Popping on decel....

[flux]

2002, 30K miles.  TOR can and offroad tune.  Just had a full service done, plugs changed, valves checked (all in spec), all that stuff.

Before and after service, my bike has been popping badly on decel for about the last month or so.  It sounds like it would be poor jetting if it were a carbed bike.  Fresh plugs didn't do anything.  We have tried all three tunes (offroad, stock, and 'aftermarket w/o cat converter') to no avail.  

I don't see anywhere that would indicate an exhaust leak.  O2 sensor failure?  I would think a code for that would have come up when we plugged it in a few weeks ago.  I know about the O2 sensor bypass thingie but everyone I talk to in person says its no good without a Power Commander, and anyway, the bike was running just fine before... can't think of what might have changed between now and then...

Any ideas?  I have a great Triumph tech here but he is at a loss as well...

[Bixxer Bob]

With you all the way mate, and if I ever find out what's doing it you can bet I'll post it here first.

Mine's always popped a bit (2005 15k, Blueflame twin port)) and I have a Tuneboy so can mess with the maps.  I've tried all the maps available, and played with the trims but nothing seems to make a lot of difference.  Except that I put a modded map in last week and dropped the long term trim 1% and it banged, never mind popped so now I'm back to the straight offroad tune, modded to richen the lower area where I still have a bit of surging.  I loaded it this afternoon and will use it for work tomorrow (70 miles) to see how it goes. Over the winter I'm going to drop the headers off and make sure I don't have an air leak there (or anywhere else for that matter).

[Bixxer Bob]

Update,  I've been doing some more reading and found this tonight.  A more reliable source of information than sundry automotive forums methinks....

http://www.mikuni.com/tg_backfires_in_exhaust.html

Depending on how my ride to work goes tomorrow, I'll load the TOR tune, then richen the idle trim and see what happens.

This would be so much easier with a dyno.....  :roll:

[John Stenhouse]

It's only an opinion but I quite like the fact it pops on the overun!

If you don't like it, the cure is simple, don't slam the throttle closed, use a very small amount of throttle and you can stop it popping quite easily.

[Bixxer Bob]

Lines up with the too lean explanation by Mikuni, ie too lean mix doesn't burn in the cylinder, builds up in the exhaust then pop or bang.

I ran a new map today in which I put some more fuel in the area where I have surging ie about 10% throttle and 2500 to 3000 revs.  It seems to have done the trick but it's now surging lower down.  I'll try that later this week.  Meanwhile I have another map to try tomorrow where I've put some fuel in the area used on overrun ie where the popping is.

More on this after I run it.

[BONANZA]

My 05 16k bike also pops on the overrun. I normally ride with earplugs in but on a short ride last week without I noticed how loud it was. Well my next door neighbour said it was loud but I explained that it was called "character". He has,ent spoken to me since.

[ChazzyB]

Popping/banging/crackling on overrun - I thought they all did it! Certainly mine does as does that of a chum. I've read an explanation somewhere, possibly on the Tuneboy web-site, about the interaction between ECU and O2 sensor injecting air into the system when it's running in closed loop mode to keep the stoichiometric ratio correct (or something like that). Dynojet sell a widget that plugs into the ECU instead of the O2 sensor wire which eliminates the banging.

[Bixxer Bob]

Trust me,  I've tried everything to stop it inc the Dynojet plug in.  Nothing really works.  My view?  The popping, like the surging, is a symptom of bad mapping so should be sortable.  I wish I could get a couple of hours on a dyno and some decent datalogging.  It would help a lot in working out what's going on instead of guesswork.  A lot of bikes do this not just Triumphs but there again lots don't either.

If nothing else,  it keeps me from getting under the wife's feet.

[flux]

Thanks guys.  

This is a problem that has developed over the last month or 2.  If my bike always did it from day one I might be okay with it but it's a new thing and sometimes the BANG! is loud enough to scare the shit outta me.  A little popping is one thing but this has gotten old.  I will bring it back to my tech over the weekend to see what he has to say.  

I forgot to mention, but he stuck a device down into the exhaust and was able to tell me it was running lean.  Maybe that bit will confirm some things for you, Bob.  Good luck!

[swamper650]

 Have an easy cure. My 02 did pop a bit on deceleration. I have moved from 18ft. above sea level, the west coast of Fl, to 5000 ft, Prescott Az. My Tiger no longer pops at all...............though it does run hotter. May be do to only being able to find a 13# replacement radiator cap. Specs call for 16#              

[Bixxer Bob]

Thanks guys.  

This is a problem that has developed over the last month or 2.  If my bike always did it from day one I might be okay with it but it's a new thing and sometimes the BANG! is loud enough to scare the shit outta me.  A little popping is one thing but this has gotten old.  I will bring it back to my tech over the weekend to see what he has to say.  

I forgot to mention, but he stuck a device down into the exhaust and was able to tell me it was running lean.  Maybe that bit will confirm some things for you, Bob.  Good luck!

Aye, more lean = more bangs.  I mapped out the some of the lean trough at tickover put there for emmissions tests by Triumph yesterday.  It was better, but not great.

[flux]

Well, I dropped my bike off at the dealer yesterday.  I know the Triumph tech there good so I just told him to ride it home so he can get the feel of what I'm talking about more.  This is not normal popping and banging here.  

I'll let ya know how it goes but right now my garage is EMPTY.   :(

[Bixxer Bob]

:roll:

 :roll:

 

 

[flux]

Well, I got it back yesterday but I'm not really impressed.  He put a call into Triumph and they said it IS going to pop and bang with the TOR can.  However, something I didn't know was that my bike was throwing a flame about a foot long when it was banging.  So, they reloaded the tune to "aftermarket exhaust w/o catalytic converter".  I haven't had time to properly run it but I ran around the street behind the shop and it IS banging much less, however it is still doing it a little.  I'm headed to Florida tonight so I'll report back over the weekend but the service manager suggested it might be a tight valve.  When my service was done the tech said 2 were on the tight side but still within spec so he didn't adjust them.  The service manager said to bring it back when I return home and he would have a different tech break into it.  

Oh well... I guess we'll get it sorted.  I have a hard time believing Triumph would sell an exhaust with an accompanying tune that won't work together without acting as a flamethrower....

But, the shop has been great to work with... I just think they are stuck on why this is happening.  I need to set up a video clip so you guys can hear it and see if I'm crazy.

Cheers

[ChazzyB]

He put a call into Triumph and they said it IS going to pop and bang with the TOR can.  However, something I didn't know was that my bike was throwing a flame about a foot long when it was banging.  

Well, I for one like the crackling and popping and the thought of flames on the overrun is nearly making me wet myself with excitement.  :lol: