What Gas do you Put In..?

[Anonymous]

What you say is true. The 850 always needed that 6th gear and/or a bit more "oomph".

That's why I went for the GS1100GK four years ago. Best move I've ever made is buying that thing. It was all the virtues (and boy, there are many such virtues!) of the 850, with considerably more kick and longer legs.

Send more pictures of that gorgeous yellow to Dan Bard, the GS Resources editor in charge of the Gallery. I'm sure he'd like to upload them, since he himself rides a yellow Gold Wing 1800.

Nick

 

[focus frenzy]

close, but not quite Tim.
carbon build up will, over time raise the compression enough to be a problem, but with bikes that get wrung out on a semi regular basis carbon build up is not a problem.
Carbon causes detonation more from its causing hot spots in the combustion chamber,triggering pre-ignition.

taking a bike and with the engine warmed up, you run it up through a couple gears at full throttle and you will "blow" out most carbon build up.

Ethanol is a alcohol and it is not "thick" it is pretty thin stuff so it doesn't "stuff" in the jets.
a byproduct of burning ethanol is a small amount of oxygen (that is part of the reason why alcohol burns so hot) this is what makes a normal carburetor engine run a bit leaner, modern fuel injected automotive engines compensate by adding a bit more fuel, hence the slightly lower fuel mileage. my bike gets the same mileage regardless of the type of fuel I use, but I have to use premium do to my higher compression.

the design of the combustion chamber has allot to do with detonation, unfortunately our bikes don't have a very good combustion chamber design.

 

[Anonymous]

There is lots of authoritative information available on this subject. Follow your owners manual instructions as to appropriate fuel. Thereafter, there is no reason to buy premium gases unless you are suffering serious and persisent knock. Premium gases do nothing else except control knock.

High octane gases have NO EXTRA POTENTIAL ENERGY, and can not provide a power boost.

Despite what some owners perceive as far as power and fuel mileage go, proper control tests results show otherwise.

Premium gases clean the engine no better than 87 octane gases, and the oil companies have been successfully sued by the US Federal Trade Commission amongst others for saying otherwise. The results and rulings are available online ...I took the time to read them. This forced truth in advertising is why the ads I hear now say: "No gasoline cleans better than [insert company name here] ultra-premium." How impressive! Our very expensive premium gas is no worse than other gases!

I have to use 94 Octane gas in the twin-cam HD I ride (as specified in the owners manual), and it still knocks under load on very hot days in stop and go traffic.
That is because it has a huge cylinder volume (725cc) and runs at low rpm. Four-cylinder Japanese bikes have small cylinder volumes and run at higher rpm's, and are naturally resistant to knock, even at moderately high compression ratios. The HD knock is the logical result of trying to wring 70hp from an antiquated engine design.

Don't waste your money on premium fuels. They actually cause air-cooled bikes to run hotter and less efficiently. True!

In my experience, most knock in mildly tuned engines like ours will go away with judicious use of the transmission. Keep the revs up under load!

 

[redliner1973]

close, but not quite Tim.
carbon build up will, over time raise the compression enough to be a problem, but with bikes that get wrung out on a semi regular basis carbon build up is not a problem.
Carbon causes detonation more from its causing hot spots in the combustion chamber,triggering pre-ignition.

taking a bike and with the engine warmed up, you run it up through a couple gears at full throttle and you will "blow" out most carbon build up.

Ethanol is a alcohol and it is not "thick" it is pretty thin stuff so it doesn't "stuff" in the jets.
a byproduct of burning ethanol is a small amount of oxygen (that is part of the reason why alcohol burns so hot) this is what makes a normal carburetor engine run a bit leaner, modern fuel injected automotive engines compensate by adding a bit more fuel, hence the slightly lower fuel mileage. my bike gets the same mileage regardless of the type of fuel I use, but I have to use premium do to my higher compression.

the design of the combustion chamber has allot to do with detonation, unfortunately our bikes don't have a very good combustion chamber design.

I have to disagree with you on this one, According to the university of Wisconsin, Madison, here are some of the following on properties of Ethanol:

Ethanol is lighter than water, if released in to water it tends to remain near the water's surface

Ethanol containing Gasoline is DENSER than unblended gasoline

When burned, Ethanol releases LESS HEAT than gasoline. 1 1/2 gallons of ethanol have approximately the same combustion properties as 1 gallon of gasoline

Ehanol has a higher ignition temp than gasoline 850F vs. 495F

At 110, Ethanol has an Octane rating simular to MTBE's. thus, when added to gasoline, Ethanol increases the Octane rating.

(http://uttu.engr.wisc.edu/UT14n4.pdf)

Now, #1 is pertinant to water in fuel only.
#2 supports the thicker fluid in same size jet = leaner condition theory.
#3 the LESS HEAT means more throttle opening for same power, and Cooler flame. ( offset, of course, by the higher throttle opening)
#4 Ethanols higher ignition temps support the lower BTU output = less power.

As for the Carbon issue, yes, I will agree 100% that Combustion design makes a world of difference, but remove the head of any engine with some miles on it, that has been 'blown out' on occasion, and you will still see a significant amount of built-up carbon on top of the piston. I have NEVER torn down an engine short of brand new that did not have some deposits on the piston crowns. this also helps to explain the myriads of 'fuel injector and combustion chamber cleaners' o the market nowadays. Combustion with fossils are just not efficient enough to prevent it. :twisted:

 

[Anonymous]

If adding ethonal to gasoline give a lower temp, then the thread about powdercoating or otherwise insulating the headers seems to make more sense in that it keeps the exhaust gas heat in the exhaust system. That would appear to help eliminate the cooler spots in the exhaust system restricting the flow.
So, then, if one is running a gas/ethanol mixture one should realize something of a reduction in the loss of power/milage if one insulates the exhaust?
It looks like it ties together, but I may have my head in an anatomically improbable place.

Harrison

 

[redliner1973]

The only thing insulating the exhaust pipe or header does is to keep the temps INSIDE the pipe high enough so that the burned gasses does not lose velocity going out the port. You may realise something, but remember that you have to compare it to a header without a coating. Example:

If header A has no coating, Gas moves at oh, say 400fps out the pipe (example only) whilst cooler ethanol runs at say, 350fps

So now you go out and coat the header.

Now, header blows out gas at 450fps. whilst ethanol, goes 400fps Yes, a coated header moved the ethanol out faster. but you have to comapre it to waht the gasoline does, not waht the coating will do. The Gas is still faster. the coating will effect BOTH fuel types equally. I hope this makes sense, as I have trouble explaining it!... :twisted:

 

[Anonymous]

No, you explained it very well. What I was trying to determine was that if gas with ethanol is a given then insulating the pipes might give back some of the loss. Obviously, if this helps a mixture, then it would definitely help with staight gas.

Harrison

 

[Anonymous]

Well...I used the handy dandy search feature to try and figure out what grade gas I should be running in my '83 550L. I was confused cause everyone I know around here (Boston) was telling me something different, and it seems as though that is what's happening in the forum. SO..My questions are...what exactly should I look for to determine if my engine is knocking/pinging? I know what it sounds like in a car, but as this is my first motorcycle I'm not sure if there is a difference.

Sorry to go back to this discussion, but I really do appreciate the help.

David

 

[Anonymous]

just listen for the same noises although they may be of a slightly different pitch. usually you wont have these kinds of problems as these engines are much more efficient than your car. if you do hear some sounds check to see that your carbs havent become either too lean or too rich by looking at your plugs. ( white is lean, black is rich, tan is about right).

 

[Pete's GS]

In the GS550 Chevron Unleaded 87 (about one cut above tomato juice). Bike runs fine. When the carbs were clogged and gunky when I first rescued it I put in premium, which has more detergents. Our mechanic recommended Chevron for the Acura and it's been fine. Supposedly it both prevents and removes deposits on the backside of intake valves. In So CA Union 76 is also said to have good premium as well. The XS650 gets only premium because it's 10:1 compression.

 

[Anonymous]

like someone said in one of the first posts, you should use the minimum rated gas that doesn't cause knocking... from my understanding of the internal combustion engine, none of our bikes will "perform" better with higher octane unless you're getting more compression in the cylinders. actually, i've heard this is how a lot of "racing" chips in cars work... compression ratios are set at the factory with the thought that most people will just put the cheapest gas in the car and expect it to run properly... the chip lets the engine know that you're not using the cheap stuff, so you can get more compression w/o any knocking. more compression = more power...

 

[Hoomgar]

Many theories. Here is mine as I have posted before. My experience is my "engines" in all my cars/bikes run much better on higher octane fuels. They also seem to run cleaner between oil changes but the best thing I can point to as any kind of proof for my findings is the fact that I definitely get better fuel economy with better fuels. Some engines more than others. Some may vary 1 or 2 mpg average but still run better. Most of my engines will give several mpg more on higher octane fuels and you can actually notice the performance increase as well as an overall quieter engine.

In my GS and my Chevy it actually works out to cost less to run the higher grade fuels than it does the lower ones due simply to the better fuel economy which I attribute more to the increased performance than anything else.

Other guys have not had the same experience so I encourage anyone that ever asks this question to keep an open mind to the possibilities of either way of going and see what you find for yourself.

 

[Planecrazy]

As I have stated in an earlier post, I always run premium in my bikes and small engines. They seem to run better and more efficiently (same experience as Hoomgar mentions) but, more importantly, if there is any truth to the claims that the "better" fuels help to keep the engine cleaner I see absolutely no reason to take a chance with lesser grade fuel. In my small engines, the presumed price penalty is more than made up for in reduced maintenance costs. ie(cleaner engine requires fewer expensive carb rebuilds over time than one that runs dirtier with lower grade fuel).

Is this true? I have no idea, but for the small difference in price (and the fact that my improved gas mileage balances this difference out to some degree), it's not worth taking a chance...

Regards,
Steve 8)