dean100yz
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 posted on 11/3/09 at 12:17 AM |
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Silencing
Ah yet another post 
Want to get it within noise limits for most trackdays. Bought a db reader from fleabay. Did the whole check from a angle at 1mtr as shown. its
analogue but reads at between 7000-7500rpm (2/3rd max revs) between 106-107db.
I need to drop this a fair bit. It sounds great on gas especially on over run but is just too loud. Anyone got the 9R and found a simple fix. I ask as
the pipe looks its built for this car and a std CBR900RR silencer may require some work to get to fit.
Also its not riveted so I cant even re-pack to try and drop db down 1 or 2. Id ideally like it under 100
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omega0684
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| posted on 11/3/09 at 12:25 AM |
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what about repacking the silencer, or get a bigger one!
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dean100yz
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| posted on 11/3/09 at 12:30 AM |
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Cant repack to the best of my knowledge as its sealed. Happy to fit bigger but what/where??
The weld on the right is easy enough to do its the curve on the left that makes me think I need something more one off
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blakep82
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| posted on 11/3/09 at 01:11 AM |
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how accurate is the meter? 
in either direction! it could be reading high, or it could be reading low.
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hughpinder
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| posted on 11/3/09 at 08:37 AM |
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Drill 2 big holes in the ends with a 25-30mm hole saw, add packing, weld round patches over holes? Or cut off end, make lap joint inside with a scrap
of mild steel strip and rivet end back on - then you have a repackable silencer by just drilling out the rivets (if you can do a neat enough weld
since they will be very visible)
Regards
Hugh
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thunderace
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| posted on 11/3/09 at 10:14 AM |
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i got a db killer from ebay for my motorbike.
http://cgi.ebay.co.uk/MOTORCYCLE-MOTORBIKE-RACE-CAN-EXHAUST-BAFFLE-DB-KILLER_W0QQitemZ360134353478QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item3601
34353478&_trksid=p3286.c0.m14&_trkparms=66%3A2%7C65%3A1%7C39%3A1%7C240%3A1318
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dean100yz
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| posted on 11/3/09 at 01:06 PM |
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quote:
Originally posted by thunderace
i got a db killer from ebay for my motorbike.
http://cgi.ebay.co.uk/MOTORCYCLE-MOTORBIKE-RACE-CAN-EXHAUST-BAFFLE-DB-KILLER_W0QQitemZ360134353478QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item3601
34353478&_trksid=p3286.c0.m14&_trkparms=66%3A2%7C65%3A1%7C39%3A1%7C240%3A1318
i know of the db killers from moto x and road bikes
myself but Havn't ever tried one. Do they really make much difference and do they last? Its an idea and there quite cheap. As for cuttin into
exhaust. I've done it on Mx bikes in the 90's before they started all becomin repackable but i dont want to go down that route if i can
help it. I may try and flea bay a std can for the bike and make an adapter. That or the db killer.
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INDY BIRD
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| posted on 14/3/09 at 09:49 PM |
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hi also when you are testing the db readings it is normally at 1/2 meter sorry to say so may be louder than when you are at 1 meter away, and correct
at 3/4 rpm,
exhaust looks like a custom chrome silencer some one may correct me though,
options are 1. to change it 2. db killer will also kill power and engine run hotter, 3. put in a 2nd silencer ? 4. get exhaust repacked if
possible,
my advice would be change the can it will be best for the long run,
good luck though also remember are you getting a lot of induction noise from engine and any pannel vibration this can help reduce db figures before
can needs changing
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David Jenkins
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| posted on 14/3/09 at 10:21 PM |
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I have one of those silencers - originally made by Custom Chrome
(LINKY). You can repack them, by undoing the
end - this allows you to pull the centre tube out so that you can tuck more packing round the outside. This technique is a total PITA!
After getting very annoyed with it, I cut around the tube at the point where the tube goes parallel. A ring was made from a strip of 1.6mm steel
about 30 - 40mm wide, spot welded into the end cap (last 2 tasks done with 907's help). After repacking (now a very easy process) the end cap
with inner tube was pushed back into the casing, a number of holes drilled through the casing into the steel strip, and the whole thing pop-riveted
together.
It the future, if it requires re-packing, all I have to do is drill the rivets out and pull it apart again.
David
(BTW: it's easier to do than to explain!  )
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dean100yz
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| posted on 16/3/09 at 08:03 PM |
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Yeah Indy Bird Im gonna keep it for road and have just bought a original CBR900 silencer from ebay for a tenner!
Ill get it polished and know someone on here who works wonders with the welder. I'll fabricate a new bracket and use it for track
The db killers dont drop it much and yeah run the engine hotter. Dont fancy that so after some thought decided against
David I checked the link - yep thats the one! Its sealed though so I assume you mean cut into the welding on the end? Id like to repack it as its nice
looking/build and sounds great. If i could just quieten it a smidge for road that'd be cool. It does sound a PITA though.
Still food for thought
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