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CRF450X muffler on an 05 CRF450R

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Fellow TT'ers, I was so impressed by several posts that I finally got an '05 CRF450X muffler to put on my '05 R. I am primarily an MX'er (for marrital reasons; can't be gone all day) but am wanting to get up into the awesome mountains of Idaho as my son gets old enough for trail riding.

Back to the posts I read about the X pipe being way more quiet than the R yet more than adequate power. To my surprise, it bolts on perfectly; no issue there. Well, I took the bike out to the MX track this morning for a workout/practice before work with a little aprehension thinking it would still be fun although it would be down on power. My first lap (I kind of always do a slow 'sighting' lap to make sure of any changes) had me kind of concerned. The bike is sooooooo much quieter. I can only describe it in three things: throttle wrist, noise, and pull. Typically, twist wrist, hear noise, and hold on big time. But with this muffler installed, the noise and perceived snap are gone. I was actually concerned that I wouldn't be able to make some of the jumps!

So I started gassing it up and picked up the speed and a fascinating thing became quite obvious. I really have to refer to a quote from Jimmy Lewis (Dirt Rider Editor/ Guru), that is "if you think you need to go faster (it's so quiet, you don't think you're going that fast), then turn the throttle more!"

I had no problem with any of the obstacles or jumps. The only thing missing was the noise. Sure, it sounded like someone was roosting around the track on an enduro bike but the speed was not limited because of it. In fact, all of the torque till mid-rpm is still there, only the very top is affected and I can really only use that when conditions are perfect (traction is present).

All and all, I agree with a post a month or so ago about any speed loss was well worth the much less sound output. I will probably use this pipe to practice with and break out the Dr. D just for races.

Also, as soon as I get the titanium header pipe fitted with the oxygen sensor, I'll be using the ********* sensor to dial the jetting in for the quiet pipe and will be able to have a better understanding of the change in requirements between the two.

MED

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Did you ever find out the optimum jetting modification? I have and X muffler for my 450R that I have not fitted to my bike yet and wondered about the jetting changes needed.

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Interesting. What sort of wide-band oxygen sensor system will you be using to tune the bike?

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Yes. Dr. D pipe for MX = 42 pilot, 175 Main

CRF450X pipe: 38 pilot, 168 main but I have to say starting isn't nearly as easy so I might go 40 on the pilot next time....

Hope this helps; also, during trail riding, I've just finished a nice ride where 6/8 guys ran out of gas on a 66 mile ride. I had 1.5 qts left in the stock tank!

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