BC Sport Bikes Forum banner

1 - 20 of 43 Posts

·
Registered Abuser
Joined
·
1,017 Posts
Discussion Starter · #1 ·
I love this planet and always wish for world peace, but I really don't think catalytic converters belong on bikes. So I've been examining my set up toying with the idea of removing it. It would drop 10-15 lbs and give me a few extra ponies. I know Honda had to increase the VFR by 32cc to compensate for the effect of adding the cat.

I've got a V4 and the headers go 4 into 2 and into 1 at the cat. A single pipe comes out of the cat and connects to the muffler. I'm wondering how easy it would be to cut the pipes at the front of the cat, cut the single pipe at the rear and get a pipe welded onto the headers and inserted into the muffler. Then I have the sensor to deal with and I'm not sure what to do about it or what the repercussions of messing with the cat are.

I'd be willing to spend a few hundred on this job, but not much more. Anybody have any experience with this?? All comments and advice are appreciated.

Thanks in advance.
 

·
The Wizard
Joined
·
2,743 Posts
would be a lot easier just to buy a pipe.

Alternatively, call Aaron at Modern Suzuki or Mspeed as they had to cut all the cats out of the '06 R6 and Gixxers for racing at Mission.
 

·
Registered Abuser
Joined
·
1,017 Posts
Discussion Starter · #4 ·
would be a lot easier just to buy a pipe.
It might be easier, but they're pretty complicated on a V4 and would probably cost well over $1k. I'm thinking that if I get the cat cut off, all I'll need is 18" of pipe bent and welded. That's what I'm hoping for anyway.
 

·
Registered
Joined
·
1,662 Posts

·
Still defying gravity...
Joined
·
2,853 Posts
rubberhead said:
I love this planet and always wish for world peace, but I really don't think catalytic converters belong on bikes.
That knock on your door is Greenpeace :)

I will let someone w/ more tech expertise answer your questions re: repurcussions (hello, calling Tee Tee) but I would assume there would be a lot less back pressure, less weight (would it be as much as 10 to 15 lbs??) and a couple more ponies, but at what price for overall performance.

I know that cat-less systems/headers are available, but new they will cost a lot more than a couple of hundred - maybe try to pick up a used set on Ebay or ??? - here is a link and picture re: the motad pipes:

http://www.motorcyclenews.com/nav?p...eId=4874301&articleCategory=NEWS_PRODUCT-NEWS
 

·
Ride Solo
Joined
·
4,218 Posts
Your VFR a 2000? IIRC, the earlier FI bikes (98/99) may have had systems without the cat. Might be worth looking into that, and then check at the wreckers.

www.vfrdiscussion.com
 

·
Registered Abuser
Joined
·
1,017 Posts
Discussion Starter · #8 ·
Hmm, the 4th generation 750's don't have a cat and might have the same pipes. But wouldn't it better and cheaper to cut off the cat and weld a pipe between the headers and join it to the muffler? This is what I need to know or else it will go way beyond what I can afford.
 

·
Registered
Joined
·
512 Posts
Why not just leave it on there? Is the VFR that lacking in power? As to the weight, if the cat's under the bike it's so close to the ground you'll only notice it when you have to push the bike (the closer to the ground it is the less effect it has on turning and balance). If you take it out the backpressure is going to change and the fuel requirements of the engine will change. If that's an O2 sensor (I assume it is) then it may compensate automaticaly. I don't know if honda would have tuned anything else in the engine to work with the cat.

All in all I think it falls in the category of "Why bother?".
 

·
Registered Abuser
Joined
·
1,017 Posts
Discussion Starter · #10 ·
The VFR has very "balanced" power. I like it for that, but a bit more never hurt anybody and I consider the cat to be of no value to the bike. I really have no idea how removing it will affect the rest of the bike's performance. I don't want to touch any of it until I know what's going to happen. It wouldn't surprise me too much if Honda did a few other things to the bike's design to work with the cat.

I guess the internet is my friend and I should do some searching...
 

·
Registered
Joined
·
2,590 Posts
No problems rubber!

The boys at vfrdiscussion.com do 'em with some regularity. They call it a "catarectomy" (or some such wording) and you keep all your existing exhaust plumbing; simply unbutton the cat, remove the honeycomb unit, and re-button it back up. I'm not aware of any real world performance gains, or re-tuning requirements, but if there are, a PC will address that issue. In any case the boys at vfrdiscussion.com have been there done that often enough
 

·
Registered
Joined
·
2,590 Posts
Make sure you keep the oxygen sensor in its current location or it won't run properly.
Nope! You should in fact remove the two O2 sensors (and replace them with O2 elims). The O2 sensors do not act like they do in cars, but are only "active" under the very specific and limited conditions related to steady state engine management.
 

·
Registered
Joined
·
241 Posts
if you have custom piping done make 100% sure that it is MANDREL bent.

the other option is to cut the pipe just in front of the cat and then take the cat outside and gut it with a steel rod, make sure you dont inhale anything. this is the cheapest option and one of the best.
 

·
Registered Abuser
Joined
·
1,017 Posts
Discussion Starter · #16 ·
Hmm... options! Gut the cat or remove it completely. As I know it, there are two O2 sensors -- one just in front of the cat and one inside. The one in front won't cause a problem if it's left alone, but if there's one inside then a sensor eliminator should do the trick.

Staintune sells headers that eliminate the cat for $700 FOB Australia. Too rich for me, but they did say that there would be no noticeable difference in performance. I would expect there would be at least an extra horsie or two or else Honda wouldn't have upped the displacement by 32 cc. At the very least, I would expect to get better mileage and maybe a better sound too :) This is going to be an interesting winter project.
 

·
Registered
Joined
·
2,590 Posts
As I know it, there are two O2 sensors -- one just in front of the cat and one inside. The one in front won't cause a problem if it's left alone, but if there's one inside then a sensor eliminator should do the trick.
Nope, both O2 sensors are pre-cat, both are found in the same relative position, one for each cylinder pair, both would require its own O2 elim thus you need 2.

You don't wanna go to vfrdiscussion.com & get yourself straightened out, what more can I say, my job here is complete :tredmill
 

·
Registered Abuser
Joined
·
1,017 Posts
Discussion Starter · #20 ·
I've been to VFRD. Still trying to figure out the best method of doing this. Gutting the cat is seeming like the cheapest and easiest approach.
 
1 - 20 of 43 Posts
Top