Hi, if i put an fmf Q4 muffler on my honda 230 would i have to rejet the carb?
Thanks

.
Yes, you will
And
Yes, you should.
Expect a lot of noise and not a lot of performance change.

 William1, on 14 June 2012 - 12:54 PM, said:

I disagree. I have the same exhaust and it is about the same loudness as a stock exhaust (with the baffle removed of course.) Also, you will gain some top end power. Remember, the "Q4" is FMF's quiet version.

 macgi77, on 20 June 2012 - 02:53 AM, said:

I'd like to see the before and after dynos sheets. Seat o the pants is notoriously inaccurate and very suspect. Failing possesion of dyno sheets, do you have multiple runs made over a set course with lap times?

 William1, on 20 June 2012 - 03:04 AM, said:

How about beating my buddy with a bbr big bore kit on the top end(he owns a 2008 230f)?  The only thing that changed on my bike was the pipe.

Prior to that he walked away from me easily every time.

Oh and btw, I weigh 40 lbs more than him.

Edited by macgi77, 20 June 2012 - 05:25 AM.

Mike Coe found the stock exhaust system nets the most overall torque under the curve during all his dyno testing.  Have a look at his website and you will see his 27 RWHP monster 230 has a stock system.  He told me he found the small 1/2 HP gains on some systems on top were not worth the losses everywhere else.  Don't forget you also have to repack these systems every 12 hours or so.  I was well on my way to buying a new system until I spoke with Mike.

My buddy had an FMF system on his late-model XR250 and it rusted, cracked, leaked, stripped, and blew packing.  It was just terrible.  He promptly replaced it with a stock system and never looked back.  Power difference?  None.

Being fast in the woods is all about net usable low-end and midrange torque.  It is NOT about peak HP on a dyno.  Just like that XR250 carb I tried.  Did it make more top-end power?  Yes.  Was the bike as fast in the woods?  Not even close.

The stock exhaust system is not that heavy and it requires zero maintenance.  It is also very easy to insert and remove the baffle as necessary.

These systems may look pretty and save a pound but that's about it.

How about it Mike - Any full dyno curves to share with us?

Edited by VortecCPI, 21 June 2012 - 04:38 AM.

Just my opinion but I have to respectfully disagree. I put a Q4 on my wifes crf230 and very happy with it. Does it boost performance? Maybe a little but mainly it has a much more pleasant sound than the stock exhaust without the peashooter. Last tested it was 93db so it's well below legal limit and again actually much easier on the ears than the stocker without the peashooter. Also it's more than a few pounds lighter. I've had several FMF exhausts on my bikes as well as friends with them  and never had any qualityreliability issues so not sure what went on with your buddy's exhaust but not my experience. Overall FMF's quality is pretty good.

Not trying to go against the thoughts around here, I was just sharing my experience with an FMF exhaust. It was the only thing replaced on my bike and gave me enough grunt to outrun a bike I could never outrun before.

I put a FMF Q on a bike to replace a Supertrap system, it was much quieter but not as quiet as stock.  Not a 230 but an XR200 and I did some tests between two XR200Rs with total bike/rider  weights within 5lbs, same gearing and same tires.  A stock XR200 exhaust had more top end than the FMF Q muffler on a Powroll header with a big bore kit.  Bottom end is another story and low back pressure rules on the XR200s, supported by dyno tests.

A thread on BMW exhaust systems on an English forum found it impossible to achieve better power and quiet  with after market or modded exhaust. The factory system were the best.

All of this just says aftermarket wants to sell product and exhaust systems are complex.

Edited by chuck4788, 21 June 2012 - 08:46 PM.