How to remove the standard silencer from a MKII.

[Paul-D]

Has anyone found the Mk2 runs too lean with after-market exhaust, necessitating an engine tune?

Or is the standard set up capable of adjusting fuelling with the less restrictive aftermarket (e.g. minus exhaust valve and cat), with or without dB killer... without need of a re-tune?

[Art]

That's what it does. Needs re-tuning to be sure and isn't removing all that kit now an MOT issue?.

[Paul-D]

Re. MOT: 

- Bikes do not have any emissions test requirement in UK - so not a problem.

- My aftermarket exhaust is fully EU certified and carries the homologation plate for EU compliance.  Fact I didn't install the CAT isn't something that the MOT test checks for.
- However, my last bike (a 2004 Tuono) had a non-homologated after market exhaust and it never failed an MOT in 5yrs.  If any MOT tester is extra particular, they usually ask that you bring the OEM exhaust, and issue a cert on the basis you have the original.

[Art]

Its not about emissions or the tester being 'particular' its about the tester doing the inspection as it was intended. You, I, the World and his wife all know a high percentage of motorcycles presented for test would fail if that test was carried out according to the book. Any Class 2 MOT tester carrying out tests according to the book would rapidly suffer a loss of business. The salient part of the test being...

DVSA MOT Inspection Manual: Motorcycles

8.1.1. Exhaust noise

If possible, you should assess the exhaust noise by revving the engine to approximately half the maximum engine speed. The engine should be warm before you carry out this check...

The exhaust system and silencer should be in such condition, or of such a type, that the noise emitted from the motorcycle is not clearly unreasonably above the level expected from a similar motorcycle with a standard silencer in average condition.

Major Defect
8.1.1.(a) Exhaust noise levels in excess of those permitted.

Louder than standard exhaust systems are a MOT issue, but you don't want to hear that.

Changing the back pressure within an exhaust system without re-mapping the ECU is, as much as you may prefer the sound, of no real benefit and can reduce power output.

[Paul-D]

I think you are confusing 'emissions' with 'noise'.  As I said, there is no emissions test for bikes in the UK. 

There has been a long standing requirement for maximum noise level though, as you have also reflected.  My comments on noise related to what happens in practice.

I think that MOT testers passing motorcycles with aftermarket noisy exhausts is more about pragmatism than it is about making money and losing business.  Think about it. If there was a clamp down and all MOT testers failed bikes with aftermarket exhaust... it would mean bikers swapped their exhausts back just for the MOT... which would be pointless bureaucracy.  That's why my local MOT station passes aftermarket exhausts that are not noisy and asks the biker to verify he has the original if they are.   Police can also prosecute if a bike exhaust is to loud, but they usually have better things to do.

Incidentally, another reason I have gone for an aftermarket exhaust is 'safety'.  However much I like the quietness of my new bike (especially compared to my last large and noisier v-twin), a quiet motorcycle is much more dangerous than a noisy one.  People and animals hear a louder bike and take precautions.  I use my bikes mostly in the country and fast A and B roads, with the aim of doing some touring on my recently acquired Mk2.  If I used it mostly for commuting though, especially in a city like London, I would stick with the std exhaust.

I haven't heard anyone mention loss of power after fitting an aftermarket exhaust. Some (on here) report that it eliminates the 3k flat spot.... which is commensurate with the fact aftermarket exhausts typically increase torque/power (typically only a few bhp) at lower revs on road bikes.  Appreciate a remap will get the best out of an aftermarket exhaust.  In fact, on the Biffer, I was of two minds whether to change from stock... but the sound the new GPR exhaust makes is very nice... and adds character.  That said, if I was just after power and mad performance, I wouldn't have sold my Tuono.

But my main concern is, "Is it necessary... because the bike can run 'too' lean... which can damage valves, plugs, etc"? 

[Art]

No confusion here, you mentioned emissions not me. I simply asked 'isn't removing all that kit now an MOT issue?'. Clearly it is.

Please, not that old 'loud pipes save lives' distraction.

What I said was 'changing the back pressure... without re-mapping... is of no real benefit and can reduce power output' not that it necessarily would. To be perfectly clear I'd expect such a modification to do little, nothing or in some cases reduce engine performance.

Without testing the effect of the modification its impossible to know the extent of any incompatibility created between the Exhaust and Fuel Systems.

[Paul-D]

Definitely confusion here Art.  You expressly asked,

"isn't removing all that kit now an MOT issue?."

I expressly explained that even though the CAT was removed... emissions isn't tested. 
You then said it wasn't about emissions...  but 'removing all that kit' is about emissions...   

As I mentioned in my first post...

My aftermarket exhaust is fully EU certified and carries the homologation plate for EU compliance

.... and not over the noise limits... so there is no MOT issue in terms of sound either!  Besides, it is wide practice that MOT testers don't fail bikes with moderately louder aftermarket exhausts.  Whether they are acting according to the letter of the law or not is immaterial to my point.

There is no doubt... that removing the original exhaust, including the exhaust valve that closes down to restrict noise at certain low and on some bikes high revs... and replacing with a freer flowing exhaust, will cause the engine to run a bit leaner.  That is a well know fact.

Hence my question for anyone who has done this... whether they had noticed or heard of any damage occurring due to the engine running hotter, especially on the Mk2.

Personally I'm not aware of any damage occurring in this scenario... as the power increase is minimal... but it's probably advisable to get the engine re-tuned at next opportunity, especially to maximise benefit of the aftermarket exhaust. 

Also, tuners prefer to tune with the baffle out (if owner will ever ride the bike with it out)... as that results in a richer mixture when the baffle is in... so eliminates risk of running too hot.

Re. 

Please, not that old 'loud pipes save lives' distraction.

- I can assure you that anything that prevents a pheasant from running a cross the road just in front of you ... isn't anything to do with 'distraction'.  You obviously haven't seen the effect a louder pipe has on wildlife or cars ahead when you open up!  And it doesn't need to be anywhere near 'hooligan loud' to benefit rider safety.

[stationzebra]

Originally Posted by Paul-D

There is no doubt... that removing the original exhaust, including the exhaust valve that closes down to restrict noise at certain low and on some bikes high revs... and replacing with a freer flowing exhaust, will cause the engine to run a bit leaner.  That is a well know fact.

Hence my question for anyone who has done this... whether they had noticed or heard of any damage occurring due to the engine running hotter, especially on the Mk2.

Personally I'm not aware of any damage occurring in this scenario... as the power increase is minimal... but it's probably advisable to get the engine re-tuned at next opportunity, especially to maximise benefit of the aftermarket exhaust.

Can you update? Did you find the engine ran leaner and needed 're-tuning' even with the baffle in...or out? did/does this make a difference?

[knapdog]

Arrow exhaust fitted.
Healtech exhaust servo eliminator fitted.
For what it's worth, ECU reset with battery removed for 30 mins, ignition switched on and throttle slowly opened fully and released slowly then ignition off ( to reset throttle sensor), ignition back on and engine started with NO throttle and allowed to run until fan kicks in and continue running for another 5 mins. (Don't know whether this works but did it anyway).
Bike runs and sounds a treat. Original exhaust weighed a "ton".

[chay]

Hi Knapdog.

And you can lose another couple of pound by removing the ballast plate on the opposite side of the bike !!

Every little helps ...