S10 picky about its fuel

[markjenn]

That's interesting. In any of the material I have read on the causes of pinging I have never seen a reference to the number of cylinders being a factor. Do you have a source for that info, it would be interesting to read.

I wasn't very clear in my post. It's not cylinder count per se which affects octane requirements, its bore size. So "everything else being equal" (i.e., similar displacement of the S10 vs. the FJR), a twin will require more octane than a four because the bore size of the twin will be much larger for its two cylinders vs. the four cylinders.

Google "engine octane requirements factors" and you can read for awhile. Most sources point to this bore size as a factor along with many other things: air vs. liquid cooling, FI vs. carbs, ambient temperatures, RPM range, etc. It makes sense - it is much harder to smoothly ignite a big dollop of mixture in a big-bore engine than a small dollop in a small-bore engine.

And there are examples galore. I used to own an R6 with a 12.5:1 compression ratio that was tuned to within an inch of its life. Octane requirement: 86. My S1000RR, probably the most highly-tuned stock motorcycle engine in the world with a 14:1 CR, requires 89. OTOH, big-twin, air-cooled Harleys with 9:1 ratios require 92 and on a hot-day climbing a grade need more, sometimes a lot more. Or take aircraft piston engines with 5"+ bores and 8.5:1 rations that require 100 to not ping.

- Mark

 

[fredz43]

Very interesting. Without looking at the manual, I don't know what the CR is on my 1998 Honda VTR1000 Super Hawk twin, but I know the manual recommends 87 and it runs great on it. It has carbs, if that is a factor.

Hey, I just realized that I must like bikes that are Super!

Super Hawk
Super Tenere

 

[markjenn]

Very interesting. Without looking at the manual, I don't know what the CR is on my 1998 Honda VTR1000 Super Hawk twin, but I know the manual recommends 87 and it runs great on it. It has carbs, if that is a factor.

Also interesting.

Carbs usually don't fuel as precisely as FI, so you're more likely to need higher octane with carbs. I'm a little surprised Honda specs 87 on a Superhawk, although this engine is in a comparatively mild state of tune and has a reputation for running very rich all the time (and getting relatively poor mileage). RC51's spec 92 as I recall.

- Mark

 

[phplemel]

I,ve been filling up on 91 fuel since I picked it up. I'm not going to worry about saving a buck a fillup :'(if it MIGHT compromise longevity. I expect to own this S10 a LONG time. I've had to run 87 same as yukondood for same reason and it seemed to run fine for me. Just for the extra $1 I'lll use 91 whenever it's available

 

[fredz43]

BTW, in checking my Super Hawk owners manual, my statement about it recommending 87 is incorrect . It recommends 86.

 

[Tremor38]

It's a twin vs. four thing. Everything else being equal, low-RPM twins require more octane to avoid pinging than higher-RPM fours.

I don't ding Yamaha for producing a bike that requires premium. Most big-bore high-performance twins do, including the S10's main competition, the R1200GS. If Yamaha were to derate this engine for regular, we'd probably lose another 5-hp and this bike is a bit horsepower challenged for its category as it is. But I do ding Yamaha for not putting a knock sensor on the engine which is a good safety net and something that the R1200GS has had since 2005. Yamaha is just being cheap.

- Mark

Yes, and that BMW knock sensor works so well that 1200GS's are frying their combustion chambers after burning low octane fuel in third world countries. Hooray for BMW and their knock sensor.

 

[rem]

If you find yourself in a location without premium, are the various octane booster products of any value, or do they just make you feel better about it all? Do they really work ??? R

 

[tc9988]

Yes, and that BMW knock sensor works so well that 1200GS's are frying their combustion chambers after burning low octane fuel in third world countries. Hooray for BMW and their knock sensor.

And where did you get that information :question:

 

[Rynn Storm]

If you find yourself in a location without premium, are the various octane booster products of any value, or do they just make you feel better about it all? Do they really work ??? R

http://www.bing.com/search?q=octane+booster+explained

 

[Nooner]

I found this old thread and got curious...

Hmm... lemme try my hand at creating an octane booster equation for Toluene:

Assuming we want to hit 91 Octane and Toluene is 114 Octane:

D = Desired Octane
x = Gallons of Gas
G = Octane Rating of Gas
y= oz. of Toluene

D = ((xG) + y(114/128))/(x + (y/128)

y = -(128x(D-G))/(D-114)

x = -((D-114)y)/(128(D-G))

this way you coudl solve for y oz. of Toluene needed to bring x gallons of gas to a desired octane rating or x gallons of gas you could add to y oz. of Toluene and still achieve the desired octane.

Let's see if the numbers make sense,

91 Desired Octane
5 gallon Fillup
89 Octane Gas

y = -(128x(D-G))/(D-114)
y = -(128(5)(91-89))/(91-114)
y = 55.65 oz

Now lets try:
91 Desired Octane
32 oz Toluene
89 Octane Pump Gas

x = -((D-114)y)/(128(D-G))
x = -((91-114)32)/(128(91-89))
x = 2.875 Gallons of Gas

I think the equations work!!! Doesn't seem like it would be very economical (in terms of space or $$$) to buy lower grade gasoline and octane boost it via Toluene vs. just buying 93 octane pump gas. Also you need roughly 10% by volume to get 89 to 91, it'll be even worse to get 87 or 85 to 91...

 

[iridemotorbikes]

I've always run 91 in my bike, figure for the small price difference between fuel grades (.20¢) maybe a dollar more per 5 gallon fill up.. $20 verse $21 I'm fine spending the extra $1 per fill up.. I also always try to use a station that has a separate hose for each grade.
Maybe a waste of a $1 but gives me piece of mind, funny to me guys will drop $5 bucks on a coffee from Starbucks but ---never mind. lol

 

[creggur]

Holy Thread-Resurrection, Batman!

Since this thread's inception it's been discussed plenty here, with the consensus being the Tenere will run on whatever octane you throw at it.

Having said that, I pay the small price difference to run premium per the manual...still amazed at where people will try and save a few pennies running a $14,000 motorcycle...

 

[dirtsailor]

Everywhere i go i always buy the most expensive gas (91 oct). The only issue i have, does ethanol effect performance??? When i was stationed in Oklahoma they were very proud about 100% gas but down here in Flordia i can't seem to find to much gas without ethanol in it. I'm coming up on 5'000 miles and i've had no issues and was just wondering if this is gonna bite me in the ass later. ::002::

 

[markjenn]

Everywhere i go i always buy the most expensive gas (91 oct). The only issue i have, does ethanol effect performance??? When i was stationed in Oklahoma they were very proud about 100% gas but down here in Flordia i can't seem to find to much gas without ethanol in it. I'm coming up on 5'000 miles and i've had no issues and was just wondering if this is gonna bite me in the ass later. ::002::

If you're worried about engine knock protection, 91 octane is 91 octane whether it is attained by mixing lower-octane gas with 10% high-octane ethanol or using pure gas with 91 to begin with. All the engine cares about is knock protection, not by the fuel blend that achieves it.

If you're worried about whether there are long-term effects of using E10 with respect to the fuel system, Yamaha says its Okay, millions of cars have been using it Okay, etc. etc. etc. There are some horror stories in the corners of the envelope, but in normal service in a modern vehicle like the S10 with a fuel system designed for E10, there is no long-term issue.

- Mark

 

[BravoBravo]

When I am riding locally, I always use ethanol-free high octane fuel. When touring, it is impossible to avoid E10 gas, but I have never experienced any issues as a result. I agree that the most important thing is to use at least 91 octane fuel. E15 gas is a whole other issue, though. Using that crap could void your warranty.
Bruce

 

[GrahamD]

With 11:0 to 1 compression I run 95 (RON). Just so you know we have (98RON, 95RON, 91RON)

Tried 98 a few times and AFIAK it was a waste of money.

When out and about though, 91RON (87 AKI) is often all you can get.

The bike runs fine on that as well. I think it has plenty of safety margin.

 

[Philistine]

All I have put in my S10 has been 98 octane, I think twice I had to put 95 octane in her, So am I wasting my money with 98 octane? or is there a benefit from running 98 octane?

 

[GrahamD]

All I have put in my S10 has been 98 octane, I think twice I had to put 95 octane in her, So am I wasting my money with 98 octane? or is there a benefit from running 98 octane?

Except for the alleged nice cleaning agents etc that are supposed to lurk in the 98 octane stuff, I don't think there is much use.

You could run a 3000 page thread about it, but I subscribe to the least safe octane rating approach. Usually the higher the octane you use above what is necessary the less energy is in the fuel and the more you consume for no real reason.

So far 91 was OK, OPAL fuel was getting a bit iffy but all it seemed to do was make the engine hunt on small throttle openings, but not ping.

95 has never been a problem for me.

Your mileage may vary. harr harrr.

 

[viewdvb]

As this is an international forum, I think we need to be clearer about which method of octane rating we are quoting when discussing fuel grades. There are at least 4 methods of rating octane. RON, used in Europe, Australia and New Zealand is several points higher than the equivalent USA, Canadian rating, AKI. For example. 91-92 RON gas is about 87 AKI in USA and Canada. Most Japanese engines built since the advent of unleaded fuel are designed for "regular" fuel. Since Japanese regular fuel is 90 RON, we can be fairly sure that 91 RON or USA 87 AKI is good enough. Since octane is only about anti-knock properties, if your engine doesn't ping or knock with regular fuel there is no obvious advantage in using any higher octane. Since 91 RON, 87 AKI is the usual minimum sold in most countries (minimum is 95 RON in Europe), there is not usually any need to worry. The one certainty is that the manufacturers' claims that their premium, higher octane fuels will give higher mileage per gallon will never repay the extra cost of the fuel. Clearly, some countries/areas may sell low octane fuel so there might be the need to use the best you can get. If you are really off round the world, you should have researched this in advance and be well prepared. At home, wherever that may be, stop worrying and ride.

 

[markjenn]

Most Japanese engines built since the advent of unleaded fuel are designed for "regular" fuel. Since Japanese regular fuel is 90 RON, we can be fairly sure that 91 RON or USA 87 AKI is good enough.

Neither of these statements rings true to me. There are lots of current Japanese engines which require premium fuel and Yamaha specs premium (91 AKI/95 RON) in the S10. Lots of folks use regular under the idea that this lightly-stressed motor probably can tolerate it fine, but this is not what Yamaha recommends and the bike has no knock sensors to protect itself. I use premium as a rule, but will run regular when it is unavailable for whatever reason.

- Mark