Honda CBR 250 Forum banner

1 - 20 of 41 Posts

·
Registered
Joined
·
51 Posts
Discussion Starter #1
Check out this youtube video...


i think its the stock exhaust,but its been altered...to great effect..
this is the kind of sound i wanted....bigger than stock,but not monstrous.
:):):)

how do we get this sound??? any ideas people??
 

·
Registered
Joined
·
51 Posts
Discussion Starter #3
yeah...but how???
 

·
Registered
Joined
·
51 Posts
Discussion Starter #4
Also check this video out...

 

·
Registered
Joined
·
51 Posts
Discussion Starter #5
is it ok to drill holes?
will the ECU be able to adjust to the comparatively freer flowing exhaust?
in any case i wont drill 8 holes...maybe just 4 of that size (as in the size of the holes in the video)
would it be harmful in any way?
 

·
Registered
Joined
·
706 Posts
Wonder how bad the rideability is after they drilled all the holes in the exhaust.
Not much different from a slip on? It wont give any power gains but it shouldn't make it drive poorly at all. Just gets louder.
 

·
Registered
Joined
·
152 Posts
"Drill baby Drill!" :D

A few extra holes in the exhaust aren't going to hurt anything.

Personally, I like how amazingly quiet/stealth this bike is.:cool:
 

·
Registered
Joined
·
999 Posts
In that first video I can't see any holes drilled in it.
I wonder if he mashed up the cat & yanked it out. (if that's even possible without tearing the pipe open)

I for one have no idea what he did but it is a nice volume. A little meatier sounding and not ridiculously & offensively loud. It should have come that way stock. :)
 

·
Registered
Joined
·
51 Posts
Discussion Starter #12
hey doc,
aapne kemone achoo...

bhaloo na kee...

aapnee aakhomiyaa manus??

Yup...I'm Axomiya...where are you from? Bengal?
 

·
Registered
Joined
·
51 Posts
Discussion Starter #13
That's the old 4 cylinder 250. Just so nobody thinks this one will sound like that. It never will.

Ha...right...
i should have noticed that the stock exhaust looks different.
sorry..my bad.
 

·
Registered
Joined
·
3,527 Posts
Smash cat?

how do we get this sound??? any ideas people??
His outlet pipe looks different than mine. It looks like he removed the outlet pipe that extends down halfway into the muffler and through a couple inner baffles and just left the back half of the can to open out the remaining hole?
You can probably get more sound and some of the performance benefits of a slip on by smashing the cat out of the inlet of the stock muffler too. Catalysts are made of a ceramic honeycomb that form a coarse filter which is then coated with a thin layer of platinum and other metals. It would be easy to break if you take the muffler off and start poking at it with a hammer and chisel. Catch what is removed to take to a metal recycler. They might pay a couple bucks for the platinum. The stock muffler will still weigh 14 pounds more than a slip on though. Removing the outlet pipe looks like quite a bit of work (fine cutting with a rotary tool?) to go through in order to keep 14 extra pounds but save $400. Maybe you can write them a message and ask what they did.
 

·
Registered
Joined
·
706 Posts
Back pressure won't be changed then?
Why would you be worried about that? If it was it would only benefit the bike. But anyways the catalytic converter inside of the muffler is going to provide most of the back pressure on our 250's.
 

·
Registered
Joined
·
3,527 Posts
Gains

Back pressure won't be changed then?
I think there will be performance gains from removing the cat material. Maybe not the full 1.5 horsepower that comes with a loud slip on because the stock baffling will still be much quieter/ restrictive, but it should improve due to less back pressure from the restriction of the cat.
 

·
Registered
Joined
·
3,527 Posts
cut away view

Here's a cut away view of the stock exhaust. It looks like drilling the back would tend to bypass all of the internal baffles and the outlet tip. This and knocking out the cat material should give most of the horsepower gains of a slip on for free while keeping the noise to something a little more reasonable. A hole in line with the end of the inlet pipe where the cat is would allow sticking a long screw driver in to start smashing the cat from that end if the bend in the inlet pipe is too sharp to get at it from the inlet. Try not to let any chuncks fall into the muffler where they would be stuck to rattle forever.
 
1 - 20 of 41 Posts
Top