Fuelology

[Chiri]

My bike has a 9.6 compression ratio, here in Costa Rica have 2 flavors... 91 and 95.

Actually, I use 91... but the exhaust was changed, took from an Intruder 1400, very quite noise, can't listen the ping (if present)

If I switch to 95 will get a better performance?.

Regards.

[SHADOW 1100T]

Honda recommends 87 octane so depending on how it rated you should be OK using 91.
This question should be on the regular forum rather than on a stickie.

[litnin]

Originally Posted by Lonerider60

This write-up definitely has a lot of good info. The gas grade subject has generally been beaten to death on every forum I've been a member of, just like "what oil to use". Right now I'm riding a 2008 FZ1 that has 11.5:1 compression and a 1981 Goldwing which is about 9:1. I run regular grade fuel from whatever station is there when I need fuel. In my area all gasoline is 10% ethanol. I can ride at 25 degrees or 90 degrees, sometimes very hard and I've never had a problem. It may be that the ethanol is a positive when it comes to preignition, I'm not realy sure, but I also get about 41 MPG on the FZ1 and that's not bad for a 130 Horse 1 litre bike. I do think that combustion chamber shape is also an important factor is how well a bike burns fuel.

The ignition system and fuel delivery system on your FZ1 is a much more
advanced system that that of the Shadow.

I don't know without looking at the specs, but your bike may have a
knock sensor on it. Most of the newer fuel injected engines do.
If the knock sensor detects detonation, it will back the timing down
until it stop detonating and that is totally seamless and to the rider.
So running lower octane fuels doesn't affect that system/engine other
than degrade performance slightly.
If it's bad enough, the performance can be a noticeable loss.
Simply switching to a higher octane gas, in that particular situation will
show a power improvement simply because the electronics are allowing
the engine to perform where it was designed to perform rather than
retard it's performance to maintain safety.
On a non-monitored system ECM controlled system, like the Shadow's have, this wouldn't not happen.

[Johny12]

Amazing Bike. I am also fond of bikes & also have a gorgeous bike as well.

[brashrube]

I have 35700+ miles on my Shadow Vt100C and I tried 85, 87 and 91 (the only choices in Colorado All with 10% Ethanol(Mandated). I consistently run with 87 now. I usually try to stay with a local King Soopers for convenience and discount but have always found Shell and BP( got out of the state about 5 yrts ago) 87 be really great for mieage, smothness + power. I have Drilled + punctured stock exhaust. Stock jets. I usually try to add chevron Progard Fuel Injector Cleaner, I get Cheap from CostCo. I don't bother to calculate fuel mileage. I just zero out my Mileage and I fillup near 140 mi. Most of the time I can make it to 150 Mi before I hit reserve with 87 and additives. 145 on average without additives. I can tell when a Gas station is cheating on the octane 87. I also notice on hot days It runs as if I had 85 in it. So the previous discussion has told me to add some 91 or an octane booster when above 90 degrees. (1 makes the bike engine vibrate. Maybe I need to check my Carb sync? Anybody in CO got a setup I can rent/donate or borrow?
I hope this helps someone in Colorado or the high country cope one of MC Shadows biggest questions.

[SHADOW 1100T]

Amazing,,,your using exactly what Honda engineers recommend Most likely the reason the higher octanes make your bike vibrate is because with the higher octane comes a longer burn time,,,something you don't need according to Honda.

[markjay50]

I don't know without looking at the specs, but your bike may have a
knock sensor on it. Most of the newer fuel injected engines do.
If the knock sensor detects detonation, it will back the timing down
until it stop detonating and that is totally seamless and to the rider. THANKS A LOT....

[JFaz525]

I read (and loved) the fuelology post. Can I ask about backfiring? I don't get it a lot but I do get it and to varying degrees. Sometimes small seamingly insignificant pops but sometimes surprisingly loud. Always happens when throttling down.
Thought backfire was caused by unburnt fuel?

What, if anything, should I do about it?

Thanks in advance!

[Cbjr]

Originally Posted by JFaz525

I read (and loved) the fuelology post. Can I ask about backfiring? I don't get it a lot but I do get it and to varying degrees. Sometimes small seamingly insignificant pops but sometimes surprisingly loud. Always happens when throttling down.
Thought backfire was caused by unburnt fuel?

What, if anything, should I do about it?

Thanks in advance!

You are correct it is caused by unburnt fuel - and that occurs when the fuel is shut off and the idle circuit that is too lean and the mixture is actually too lean to fire with every spark - building up unburnt fuel in the exhaust until the next mixture that is ignitable fires, then it also light the fuel in the exhaust.

Also decel popping can occur when there is not a good exhaust seal at the head. But the hondas are so lean from factor the first scenario is pretty normal and doesn't hurt anything.

[Premium Speed]

I wanted to add something to this...

I have always been a motorhead and i always believed in running 93 octane in all my "performance" vehicles just because i figured it was the best. In some of my fuel injected mustangs i noticed some slight pinging under WOT with 87/89 in the Houston heat, so i have been trained to always run 93 in all performance cars.

Well, i purchased my 2010 Shadow Phantom a few weeks ago and had the same mentality. I used 93 octane in it since day 1 and drove about 700 miles with only using 93. I was noticing some vibrations over 60mph that concerned me because it was bad enough to make my side mirrors useless. I spoke with a friend who worked at a local motorcycle shop and he told me to run some 87 through it and see if that helped. Well, sure enough about 10 miles after i switched to 87 octane my Phantom is idleing smoother and running better all around at any speed. On the freeway at 70mph the vibration is gone and my mirrors are now working as intended.

Anyway, just wanted to add my .02 because this made a huge difference in the performance of my bike.


-Premium