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Quote from: Wantabe_Wryder on February 01, 2006, 11:16:01 AM
I haven't been riding recently (multiple reasons) and was starting to get a little concerned about the bike just sitting in the garage unused, so a couple of weeks ago I topped off the tank (it's all 89 octane) and poured some Sta-Bil in there- more than I intended, actually. I was shooting for half of the little bottle- I think it's 4oz?- but ended up pouring more like two-thirds of it in there before I realized it, maybe closer to three-quarters. No big deal, I thought- there are lots of posts saying "just dump the whole bottle in there". Ran the engine for 15-20 minutes to (hopefully) get it into the carbs, and didn't notice anything unusual at the time.

Possibly relevant fact: This is a 2002 model, stock, so it has what was previously only the "California" model five-degree ignition advancer/rotor. And, of course, it's jetted lean, and takes forever to warm up properly.

So, recently I'm working out in the garage, and I pull the bike out and fire her up. Starts fine, idles fine. Now, though, when she's about as warmed up as she gets, where there used to be a "flat spot" around 4-5k, it's a really noticable stumble- as in, it misses. Once I get above that, it seems ok, but it's a definite miss trying to roll the throttle through that RPM range. I kept waiting for it to go away as the engine warmed up, but it never did, always hesitated and stumbled, "missed" a few times at about the same place when revving it up. On top of that, the last time I did it, with the engine good and warm, it knocked 5 times loudly in rapid succession when I rolled BACK the throttle, on the way down through the RPM range. Just that, 5 knocks and then a smooth idle again. At that point I figured that whatever the problem was, I wasn't doing it any good, and I shut her down.

At the time, I was reminded of the Dorothy Parker quote:

"WHAT FRESH HELL IS THIS?" 

Far classier than "WTF??", but the same basic sentiment.

All of this is without a load- the bike transitioned from legal to illegal to ride in the interim (temporary tags expired before I got it to state inspection), so I can't really ride it at the moment. I expect to correct that situation next week.

Ok, there's only one variable that I'm aware of, and my guess is that this thing is tuned on the ragged edge of acceptable performance from the factory anyway, and by dumping somewhat too much Sta-Bil in there I've reduced the octane of the gas to the point where it no longer runs well at all, and can even detonate if the revs drop quickly- but that's just a guess at this point, and not a very well informed one at that.

What's the consensus of you folks who are more experienced than I am with the GS (practically everyone here), especially those who know/have the 2001-2002 models? Is it most likely just the additive, or have I just come up with some new, unrelated problem?

TIA

How long was the bike sitting with old gas before you dumped the Stabil in?  Stabil doesn't make old fuel better, it just keeps new fuel from deteriorating.

Probably a fresh tank of gas will fix everything.

99' GS500E -I had a similar reaction to too much fuel additive.  Although, I have to admit mine was more on the idiot side.
The additive I bought was for 26 gallons. I dumped in 3/4 of the bottle before I read the instructions.  

Reading your symptons reminds me of that day, except I had a definite bogging down of power (in low RPMS) and no knocking.

The cure for my bike was a simple syphoning of the fuel tank and fresh gas. she purrrs.

For you I'd be more concerned about the "knocking" thats a definite WTF, especially if it just went away. How can a fuel additive cause a ghost knock?
I can't wait to see what people have to say about that.
good luck, Dude!

where there used to be a "flat spot" around 4-5k, it's a really noticable stumble- as in, it misses.

I am not 100% sure but I believe this is a symptom of too much octane (raises the pressure in the combustion chamber)

Don't quote me on it though.
Syphon out your gas and replace. let us know what happens

That could explain the knocking as you throttle down. I think Sta-bil is an octane booster, making your fuel super potent.
It may knockon the throtlle-back simple because it is popping stronger than normal.

again, don't quote me on this. I am just thinking out loud (and typing)

[^3

5 gallons of bad gas makes for a great parts cleaning bucket!!!

If you can't find a metal 5 gal bucket. use a house paint can (1 gal)

and dump the rest.  Most auto parts store will take waste oil/gas/liquids.

you could always just burn it

I would say the gas was bad way before you put the stabil in.. so It wouldnt have helped. I agree.. drain out the gas.. and start w/ new.. and maybe a bottle of good ole' STP fuel treatment 

Quote from: 3imo on February 01, 2006, 01:19:33 PM
5 gallons of bad gas makes for a great parts cleaning bucket!!!

If you can't find a metal 5 gal bucket. use a house paint can (1 gal)

and dump the rest.  Most auto parts store will take waste oil/gas/liquids.

you could always just burn it

Stabil reduces octane.  That is why when I am using it, I fill up with 93 octane fuel. 

I take old gas and dump it into my Astro van a couple of gallons at a time into a almost full fuel tank.  Since it holds 27 gallons, it isn't an isuue.  BTW, don't do this if the gas has any water in it.

Quote from: Wantabe_Wryder on February 01, 2006, 01:15:17 PM... So.... what the heck does one do with 5 gallons of bad gas???

If you don't want to take a chance, buy a 5-Gallon gas can and use it in your lawn mower over the summer.  Give it to your neighbour if you don't have a gas mower of your own.

Stabil makes my bike starts easier and idles better.  At least that's my experience.  So I suppose it does change the characteristics of the fuel.

Cheers,
e.

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