New here, take it easy on me.

I have a 2011 RK with about 500 miles on it. I have carriage work slip ons, everything else is stock. If i remove the cat, do i need to retune?

Tommorrow is suppose to 80, today im thinking about removing the cat but I want to make sure I dont hurt it. Then in a couple weeks I will stage 1 it with PC5 and then DYNO.

thanks

 

Welcome to the forum! I believe the short answer is no you don't need to tune it.

 

Welcome & Congrats on your new ride. I'm sure someone will chime in OR use the "SEARCH" in header bar.

 

Most every motor will run considerably better (more efficiently, cooler, last longer) if it's tuned properly.

Does this NEED to be done? Probably not...

 

If you just change the slipons, no.....but once you let the Cat out, yes. You need to get a tune or a tuner. The Cat controlls alot of the backpressure, without the tune you will loose a considerable amount of your low to mid-range torque.

 

Can you support this claim or is this just your assumption that something in the head pipe must be a restriction. I can only speak on the 2010 OEM 2:1 headpipe, but the catalyst is not a restriction it's just a heat trap. The cross section of the catalyst portion of the pipe is way bigger than the two primary tubes combined, the open space area of the catalyst mesh is greater than the headpipe outlet area behind the catalyst, so the outlet is the restriction, at least in the 2010 2:1.

You only need to tune your bike if you want it to run at optimum performance.

 

Personally, I tune a stock bike. Too lean, too hot.

 

You loose the venturi effect of the exhaust pulse. The exhaust flow is interupted and has to spread the pressure out evenly against the cat wall. You get your area of flow after the cat absorbs the heat but in turn loose back pressure. It also restricks your sound in a similar matter.

 

Sounds reasonable enough, that the non-open area of the catlyst disturbs the previously free flowing gasses, even if the open area is equal or greater than the feeder primarys. The heat sink effect alone, drawing heat energy out of the exhaust gasses, would produce a pressure differntial on either side of the catalyst. The sound wave would be reflected off the face of the catalyst and back up the primary, further retarding exhaust gas flow. The venturi effect is typically associated with a merge collector but that design really isn't incorporated in the stock 2:1:2, I'm not really tracking that component of your explanation.

 

y'all may be rocket scientists, and all that may be the 'correct' answer, but in my case, after i removed the cat, i did not notice any of what you say. time didn't start running backwards and the world did not end. in other words, the ecm did not throw any codes. what did happen, however, was a very dramatic decrease in the amount of heat by my right leg. my performance did not decrease, my mpg did not suffer, the exhaust did sound a whole lot better though, both the stock muffler and the se nightstick.

i ran my bike with the stock ac, cat removed headpipe, and se nightstick, and no additional fuel management for almost a year (13,000 miles) with no problems. i've only just recently added the se ac and powervision tuner, and still loving it!