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Author: Subject: repacking r1 silencer, 99.8db
andy188

posted on 15/6/18 at 06:08 AM Reply With Quote
repacking r1 silencer, 99.8db

Hi All,

After some advise etc,

following our first track day at Abingdon, I only just got through noise test with standard blue sleeved silencer, my sons got through easily 95db, and 94.8db they have grey sleeved silencer, so im looking at locost ways off improving mine, im going to repack it, has any one done this, have any advise,

Thanks

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ttalps2000

posted on 15/6/18 at 12:35 PM Reply With Quote
always been recommended acoustafil

can get it from Demon Tweeks

Fuoura products do a copy of it and is a bit cheaper.

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mark chandler

posted on 15/6/18 at 08:24 PM Reply With Quote
If it's a standard blue sleeve then you have no packing as such, the gases go into a big chamber, this has a couple of little pipes into the next, I think the gases come back upon themselves then go into a chamber at the rear and out the back.

If it's been hacked then I expect it will have a straight through bit of perforated tube with wadding.

Later ones are pretty much the same, they really kill power.

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number-1

posted on 15/6/18 at 11:25 PM Reply With Quote
I used Acusta-fil on an old race car and it did the job, just dont over pack it! If you decide to buy a spare set instead, ive got 2 R1 5VY grey ones in the garage that need a home.
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andy188

posted on 16/6/18 at 06:26 PM Reply With Quote
Hi guys,

Thanks for the advise, had the silencer off today, to sort parts for a rebuild ?.

yes your right, big hollow chamber, then into some small tubes, ive ordered new perforated tube (same size as i/d of inlet) and acoustic wadding, looking at rebuilding it next weekend, ill try to take some photos for future reference.

might need to take up the offer off spare silencer,


soo it might gain some more power, could be a win win.

Cheers guys.

Andy

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SPYDER

posted on 16/6/18 at 07:14 PM Reply With Quote
quote:
Originally posted by mark chandler

Later ones are pretty much the same, they really kill power.


I'd be really interested to know if anyone has done any back to back testing to see how restrictive the standard R1 can is. I've chopped one to bits and they do look pretty piss-poor to the layman's eye but surely Yamaha know what they are doing.
How much extra power did they get on the bike by fitting a noisy can? 5hp?
I have a standard blue case can on my 3SGE engined car. It was dyno tested prior to fitting 42mm ITBs and was virtually bang on the money for the spec. It was tested again after fitting ITBs and picked up 16-18 ftlbs right across the range.
I am presently building a new engine with higher comp and better cams together with a little head work and 46mm ITBs. If the can really is that bad then I would expect the top end to be stunted. We'll see. I might have to try a "gutted" R1 can whilst on the rollers.

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mark chandler

posted on 16/6/18 at 07:25 PM Reply With Quote
It will be very noisy with a perforated tube, you will struggle to get under 105db, they are just not long enough.

I ran it standard on a 893 blade engine, gutted and 2" perforated tube, had to replace the jets, much stronger in the higher revs, I have no data for this.

Factory is always compromised to meet standards, that's why there is such a big market for alternative cans on motorbikes or cars come to that.

Have a look for exhaust calculators, these figures are for a 3.2 litre v6

4000rpm
Your Primary Tube Length is 46.19
Your Primary Tube Diameter is 1.37 inches
Your Collector Diameter is 2.70 inches Two Collectors

5000rpm
Your Primary Tube Length is 34.79
Your Primary Tube Diameter is 1.54 inches
Your Collector Diameter is 3.04 Two Collectors

6000rpm
Your Primary Tube Length is 27.19
Your Primary Tube Diameter is 1.70 inches
Your Collector Diameter is 3.37 inches Two Collectors

So two times 1.6 litre 4 valve engines as this is for 2 x 3:1

Your standard r1 can is poking gases into 2 x 1" tubes where you should be looking at 3"

Surface area is then only 2/3rds of what you need with the gases bashing around in the big chamber as they try and find the exit when the collector flows the gases into the 3" pipe.

[Edited on 16/6/18 by mark chandler]

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andy188

posted on 17/6/18 at 03:00 PM Reply With Quote
Hi, Thanks for the info, ill try to make it longer, looks like im in for a struggle to get the noise level down,

Andy

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