Spitfire Scrambler Mufflers/Silencers

[Superarnie]

I have now completed the restoration of my 1960 Spitfire Scrambler, can I take this opportunity to thank everyone who has provided some advice to me with a few glitches I encounted towards the end, it was very much appreciated.
I have a non urgent question re the exhausts on my bike. As many will know the Spitfire has two straight through, non baffled, exhaust pipes running down the left hand side. They are very loud which isn't ideal if I plan to ride the bike to work at 6.30 in the morning; it won't make me popular with my neighbours. I have found some baffles on eBay that can be inserted up each pipe and they are hidden from view. Can anyone tell me if they are effective but also, will the resultant back pressure (reducing exhaust cylinder scavenging?) require an alteration to the timing or general tune of the engine?
Many thanks
Gary

[muskrat]

G'day Gary.
I have seen (but not used) those inserts. I doubt they will quell the roar that much.
Timing shouldn't be affected but carb tune will be out slightly.
Cheers

[Superarnie]

Thanks Muscrat.
I suspect they will make little difference!

Here is a like to a YouTube video I have posted of my bike ticking over.

https://youtu.be/Tf-16Sv5BAE?feature=shared

[Minto]

I'd move house before I baffled those pipes, just a glorious noise mate. Such a cool bike!

[Superarnie]

Ha! Great reply! Thanks Minto.

[BSA_54A10]

Simple solution is a clamp on muffler or a pair of right angle outlets
This will sound funny but if angled directly up the precieved noise is substantially less because it goes strait up so does not echo off the road or surrounding buildings ( unless you are in a high rise building )BAck in the days when you rode your race bike to the meeting, raced ( making sure you did not crash ) then ride home slip on mufflers were the go.
No baffels just the outlet off set to the inlet just enough to break up the wave formations .

[BagONails]

Hi Arnie,
" I have found some baffles on eBay that can be inserted up each pipe and they are hidden from view. Can anyone tell me if they are effective but also, will the resultant back pressure (reducing exhaust cylinder scavenging?) require an alteration to the timing or general tune of the engine?"

I think they term them dB killers?  They do work. Not silenced but will take the sting out of it as long as you don't wring its neck....

I shoved one up the 'silencer' on my Kwacka W800 which has an aftermarket high level 2 into 1 on it. Much more acceptable sound so worth a try and pretty cheap.

[muskrat]

G'day Gary.
With pipes sounding that good you can move in next door to me 
Cheers

[RichardL]

The pipes sound great and we also need to focus on what a great looking bike that is. Baffles might make enough difference to keep the neighbors at bay. You might want to set off without them for a couple of days, then, be sure you install them in full view of neighbors looking out their windows. They will probably perceive more  attenuation than actually happening, just based on seeing the due diligence. I found this interesting: https://www.youtube.com/watch?list=PLw4M7opUsW-JVkzsQxMmShGtlx8P5VDOH&v=qrnrykGynu8

Richar L.

[Superarnie]

Thank you all for you kind and some hilarious comments!

I have bought a pair of those DB Killers type inserts that fit up the exhaust pipes and are hidden out of view. I have installed a decibel metre 'app' on my phone and view the readings before and after. I'll  let you know the results in due course!
Regards
Gary

[Superarnie]

RichardL, the centre baffle on your linked video is what I have bought. I've also bought some fibreglass wadding, let's see what difference it makes to my bike!!

[muskrat]

G'day Gary.
The one you chose will give the most back pressure and with wrapping be the quietest BUT will need the carb to be jetted leaner.
I personally would have gone for the short one with little restriction to flow.
It will be interesting to hear the difference in sound and your feelings on performance.
Cheers 

[berger]

i bet your neighbours are buying sacks of spuds to ram in your tubes, mind you i've some need to talk my missus hears betsy from half a mile away, then puts the kettle on

[BagONails]

Yes the bike looks great and sounds wonderful of course to the enthusiastic ear, not so much at 5am however...

Another wizard wheeze I tried and it got me through the noise test for the roadworthy was one or two of those stainless steel pan scrubbers in a ball all scrunched up and shoved up the pipe with the short dB killer to finish and of course prevent the scrubbies from being blown out. On my phone app it went from 98dB to 82dB which is massive.

Currently riding with dB killer only...it was too quiet! The "W" is fuel injected however so can't help with carburation effects sorry.

[Triton Thrasher]

Would you slow the bike down with restrictions stuffed into the pipes, just to keep the looks of the unrestricted pipes?

It sounds perverse to me.