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Main Area => General GS500 Discussion => Topic started by: BigTwin on May 11, 2005, 08:42:36 AM

Title: Octane w/Bob B Ignition Advance?
Post by: BigTwin on May 11, 2005, 08:42:36 AM
Trust me I've searched through alot of pages with no luck.

My bike will soon have the Bob B Ignition Advance, Wileyco w/Srinath Flange (Choker), and no re-jet yet.

So what octane is the best for performance (not power, but reliabilty) and I've heard some octanes run cooler, is that true?

THANKS, BigTwin
Title: Octane w/Bob B Ignition Advance?
Post by: tdan553527 on May 11, 2005, 08:44:55 AM
Lower octane runs cooler.
Title: Octane w/Bob B Ignition Advance?
Post by: V8Pinto on May 11, 2005, 11:26:02 AM
Higher octane is only necessary if you "do" something with it e.g. advance timing (which you did).  I believe higher octane (somebody correct me) has a slower flame front.

Since you are running the choker flange and no rejet, I would think that higher octane is probably not needed as long as you're not pinging.  I don't know how much the advancer puts in there though.  If it's only a few degrees, I wouldn't worry about it unless you start hearing popcorn ;)
Title: Octane w/Bob B Ignition Advance?
Post by: scratch on May 11, 2005, 12:36:59 PM
Quote from: V8PintoI believe higher octane (somebody correct me) has a slower flame front.

You are correct. In effect you are "retarding" your timing by running a higher octane.
Title: Octane w/Bob B Ignition Advance?
Post by: BigTwin on May 11, 2005, 12:46:30 PM
Well I advanced my timing 12 degrees, so should I go with high octane?

All we have in Ohio is 87,89,93 so no 91. What is best?

THANKS, BigTwin
Title: Octane w/Bob B Ignition Advance?
Post by: scratch on May 11, 2005, 01:02:46 PM
Run the 87.
Title: Octane w/Bob B Ignition Advance?
Post by: 94suzuki500 on May 11, 2005, 03:37:59 PM
ya octane is the resistance to combustion.  It is so you can have the gas compressed more with out it combusting unless there is spark.  to a point of course.
Title: Octane w/Bob B Ignition Advance?
Post by: cozy on May 11, 2005, 03:55:59 PM
Is there a greater chance of preignition with lower octane?
Title: Octane w/Bob B Ignition Advance?
Post by: 94suzuki500 on May 11, 2005, 07:11:34 PM
yes, but I havent had any problems running the low octane, I really dont think you have anything to worry about unless you start to hear some ping knock sounds.
Title: Octane w/Bob B Ignition Advance?
Post by: BigTwin on May 11, 2005, 07:54:15 PM
When I was putting on my Bob B advancer earlier today I turned the advancer to the right (meaning while tightening it I rotated it) and I'm not sure if this is a problem? I don't know if it has to be pointing a certain direction?

Bike runs great with it by the way, I also ran out of gas while riding. I pulled over to the side of the road and switched to Reserve, but it ran like crap and only ran for a mile then it died again, is this normal? How long should I put it on prime for? I did it for a few seconds and it started, but a short, I mean short while later it was just bogging down and completely died and wouldn't start back up. Luckily it died at the intersection of my gas station.

What could be my predicament?

And I got 93 octane because this all happened prior to this thread happening, any problems when I switch back to the low octane? This is my first time filling up also, it held 4.9 gallons is that normal?

THANKS to all who replied, BigTwin
Title: Octane w/Bob B Ignition Advance?
Post by: 70 Cam Guy on May 11, 2005, 08:21:08 PM
I have the Bob B advancer, and my bike runs great with mid-grade (89).  I actually get the worst gas mileage with super (91).  I suppose I ought to try the 87 at some point but I am fine with mid-grade.  Over 2.5-3 gallons it takes to fill, an extra 30 cents won't kill me
Title: Octane w/Bob B Ignition Advance?
Post by: Kerry on May 11, 2005, 08:53:55 PM
Quote from: BigTwinI also ran out of gas while riding. I pulled over to the side of the road and switched to Reserve, but it [...] only ran for a mile then it died again, is this normal?
No.  The ON and RES fuel hoses are probably switched.  (Meaning that you ran your REServe out with the fuel selector set to ON.  Then when you switched to RES you had nothing left.)


Quote from: BigTwinHow long should I put it on prime for?
15 or 20 seconds or so.


Quote from: BigTwinit started, but a short, I mean short while later it was just bogging down and completely died and wouldn't start back up.
That's the perfect time to move the switch to PRIme and leave it there.  But if your hoses are swapped that won't help.  :(


Quote from: BigTwinThis is my first time filling up also, it held 4.9 gallons is that normal?
The '01+ tank is supposed to hold 5.3 gallons MAX, so that's a pretty good fillup.

PS - I have used 85 octane for most of my 34,000 miles....   :dunno: