Pops And Bangs

Before you do that I would make sure there are no air leaks.

 

First question have you done the re-mapping process?
My 1200R pops on overrun (although I quite like it) and reading thorough lots of posts on Thruxton modifications I believe it's due to the emissions requirements to get through Euro 4 (& Euro 5) regulations that the fuelling at low throttle openings is quite weak, it then richens up as you open the throttle and that's OK because Euro 4 regs don't measure emissions further up the rev range.
(It can also be that there's a leak in the exhaust system).
You can alter the fuelling map, but that's a dark art, and I wouldn't risk it, but as part of my Thruxton fettling, I've just removed the airbox snorkel (it's there to reduce intake noise, again for regulations only) and fitted a Power Booster which is plugged between the airbox air temperature sensor and the ECU and fools the ECU into thinking the air temperature is much colder so it then richens up the fuel mixture (but only at low revs). There's a lot of people who've said it improves low speed and mid range power, lowers the engine temperature (a weak mixture makes an engine run hot) and the engine runs smoother. It was easy to fit, but the weather has closed in, so I've not had a chance to ride the bike since. But I did warm the engine and the tickover did sound good.
https://www.squaredeals-ltd.co.uk/t...he-power-just-plug-and-play--enjoy-4687-p.asp
Hope this helps.

 

What year is your bike?
Presumably your full system included a de-cat? This uncovers a lot of noise that was previously suppressed by it.
I know that Arrow headers without the balance pipe seem to produce a lot more noise that those with it.
Shorter cone silencers are also much more raucous than longer types like the V&H options etc. You might find that the even the US spec V&H (if you can find any for sale) produce a more mellow note or even consider the EU spec ones with the baffle in place.Interestingly, the OE silencers can have their baffles removed using a hole saw so this could be a cheaper route to baffle free silencers. As I mentioned, the cat removal releases most of the noise so you wouldn't feel cheated but it would tone it down a little.
Mine (2017 R) has the OE headers, US spec V&H with a de-cat and also has a Power Commander with a Dyno derived map installed. You can hear the pops but it's not excessive or offensive. I think that there's a chance that a good map quietens things down a little but I couldn't be sure as I didn't get an opportunity for a before/after check.

I personally think Booster plugs are a waste of money having tried one. I noticed no discernible difference. My bike was one of those affected by random stalling and the Triumph developed map that was designed to fix this didn't work 100% of the time. I tried a BP as the advertising at the time claimed it could address this - it didn't. There is also evidence over on Triumph Rat that the BP can actually change the throttle response at small openings for the (perceived) better but at the detriment to wider throttle openings. This is how I came to eventually fitting a Power Commander. Not only did it fix the issue it improved torque below 3.5k rpm by about 20%. Throttle was smoother too. BHP gains are low, about 3 but you'd never notice this even if it were 5. There's much more to tuning than BHP.

You can use Tune ECU for mapping but many Dyno operators don't use it as it's slow to use for them. A Power Commander allows live mapping and is quicker to make changes. It also doesn't interfere with the ECU so is perhaps preferable from a warranty perspective.

These motors run lean to meet Euro 4 legislation and it's one of the reasons there were so many changes made by Triumph to meet Euro 5. I believe the necessary changes were packaged as performance upgrades rather than an admission that the old engine was no good for Euro 5. The original motor would have no chance. There was also considerable variability between like for like engines - one of the reasons custom maps work better than generic maps. No two engines are the same.

Somebody may mention Ducati spacers. These simply take out the slack in the throttle tube. They do nothing else, some claim they smooth the throttle out which is impossible. If you don't like play in the throttle then by all means. When I ride and am moving I never have a fully closed throttle so never notice the slack when using varying throttle. It's only evident when moving off and it's not something I notice then either.

The 12 minute tune you'll hear about is simply an adaptation, a reset if you like. The ECU has limited scope for adjustment, it's designed to make minor changes for environment and fuel quality etc. It's not a magic bullet although can be useful after major work.

As has already been mentioned, before you leap in at the deep end check off all the basics like leaks etc.

 

Just thought I'd mention my experience with regards this issue. I removed the catalytic converter from my Street Twin and fitted a Motone X-pipe. This produced the characteristic popping and banging, especially on the over-run. As far as I understand it, this is caused by unburnt fuel (which was previously absorbed by the cat) igniting in the hot exhaust system. Whether you find the sound enjoyable or offensive is obviously up to you. I was initially a little concerned but quickly came to love it.
That was around 3 years ago. I am certain the popping and banging has dropped off somewhat and is now far less noticeable than it was. Personally I think that's a shame but there you go. My point being, I would give it a little while longer and see if the volume or frequency declines.
Of course it could be that I've just grown used to it but at the start it used to turn heads on every ride but now that only happens occasionally. It has definitely quietened down.

 

I think (maybe) that the unused fuel in the exhaust idea is flawed, the cat deal with gases and it's there to change the chemical in the gas to sonething less toxic, using expensive metals (which is why they're nicked off cars) so burning fuel in there wouldn't do the cat itself much good. Secondly "somewhere" on a Triumph ECU mapping group I saw that the map effectively turns the fuel off when the throttle is closed, thus making the engine run weak on overrun, I guess a good remap could get rid of that. Have you looked at the TuneECU forum on the Internet and one on Facebook?

 

Yeah, I wasn't sure that the unused fuel being absorbed by the cat idea was correct, because you're right, it would bugger up the catalytic function. But I'd like an explanation as to what causes the popping&banging. How about the ignition of unburned GASES, which would have previously been absorbed (or converted/catalysed)? That sounds more feasible wouldn't you agree?

On another issue mentioned by 7Thruxton, the cam upgrade. I fitted a TEC camshaft to my 1st gen. Street Twin. It has made a huge difference and is easily the best mod I've done. I know the 2nd gen. ST is more powerful than the 1st but my upgraded cam, together with the Motone X-pipe and less restrictive TEC cans, has given my bike more power than the 2nd gen. and is only a few bhp's short of the T120. I've tested it back-to-back with my brother's T120. On a motorway the 120 has the edge but on a twisty, roller-coaster road, I'd choose my bike anytime.

 

The problem with the unburnt fuel theory is that the cat wouldn't be able to process that (cos it can only deal with gases) so that would ruin the emissions...and whole point these engines was to get through the stringent testing of Euro4 which the previous EFI models couldn't do. I've just fitted a Booster Plug to mine, that richens up the fuel at low throttle openings for smooter running.

 

My limited understanding is that the change in a full system which includes significantly lengthening or shortening the end can mean the fuel to air ratio is not correct for the changes made. unburnt fuel will then likely be drawn into the exhaust and ignite there opposed to inside the engine.
With end cans upgraded alone it doesn’t always require a re map as the fuel to air ratio is impacted less if the exhaust is os similar length to the original coupled with manufacturers data complimenting this. I remember my old R6 having a carbon Akrapovic end can. It used to backfire every so often when blipping on downshifts assuming that is what you are referring to also. The backfiring did not improve over time. There was no requirement for a re map according to Akrapovic. If I had opted for a full system they recommended a re map in order to make sure it didnt run like a box of spanners and likely backfire like no mans business. Like others have said check leaks first, if not then manufacturer of the exhaust system is good second port of call. Sorry if I missed this, what is the manufacturer of the full system which you have installed?
Finally I presume it didn’t do it with the stock exhausts did it?

 

Yup, we know the unburnt fuel idea thing is wrong, as you already pointed out in your post previous to this one. But I'm still hanging on to the idea that it's unburnt GASES that ignite in the exhaust, although I'm happy to be corrected.

I also fitted a Booster Plug to my ST but it made no noticeable difference. Both positive and negative comments have been posted on this forum regarding its effectiveness. When I took my bike to Youles in Manchester to have the TEC cam fitted, I was told that the Booster Plug actually interfered with the smooth running of the engine with the new cam. So they disconnected it. Anyone want to buy a hardly used Booster Plug?

 

There's the difference in gear ratios at play here too. Doesn't the Street Twin have 5 gears vs 6 of 1200? What's the change in torque on yours after the cam installation? I had a T100 which was a 5 speed alongside my Thruxton, which I still have. I noticed the difference in ratios and thought the 5 speed was really well judged for urban/lower speed (rpm) use.

 

You're right, the Street Twin has 5 gears and the T120 has 6. There are times on the long straight bits when I feel the ST could do with another gear, but it wasn't really designed for motorway cruising, although it copes perfectly well.
When it came out it was praised for it's low-down torque and I don't think the cam upgrade has altered this. That's just a seat-of-the-pants observation, I have no figures to back this up. However if you watch the TEC Parts You Tube vid on how to fit their cam, they take a more scientific approach and show there's no significant difference. That low-down punch is still there but it now extends further up the range, so at higher speeds there's no need to drop down a gear to get past that queue of dozy car drivers