switching from regular to "high tests" gas

[frankieG]

so since gas went down in my area i began putting in high octane fuel in my bike.  normally i have always run regular gas in my gs's....89, 00 and 04.  since switching to the higher octane two or three tanks ago i have noticed some changes.  the bike is not performing any better, actually the opposite is true.  it is sputtering and backfiring both cold and warm.  so i am thinking that "high test" is not what is best for the gs.  we all know that the manual says to use regular gas and from my experience so far, and very limited, this would seem to be true. 

please let me know that you guys think and let me know what your experiences are.  my goal is to add to our huge yet never ending data base of gs performance , maintenance and what is best for our type of bike.

frankie

[Kurlon]

Generally speaking, you get the best performance by running the lowest octane fuel your motor can tolerate without pinging.  Higher octane fuel burns slower, hence needing more compression and advance to have any benefit.  Our motors are decidedly NOT high strung big compression machines, so low test should be fine in most cases.

I'm forced to run 93 as a spec fuel... gotta find a way to make the bike use it better...

[simon79]

My stock 2001 normally runs on 95 octane fuel.
Once in a while, (say every 3rd-4th refuelling or so) I fill it up on 98 octane (a suggestion from my mechanic, after some issues with carb floats tending to stick).
Actually my bike seems to run better with higher octane fuel, maybe it's just me but I feel it revs up faster and makes smoother takeoffs. No backfiring or sputtering of any kind, both cold and hot.
Gas mileage is a bit better apparently, but this I cannot say for sure by now. And even if it were true, I doubt I'd have some kind of a benefit 'cause 98 octane sells for an insanely high price.

[The Buddha]

You rejet frankie ?? if so unrejet it ... dunno how much smaller though ... stock /-1 maybe ...
Cool.
Buddha.

[werase643]

I'm forced to run 93 as a spec fuel... gotta find a way to make the bike use it better...



and how do they enforce this.....

[The Buddha]

I'm forced to run 93 as a spec fuel... gotta find a way to make the bike use it better...



and how do they enforce this.....

Yea run 140 mains (or smaller) with K&N lunch box filter and pipe ... lean as heck, even 93 will detonate ... 
Cool.
Buddha.

[Kurlon]

I'm forced to run 93 as a spec fuel... gotta find a way to make the bike use it better...

and how do they enforce this.....

We have a new random gas testing regimine in place.  There are three offical spec fuels, two VP products, and 93 'high test' from a specific Shell station beside the track.  (Sweet deal for them...)  No mixing, no additives.  The tech team has a test setup that measures two attributes of the fuel and compares it against fresh samples of the spec fuels.  If you don't match, you're out.

Buddha, I'd toss a pipe and filter on, but I'm restricted to a stock airbox and filter, stock pipes for the production twins class.

[The Buddha]

What ... GS 500 with stock filter and pipe ... do they even exist.
Yea, maybe run 115 mains.
Cool.
Buddha.

[galahs]

I am a high octane petrol user.. .why...

because I rode 6,000 km's around Australia using Premium.... then I decided I should just use regular..... got a bad batch of fuel and some outback tman and a dog town... ended up riding for 10 hours through a boiling hot dessert with a bike that couldn't go over 80km/h (50MPH).

So I now use premium with the hope the chances of getting a bad batch is reduced in comparision to regular.

[applecrew]

I've got an 07 f model - although the manual says 87 octane with up to 10% ethanol is acceptable, the dealer said I should only run 91 octane or better.  So, with over 3500 miles, I thought I'd try some mid-grade 89 octane.  I'm on my second tank of 89 octane (not a major brand name) , and now I think I've developed a sticking float or something - as of this morning, when I should be full into the no-name brand, she's started racing at idle up to 4K rpm.  I'm pretty f'ing annoyed right now.

I'm going to throw some Sunoco 93 octane in her tomorrow to see if that'll settle her down.  Not cool, I hope this will help resolve the issue, cause I'm otherwise diggin this bike big time!

If this clears up my 'issue', then I'd have to say I'm resigned to having to stick w/ high test.  Prior to this, she was running pretty sweetly and I'm averaging 58 mpg since I boght her from new.  My mileage has actually gotten better over the last 1000 miles on premium grade.



Mike