What is the cause for afterfiring
- Thread starter Habechian
- Start date
TxRIIIRider
Living Legend
Either running too lean or an exhaust leak.. If you've done any exhaust mods, but have not had the appropriate fuel map loaded, you will be running too lean..
Jamie
Living Legend
Too lean a fuel/air mixture, indeed. Or, if backfiring aka decel popping is happening to you all of a sudden, all other factors (pipes, e:tune, etc,) being unchanged, a micro crack in the cat weldings is a likely possibility. Jamie
scot in exile
Living Legend
Not good for the bike not good at all. Tuneboy has or had a group buy going you should look into it.
STRIPES
\\\STRIPES/// going to the HD shop.
popping
Here's something curious. I took the baffles completely out of the Jars. Very little popping on decel. Couldn't stand the ears ringing after riding so decided to put them back after a slight modification. The only other change was removing the secondaries. Since putting the baffles back in (they sound sweeeeet), I don't just get "popping" ....more like gunshots! Man o man! Loud enough to make people jump! I haf'ta admit....kind'a fun
The pipes now have a much lower growl like a big tractor trailer rig with straights.
Here's something curious. I took the baffles completely out of the Jars. Very little popping on decel. Couldn't stand the ears ringing after riding so decided to put them back after a slight modification. The only other change was removing the secondaries. Since putting the baffles back in (they sound sweeeeet), I don't just get "popping" ....more like gunshots! Man o man! Loud enough to make people jump! I haf'ta admit....kind'a fun
The pipes now have a much lower growl like a big tractor trailer rig with straights.
Power-Tripp
Turbocharged
Like others have said, popping on deceleration is caused by lean conditions in the exhaust.
Little spots (weld slag, poor cuts, etc.) in the exhaust can easily become glowing red hot if the residual gases are lean - especially if ignition advance is a more than a few degrees less than optimum. This can also be more of an issue when cruising since the engine is using the Lambda (O2) sensor to lean the running conditions under low load - causing warmer exhaust gas temps. These spots become just like glow plugs in diesel engines, and ignite residual unburned fuel. Pop, POP, bang, BANG!
If you can access all the rough spots in the exhaust, smoothing these with a grinder and sanding rolls can reduce this greatly.
If not, a bit of fuel added at lower throttle openings - at higher engine speeds - normally fixes the issue by cooling the exhaust gases and pipes under the self ignition temp for the pressures seen in the exhaust. But you will need some way to adjust fueling under the correct conditions - PCIII, or TuneEdit.
I hope this helps.
Little spots (weld slag, poor cuts, etc.) in the exhaust can easily become glowing red hot if the residual gases are lean - especially if ignition advance is a more than a few degrees less than optimum. This can also be more of an issue when cruising since the engine is using the Lambda (O2) sensor to lean the running conditions under low load - causing warmer exhaust gas temps. These spots become just like glow plugs in diesel engines, and ignite residual unburned fuel. Pop, POP, bang, BANG!
If you can access all the rough spots in the exhaust, smoothing these with a grinder and sanding rolls can reduce this greatly.
If not, a bit of fuel added at lower throttle openings - at higher engine speeds - normally fixes the issue by cooling the exhaust gases and pipes under the self ignition temp for the pressures seen in the exhaust. But you will need some way to adjust fueling under the correct conditions - PCIII, or TuneEdit.
I hope this helps.
Pig9r
Living Legend
Habechian - you are in Brazil correct? I would be careful loading tunes into your bike - I believe your country uses 100% ethanol. I wonder if Triumph has a special tune for Brazilian bikes?
Power-Tripp
Turbocharged
Both 675s and the Speed Triple definitely have different tunes for the Brazilian bikes.
I would assume the R3 would as well.
FWIW, Ethanol (E85, E90, and E98) runs great in bikes.
E85 is worth ~5% torque, and 4.5% peak power in most applications. E98 is about the same... just a touch less than most E85 blends.
A good custom blend E90 is worth 6% power and torque across the board, with engine great cooling, and ~112 octane - GREAT for supercharging and nitrous.
The R3 injectors can handle the flow for mildly modified engines on ethanol blends, but once you bump compression, head flow, and cam profiles, you will need larger injectors. Luckily, Honda used just what is needed, and these are readily available.
Well tuned, you need 28-32% more injector flow than for gasoline fuels. Fuel consumption at cruise can be just as good... even slightly better, than on gas.
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