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Offline ronjr009

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Killing the Cat
« on: July 12, 2017, 07:45:43 PM »
Decided to make a little modification today.  That modification is to "kill the cat".  Already removed it and took it down to the welder this afternoon.  Should have back by tomorrow for reinstall.  There are several benefits to removing the Cataylist.  A little more oomph,  cooler engine temps, and increased fuel efficiency.  A few things to know before you run to the garage and start hacking at your cat....

1.  For race or off road purposes only  :038:

2.  You will need to have some type of fuel management system.  In my case, I have the Dobeck AFR 4+ Autotune System which self adjusts to the Air fuel ratio values that I've programmed in to the bike.  What's great about this is no matter how many changes or what changes I make, the system will automatically compensate and make sure that the bike runs at the desired A/F ratio.  This is achieved by using a wideband O2 sensor paired with the Dobeck system instead of a narrowband sensor which is what comes on the bike.  Other fuel management systems are fine as well as long as you have a map that is designed for the mod which may mean extra time and $$$ with the dyno dude or getting a map known to work for a full pipe from a nice person who is willing to share.

3.  You will need some type of decent metal cutter or plasma cutter to get the cat out.  In my case, I used a 3 inch metal wheel cutter from harbor freight.  It wasn't pretty, but it got the job done.  An air powered cutter or plasma cutter is best.  The cat is attached to a metal backing plate which is then tack welded in 4 places (2 on top and 2 on bottom) to the Catalyst Exhaust housing.  I could not get the plate off without damaging the housing so my welder is going to take it off for me and will then weld the cover back on to seal up the housing.

My current setup includes A Delkevic Slip-On Exhaust, Dobeck AFR+ Tuner, K&N Air filter, and now de-catting.  I saw a dyno test with a guy on his CBR 500R who had a full exhaust system (no cat) with tune and filter who achieved 50.2 HP at the wheel which is pretty darn good for this engine.  I don't believe I will get that since I am still using the stock header pipe but with the slip on exhaust and no cat, I should get a good bit more maybe 46-48 HP at the rear wheel.  I suspect I will be able to tell from the "seat of my pants".  Another thing I noticed was a few small metal beads and rough edges in the pipes near the exhaust manifold.  I am going to break out the die grinder and due a little deburring and polishing to make these imperfections nice and smooth.  Will finish up by polishing the outer pipes and reinstall.

Will report back once I have it all back together and go for an "offroad" test


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Offline ronjr009

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Re: Killing the Cat
« Reply #1 on: July 13, 2017, 05:31:13 PM »
Got the exhaust back from the welder, cleaned up the rough spots on the headers and reinstalled.  Took a short 3 mile ride.  She is definitely punching harder than before.  Going to go hit the mountains for the afternoon to get a more proper and thorough eval.... 
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Offline CB-500-X

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Re: Killing the Cat
« Reply #2 on: July 13, 2017, 09:17:19 PM »
does it sound better ?
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Offline ronjr009

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Re: Killing the Cat
« Reply #3 on: July 14, 2017, 04:38:23 PM »
Hi CB.  Surprisingly no.  I thought it would be louder because the catalyst is part of the noise suppression in the exhaust system.  I honestly couldn't tell any difference from before.  I expected to have to put the decibel killer back in but I am going to leave it off.  She is definitely quicker.  I think power is better all the way through the RPM range but you really begin to feel the extra grunt most when the rpm's begin to pick up.  The one thing I really noticed the most is when you go to pass, that is where you seem to be able to definitely tell that the power output is better.  I found the bike able to make passes easier.  Those passes where I had to wind it up and ease on by can now be made with a little bit of authority.  Anytime the RPM's are up over 4500, you can definitely feel the extra grunt.  Coming out of corners is also very noticeable as long as you are over 4500 RPM's as well. Without a doubt, the biggest bang for the buck provided you have a fuel tuner (auto tune is best).  The welder charged me $20.00 for the labor so I can't complain about this mod at all.  Also.  I'll need to run a few more tanks of fuel to get an accurate picture but the MPG's were just as good as before and maybe just a little better.  Overall, I'm more than pleased as this has made more of a difference than anything else I have done.  Every time I've made a change to the bike, I've went down to the local 1/8 mile dragstrip to test/tune and get some times.  I plan on heading down tonight so I can compare tonight's times to those that I ran last summer (See Below).  I will preface this by saying that I have changed my gearing though since my last test and added a slip-on exhaust.  My last test I ran a 16 tooth front and a 39 tooth rear sprocket and stock exhaust.  Since then I have went back to the 41 tooth rear so that is going to help the time be quicker for sure.  With the extra ponies I am expecting a much quicker time this evening at the track.  I would expect to run at least a 10.2 but I think/hope quicker.    We will see!

(Summer of 2016)
Stock Honda fuel map stock exhaust
3 runs/passes down the strip
Average time was 10.746 at an average speed of 64.080 MPH

(Summer of 2016)
Dobeck AFR+4 fuel map stock Exhaust
3 runs/passes down the strip
Average time was 10.461 with an average speed of 66.306 MPH

(Tonight July, 14th)
Dobeck AFR+4 fuel map W/Delkevic Slip-On Exhaust
??????? I'll find out tonight!!!!
« Last Edit: July 14, 2017, 04:51:54 PM by ronjr009 »
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Offline CB-500-X

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Re: Killing the Cat
« Reply #4 on: July 14, 2017, 05:21:36 PM »
Let's see what it does. I'm sure you will have to make a few passes and change the tune a bit. Good luck. :306:
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Offline ronjr009

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Re: Killing the Cat
« Reply #5 on: July 15, 2017, 02:17:01 AM »
Alright... Just got back from the drag strip.  My personal expectations were greatly exceeded but everyone can judge for themselves by looking at today's numbers compared  to those from the past as listed in my last post above.   Today's runs were 9.78, 9.98, 9.96, 9.72, and 9.81 for an average of 9.85.  The runs in the 70's and 80's were with good launches and the 90's were a little off due to driver error.  This is over half a second quicker compared to the previous best of 10.44.  Obviously, going back to the 41 tooth gear factored in there as well but a half a second is dramatic improvement  in an eighth of a mile.  Also, speeds were over 70 mph each of these runs with an average speed of 71.605 as compared to the previous best of 66.306 for a 5+ MPH gain from the previous best.  No dyno numbers unfortunately.  But these drag runs are pretty consistent and did confirm in my mind what I was feeling during yesterday's rides.  This mod will give the X a fair and perceptible amount of gain which makes me think that a full on exhaust with a tuner may be worth the price for some people. 
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Offline jsonder

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Re: Killing the Cat
« Reply #6 on: July 21, 2017, 12:08:32 AM »
Congratulations on a decent improvement.

As I don't race, I guess that I will have to keep the cat.

John  '14CB500XA (Daily Rider),  '09CRF230L (L'il Red Piglet), '89NX250 (sold)
Nekkid motorcycles feel faster
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Offline hilldweller

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Re: Killing the Cat
« Reply #7 on: July 21, 2017, 11:53:34 AM »
*Originally Posted by ronjr009 >>>> link hidden <<<<
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but a half a second is dramatic

If you want dramatic, on a similar bike, go try a Tracer 700. It struck me as DRAMATIC compared to the X.

I still have my X and though I lust after the 700 for the thrill my licence tells me NO.
Brian.

Offline billyedtimmy

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Re: Killing the Cat
« Reply #8 on: August 01, 2017, 06:49:29 PM »
I'm curious if you have any thoughts on an easier way to do this than cutting open the side. Like perhaps ream out the interior of the cat by inserting a blunt object with force? I'm not sure I have the tools/skill to cut open the side like that, but I like the sound of the results you've achieved (a little more power on this bike would be nice).

Offline ronjr009

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Re: Killing the Cat
« Reply #9 on: September 26, 2017, 01:29:09 AM »
Billyedtimmy.... I thought about this long and hard before I began the project.  I looked at the exhaust very carefully to see if I thought I could punch it out as some have done this on other bikes.  I am not saying it's impossible, but I think it would be very difficult at best.  It is hard to get a tool into there at multiple angles to punch all of that stuff out of there due to how the exhuast tubing curves.  This is especially true to due to the fact that the catalyst is tack welded in 4 places.  But I'll tell you this... I am so glad I did this mod.  It has really made a difference in how this bike performs.  I can power up mountains and make passes a good bit better then before! It will leave you with a small grin on you face when you feel it for the first time.   My friend just bought a 2016 CB 500X.  I went ahead and put the 16t front sprocket on his bike so we are now set up identically.  I am going to have to see if I can get him to bring his bike to the dragstrip so we can compare numbers.
« Last Edit: September 26, 2017, 01:41:23 AM by ronjr009 »
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