Hard starting - must drain fuel bowl(s) to start

25 replies to this topic
  • grayracer513

Posted June 18, 2013 - 12:27 PM


Most of the above are somewhat irrelevant to the overall question of fuel stability, as ethanol is far from the only added component contributing to the problem. "Pure" gasoline is not a single chemical compound. It has something like 8 major chemical components blended together in varying proportions to achieve a certain number of goals, among which are octane level, oxygenation, emissions reduction, and energy output. Race fuels are usually superior from a performance standpoint, not because of their lack of ethanol so much as their totally different balance of higher energy components in proportion to the more inert parts. Sometimes they can be just as unstable, and anyone who ever dealt with the original formulation of VP's U4 will tell you that.

Ethanol started out as a cheap oxygenate, but with the risible fixation with renewable fuels, it became mandated indirectly. MTBE was used in California as an oxygenate, but has fallen out of favor due to its toxicity and its hygroscopic nature. It was turning up in the ground water in places where there had never been a significant spill.

On the stability issue, MTBE was not as big a problem as ethanol because it takes less of it to release the same volume of oxygen into the combustion process as ethanol, and while both will bind to atmospheric water, ethanol is better at doing so in the first place, and as mentioned, there is usually more of it than there would be MTBE. Neither of these two are the only component of some of the many fuel blends available in the US that contribute to the instability of fuels stored over time, either, so the ethanol content is not a particularly important point in the discussion.

As far as octane goes, several regional blends sporting AKI ratings of 100+ are available in parts of the US, too. In general, one should not expect to be able to store gasoline in a vented container with a lot of airspace for more than 3-4 months at the most, especially in hot weather.

  • Do I Care?

Posted June 18, 2013 - 03:14 PM


Thanks Gray but you said the Octane level would be lower than the US. It is not.
Ethanol is horrible stuff and clogs the carb so why the ethanol info, all relevant.

  • grayracer513

Posted June 18, 2013 - 08:52 PM


Until the fuel has actually been subjected to a Motor Octane Method test and rated so that an average of the two can be taken, neither one of us knows that the octane rating of your 95 RON fuel would be expressed as an AKI rating. What I said was, again, that fuels that rate 95 RON will normally end up with an AKI of 90-92 as a general rule.

The Research Octane Method is widely regarded as not particularly pertinent too the requirements of small displacement, high rpm, high relative output engines, and most engineers consider the Motor Octane method to be a much more accurate representation of the conditions such engines operate under. Oil company marketing departments long ago started hyping high octane fuels as a way to get more power from your engine, even though in fact, the only connection octane number has to power output is that high compression engines require higher octane.

Having taken the public down that road for the last 50+ years, it's not hard to figure out that they would use the Research Method to hawk their wares. After all, who would buy an 89 Motor Octane fuel when they could have a 95 RON blend? But 89 MON is typically a higher rating than 95 RON by about 3-4 points on that scale. The US AKI thing was another example of the gov't trying to look after its public by not taking sides, and just confusing the whole thing further.

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  • Do I Care?

Posted June 20, 2013 - 02:09 AM


Cheers Gray, your always so informative. :thumbsup:
Just so you know- we have strict fuel standards here and is subjected to regular testing. If it is labeled 96-98 premium, it must be 96-98 premium.

Not like most other countries where they can just label it as anything they like.
Not having a crack at anyone, just stating the facts.

  • grayracer513

Posted June 20, 2013 - 07:07 AM


Just so you know, there are few governments on Earth more fascinated with the concept of micromanaging every detail of everything than ours, and our standards for fuel labeling are as strict as any in the world. Not smart, necessarily, as most of it was written by people who know little about it, but strict, nevertheless.

I'm certain that your 96-98 octane fuel rates exactly that when subjected to the Research Method only. The point is that a Motor Octane test will rate that same fuel 8-10 points lower, simply because of how it works, and the average of the two tests will factor out to an AKI of about 93-94. If you brought that same fuel here, that's the label it would get. The same gas, the same resistance to detonation, just a different way of rating the octane.



Sections 6.4 through 6.9 are particularly germane to the discussion.

  • Do I Care?

Posted June 20, 2013 - 07:31 AM





Sections 6.4 through 6.9 are particularly germane to the discussion.

Wow, give me ten years and I'll be through reading it :)


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