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Bulldog2

XVS1300A with Cobra 4" slip-on exhaust

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For anyone with a Cobra 4" slip-on exhaust fitted to their XVS1300A I have measured the sound level as it comes out of the box and also with a Smartpartz Hard Kore quiet baffle fitted. Apologies to Clarkegray for reminding him of the joys of this bike and for not purchasing his pipe when I had the chance but I didn't know about this quiet baffle.

I based my measurements on the American spec J2825 (you can find a Youtube clip on a guy doing the measurement - How to Perform a SAE J2825 Motorcycle Sound Test ). Whether this has any weight in the UK I doubt but it at least gave me a basis for measuring. I used an iPhone 4S with the app SPL Meter which is probably not accurate but again it provides relative readings.
I measured 3 bikes; BMW 1200RT, Yamaha FJR1300A and the Yamaha XVS1300A. Readings were taken at idle for all and at 2krpm for the beemer and XVS, and at 5krpm for the FJR as specified in the J spec. This spec says max 92dBA at idle and 96dBA for twins (100dBA for more cylinders). The results were (readings in dBA with slow response setting):
BMW idle 66 @2k 75
FJR idle 70 @5k 82
XVS with Cobra idle 85 @2k 95
I then fitted the Smartpartz Hard Kore quiet baffle into the Cobra and the result was idle 79 @2k 91
So, a 6dB reduction at idle and 4dB at what I estimate to be around 2krpm (as we don't have a tacho on this bike). A 3dB reduction is half the power and 6dB is a quarter of the power so yes, the baffle does reduce the sound level reasonably at idle and over half at 2krpm. Still much louder than standard exhausts but not so much that the exhaust is neutered. And, subject to the accuracy of my measurements, it would appear that the Cobra is legal - which I somehow doubt. It certainly doesn't have any markings such as E or BS so it would probably fail the UK MOT but not annoy anyone as much.
I posted a youtube video XVS with cobra by Bulldog 5714 https://www.youtube.com/watch?v=uf5E8CPwE40 which has the above XVS sounds. Again it was done on an iPhone so don't expect a professional movie!
As the baffles come as a pair I do have one to sell - let me know if you are interested. They cost me around £100 for the pair including import VAT and handling - not cheap I know but worth it.
Bob

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:'(

You know I ALMOST bought my old XVS1300 back but the missus wouldn't let me... (Though she did let me buy the 950...I'll talk about this in a separate post)

Am glad you're enjoying the Cobra exhaust. I had a chat with my dealer mechanic who seemed to say so long as it isn't stamped "not for road use" it should be ok at MOT. As for noise level, at the moment it's down to the tester so he said it would be fine - most Harleys with aftermarket exhausts are much louder. Maybe Phil will see this and say if his passed MOT with Cobra straight thru pipes on, that was a LOUD (like Brian Blessed) bike!

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Just happens I was behind a XVS 950 in traffic on the way home from work last night, and it had the Cobra muffler fitted. Fairly decidedly loud, but not excessively so; and the guy was keeping the revs low. I loved the way it sounded! And nice to see the fairly bulky 950 filtering with the best of them in New Cross Gate!

When I fitted vance&hines cruzers to my 650 I thought they were way too loud, so I went for the smartpartz quiet baffles too (cost me about the same to import as you). I think they cut between 8-10dB from idle (which is now perhaps a bit too quiet!), and about 8dB from higher revs, making it more comfortable with cruising.

But apart from everything else I think that beyond a certain displacement, say 800-900cc, the exhaust note becomes deep enough to get away with it being quite loud. My 650, bless it, sounds lovely the way it's set up now, but doesn't have quite a deep enough rumble to justify too much loudness!

Oh and you will have probably noticed the quiet baffle killed some of the raspiness to that exhaust note, did it not?

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Finally got to give the bike a run out yesterday and I couldn't have wished for a better result. Yes the rasping top end has gone as has the loudness that makes you grit your teeth in town. However the most pleasing change is that the sound is so mellow - it's a real pleasure to hear and really makes you want to gun it.

I did reconnect the O2 sensor eliminator before I took it out and to be honest I think it's just fine as there is no back-firing on the run down although I will try it again without at some point.

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Well I'm still on good ol' fashioned carbs, but don't you need to have the O2 sensor connected for the injector to work properly?

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Re-reading what I wrote I see that it is confusing. I actually removed the O2 sensor eliminator and remade the original connection. I don't fully understand how fitting an eliminator affects the mixture but I think cutting out the sensor just richens the mixture at low revs. Maybe someone else can expand on this?

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Are you talking about the O2 sensor mod? If so this will explain it better than me...

http://vstar1300.pbworks.com/w/page/5760698/Jack's%20O2%20Mod

The exhaust sounds much better than stock. I just need to convince the other half my 950 needs one (might be a while for that!)

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I've just taken my 1300 for it's 1st test (can't believe i've had it 3 years already!) it has a cobra power pro 2-1 fitted with spartpartz baffle, it passed but they put an advisory on for loud exhaust!!! must take the baffle out to see what it really sounds like

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im running cobra speedster shorts, no baffles, this bike is loud, graham (clarkegray) would testify to this, the exhaust doesnt say 'not for road use', and it is down to the testers discretion, 3 of them crowded round the bike looking at it as lets face it , this isnt a common bike and all commented how nice it sounded ... lol, and yes, it passed, i have my second MOT coming up in june ...four years old, 16,000 miles, how time flies

20130227_102604.jpg

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Great looking bike, this is the first time I've seen a photo of it although I have read lots about it. I struggle to understand the logic of the exhausts passing the MOT! Pleased I am for sure despite having spent good money on quiet baffles however, I do get a little self-conscious rocking up in town making too much noise.

Shame Clarkegray has had to sell his 950.

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It was more of a shame I had to sell my 1300! One day I'll be back on an XVS (again) even if it's an XVS125... :)

[i've still not advertised the 950 keep putting it off and this snow doesn't help. Maybe one more run out first]

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many thanks bulldog, where have you read lots about my bike ?, lol, my latest additions this year are those highway pegs you can see, national cycle clear handguards that are more difficult to see in the photo, a full length black mesh radiator guard that you cannot see, that actually looks pretty nice, and those avon cobra whitewalls, the front is a factory whitewall, the rear is a 180/65/16 that doesnt come whitewall, i had to paint it with the proper paint that was £14 for quarter of a litre. the only thing missing in this photo is my touring screen that i only put on for long journeys, the next one being to the Netherlands in 3 weeks time.

theres quite a few other bits and bobs ive added and changed , CWI (custom world international) luggage rack, front fender tip, throttle lock, pro pad mini beast 5, a rear light conversion that gives me additional sidelights and brake lights in my rear indicators.....and other stuff i cant remember that has been added over the last 4 years. She is starting to look a little cluttered now for my taste.

Good luck with whatever you decide to do graham

im running cobra speedster shorts, no baffles, this bike is loud, graham (clarkegray) would testify to this, the exhaust doesnt say 'not for road use', and it is down to the testers discretion, 3 of them crowded round the bike looking at it as lets face it , this isnt a common bike and all commented how nice it sounded ... lol, and yes, it passed, i have my second MOT coming up in june ...four years old, 16,000 miles, how time flies

20130227_102604.jpg

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It's a matter of personal taste isn't it. I probably wouldn't go with the white sidewalls but then my bike is black. Actually I do now recall seeing a photo of the bike on an earlier post with Clarkegray where you mentioned the new hooter. I presume that you have had to install a relay for it, and do you just remove the plastic cover at that location and bolt on the horn?

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The horn had to be through a relay or it a would have toasted the switch, it comes in its own casing and I've made a hefty bracket and bolted it to the side of the engine in place of the dummy chrome cover on the left side of the engine I'm sure there is a photo of it on here somewhere in one of my other posts

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The horn had to be through a relay or it a would have toasted the switch, it comes in its own casing and I've made a hefty bracket and bolted it to the side of the engine in place of the dummy chrome cover on the left side of the engine...here it is

DSCF0829.jpg

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That still looks good Phil. I'm glad the dealership sold on my 1300 as I'd probably have ended up in BIG trouble from the other half when I turned up on it next week...

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I drilled the stock pipe which improved the sound but I am wondering if the cobra slip on will be louder?

I am tempted to go for something like the Hard Krome 3" drag pipes but if the cobra slip on is much louder than the drilled stock then I would settle for this. 

I am also worried that a slip on or complete exhaust might be too harsh and metallic sounding? I want a low deep rumble sound

Any advice?

 

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I would suggest a first post asking for advice on a 5 year old thread won't get much action.

If you had a look round the site first you would see that the general etiquette is you post in the new members section before launching in asking a question.  And take the time to fill in some details about yourself in your profile.  Lazy.

Edited by cotterpot
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