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Re: [St] Using Regular Gas In A Sprint ST?



Hmmm.  My 2000 Sprint RS manual says 91 RON.  I got into a deep investigation  in 2001 because in the USA, like someone previously pointed, our octane rating is (RON+MON)/2.  I was told by two different petrol companies that our 89 octane will typically meet the 91 RON rating unless you're using a cheap company.  From experience since then, I believe him because I notice a difference depending on whos gas I use.  Some cheap sources ping when a Mobil or Shell did not.

Something I also learned during that investigation was that engine ping is pre-detonation.  A mechanical engineer explained it to me that is when the next burn occurs before the piston is completely up and ready for it's next detonation down stroke.  So the air-fuel mixture fires and is trying to push the piston down while the piston is still moving up.  He said that's why my wife's Jeep, which has 250,000 miles on it now requires a higher octane than when it was brand new.  Things get worn and loose.  

Increasing the octane slows the burn rate.  So when ping (i.e. pre-detonation) happens we should bump up the octane until ping goes away.

----- Original Message ----
From: Matt Knowles <matt@xxxxxxxxxxxxxxxxxxx>
To: ST@xxxxxxxxxxxxxx
Sent: Thursday, March 13, 2008 11:36:09 AM
Subject: Re: [St] Using Regular Gas In A Sprint ST?

I've had the same experience. 89 is what is spec'd for the bike.  
Ferndale only has one gas station and it only has 87 as do some of  
the other rural stations around here. Every once in a while I get  
caught low enough that it's either 87 or walk so I've chosen to use  
87. But the bike pings on 87 so I have to be real careful not to lug  
it. Not the way I like running the Sprint and certainly not worth  
saving 50 cents or so per tank.


On Mar 13, 2008, at 8:21 AM, Rupert Galea wrote:

> I could not detect any difference in how the bike runs between 89 and
> 91 Octane (in the USA). I tried 87 but in hot weather it would
> occasionally ping. So I run 89.

Matt Knowles - Ferndale, CA - http://www.knowlesville.com/matt/ 
motorcycles
  '99 Sprint ST - for going fast and far (2CZUSA)
  '01 KLR650 (A15) - for exploring the North Coast backroads
  '97 KLX300 & '01 Lakota - for playing in the dirt
  '79 KZ400 - just because it was the first vehicle I ever owned


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