Mod. Stock Exhaust

[Kleinfalls]

i tryed drilling the holes it just didnt work, this is not to bad sounds just right for the bike. i just wnated my wife to be hurd when she is riding in traffic

Did you have to contour the back of your tip as well to match the factory box contour? how did you get around that issue? I was thinking if you made the hole slightly bigger than whatever your tip inlet is - it would slide inside and weld - no need for tons of cutting on the backside of the new tip. What size is that automotive tip?? 3"?

I found some sport bike guys at a muffler shop - they are going to do it for me - I just want to know the easiest and cleanest way to do it.

 

[joloy133]

Did you have to contour the back of your tip as well to match the factory box contour? how did you get around that issue? I was thinking if you made the hole slightly bigger than whatever your tip inlet is - it would slide inside and weld - no need for tons of cutting on the backside of the new tip. What size is that automotive tip?? 3"?

I found some sport bike guys at a muffler shop - they are going to do it for me - I just want to know the easiest and cleanest way to do it.

My muffler guy just took the pipe and we decided on positioning beforehand. I went round at the muffler, 2 1/4 inches, oval shaped at the exit and tapered/slash cut with slight downward angle. He did the rest and as I remember he traced a rough contour to match the end to the weld area, tacked it for final look, then welded it. Your guy will know what to do. (You could go 2 1/2" round to 2 x 1 1/4" dual outlet!)

 

[Kleinfalls]

well i went to muffler shop and the owner got worried about messing with it - luckily the guy that works there has a welder and fabricates bikes - so I am going to try to meet up with him next weekend to get it taken care of - he is about an hour away though lol

 

[joloy133]

well i went to muffler shop and the owner got worried about messing with it - luckily the guy that works there has a welder and fabricates bikes - so I am going to try to meet up with him next weekend to get it taken care of - he is about an hour away though lol

My muffler guy was the owner, he just said he couldn't guarantee the sound and that the muffler would be somewhat damaged if I wanted to replace the original cut out piece. He could have welded it back so you may want to save the tailpiece remnant. This mod has been done numerous times now so whatever risk is minimal.

 

[Kleinfalls]

Well - I used a sawzall to hack off that wimpy factory 1 1/2 pipe coming out of the muffler last night - then I used a drill to drill a series of holes underneath the existing pipe - just adding about 6 drill holes underneath the existing pipe - made a huge difference in how throaty the exhaust sounds - removed the muffler from the bike and took it by a muffler shop this morning - bought a stainless steel tip for $20 - and they only charged me $15 to weld it on - will post pics tonight and hopefully a video after I get everything back together

 

[joloy133]

If I understand you correctly, you have a 1 1/2" hole that used to be the pipe and 6 holes around that, which essentially is a baffle. Your tip will be welded over this onto the muffler body to finish. I thinks thats a good way to go because there is a drone that some may find annoying which is positively affected by a baffle. Good job and even cheaper than $65! The finished sound will be effected by the final tailpipe, if you leave the piece at its longest length you could listen to the tone and shorten for effect. What diameter finished pipe did you choose?

 

[Kleinfalls]

mine sticks out a bit - 2 1/2 at muffler to 3" angled tip 6" length - the drill holes are not really all the way around - more like a crescent moon shape all underneath the original pipe - i ran home at lunch and reassembled everything - take pics when i get home tonight - the guy at the muffler shop told me to tape off the outside of the tip and then spary some black engine enamel inside the tip and on the edge of the round opening of the tip - to prevent any rust - helpful tip - sounds so much better - has that nice low throaty rumble at low RPMs

 

[joloy133]

mine sticks out a bit - 2 1/2 at muffler to 3" angled tip 6" length - the drill holes are not really all the way around - more like a crescent moon shape all underneath the original pipe - i ran home at lunch and reassembled everything - take pics when i get home tonight - the guy at the muffler shop told me to tape off the outside of the tip and then spary some black engine enamel inside the tip and on the edge of the round opening of the tip - to prevent any rust - helpful tip - sounds so much better - has that nice low throaty rumble at low RPMs

Awesome....$ left over for suspension mod? You'll find a definite performance improvement also.

 

[Kleinfalls]

here are the pics....


and the video
http://www.kleinfalls.com/muffler.mpg

The holes I drilled below the original pipe were real clean - but from the heat of the welder - they warped some - haven't used the black engine enamel yet on the inside - should clean it up nicely

 

[joloy133]

My mod actually finished with a 2 1/4 " diameter opening, a larger opening of the exhaust then yours. If you wanted, you could use a long bit to remove even more of the muffler wall in the future. Enjoy that exhaust note!

 

[JSP]

How are you keeping the metal from falling into the muffler when drilling??? Seems it would fall in and rattle like crazy.

 

[Kleinfalls]

well you have to take it off to weld - if anything falls in - you just hold it and shake it - no extra noises - plus with a drill bit - most debris comes is moved away from the hole

 

[ktmshorty]

I was looking at the stock exhaust and had a thought. Let me know your thoughts. I was thinking that it might be possible to cut the stock exhaust system just prior to the cat. but after the headers merge into one pipe. Then use a stainless reducer to reduce the (approximately) 3 " pipe to the normal size of the R-6 pipe that the slip ons fit on. This way the any slip ons for the R-6 can be used on our bikes. My only question to those that have either a TBR or M4 exhaust does it come with a place to install the O2sensor? If so, I guess the appropriate fitting would have to be mounted somewhere along the system. Any thoughts?

 

[joloy133]

I was looking at the stock exhaust and had a thought. Let me know your thoughts. I was thinking that it might be possible to cut the stock exhaust system just prior to the cat. but after the headers merge into one pipe. Then use a stainless reducer to reduce the (approximately) 3 " pipe to the normal size of the R-6 pipe that the slip ons fit on. This way the any slip ons for the R-6 can be used on our bikes. My only question to those that have either a TBR or M4 exhaust does it come with a place to install the O2sensor? If so, I guess the appropriate fitting would have to be mounted somewhere along the system. Any thoughts?

Stock pipes go from 4 to 2, then into the muffler/cat system. I've always believed you could cut the stock pipe to singles and fab however you wanted. Just don't know what you've got till its done, it could be worse or no better! (Remember there is significant R&D $ in the stock system.) What is the goal; sound, performance, looks?

 

[RockZooky]

I was looking at the stock exhaust and had a thought. Let me know your thoughts. I was thinking that it might be possible to cut the stock exhaust system just prior to the cat. but after the headers merge into one pipe. Then use a stainless reducer to reduce the (approximately) 3 " pipe to the normal size of the R-6 pipe that the slip ons fit on. This way the any slip ons for the R-6 can be used on our bikes. My only question to those that have either a TBR or M4 exhaust does it come with a place to install the O2sensor? If so, I guess the appropriate fitting would have to be mounted somewhere along the system. Any thoughts?

I had the same idea but never investigated it. It seems like a custom piece could be made to fit over the end of the header then to a slip on. If I remember correctly the header ends in an oval shape.

 

[Kleinfalls]

I was thinking the same thing - chop it off before the muffler and then install a slip on etc - but you would have to build some kind of a custom hanger to match up to the existing moutning holes - don't think you would want the weight of a slip on etc hanging by the header mounts - plus you have to make sure you get the right type of air flow resistance the engine is expecting - just opening up the hole on mine and welding on the auto tip - until it warms up - it's a little sluggish in the lower RPMs - wasn't like that before - has to build up the back pressure i guess etc

 

[GF_Playa]

So for those of you who have did mod, most have did a 2 1/4 -2 1/2" pipe. obviously the sound change isnt gonna be dramatic but would moving to somethin bigger like a 3-4" help any?

 

[joloy133]

So for those of you who have did mod, most have did a 2 1/4 -2 1/2" pipe. obviously the sound change isnt gonna be dramatic but would moving to somethin bigger like a 3-4" help any?

Moving to the 2 1/4" or 2 1/2" pipe is dramatic compared to stock! It's even better rolling. No need to go bigger than 2 1/2" IMO, plenty loud enough w/o being excessive. To some the TBR is too loud...... which can be addressed easily.

 

[Spunky99]

I listened to the sound bytes and it sounds pretty impressive on all the vids.

One observation tho...I thought I noticed a slight hesitation in RPM build after the mod and that makes me wonder if the required amount of restriction is less than needed for the application.

I ask this because a few years back there were some tunable Thrush mufflers for cars. It seemed the Jeep cherokees with the 6 cylinder motors needed more restriction than some of the other cars that they put them on at a speed shop. I knew the owner and mechanics and they tuned them for each car by moving some adjustable restrictor. The 68 Chevy El Camino with the 350 Cleveland needed almost zero restriction.

Just wondering.....

 

[joloy133]

After the mod the bike ran fine, just too lean. I had 2 episodes of a backfire but nothing major. When I got a free dyno and analysis is when I decided just to do everything else. (Mod bug was raging!) With the cat still in place I suspect there is enough restriction to negate any back pressure issues, especially considering the shape of the can and a side exit vs a perforated straight shot tube. If my main focus was performance, aftermarket or custom is what I'd do.