How to install FMF Q4 Quiet Core Exhaust Muffler on Honda CRF250L (Yoshimura, Delkavic) + SPL Test

Step-by-step video tutorial demonstrating how to install FMF Q4 Quiet Core Exhaust Muffler on Honda CRF250L. The procedure is likely to be very similar for the Honda CRF250 Rally.
I decided to install a slip-on muffler onto my Honda CRF250L because of its weight. I was pretty happy with the sound of the stock exhaust and with how quiet it was. However, I’m trying to reduce the weight of my CRF250L, and one of the most cost-effective weigh savings one can make is a slip-on muffler. I purchased the FMF Q4 Hex S/A Silencer because it can be used with a factory fairing (heat shield). There a number of other, equally good options on the market, such us Yoshimura RS-4 Race Series exhaust system with stainless steel muffler or range of Delkavic mufflers for Honda CRF250L. Every one of these options will provide a significant weight saving versus the stock exhaust.
The video also includes a loudness test (SPL test) of both the Honda CRF250L stock exhaust versus FMF Q4 HEX S/A exhaust silencer.
Necessary Parts:
FMF Q4 HEX S/A - Part Number: 041568 (06-1697.FMF.Q4H)
High Temp Silicone: RTV Visbella Silicone Gasket Maker
Torque Values:
Muffler Mounting Point: 32Nm = 23.6lbf-ft
Muffler Header Mounting Point: 32Nm = 23.6lbf-ft
Fairing Bracket Mounting Point: 5Nm = 4.4lbf-ft
Weight Difference:
Stock Silencer: 4,980g
Stock Heatshield without Fearing: 305g
Stock Total: 5,285g
FMF Q4 Silencer: 2,471g
FMF Q4 Fairing Bracket: 141g
FMF Q4 Total: 2,612g
Total Weight Saving: 2,673g
SPL Difference:
Stock Exhaust Muffler at 2,000rpm: 76.8dBA
Stock Exhaust Muffler at 6,000rpm: 87.4dBA
FMF Q4 Exhaust Muffler at 2,000rpm: 84.5dBA
FMF Q4 Exhaust Muffler at 6,000rpm: 92.7dBA
Video Shortcuts:
Intro & Measuring SPL Framework: 00:00
My Reason for Slip-On Muffler: 01:12
Why FMF and Not the Other Brands: 02:51
Stock Exhaust Removal: 05:11
Stock Heatshield Disassembly: 06:44
Weight Difference - Stock vs FMF Q4 Muffler: 07:17
Attaching Fairing to FMF Q4 Muffler Bracket: 08:35
FMF Q4 Exhaust Silencer Installation: 09:07
Side Fairing Gap Size Issue: 15:03
SPL Test - Stock vs FMF Q4 Muffler: 17:12
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Tags:
#CRF250L #FMFQ4 #Muffler

[@Shem]

Intro & Measuring SPL Framework: 00:00​
My Reason for Slip-On Muffler: 01:12​
Why FMF and Not the Other Brands: 02:51​
Stock Exhaust Removal: 05:11​
Stock Heatshield Disassembly: 06:44​
Weight Difference - Stock vs FMF Q4 Muffler: 07:17​
Attaching Fairing to FMF Q4 Muffler Bracket: 08:35​
FMF Q4 Exhaust Silencer Installation: 09:07​
Side Fairing Gap Size Issue: 15:03​
SPL Test - Stock vs FMF Q4 Muffler: 17:12

[@xcaceuk]

Thanks for a very informative and useful video. Would be great to have a dedicated video about all of the weight saving options for the CRF250L and the total possible reduction that can be achieved. Thanks 🙏

[@Shem]

Thanks! The weight reduction video may be a while as it gets quite expensive once you've changed the 'biggest offenders'. It would be a good material for a video but you could easily spend £2 to £3k on it, and by that time, you may as well get a better and lighter bike. I will definitely make a video about it, even if I don't get to change all the parts myself.

[@heynow3788]

Another great, in-depth video! I have a 250L and since I'm doing all the mods, your videos are a great source of info.

[@Shem]

Thank you. Let me know if you do any modes that are not in these videos that may be worth considering.

[@djhowse]

It’s only a matter of time before... EJK and the K&N demons get you..🤣🤣😉

[@Shem]

Haha, I hope not, but you never know! ;)

[@bradlorenzen5578]

Great video, very precise measuring of sound and weight.

[@Shem]

Thank you.

[@TheJimmyThreeSticks]

great video

[@Shem]

Thanks!

[@xcaceuk]

Hi Shem, I’ve just changed to the FMF Q4 too.
Love the weight reduction, quality and look, but I’m finding it very noisy. Have you any thoughts on the most effective way of reducing the noise level ? Thanks 🙏

[@Shem]

Hey xcace! Due to lock down, I have only managed to take the bike out for 10 min. Yes, I completely agree with you, it sounds much louder than the stock. I'll be looking into noise reduction in the future but don't have anything conclusive yet. I think the first thing that I will give a go is an FMF Quiet Core insert front their PowerCore mufflers, but you don't seem to be able to get them anywhere. Let me know if you find a good solution in the meantime.

[@leonwaldman3081]

Thanks Shem for a great video! I have a question: shouldn't you install also jet kit with fuel controller together with muffler changing?

[@Shem]

Hi Leon. Good question, I wondered that myself as the FMF muffler is definitely more open.
With a carburetted bike, after a muffler change, I’d definitely be looking at adjusting the jets. With fuel injected bike, probably a fuel controller change would be sufficient.
Saying that, from what I found, both FMF and Yoshimura sell these as slip-on mufflers and claim that these can be used instead of stock silencer without a need for any modifications.

[@leonwaldman3081]

@@Shem Thank you, then it makes sense 😃

[@JanPestaVonArx]

nice ! what company "del coverage" are ou taliking about do you have a link ?

[@Shem]

Thanks! I was referring to this: delkevic.co.uk/

[@superscalesy8240]

How did you mod your FMF to sound like stock mate?

[@Shem]

Not sure what you mean - they sound quite different.

[@Johnnysixpac]

I aint using no damn silicone. I'm going in raw

[@JanPestaVonArx]

the entire muffer is to low.. in my opignon..