What did I do to my bikes performance?

[Unknown]

To make it run "better"?
I've noticed over the course of my ownership that my bike just about redlines at 10.5 rpms at 115-120mph.
When I was in first gear I wouldnt get over 20mph before I had to shift into second.
When I was in 5th gear, going 60mph would leave me at around 7 thousand rpms.

A few weeks ago I recently changed the oil, oil filter, and air filter. Which gave it a noticeable jump in low end torque (like it can finally "breathe") but my speed:rpm ratio was still the same.
I lube up the chain ever 3 fill ups and check tire pressure, etc.

When engine breaking I notice it popping, bogging, and whining and I read somewhere to add a higher octane of fuel. So I went from 87 to 89.
I did this for a few fill ups so it would circulate the new gas as 89 and not half 87, half 89.

three days later, it now seems to be running "better"
I would go almost 40 mph in 1st gear before I had to shift (at the same rpms as when I was going 20mph)
I am in 4th gear going over 60mph
70mph in 5th gear leaves me with 6 thousand rpms.
But when I'm in 6th it seems to limit itself to 8.5-9 rpms at 100-110 mph. In fact, I have a quarter throttle more to crank down but it doesnt do anything, as if it was governed/limited.

What happened behind the scenes if switching octanes is actually the culprit? And what about the use of the throttle not doing anything more?

[tussey]

Switching octanes does nothing but waste your money. Been discussed 80 billion times. Please just go search google.


It's in your head. Running 89 doesn't make your bike run better. Your gs500 could always reach 40mph in first gear, regardless of the octane of the gas you put in it.

[Unknown]

6 days ago my bike would redline in 1st at 40mph. I've been riding almost 300 miles a day, this is not in my head

if higher octane isnt it, then what is? because the fact still remains, regardless of octane increase, its running better. I've changed the filters 3 weeks ago and its JUST now doing this.

[kml.krk]

looks like a beginning of the war 

back to the topic, I have no clue what have helped but I'm glad your bike pulls better now. Did you ever opened up carburetors? How are your plugs looking? Maybe one of the jets is partially clogged, maybe your spark plugs need to be replaced   
I'm just throwing some ideas.
good luck

[Roadstergal]

I would go almost 40 mph in 1st gear before I had to shift (at the same rpms as when I was going 20mph)

Er - if I'm reading this properly, you're saying that octane changed your gearing...?

[Unknown]

Yeah, Ill be checking all of those things when I get the time.. But what I'm saying is that changing the octane is very coincidently close to the change in performance

[ecpreston]

Er - if I'm reading this properly, you're saying that octane changed your gearing...?

that's what most of the post seems to be about to me too 

Nothing changes the redline. It's at 11. Most of them run out of steam around 10.
At any given speed, in a given gear, you'll be turning the same RPMs.
And limit of 9k at 110MPH? Yeah, that's a function of wind resistance and our ~42HP. Sounds about right to me, they hit a wall around 100, 110. The fact that you got to 115, 120 before.... well you must have been going downhill or there was wind at your back. 

[NEWGS500F]

Maybe the extra 10mph noted by the OP, is all to do with the speedo being off a bit at the top end...

Unlikely to make a genuine 120.

Either way, if the bike, it doth run better, then rejoice and be happy....yeeahmon.   

[Mdow]

clutch slip? tach or speedo off?

[bombadillo]

has to be clutch slip with an oil change, or someone's smokin a little too much on the ol hooka~!

[TarzanBoy]

It could be other things.... when is the last time you changed your spark plugs?  You might have intermittent sparking on one of them.

[ohgood]

To make it run "better"?
I've noticed over the course of my ownership that my bike just about redlines at 10.5 rpms at 115-120mph.
1) When I was in first gear I wouldnt get over 20mph before I had to shift into second.

2) When I was in 5th gear, going 60mph would leave me at around 7 thousand rpms.

3 - 3.5) A few weeks ago I recently changed the oil, oil filter, and air filter Which
gave it a noticeable jump in low end torque (like it can finally "breathe") but my speed:rpm ratio was still the same.
I lube up the chain ever 3 fill ups and check tire pressure, etc.

4) When engine breaking I notice it popping, bogging, and whining and I read somewhere to add a higher octane of fuel.
5) So I went from 87 to 89.
I did this for a few fill ups so it would circulate the new gas as 89 and not half 87, half 89.

6) three days later, it now seems to be running "better"
I would go almost 40 mph in 1st gear before I had to shift (at the same rpms as when I was going 20mph)
I am in 4th gear going over 60mph
70mph in 5th gear leaves me with 6 thousand rpms.
But when I'm in 6th it seems to limit itself to 8.5-9 rpms at 100-110 mph. In fact, I have a quarter throttle more to crank down but it doesnt do anything, as if it was governed/limited.

7-8-9-etc) What happened behind the scenes if switching octanes is actually the culprit? And what about the use of the throttle not doing anything more?

1) I usually don't watch the rpm's that much, especially during slow speed stuff, no real comment there.
2) OK, 6,000 or 7,000 or 9,000, whatever, it depends on your gearing (someone may have changed that already)
3 - 3.5) Yessire, you are correct. An oil change and filter replacement (or cleaning) is a sure way to FEEL a difference, bump things back where they should be (vacuum hoses, fuel lines, cables, etc) and make the bike run MUCH better. Agreed.
4) Popping and bogging while engine braking would make me think there is a lean issue and a partially clogged jet. Off-idle performance would be (just off engine braking too) close to there.

5) complete waste of money. totally. really, no kidding. completely coincidental unless you have the uber high compression turbo model of the gs, which you don't. sorry.
6) yep, atmospheric changes and a fresh air filter will do that. even more so the atmospheric changes. one day it runs like crap, the next it's greased lightening (well, up to about 95 mph   )

7-infinity) forget the octane thing. it's complete hooey. Already mentioned stuff may be to 'blame' for the increased performance you've found. Replacing your plugs, setting your float height properly, making sure your choke circuit isn't partially 'on', a clean filter and cleanish oil will make the bike come alive (for a gs). If anyone tries to tell you it's your flux capacitor or that you need special motorcycle oil, a $200 dollar chain or some cool fuzzy dice, you know they're kidding you.

Good luck ! Check your vacuum / fuel  lines ! Bubbles in yer gas = intermittent performance.

[Unknown]

Well I thank everyone who's replied with good information, most notably ohgood. Later today I will be taking out the spark plugs for inspection and cleaning. And the octane will be changed back from this little experiment. So far I put about 30 gallons of 89 since I started so that would be a grand total of around $3.00 wasted. Which by now, at the rate our dollar is falling, would mean $26.30

[ohgood]

Well I thank everyone who's replied with good information, most notably ohgood. Later today I will be taking out the spark plugs for inspection and cleaning. And the octane will be changed back from this little experiment. So far I put about 30 gallons of 89 since I started so that would be a grand total of around $3.00 wasted. Which by now, at the rate our dollar is falling, would mean $26.30

lol, in a public library. thanks man, you just made my day