Backfiring

[SpencerW]

Hello all,

I have an '09 RIII. I do love this bike. It is about 6 months old and has about 8500 km on it.

However, I have noticed it is starting to backfire a lot more than it did (not the lovely decel rumble but loud back fires). I have the Triumph high flow air filter, cat remover, and performance exhaust on the bike. I have confirmed the "correct" map is loaded—the max power map for the above set up.

The last month or so I have noticed that the bike stumbles sometimes when it is cold at a fairly low-moderate throttle positions (I live in Singapore so "cold" is about 29c or 80f). It kind of makes a coughing sound like it is missing or something. Once warm it is fine.

As mentioned, it is also backfiring more. Even my friends who have owned RIIIs have commented on it. It back fires on decel, but also a lowish speed at a constant throttle sometimes it will backfire mildly.

So I have 2 questions:

What could be causing this?

Is it anything potentially damaging to the engine?

Thanks for your help.

Regards,
Spencer

 

[Sidecar Flip]

Sounds to me like at least a 12 minute tune is in order. What kind of gasoline is sold in Singapore? is it ethanol laced and if it is, what is the percentage of corn liquor? Rockets don't like ethanol as a rule or 'oxygenated (mbte) additives'.

'Green' additives upset the digestive system.

 

[tdragger]

First thing I would ask is what fuel grade are you using? Some new riders have been given the wrong information to run Premium (I believe it would be 95 RON octane in your area). This will result in the backfiring that you describe. Make sure that you are running the recommended 92 RON. The Rocket is a low compression engine and higher octanes do not burn completely and result in fuel still burning during the exhaust cycle.

 

[dougl]

If you have the cat bypass and/or off-road pipes, it's running lean at low throttle positions. This is causing the ignition of unburned fuel in the exhaust manifold on decel. It's not a problem - other than the noise.

 

[Sidecar Flip]

First thing I would ask is what fuel grade are you using? Some new riders have been given the wrong information to run Premium (I believe it would be 95 RON octane in your area). This will result in the backfiring that you describe. Make sure that you are running the recommended 92 RON. The Rocket is a low compression engine and higher octanes do not burn completely and result in fuel still burning during the exhaust cycle.

.
..........Your basic agricultrial engine.

 

[SpencerW]

First thing I would ask is what fuel grade are you using? Some new riders have been given the wrong information to run Premium (I believe it would be 95 RON octane in your area). This will result in the backfiring that you describe. Make sure that you are running the recommended 92 RON. The Rocket is a low compression engine and higher octanes do not burn completely and result in fuel still burning during the exhaust cycle.

Yes, I have been running 95 RON gas in it. I will switch to the lower 92 RON and see if that helps.

 

[SpencerW]

Sounds to me like at least a 12 minute tune is in order. What kind of gasoline is sold in Singapore? is it ethanol laced and if it is, what is the percentage of corn liquor? Rockets don't like ethanol as a rule or 'oxygenated (mbte) additives'.

'Green' additives upset the digestive system.

No ethanol in the gas here.

 

[xhdskip]

They make ethanol out of corn here.
What would they call gas made from rice?
Sakihol or riceahol?
Any of that over there?

 

[tdragger]

borrowed from G-man at the .com site. (NOTE: 89 octance RM/2 = 92 RON, 93 RM/2 = 95 RON):

A parameter of octane rating is resistance to ignition and the rate of combustion.
Higher octane; higher resistance to ignition and a more controlled combustion rate.
Higher octane is for compression ratios of 10:1 or higher and or hotter (temperature) engines to eliminate pre-detonation.
A quality 89 octane (US, RM/2) is perfect for the Rocket that still retains OEM compression ratio and timing advance.
I have a Rocket buddy with TORs and cat-bypass that I would hate to ride behind because of all the popping and farting on decel.
One day we are riding and pull in for gas.
I see him putting 93 octane in.........WTF!!!!
I tell him NO!!!...use the 89!!!!....this is why your Rocket sounds like the 4th of July on decel.
He is now convinced and only uses 89...most if not all of the decel popping is gone.
The 93 octane WILL NOT completely ignite in a stock Rocket engine with 8.9 CR and simply collects in exhaust.
During decel when your Rocket engine turns into a 2300cc air pump you get the ingredients for pop-boom-bang!!!
Un-burned fuel, fresh air and a hot exhaust providing a secondary ignition source.
This is all I would like to say.
Hope this helps someone, somewhere....somehow...

Gary

 

[georgia]

cool.. thanks for that!

cheers
geo