Rough engine poor gas mileage

[Igofar]

It always went to 3 bars and stayed there, so I'm pretty sure my thermostat was good. During winter it would obviously take a little longer to get there, but it would reach 3 bars after 10-15 min and be rock solid. I never saw 4 bars in my five years of riding it. I read that it's possible to adjust the "cold idle" but I never attempted it. I may have been able to reduce the cold morning starts to say 2,000 rather than 3-4,000 RPM - but I was always afraid that I would mess up the warm idle, which was always nice just below 1,000 RPM

If your bike took 10-15 minutes to reach 3 bars, your T-stat was frozen open, and not working at all!
Even in colder locations, an ST should reach 3 bars in 2-3 minutes.
And If a person started to ride the bike before you reached 3 bars, you would be running with a richer condition (think choke on) and have poor MPG and gum up the 5 way tee sooner.

 

[Igofar]

Wow! At what speed(s)?

On these flat desert roads I now roam on, I'm getting 56-58 mpg (doing the math) at 65-75 mph.
I've gotten as high as 64-68 mpg when held at a steady 65 mph for long periods of time.

 

[MerlF]

Thanks to the members who nailed the problem for me. I decided to try a tank of Techron with 2oz of Acetone in the tank. Wow almost an immediate response. Motor is noticeably getting better and I would even go so far as to say it's smoother than I remember the 2006 ST I had, and I haven't gone through a full tank yet. What a nice surprise.
Interesting to note that before this, I did notice an improvement in the motor after I had given it a few handful's of throttle up to near red-line.
Haven't checked the total gas mileage yet but the motor is now running as smooth as silk. I am once again very happy with the bike, and especially with the members here, thank you once more.

 

[mortenk]

If your bike took 10-15 minutes to reach 3 bars, your T-stat was frozen open, and not working at all!
Even in colder locations, an ST should reach 3 bars in 2-3 minutes.
And If a person started to ride the bike before you reached 3 bars, you would be running with a richer condition (think choke on) and have poor MPG and gum up the 5 way tee sooner.

OK - I didn't time it, but when I leave my house in 20 degF it definitely takes more than 3 min to reach 3 bars. There is no way I can wait for the bike to warm - I want to maintain a good relationship with my neighbors and 3,000+ RPM at 6 AM may not please everybody . So I would ride it immediately fully ware of the rich conditions and resulting low mpg, which is what really prompted this thread. Did I have a frozen open T-stat all those years? Who knows...

 

[Savago]

@MerlF given is a new bike (for you), I'm assuming you already changed the oil + filter?

Use whatever oil filter you want, but not a K&R as they are overpriced and there was a bad patch that could leak oil through the soldered 'nut' at its bottom.

Another maintenance items to pay attention are:
a) Brake fluid: it will get pretty nasty and milky with time. A proper fluid change will do wonders for your brake efficiency.
b) Coolant fluid: first step to avoid damaging the T-stat valve.

 

[T_C]

And If a person started to ride the bike before you reached 3 bars, you would be running with a richer condition (think choke on) and have poor MPG and gum up the 5 way tee sooner.

Ummm.... if I am not riding during warm-up, it's even lower MPG. Gas burning with zero forward progress is just about as low as you can go.


Now on a really cold morning, sub freezing, I'll let it warm a for a minute and be easy on the acceleration, but that is more concern about oil flow and through transmission.

 

[Igofar]

OK - I didn't time it, but when I leave my house in 20 degF it definitely takes more than 3 min to reach 3 bars. There is no way I can wait for the bike to warm - I want to maintain a good relationship with my neighbors and 3,000+ RPM at 6 AM may not please everybody . So I would ride it immediately fully ware of the rich conditions and resulting low mpg, which is what really prompted this thread. Did I have a frozen open T-stat all those years? Who knows...

IF it took you 10-15 minutes before you reached 3 bars, I would be very comfortable betting you $100 dollars cash that your T-stat was frozen....
I've not lost that bet yet

 

[Igofar]

Ummm.... if I am not riding during warm-up, it's even lower MPG. Gas burning with zero forward progress is just about as low as you can go.


Now on a really cold morning, sub freezing, I'll let it warm a for a minute and be easy on the acceleration, but that is more concern about oil flow and through transmission.

The service manual states that you can/should operate the bike when 1 bar is showing.
As far as the forward progress goes pretty funny comment.
I would not worry as much about MPG as I would clogging up the 5 way tee and having FI lights flash at you