MotoHouston.com MotoHouston.com
Register Members List Member Map Media Calendar Garage Forum Home Mark Forums Read

Go Back   MotoHouston.com > General Discussion > General Discussion (Moto Related)
Forgot info?

Welcome to MotoHouston.com! You are currently viewing our forums as a guest which gives you limited access to the community. By joining our free community you will have access to great discounts from our sponsors, the ability to post topics, communicate privately with other members, respond to polls, upload content, free email, classifieds, and access many other special features. Registration is fast, simple and absolutely free, join our community!

Register Today!

If you have any problems with the registration process or your account login, please contact us.


Like us on Facebook! Regular shirt GIVEAWAYS and more

Advertisement

Reply
Share This Thread: 
Subscribe to this Thread Thread Tools
Old 01-14-2009, 02:18 AM   #21
level5
moving chicane
 
Join Date: Aug 2006
Feedback Rating: (0)
Posts: 5,825












Quote:
Originally Posted by navigator View Post
Your 675 will run fine on 89 octane. Mine does and that is what the manual calls for. RPM's are not the concern when it comes to detonation. It usually occurs at low rpm. The faster the engine is running the less opportunity for precombustion.

You shouldn't compare compression ratios from auto engines to 4 cylinder motorcycle engines. Motorcycles have much smaller diameter cylinders which are more effecient burning. A 1200 cc motorcycle engine at 11:1 compression will function just fine on 87 octane where a 350 chevy or a big vee twin at the same compression will rattle the heads off.
Does that means that the precombustion happens when it is in low speed or idle? Pre-ignition happens when under load or highspeed/rev goes the same for valve overlapping meaning both valve opens.
you shouldn't compare a small engine to a bigger displacement engine for effeciency because bigger engine requires more fuel as to air fuel ratio. Performance engine rerquired good or high octane fuel to prevent from pre-ignition/detonation.
Quote:
Originally Posted by FlipSideUp View Post
The lowest octane useable without pinging yields the most money back in your pocket.

The higher the octane, the slower the fuel burns which yields a higher compression detonation = more power but less engine life.
Fixed.

Read your manual if you are not sure which gas to use. If it calls for 87 then use 87 if you want an extra 1 or 2 hp by going to highter octane gas then by all means do it. Manufacturer engineered and suggested an octane number for a reason of reliability. If you used a higher octane and gain a little performance but your rings and bearings will pay for the extra effort. Same goes for add on performance parts, if you make more hp, you will need better clutch. If you can make it go faster, you need better suspension and brakes....you get my meaning, right?
level5 is offline   Reply With Quote
Similar Topics
Thread Thread Starter Forum Replies Last Post
Motorcycles have a much higher fatality rate than cars Scorch General Discussion (Moto Related) 19 07-08-2013 05:48 PM
Lojack Sale!! Motorcycles & Cars!! Patrick Motorcycles Unlimited 6 07-08-2010 06:26 PM
Why don't cars/motorcycles come with top speed limiters from factory? BaylorNinja500 General Discussion (Moto Related) 90 06-29-2010 02:42 PM
Advertisement
Old 01-14-2009, 02:27 AM   #22
The_Gunslinger
Kamakasi
 
The_Gunslinger's Avatar
 
Join Date: Oct 2008
Location: southeast houston
Feedback Rating: (0)
Posts: 591

Experience: 9 years
Trackdays: 10+

Bike(s):
'07 zx6r
'02 xr250r








my zixxer has high compression. gotta use teh good stuff if i wanna run it hard.
The_Gunslinger is offline   Reply With Quote
Old 01-14-2009, 02:36 AM   #23
Mr Richards
Insert Clever Quote Here
 
Mr Richards's Avatar
 
Join Date: Jun 2008
Location: League City
Feedback Rating: (3)
Posts: 1,256

Experience: 10+ years

Bike(s):
2005 Yamaha R1 (Street)
2005 Yamaha R1 (Track)



Member Garage





Quote:
Originally Posted by level5 View Post

Read your manual if you are not sure which gas to use. If it calls for 87 then use 87 if you want an extra 1 or 2 hp by going to highter octane gas then by all means do it. Manufacturer engineered and suggested an octane number for a reason of reliability. If you used a higher octane and gain a little performance but your rings and bearings will pay for the extra effort. Same goes for add on performance parts, if you make more hp, you will need better clutch. If you can make it go faster, you need better suspension and brakes....you get my meaning, right?
Negative. This is incorrect.

Higher octane is better in terms of reliability and does not make more HP.
__________________
I am a Nobody. Nobody is Perfect. Therefore, I am perfect.
Mr Richards is offline   Reply With Quote
Old 01-14-2009, 02:47 AM   #24
zorn
$5 scratch off winner
 
zorn's Avatar
 
Join Date: Jul 2008
Location: mean streets of Willis
Feedback Rating: (0)
Posts: 213

Experience: 4 years

Bike(s):
02 Honda 954
2003 Rc51








My 54 recommends min of 86 or higher but what I have noticed is when I fill up in Montgomery county that has 10% ethanol it runs like on the cheap stuff also has a noticeable loss of power and I also notice my mileage drops so I opt for premium. now when I fill up in at a station that doesn’t have 10% ethanol it will run like a top on the cheap stuff. I also notice the same effects in the truck it actually will knock when I use the cheap stuff here in town. but then again im no tech this is just what i have noticed in my rides

Last edited by zorn; 01-14-2009 at 02:51 AM. Reason: left out text
zorn is offline   Reply With Quote
Old 01-14-2009, 03:05 AM   #25
level5
moving chicane
 
Join Date: Aug 2006
Feedback Rating: (0)
Posts: 5,825












Quote:
Originally Posted by Mr Richards View Post
Negative. This is incorrect.

Higher octane is better in terms of reliability and does not make more HP.
Is it more in terms of reliability because of less engine work? It may not make more hp in some motor but in others it might.
level5 is offline   Reply With Quote
Old 01-14-2009, 03:14 AM   #26
zorn
$5 scratch off winner
 
zorn's Avatar
 
Join Date: Jul 2008
Location: mean streets of Willis
Feedback Rating: (0)
Posts: 213

Experience: 4 years

Bike(s):
02 Honda 954
2003 Rc51








Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause detonation.

It might seem odd that fuels with higher octane ratings explode less easily and can therefore be used in more powerful engines. However, an explosion is not desired in an internal combustion engine. An explosion will cause the pressure in the cylinder to rise far beyond the cylinder's design limits, before the force of the expanding gases can be absorbed by the piston traveling downward. This actually reduces power output, because much of the energy of combustion is absorbed as strain and heat in parts of the engine, rather than being converted to torque at the crankshaft.

A fuel with a higher octane rating can be run at a higher compression ratio without detonating. Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more power. Engine power is a function of the fuel as well as the engine design and is related to octane rating of the fuel. Power is limited by the maximum amount of fuel-air mixture that can be forced into the combustion chamber. When the throttle is partially open, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than when the throttle is opened fully and the manifold pressure increases to atmospheric pressure, or higher in the case of supercharged or turbocharged engines.

Many high-performance engines are designed to operate with a high maximum compression and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.

However, burning fuel with a lower octane rating than required by the engine often reduces power output and efficiency one way or another. If the engine begins to detonate (knock), that reduces power and efficiency for the reasons stated above. Many modern car engines feature a knock sensor a small piezoelectric microphone which detects knock and then sends a signal to the engine control unit to the ignition timing. Retarding the ignition timing reduces the tendency to detonate, but also reduces power output and fuel efficiency.

Most fuel stations have two storage tanks (even those offering 3 or 4 octane levels), and you are given a mixture of the higher and lower octane fuel. Purchasing premium simply means more fuel from the higher octane tank. The detergents in the fuel are the same, Premium does not "burn cleaner."
zorn is offline   Reply With Quote
Old 01-14-2009, 03:19 AM   #27
The_Gunslinger
Kamakasi
 
The_Gunslinger's Avatar
 
Join Date: Oct 2008
Location: southeast houston
Feedback Rating: (0)
Posts: 591

Experience: 9 years
Trackdays: 10+

Bike(s):
'07 zx6r
'02 xr250r








swill (which is used by most cars) is usually much fresher than the good stuff (which lives in the underground tanks for quite some time)
The_Gunslinger is offline   Reply With Quote
Old 01-14-2009, 09:31 AM   #28
FlipSideUp
This Flip Rides Nekkid
 
FlipSideUp's Avatar
 
Join Date: Aug 2007
Location: Houston - Memorial
Feedback Rating: (13)
Posts: 4,605

Experience: 10+ years
Trackdays: 10+

Bike(s):
'03 Honda 919 Hornet
'89 Yamaha FZR400 Trackbike
'83 Honda CB650SC Nighthawk
'07 Step-2 (ok, it's my daughter's)






Quote:
Originally Posted by Squanto84 View Post
Yeah, we covered that in greater detail in post #7..
I just figured I'd put it in simple terms. Key words are "without pinging".
FlipSideUp is offline   Reply With Quote
Old 01-14-2009, 11:04 AM   #29
Yamawhore
Senior Member
 
Join Date: Jan 2008
Feedback Rating: (0)
Posts: 1,219


Bike(s):
2014 Z1000
2008 CBR600RR (sold)
2009 R6 (sold)
2009 R6 (wreck)
2007 R6 (sold)






With the high compressions of 600s, high octane is a must.
Higher octane will burn cooler = Longevity and reliability.

Last edited by Yamawhore; 01-14-2009 at 11:06 AM.
Yamawhore is offline   Reply With Quote
Old 01-14-2009, 11:30 AM   #30
blends
NYYYYYYEAAOWWWWWW
 
Join Date: Apr 2008
Location: mission bend
Feedback Rating: (3)
Posts: 7,307

Experience: 2 years
Trackdays: 10+






Member Garage





Send a message via AIM to blends
i burn 87 because my owners manual says that's what my motorcycle drinks.
__________________
ಠ_ಠ
blends is offline   Reply With Quote
Old 01-14-2009, 11:32 AM   #31
Chubby Racer
The Confusion
 
Chubby Racer's Avatar
 
Join Date: Jun 2005
Location: between a chair and a screen
Feedback Rating: (2)
Posts: 19,403

Experience: 8 years
Trackdays: 10+

Bike(s):
'07 R6
'02 KLX110(tarded)








Send a message via ICQ to Chubby Racer Send a message via AIM to Chubby Racer Send a message via MSN to Chubby Racer Send a message via Yahoo to Chubby Racer
Quote:
Originally Posted by Mr Richards View Post
I wonder if the manual takes into consideration the 10% ethanol that is added to all of the gas now?
Ethanol reduces the energy in a given volume of fuel, but shouldn't change the octane rating if mixed properly. That being said, its entirely possible that distributors start with an 87 octane "pure gas" stock, add in ethanol (~110 octane) and sell it as 87 still.
__________________
A motorcycle is a joy machine. It's a machine of wonders, a metal bird, a motorized prosthetic. It's light and dark and shiny and dirty and warm and cold lapping over each other; it's a conduit of grace, it's a catalyst for bonding the gritty and the holy.

CMRA #302
Chubby Racer is offline   Reply With Quote
Old 01-14-2009, 11:34 AM   #32
Chubby Racer
The Confusion
 
Chubby Racer's Avatar
 
Join Date: Jun 2005
Location: between a chair and a screen
Feedback Rating: (2)
Posts: 19,403

Experience: 8 years
Trackdays: 10+

Bike(s):
'07 R6
'02 KLX110(tarded)








Send a message via ICQ to Chubby Racer Send a message via AIM to Chubby Racer Send a message via MSN to Chubby Racer Send a message via Yahoo to Chubby Racer
Quote:
Originally Posted by Yamawhore View Post
Higher octane will burn cooler = Longevity and reliability.
Incorrect. There's nothing inherit in the octane rating that makes it burn cooler. A higher octane rating just means that it requires more energy to start to burn, and therefore resists detonation. It also takes longer to completely burn under fixed conditions than a lower octane fuel does.
__________________
A motorcycle is a joy machine. It's a machine of wonders, a metal bird, a motorized prosthetic. It's light and dark and shiny and dirty and warm and cold lapping over each other; it's a conduit of grace, it's a catalyst for bonding the gritty and the holy.

CMRA #302
Chubby Racer is offline   Reply With Quote
Old 01-14-2009, 11:37 AM   #33
SexualChocolate
JapLac on 22s
 
SexualChocolate's Avatar
 
Join Date: Jan 2006
Location: Dickinson
Feedback Rating: (0)
Posts: 5,197

Experience: 3 years

Bike(s):
998CCs of KING KONG...









Send a message via AIM to SexualChocolate
Use whatever you want. If it is not the correct octane rating the bike will tell you in one way or another.

One way would be a power loss...another would be catastrophic engine failure over a long period of time Ok I am exaggerating a little.
__________________
A few motorcycles, bicycles, and cars...and still in recovery phase

mybanner4a260100b5617
SexualChocolate is offline   Reply With Quote
Old 01-14-2009, 11:39 AM   #34
Chubby Racer
The Confusion
 
Chubby Racer's Avatar
 
Join Date: Jun 2005
Location: between a chair and a screen
Feedback Rating: (2)
Posts: 19,403

Experience: 8 years
Trackdays: 10+

Bike(s):
'07 R6
'02 KLX110(tarded)








Send a message via ICQ to Chubby Racer Send a message via AIM to Chubby Racer Send a message via MSN to Chubby Racer Send a message via Yahoo to Chubby Racer
Quote:
Originally Posted by level5 View Post
Is it more in terms of reliability because of less engine work? It may not make more hp in some motor but in others it might.

Incorrect. If a motor does not detonate on a particular octane fuel, it will make LESS power (only slightly) on a higher octane fuel. If its still confusing I could attempt to explain how combustion works, but a simple explanation is that with higher-than-necessary octane fuel your flame front travels too slowly to reach peak cylinder pressure.
__________________
A motorcycle is a joy machine. It's a machine of wonders, a metal bird, a motorized prosthetic. It's light and dark and shiny and dirty and warm and cold lapping over each other; it's a conduit of grace, it's a catalyst for bonding the gritty and the holy.

CMRA #302
Chubby Racer is offline   Reply With Quote
Reply


Thread Tools

Advertisement


All times are GMT -5. The time now is 07:32 AM.


MotoHouston.com is not responsible for the content posted by users.
Privacy Policy