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

what about repacking the silencer, or get a bigger one!

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

how accurate is the meter?
in either direction! it could be reading high, or it could be reading low.

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

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

quote:

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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

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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

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! )

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