For easier mixing I have the 2-gallon can marked of at 1 gallon and 2 gallons. I'm thinking that the non-ethanol Premium should have a "shelf life" of a few months. If not, I can add Sta-Bil to the supply. I keep a few gallons of Regular ethanol-free around for the BMW so I can top it up without needing to drive 3-4 miles to the station all the time. As I see how my gas useage with the Hodie develops, I may mix more than a couple of gallons at a time.

But this is the SOP I've developed for now. Somewhat similar to my supply for the chain saw and weed-eater and lawn eqpt.

--Bill

Sometime between 2005 and 2010 I ran a bit of 100 Av-gas thru my Hodie. It certainly won't damage your engine, but it does have properties which are optimized for use in aircraft and which aren't the best for our Hodies (performance will be down a bit). Since most areas have a station listed in the "pure-gas" information, it would seem much better (and probably wayeeee more economical) to simply find one of those stations and purchase "pure" premium grade gasoline.
Ed

I used to like fresh gas for racing but for normal use premium should have a shelf life of more than a few months ? Just asking ------------Clarence

I can't think of a single reason to use low lead AV gas in a motorcycle. If you absolutely have to use high octane fuel, there are suppliers who sell race gas as such, and that way you know what you get. I don't use race gas because it is expensive, and mine runs fine on pump gas. Whether ethanol actually hurts an air cooled two stroke, I am not sure. Ethanol does make less power than just gasoline, but whether it is harmful is a different question. It is hard to separate urban legend from fact.

Not to mention that use of leaded Aviation gas in a land vehicle is illegal. Not a priority with the FAA/EPA, but the potential for a bored bureaucrat to nail you is there. Back in the day, when lead was phased out of gasoline and before we got good unleaded-fuel valves and valve seats people would "spike" their tanks with a little LL AvGas to keep the lead levels up. Lead, in addition to "boosting" octane and preventing detonation was an excellent lubricant for the valves and seats. Not a good thing because lead is a nasty and persistent environmental toxin.

--Bill

Shorty wrote:Whether ethanol actually hurts an air cooled two stroke, I am not sure. Ethanol does make less power than just gasoline, but whether it is harmful is a different question. It is hard to separate urban legend from fact.

Right. Lotsa BS with the facts. Ethyl Alcohol is a burnable dilutant to the petro-hydrocanbon mix of gasoline and it's used more for socio-economic political reasons than technical ones. It does burn, but also absorbs water from the air and can dissolve and corrode fuel system components. In new engines designed to work with that witch's brew it's probably OK. But in our older engines which are designed to run with a certain exact ratio of gasoline to air, it can upset that ratio and melt aluminium. Especially in oddball engine designs where the engine bearing and piston lubricant is mixed in the fuel.

Also, we have the "holy water mystique" of hunting up non-alky gas.



--Bill

Thanks for the info. I actually posted this question after I already filled up with the AV gas and I can say that the toad is not a fan of the stuff. I knew almost immediately that something was not right with how the bike was running. It felt as though it was breaking up under a load. I am still working on some carb adjustments so there is definitely an X factor involved however I ended up draining the AV gas after about 5 miles of riding and filled up with 89 pump gas, things smoothed out to how they were before. My next test will be with some 90 octane gas from a marina that is not nearly as close as the airport but still probably worth me checking out. Of course I hope to have my carb dialed in a little better by then. By the way, what position is the needle set at the factory for a 99 toad??

http://www.strictlyhodaka.com/v/vspfile ... /SH_99.jpg

Third notch standard. Doesn't mean it is right, it was just where it needed to be in the mid seventies.

Bought a new Super Combat in 1974. Been sitting in basement for last 30 years. Did a restore on it and now ready to ride. I have a local supply of 87 octane straight gas. Problem is bike wants 92 or higher octane to run good. Have a bottle of "Hi Test" octane booster which seems to be mostly toluene. Does anybody have experiance with this or can recommend another brand of octane booster ?

It'll like Premium non-ethanol gasoline much better. Go to pur-gas.org to locate your stations that carry no-alcohol Premium gasoline. Ethanol-free gas keeps much better than the alky-stuff. I buy my Hodaka fuel five gallons at a time, and if I can't use it soon enough I can put it in my other other vehicles.

Greg! Thanks for your post with the OM pages for the Model 99. In my long running post about the Red Toad, I posted pic from mine & it says .008 to .010 for the breaker gap!!! I'm playing hell with this bike trying to get it to run. It's like there's 2 diff books on the matter for the same bike. I wonder if the OWNERS MANUAL given me is for the Model 02? Is there a difference between the Model 99 & Model 02 for breaker gap? This motor is driving me nuts!

On the fuel issue, we only have one gas station in all of Santa Fe which offered non-E fuel. It's about a mile & 1/2 away from me and it's only 90 octane rated on the pump.

Maxie also says airplane fuel has lead. Now, I know there are rules against not using Leaded fuels but weren't all the fuels in the late 60's to early 70's leaded? Wasn't 1975 the first year they required unleaded fuel, or was it earlier? Victor

Here in SoCal we don't have a choice but ethanol, I could but VP race fuel but $$. I've been running ethanol 93 octane in my Super Tat 40:1 Yamalube for around 8 years racing. Yes same bike I raced at the HT Cup with know issues. I have a CW in my storage that I ride once a year at Hodaka Days with same old gas left in tank with no problems.
Now I do run into issue on the 03 Wombat with oil injection as the straight gas in tank plugging the jet if I didn't ride or start it every other week.