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[Waltr]

Anybody with the 91087 silencer with or without the 91085 exhaust head pipe have any comment on the sound? I am not out to wake the dead but would like to hear it.

[CGT 535]

Sorry - I have the 91120 system fitted. Initially I ran it with the baffles removed, but then refitted the baffle with the tangs opened up slightly. It's fairly quiete and pleasant sounding.

[Gaz262]

I have the 91080 'silencer' fitted Waltr - it sounds & goes like a big British single should!
I run it with the baffles installed though they are removable if you want it louder.
I've not had to install the PCV, though that will be an option in the near future as there is also a K&N air filter fitted to the EFI unit.

[jefrs]

I can't speak for the stainless 91087 silencer but do have the complete system 91130 which comprises of silencer 91080 and pipe 91085. The retort is fairly loud but by no means excessive, the note is pleasant. Neighbours have said they like it because it sounds proper. When cruising the noise is subdued, it barks when opened up, it sounds like a big single should.



The downpipe needs to be well sealed to the head (gasket 582638) or it can be very noisy. The baffles are (cof) adjustable, I have the points of the baffles about 6-8mm apart, you can push them in with a screwdriver and push them out with a steel bar. We need back pressure to provide mid-range torque, counter-intuitively closing the baffles right up makes more noise, the exhaust note gets compressed and makes loud 'bangs'.

[jefrs]

The PCV, love it or hate it, it is a large expense and won't add a penny to the value of the bike. The exhaust swap alone can add more torque if you get the baffles right. You can most likely do an exhaust chop without adding a PCV but not if you also add a K&N as the air mix gets thrown all over the place and confuses the hell out of the stock ECU. I do have a PCV but also have the AT-200 Autotune (definitely not normal). I can turn the PCV map off and use the ECU mapping on its own, and the Autotune then shows me the air mix going all over the place. The ECU and its narrow-band O2 Lambda sensor is alleged to cope with just an exhaust swap. The AT-200 uses a wide-band Bosch O2 sensor that can regulate (and data-log) the mix in real time.



You don't have to add the PCV if you only do an exhaust swap. The benefit of the PCV is better mapping for smoother running and considerably more torque. And adjust-ability, we cannot adjust the mix and A/R on the ECU. For most folks it is fit and forget but you can tweak the thing like you can a carb, but it is all numerical and many folks just run away from pages of numbers on a computer spread sheet. (there is a carb conversion but you don't get the PCV's control over the A/R).



At the end of the day though, you don't need the PCV for just an exhaust swap. The stock silencer is very heavy as well as pug ugly towing-a-log. Silencer 91080 is very much lighter than the stock silencer and will be lighter than stainless 91085. The exhaust note of system 91130 is a little louder than the stock system but sounds great.

[jefrs]

typo - stainless 91087 (silencer)

[jefrs]

Waltr, I know you are in the USA. Some states have very strict emission laws and do not permit you to swap the exhaust out, certainly not remove the catalytic convertor, which we can do in the UK. Anyone with a Harley might be familiar with the Dynojet Power Commander but in some states these are 'off road use only'. As with any piggyback device, it is no good just fitting them, they have to be dyno-mapped and as far as I'm aware Hitchcocks are the only company that have done dyno development work for Royal Enfield on the Power Commander (and supply the PCV mapped for RE). Doing an silencer swap is usually the first mod because the original looks like a pile of poo but you need to check out what you are allowed to do, especially as you are selling these bikes...

[Waltr]

Some areas with a large population of open pipe Harleys have started to clamp don on noise. Most states have given up on emissions testing for bikes. Of course I have no idea what California is doing. The issue that Harley faces is that the Race Tuner gave the ability to tune up to the tuner with little regard to emissions and more so was being sold by the Factory.
Again the question is about the 91087 Silencer, anybody using it that wishes to give feedback.

[jefrs]

Waltr, stainless 91087 will be heavier than 91080 because it is stainless. That will alter the sound a trifle. As I said before, 91080 on 91087 has a very pleasant sound. Typical traditional british big single, not a racing single going up the mountain though. Fairly loud but acceptable, nothing at all like an open pipe Harley, not even as loud as my neighbour's sensible pipe Harley.

[Waltr]

jefrs,
I watched your video and a few others with the silencer you are using and agree that the sound is glorious. The reason for the questions on the stainless is a recommendation from Hicthcock's as to the stainlees Motad silencer. The problem is there seems no feedback from owners. The Stainless Motad on the outside appears to be similar size to the Punjab long bottle but it is my understanding the sans Punjab pipe has no baffle unlike the Motad. Decisions...decisions.