[OkPanky]

I usually use 87 octane but a few days ago did 93. Today in 3rd gear close to 3 RPM the bike felt like it upshifted by itself. This happen to anyone? Maybe I hit something in the road like a rock but it sure felt like it was the bike.

 

[Mortikus]

The fuel should have no impact whatsover with your clutch or shifting, but it does burn at a different desired temperature. Fact: 93 octane requires a higher burn temp. Your bike is designed by many, many engineers for it to function properly using 87 octane fuel so the correct temperature burn takes place.

Mort

 

[bull117]

I agree with Mort...do not believe your issue is gas related.

Bull

 

[doug48317]

Might not be the case here at all but I did that once and it caught me off guard, I tend to keep my foot very close to the shifter and one day I hit pothole that jumped in front of me and I ended up shifting up a gear at the same time.
Think that may be the case with yours at the time?

 

[OkPanky]

Thanks guys. So you can upshift without pulling in the clutch?

 

[Mortikus]

Thanks guys. So you can upshift without pulling in the clutch?

You shouldn't, but I it can be done. Not good for the ride, but I think even some drag folks do that for the speed of the shift.

Mort

 

[h.arachnid]

Thanks guys. So you can upshift without pulling in the clutch?

Sure! If you have the motor turning at the right RPM, it slips right in. May take a while to learn it. Useful for emergencies, like if the clutch lever breaks.

 

[Mortikus]

Sure! If you have the motor turning at the right RPM, it slips right in. May take a while to learn it. Useful for emergencies, like if the clutch lever breaks.

That's the kicker... I suppose I should have said it can be harmful if not done correctly... which in most cases would be the case without either good instruction, training, or simply experience.

The same is needed for racing true race cars... there is no slip differential in the teeth for gearing, so 'close' doesn't lock one gear to the drive train... rpm's must be matched. Perhaps there are some exceptions, the race cars I'm referring to are Indy type open wheels (F1, Le Mans prototypes too, etc).

Mort

 

[dugsamin]

That's the kicker... I suppose I should have said it can be harmful if not done correctly... which in most cases would be the case without either good instruction, training, or simply experience.

The same is needed for racing true race cars... there is no slip differential in the teeth for gearing, so 'close' doesn't lock one gear to the drive train... rpm's must be matched. Perhaps there are some exceptions, the race cars I'm referring to are Indy type open wheels (F1, Le Mans prototypes too, etc).

Mort

Any heavy haul truck w/o a synchronized transmission is the same way. Have to match engine speed to road speed, even if you use the clutch.:nono::hmm2:

 

[7schulz]

So do all of you use 87? I have been using 93 because that is what my buddies use in their rockets.

 

[cschnauf]

87 yes! Always. As for the shifting, my T does it once in a while...Seems like there is always a slight bump involved when it does.

 

[22600]

87 is all you need. doesn't run any better on 93. :choppersm

 

[lamaybl5711]

87 for my VTX, I use 93 (or better) in my Ducati but don't know if it's necessary for it. I do know from many threads, 87 is all that's needed for the VTX. As for shifting, if done correctly, shifting without the clutch won't harm anything...I've been doing it to my pickup for about 15 years and no problems (same truck, now at 250k miles).

 

[hogcowboy]

I had what felt like a shift up but what it was, was a fouled plug that suddenly started firing again. At least that's what I think. It was running a little rough and then boom, it took off like a shot. Maybe that's what you felt as well.

 

[OkPanky]

I'll check the plugs out although I only have 1100 miles.

 

[Mortikus]

Here is an excellent read on the subject of octane, I believe worth the read.

http://www.state.mn.us/mn/externalDocs/Commerce/Gasoline_Octane_Facts_102902052227_OctaneFacts.pdf

Mort

 

[Good Old Rebel]

The VTX is a low compression motor and higher octane is for higher compression motors. In a low compression motor, the fuel/air mix is only moderately compressed and the lower octane fuel does not explode until the piston is in the right place and a spark from the spark plug ignites it. In a high compression motor, low octane fuel will explode (without a spark from the spark plug) before the piston is at the proper location in the cylinder. This is called detonation and it is not a good thing! Using higher octane gas in the VTX is like using bottled water to make a mud pie.

Rebel

 

[Mortikus]

Using higher octane gas in the VTX is like using bottled water to make a mud pie.

Rebel

But not to say the 93 octane is any way 'cleaner' than the 87, so there is 'no' benefit. It is the same cleanliness of fuel, it simply has a different amount of hydrocarbon mixture to burn differently.

M

 

[BigGuy66]

So let me get this straight.... even though a buddy said "always use 93 octane" - and he owns an 1800 - I should only use 87?!? I am new to the vtx 1800... does the year and fuel injection make a difference? 2003 1800S

 

[Mortikus]

So let me get this straight.... even though a buddy said "always use 93 octane" - and he owns an 1800 - I should only use 87?!? I am new to the vtx 1800... does the year and fuel injection make a difference? 2003 1800S

Yes. No... the vehicle doesn't make any difference, from bike, to car, to boat... high compression engines use higher octane, lower compression (your VTX) use lower octane... it's not an 'elite' thing, it's just what it's made for.

Ignore the term premium, ignore the numbers of octane... consider it type A, type B, and type C. Your bike is designed and wants type A... there's no reason to give it type C.

Mort