[yogeshnaik]

Most of us are Royal Enfield fans and try to get the legendary exhaust note from our new UCE Royal Enfield Bullet Bike. This blog is on a comparison between a Royal Enfield Bullet OEM silencer and a short bottle silencer. I have used an Indore short bottle silencer and an OEM silencer to compare and get nearly approximate dB values on a Royal Enfield Bullet Electra UCE, 2012 model. This is my personal experience that I am sharing to the Team-BHP community in a form of this thread. At the end of the thread, I have posted a link of a comparison video and another video on exhaust notes of short bottle silencer.

From this blog, you will identify and conclude on which is a better silencer option for your Royal Enfield Bullet.

Construction of Royal Enfield’s OEM Silencer:
The silencer has 4 stoppers like baffles that helps in muting the noise generated from the exhaust stroke from the exhaust valve. Apart from this there is a catalytic converter which helps in reducing the toxic exhaust gases that helps our beloved environment in lessening the pollution. The muffler has multiple baffle chambers. The catalytic converter in OEM also muffles the sound. The weight of OEM silencer is 4.6 Kg.

Construction of Short Bottle Indore Silencer:
This is very similar to the old Bullet’s silencer, used to get exhaust notes like old Bullet's CI engines. I said 'like Bullet’s' because these give sound without a hard thump, there is hollowness if you use this silencer in the UCE engines. The silencer has only two baffle stoppers with 3 chambers but without a catalytic converter. The weight of OEM silencer is approximately 2.8 Kg and the weight varies from manufacturer to manufacturer.

Differences between Cast Iron Engine (CI) and Unit Construction Engine (UCE) exhaust notes:
The Royal Enfield Bullet Electra Unit Construction Engine (UCE) fitted with Indore short bottle silencer gives the original exhaust note with a THUMPH but due to the engine characteristics, the thump is only prominent when throttle is opened and when the engine has some load on it like a small inclination or a hill climb.

The differences between CI Engine and UC Engine thumps:
1. At idle speed CI has a thump whereas UCE does not.
2. CI has thump at all RPMs irrespective of load on the engine where the thump in UCE is prominent during opening the throttle and when the engine has load.
3. CI has a pure exhaust note, the UCE exhaust note has additional audible noises from CAM, Tappets, CAM governor etc.
4. Idle RPM is low in CI, idle RPM is much higher in UCE, due to the needed oil circulation.

Due to the above differences known to the core Bullet Riders, the missing of original thump in UCE is caught easily. When a short bottle silencer is used on UC Engine, it gives a thump but with a hollow note.

With some load on bike and giving throttle I could see the Indore short bottle silencer reached up to 84dB maximum while climbing uphill that was impacting the riders ears whereas the OEM silencer’s peak sound level goes up to 78dB for a narrow duration that is at a fraction of a second, but the real feel is still lower ranged between 68-70dB because the frequency spectrum has scarcely populated frequencies which is better, that implies energy is not wasted.
The bike gives an average of 41Kmpl with OEM silencer and 35Kmpl with short bottle silencer.


Short bottle silencer:
Pros:
Good initial pickup, old Bullet like sound.

Cons:
Low mileage of 35Kmpl, maximum speed struggled is at 72Kmph on my Bullet Electra, more misfiring, more heat, no catalytic converters, no back pressure, more vibration, irritation starts after a while for a rider and one who follows behind the bike, lessens engine life, a hollow exhaust note in UCE when compared to CI engines and finally not a street legal.

This silencer contributes to sound and air pollution.

I do not not recommended a short bottle silencer or any aftermarket silencer for Royal Enfield UCE engines because no back pressure is generated which is very much necessary to empty the gases from the cylinder.

OEM silencer:
Pros:
Higher mileage of 41 Kmpl, higher maximum speed up to 100+ Kmph with ease, catalytic converter, well maintained reverse back pressure with no misfiring, less heat generated, less vibration, anything with less strain means engine life is more, pleasant for a rider and one who follows behind the bike.

The most important is if you use OEM silencer, it will not disturb senior citizens and environment friendly due to catalytic converter.

Cons:
Heavier due to its design and construction. Need to be little careful when going over potholes as the silencer protrudes due to it more length that projects outside the periphery of rear wheel and sometimes rubs the ground.
This issue is solved in the latest models as they provided a slight angle slight upswept pipe. No complaints.


Video links:

https://www.youtube.com/watch?v=frVxQ1gcoDw

Royal Enfield Bullet Electra Short Bottle vs OEM Silencer sound comparison in decibel

https://www.youtube.com/watch?v=yLZ5mVrUEME

Bullet Electra UCE with Indore Exhaust

[Aditya]

Thread moved out from the Assembly Line. Thanks for sharing!

[tharian]

Some in depth comparison of both the mufflers

Few observations from me having tried a multitude of different mufflers on my CI Electra and 500.

- The thump that the old CI has is because of the heavy crank which is why even on idle, it is so prominent. My Electra is a CI, but with a light crank and it is softer than the UCE with a short bottle muffler.
- The short bottle has just two chambers. Both the OEM muffler and the short bottle have perforated pipes inside the chambers which basically reduces the sound further. The chamber walls cancels the more louder sound waves.
- I don't think the mufflers have cat-cons in them as they won't be effective as they are away from the engine. The cat-cons as far as I know are in the bend pipe. On the BS6 bikes, they are prominent because of the bulge.
- The back pressure is lost only if it is a straight through pipe. On the short bottle, back pressure is reduced mainly because the volume of air it holds is half of that of the OEM and the exhaust gas has to travel further down before part of it causes the back pressure. Which is also why vibrations increase and torque reduces.

My Electra is a 2002 model which came with the long muffler and it was when the long muffler was first introduced. I chopped it up and removed the 'flutes' from couple of chambers and even made two chambers into one. The only outcome was the note became a bit more flat but it was still muffled. The best muffler that I tried was the last type of muffler that came with the CI engined bikes before they stopped making them. It was a mix of chambered sections and straight through pipe stuffed with glass wool. It had a muffled thump that could be heard if you are standing right next to the bike, otherwise it was silent from a distance and it ran perfectly smooth with my engine.

The best way to check decibel levels is to keep the meter away from exhaust pipe and few feet behind and rev the engine a bit. Keeping the meter right next to it will anyway register a high decibel reading.

There is a dedicated thread for Enfield exhausts and mufflers on the forum which was started years ago which will be interesting for you.

[SS80]

Fantastic thread, I have a 2012 electra with stock silencer. Recently one of my friend's sold his classic 350 which had a short bottle silencer, so I borrowed that and fixed in my bike..

Pros
Better initial pick up.
Enjoyable loud thump at lower gears (higher rpms)
Easy to reach 60kmph

Cons
Reduced top speed
Irritation due to the non stop thump
Vibrations increased even more

I did a ride to airport, reached home and threw that short bottle non sense and stuck the stock one back.

Would love to know if anyone has tried the "upswept off road silencer of RE"

Here is the pic of the silencer I am referring to.

[CarBot]

I had the upswept silencer on my electra (now sold). My experience was it was much better than OEM that came with bike. Thump was good for my ears and neighbors . Below is the pic of my Electra.

[CARDEEP]

Originally Posted by CarBot

I had the upswept silencer on my electra (now sold). My experience was it was much better than OEM that came with bike. Thump was good for my ears and neighbors . Below is the pic of my Electra.

Same observation from my side. The upswept OEM exhaust has better sound as compared to straight one. I had Goldstar on my TB350, which was louder.

[SS80]

Originally Posted by CarBot

I had the upswept silencer on my electra (now sold). My experience was it was much better than OEM that came with bike. Thump was good for my ears and neighbors . Below is the pic of my Electra.

How about top speed, was that reduced?
Was it too loud like the short bottle ones?

[rakesh_r]

Originally Posted by SS80

Would love to know if anyone has tried the "upswept off road silencer of RE"

Here is the pic of the silencer I am referring to.
Attachment 2066616

I had the RE issued upswept silencer on my Cl 500. Was one of the best sounding exhaust for the UCE. Felt it was better than the Red Rooster and AEW wild boar.

[ron_9191]

To me, a good sounding exhaust for the UCE Bullets are the ones that sounds very similar to the upswept ones that came for the first Classic 500's and the 350's are just about perfect. If you plan to take something like a single pot Continental GT 535 on a trackday, probably a megaphone type exhaust should sound sweet. Anything else is absolute nonsense and a nuisance to the community.

[CARDEEP]

Originally Posted by SS80

How about top speed, was that reduced?
Was it too loud like the short bottle ones?

What top speed are you looking at on a RE? Frankly it's scary on winding roads over 120 imo.
There's a recent video where a RE Continental 650 rider met an accident as his bike went over road undulation at 160 kmph.
I had 2010 RETB350, & those are not very mod friendly, reliability-wise. Many riders would opt for change in sprocket size to increase top whack, buy that had impact on initial pickup. You could also add better air intakes & free flow exhaust, but IMO it's a compromise on reliability. Newer ones could be better, but, I would rather prefer Honda H'ness or Jawa than REs for such mods.

[SS80]

Also in most Electra bikes, the stock silencer is too close the brake adjustment lever. That is one reason I was looking to change, not looking for any louder thump or exhaust note.



I just want to be able to do the stock speeds (max 100kmph only if needed). Just wanted to know if this upswept silencer will still allow cruising at 80kmph.

[CarBot]

Below is the pic of Short bottle, my journey with RE silencers were as below
1 year with OEM long silencer -> 4 years with upswept -> last 1 year with short bottle. Below pic was taken just before selling electra.
There was no change in top speed between upswept and short bottle. I felt OEM long silencer was better with performance and heat.
My favorite was and is upswept, it looks good, sounds better than OEM long silencer and not as loud as short bottle.

[su1978]

I am not sure why i see and watch many people change silencers on their RE bikes. I own a TB350 UCE BS-4 and am sure that many people do not like Thunderbird because it is more or less very muted even compared to Classics. Let alone any other model. I have always been a fan of more work-less noise from the vehicles. Am sure that we all are great fans of less NVH levels in our cars. Somewhere down the line, we may take a fancy for vehicles with a loud exhaust note. But that would be for some time. On the other hand, we all will want to ride a bike/vehicle with less noise if we have to ride/drive for long hours.

Secondly, i have seen many videos on you tube of many bullet gurus denouncing use of after market exhausts which do more harm than good. It is a matter of great deliberation that OEM's spend huge amount of money on R&D before launching any new product and we focus more on style quotient rather than substance. It may be style quotient to some and irritant for some. For me it is just nuisance mongering.