Air intake backfire

pascal

.020 Over
Joined
Mar 16, 2007
Messages
27
Location
ROCKVILLE, MD
Need some hints about air intake backfire.
My bike is a 05 with the empty catalyst box, stock exhaust, underpants KN Filter, PC III.
My Rocket just started to have small backfires in the air intake when opening the throttle from idle to full power without load (static in parking).
Ths started after having decided, after refuelling, to make a 12 min reset of the ECM after having positively tested the PC III tune 510-002 + 2 dots positive on the low RPM setting on the PC III box for the KN filter.
It started when I showed to my 2 year old son the engine sound, yes he loves the bike as much as I do!
I suspect the fuel quality and just filled and added drying fuel additive, I'll see tomorrow.
I drove for few weeks on the PC III settings and never got this, neither the exhaust backfires.
Does anyone knows a possible cause of this problem?:confused:
 

Pig9r

Living Legend
Joined
Mar 5, 2006
Messages
4,848
Location
Kansas City, MO USA
I get them on occasion too. Even with the stock set up I would get a backfire out of the intake. I could feel them under the seat. It seems it happen for me after cutting the throttle.
 

Toystoretom

Living Legend
Joined
Feb 25, 2006
Messages
2,449
There have been a few reports of the O ring between the throttle bodies and the head getting sucked in and causing an intake leak. If your backfiring doesn't go away with fresh gas or possibly re try the 12 minute tune, it might be something to check.
 
Last edited:

pascal

.020 Over
Joined
Mar 16, 2007
Messages
27
Location
ROCKVILLE, MD
Can't wait to see if still happens after collector check, fuel drying and a 12 min reset. Going for a frosty (32" Farenheit):roll: run and I'll be back after for update.
Thanks.
 

pascal

.020 Over
Joined
Mar 16, 2007
Messages
27
Location
ROCKVILLE, MD
Back in business:D ,
no backfires anymore. But what caused it, can't be certain since corrected few things at the same time.
Nevertheless, about a leak somewhere around the airbox, I've found the added PC III plug pushing on the MAP sensor when the fuel tank is put in place, I moved earlier this plug after working on the new wires for air horn!
So, if I push now on the MAP plug, I see him moving a bit out of his airbox lodging, consequence of the previous pressure of the plug , I don't know?
Question: must this be firmly tight in the lodging and if yes, how can I tight this MAP sensor?
This could have been the cause of backfire since one of the causes of intake backfires for injection engine is an air leak leading to la ean mixture(Wikipedia)?...
Anyway a lesson learned for me is go back to the changes you made previously to a sudden problem to find out if you didn't mess up when reassembling the bike!:bch:
 

Sidecar Flip

Living Legend
Joined
Jul 16, 2006
Messages
6,359
Location
20150 Mc Carty Rd. Deerfield, Michigan 49238
My bike is all stock and it backfires through the intake on ocassion just like Pig9r's. My T100 does the same thing and it's carbureted with Kehin CV's. I've even blown a carb off an intake runner on that bike. I believe it's due to the lean emission mixture even though I''m running 118's on the mains and 43 idle jets with 2 shims on the needles. I know, that's not about R3's but I cite it because the R3 isn't unique in backfiring through the intake. Come to think of it, my quad does it too.
 

pascal

.020 Over
Joined
Mar 16, 2007
Messages
27
Location
ROCKVILLE, MD
Thanks for sharing your experience.
It's seems that my yesterday run is blown away by my morning trip to work.
I actually got it back arriving at work when engine's hot and back home this late afternoon.
I straight tried to remove my rich mixture in the low RPM by 3 dots on the PC III and it was gone!
Could it come from a too rich A/F ratio too, when engine is hot or the acceleration booster on the PC III that inject too much fuel on sudden throttle openings. I've put it on 77% sensitivity, 20% fuel increase during 30 RPM? Any clue somebody?
I don't know, but will try next sorties to see what's up and post results tomorrow.:cool:
 

Claviger

Aspiring Student
Joined
Jul 25, 2014
Messages
6,419
Location
Olympia Washington
Ride
'14 R3R, '02 Daytona 955i
It comes from reversion of a rich enough mixture the fuel is making it out past the intake valve in enough quantity to ignite when the plug fires. The people getting it with bad orings etc, are getting it for the same reasons as everyone else, the bad orings, and throttle body connectors are a result of it not the cause.

Can be solved by reducing fuel, or adjusting timing. Many stock bikes do it, swap out tunes for a different one using TuneECU.
 

cr0ft

Living Legend
Joined
Jun 28, 2012
Messages
2,401
Location
Finland
Ride
Triumph Rocket III Touring 2010
My Touring does it if you give it a lot of gas from idle.

Planning on getting her onto a dyno to see just what's going on with the map, runs like a top when she has some revs but the backfires are annoying. Not that frequent, but occasional.
 

Similar threads

Top
AdBlock Detected

We get it, advertisements are annoying!

Ad-blocking software does a great job at blocking ads, but it also blocks some useful and important features of R3Owners. For the best possible site experience please take a moment to disable your AdBlocker for R3Owners.Net.

I've Disabled AdBlock