Trading my harley for first ducati...maybe

[Jarvicious]

navy its true... but my hubby is in a small squadron that does dc-9 passenger jets. i am an emergency room nurse. but my 695 definately gets snotty on the cheap gas much to my chagrin. it occasionally misfires when i put in 87 or 89. is there some kind of additive i can put into it to make it run well on the cheaper stuff?
tara

Thread jack
We can't find anything above 91 octane here in MO so I chuck in octane boost they sell at the local Harley shop.  It can also reputedly be found at Walmart, but I've had no luck there.  The owners manual asks for 95 octane, and that's really what the engine likes.  It runs smoother, it definitely got rid of my back fire problem on decel, and I've even been getting better gas mileage.  Well worth the $1.xx you pay for it, IMHO. 
End Thread Jack

Ditch the hog, pick up a duc!

[cmorgan47]

scrambler.....I will own one some day!

they're cool looking, but they weigh about 500lbs.  seems ridiculous for a scrambler.

seriously, i like that whole bonneville line, but they just don't seem to have the right numbers.

[metallimonster]

I'm pretty sure that the 95 octane rating that is in the manual is in European ratings.  There is a really good thread on this on TOB you might want to check it out.

[cmorgan47]

I'm pretty sure that the 95 octane rating that is in the manual is in European ratings.  There is a really good thread on this on TOB you might want to check it out.

true.  they have a different standard.  i think it works out to about 89 here

[zarn02]

Maybe it just took some getting used to, but there were all sorts of odd noises coming out of that thing.

so logically, a bike with a dry clutch is our recommendation for a "step up."

[Jarvicious]

so logically, a bike with a dry clutch is our recommendation for a "step up."

Touche zarn, never thought of it that way!  In response, the noise out of the dry clutch is a much healthier "bad noise" than whatever crank case/gear box/exhaust sounds you get out of an HD.  I may, or may not be an irrational Ducati fanatic here. 

I did just remember though, one of the guys who does local weekly rides here in town just traded his 848 in for a new CBR1000RR and says he will never go back to Ducati.  I guess it's whatever floats your boat. 

[mitt]

Thread jack
We can't find anything above 91 octane here in MO so I chuck in octane boost they sell at the local Harley shop.  It can also reputedly be found at Walmart, but I've had no luck there.  The owners manual asks for 95 octane, and that's really what the engine likes.  It runs smoother, it definitely got rid of my back fire problem on decel, and I've even been getting better gas mileage.  Well worth the $1.xx you pay for it, IMHO. 
End Thread Jack

Yep, 95 is based on Euro ratings, which are different than US (MON vs RON).  There is no precise conversion (octane grading is not precise anyway), but most owners generally report no problems with 87 or 89.

Unless an engine has ping detection, and adjusts timing accordingly, there is no mpg advantage in higher octane gas.  The higher the octane, the less energy per unit volume the gas has.

mitt

[Jarvicious]

The higher the octane, the less energy per unit volume the gas has.

mitt

My local guy explained it to me as such:


Gasoline burns extremely quickly (duh) and even more quickly when it's compressed and has the proper chunk of oxygen mixed in with it.  The lower octane rated gasolines basically have a quicker burn time (higher energy) than the higher octane ratings (remember this is just what the tech told me, please correct me if I'm wrong).  The problem with the lower octane gas is that it burns the entirety of the gas that has been injected into the cylinder before the piston has completed its full down stroke.  So in other words the piston is finishing xx% of its travel on momentum/compression/vacuum alone whereas the higher rated gasoline burns through the whole piston stroke and therefore forcing the piston down as opposed to letting it "coast".  The only problem here is if you get a gasoline that is still burning when the engine is trying to re-compress the chamber and push the piston back up into its top dead center position, or conversely when you have a gas that ignites due to compression before the spark plugs/ ignition system are ready to fire.


The octane rating is not the percentage of octane to heptane, or whatever other additives they add to a gasoline mixture, it's simply a measure of how much compression the gasoline can stand before self igniting (knock).  The lower octane gas can handle less compression before self-ignition than the higher level octane.  I don't know how whichever kind of gas could relate to the stock compression ratio of the monster though.  I'm sure all this differs per engine style (vtwin vs. inline) and it also depends on what rpm you're running at and whether you're just putzing around or on the throttle hard.  I guess the only way to be able to tell for certain is to do some more exact lab testing as opposed to "well, I get 48 here and 52 there".  I think I'm going to do some week by week comparisons.  87, 91, and 91 plus octane boost.  Does anyone have a pretty regular route to work they can use as a control?  I just ride around at random so it's just that, random. 

http://en.wikipedia.org/wiki/Octane_rating
http://auto.howstuffworks.com/question90.htm

[acalles]

Unless an engine has ping detection, and adjusts timing accordingly, there is no mpg advantage in higher octane gas.  The higher the octane, the less energy per unit volume the gas has.

mitt

umm... thats not really true. maybe with alcohol based fuels, but not gasoline.

higher octane, means its less pron to pre ignition because its more difficult to burn and according to wikipedia, premium (95 ron @ 39.5MJ/liter) has more energy then regular (91ron@ 3.48 MJ/liter.)

the better mileage in modern vehicles is for a few reasons, one is more energy, the other is modern fuel injection adds fuel as a strategy to reduce combustion temps and pre-ignition. 

but, I'm sure what octane to use in your bike has been beaten into submission. considering its high compression, and air cooled, I won't run less then 90 in mine and prefer higher up to a point.

[mitt]

My local guy explained it to me as such:


Gasoline burns extremely quickly (duh) and even more quickly when it's compressed and has the proper chunk of oxygen mixed in with it.  The lower octane rated gasolines basically have a quicker burn time (higher energy) than the higher octane ratings (remember this is just what the tech told me, please correct me if I'm wrong).  The problem with the lower octane gas is that it burns the entirety of the gas that has been injected into the cylinder before the piston has completed its full down stroke.  So in other words the piston is finishing xx% of its travel on momentum/compression/vacuum alone whereas the higher rated gasoline burns through the whole piston stroke and therefore forcing the piston down as opposed to letting it "coast".  The only problem here is if you get a gasoline that is still burning when the engine is trying to re-compress the chamber and push the piston back up into its top dead center position, or conversely when you have a gas that ignites due to compression before the spark plugs/ ignition system are ready to fire.

Not exactly how I understand it.  The initial ignition occurs before TDC (5 to 30degrees), and continues until max pressure is achieved when the piston & rod have the best (90deg) mechanical advantage on the crank pin.   What happens when there is knock, is that the spark plug still ignites the mixture normally, but a portion of the mixture burns too quickly, and the pressures are way too high while the piston is at poor mechanical advantage, causing destructive forces and the 'knock' noise.  So, an engine that senses this can change the ingnition from say 15 degress before TDC to 5 degrees TDC, delaying the whole burn sequence, and preventing the entire charge to burn before the piston can apply force effectvely to the crank.   In addition, the ECU can richen the fuel ratio, thus getting worse fuel mileage than a higher octance fuel in the same engine.  But, our ducs, at least now, don't do that.

mitt

[mitt]

the better mileage in modern vehicles is for a few reasons, one is more energy, the other is modern fuel injection adds fuel as a strategy to reduce combustion temps and pre-ignition. 

but, I'm sure what octane to use in your bike has been beaten into submission. considering its high compression, and air cooled, I won't run less then 90 in mine and prefer higher up to a point.

Again, anything higher than the minum you bike needs to avoid knocking is wasted money, and lower performance, unless the engine can adjust for it. 

The higher miles per gallon with higher octane comes from advanced ignition timing, causing higher pressure, more force on the crank, therefore less fuel for the same speed, not more energy in the fuel.  Using a lower octane gas is like advancing the timing without adjusting actual timing.

If you don't knock with 87, then in theory, you should get more power at the wheel with 87 gas than 91 assuming the engine can't adjust timing or air fuel ratios.

mitt

[acalles]

   What happens when there is knock, is that the spark plug still ignites the mixture normally, but a portion of the mixture burns too quickly, and the pressures are way too high while the piston is at poor mechanical advantage, causing destructive forces and the 'knock' noise. 

well, there are a few things that cause it, one is from timing too advanced causing the flame front to hit the pistion while its still rising, this is very destructive. very hard on the bearings, but also very audible (sounds like a rattle).

another has to do with octane, compression, cyl head design, ect. As the piston moves up and compresses the a/f charge, it also heats up. If it heats to a point above the flash point of the fuel, or if theres any small hot spot in the engine, it can combust, this is a very dangerous situation, because opposite to this, the spark plug is firing, creating another flame front. when the two fronts meet, the pressure goes VERY high the resulting explosion tends to blast off little pieces of cyl head or piston top. this sounds a bit like spoons clacking together and can be more difficult to hear..

After years of building turbo cars, I've seen my fair share of it, and ignition timing isn't the whole story.

The higher miles per gallon with higher octane comes from advanced ignition timing, causing higher pressure, more force on the crank, therefore less fuel for the same speed, not more energy in the fuel.  Using a lower octane gas is like advancing the timing without adjusting actual timing.

a faster burning charge may cause a more violent explosion, but it doesn't mean theres more energy released.

using a lower octane fuel isn't like advancing the timing, it just causes the fuel to burn easier, to explode rather then burn at a controlled rate.

when you advance timing, you start the process sooner along with using higher octane making it burn slower allows more energy to be released over a longer amount of time.

the combustion process isn't starting any sooner with lower octane, its just burning more violently.

I get what your saying, it just isn't really true. I look at the engine on my bike, no different then any engine.. 10.5:1, high performance, and air cooled = heat. best way to keep it running for a long time is to reduce the accidental explosions.. and that to me is worth the $.35 at the pump and loss of maybe 2 hard to prove HP.

[MendoDave]

navy its true... but my hubby is in a small squadron that does dc-9 passenger jets. i am an emergency room nurse. but my 695 definately gets snotty on the cheap gas much to my chagrin. it occasionally misfires when i put in 87 or 89. is there some kind of additive i can put into it to make it run well on the cheaper stuff?
tara

Sounds like the Totems. I was in the same VR wing long time ago.

[Le Pirate]

make the switch 

come on...you know you wanna 


my dad has a HD, and he loves to get on my 620 when I go visit to tool around. He says it's way more fun than his for just scootin around town on.


Maybe check out a multi for riding 2 up? they're pretty fun. Some say they're ugly, but I like em'.


just...whatever you do....don't take a hypertard for a test ride  [moto]

[devils haircut]

Well, the dealership told me they would call me when they got the numbers from the bank, but when I called them yesterday, I was told: "who is this again?...Oh yeah we still haven't heard anything.  We'll call you back."  It's been four days now.  They were closed sunday and monday though.  Is this waiting period normal?  I have traded cars before and it happened on the spot, not four or five days later.