KTM 250SXF 94db Exhaust?

[moosey]

Racing this machine in the North American World Enduro Championship (WEC) rounds and New Zealand 6 days. Need to meet 94db sound requirement. Not sure if an FMF 'Q' is quiet enough. Leo Vince claims they have a 94db insert, but system is hard to obtain. Heard that stock EXC exhaust will fit and is below 94db. Apparently a lot of the Euro's are running this set up?

Any feedback would be appreciated.

[Crash217]

the Q is supposed to be 93db... I'll let you know for sure sunday night when i get back from the leadbelt national enduro, as that will be the first time I'll have it sound tested.

[renthal1]

I live in NZ!!! were are you riding? I live in Auckland. You shipping your bike(s) over?

[moosey]

Right on - let me know how the sound test goes. How do you like the 'Q'? Better / Worse than stock - Any power loss?

[Crash217]

welp, didn't get to race the bike this weekend as I came down with the flu the night before the event... But I did get to poke around the pits a little bit and go through sound test with the Q installed.

At idle, the bike will barely pass the 98db limit our series has, But it quiets down a bit as you reach the 3500rpm test and it went through at a smidgen under 94db. I could probably get a it a little more quiet if I played with stuffing the air box, and put some foam between the skid plate and engine.

As for how it runs, I can't give much info as I didn't get to ride it far, but it seemed to make it more punchy right off idle and the bike seemed to be smoothed out a tad.

Called FMF late last week, and they don't have any jetting specs on the pipe, just stock jetting. So if you had one of the bikes that was jetted way lean like most of them were from the factory your probably good to go with the stock jetting. Mine was jetted way rich from the factory and I had to lean it out before getting the muffler and it seems to run fine now too. I also put in a Honda leak jet, played with the accelerator pump, and put in a PowerNow adapter before putting on the muffler.

[mechdh125]

Stuffing your airbox won't help passing a FIM sound test as it is done at about one meter at 45 degree angle behind the exhaust.

At the moment I know of 3 systems that will work

1 stock header with EXC silencer

2 Acrapovic Enduro system ( as the factory bikes run)

3 HGS Enduro (dutch made exhaust system)

I am running the last one currently and it tested at 92 db with a 1hp increase over a stock sxf pipe. I did change jetting to a 175 main and 45 pilot with fuel screw at 1.25 to 1.5

I know for a fact they will test each bike and not meeting any of the requirements in technical rule book will exclude you from the race.

[grunkthump]

Crash the test in Missouri was at only 3500rpm?? That's not correct I coulda sworn the book says to test it at over 5000 rpm (5250??)...something like that. Makes a HUGE difference!!

[dmcca]

Interested in hearing more on the quiet exhaust for the 250sxf... anyone had any luck getting/using one yet? If so, whats the performance/noise like?

[trailsweep]

ok Ive got the stock 450 exc muffler on my 250sxf and it blew 95 on our enduro sound check..one bad thing is that it took some of the punch from the mid range away but o-well nice to be quiet...using the stock 250sxf header and yes the muffler is a bolt on....later

[moosey]

Interesting! I put a brand new 450 EXC can on my 'F' and it blew over 96db on FIM sound test. More like 97-98db measured 20" at 45 degress angle at around 5500-6000RPM. I think that the european EXC cans are different than what we get in North America - especially if they are passing 94db.

Anyways, I am going with a Leo Vince system with 94db insert. I will us at AMA ISDE qualifier in Idaho City next weekend. Will post sound / performance results when I return.

Would appreciate any suggestions on jetting with this system. Currently using JD jetting - red needle -5th position-175main-40pj-2.5as, plus 60 leak jet mode in float bowl. Elevation at 4500' and temps. around 65-75 F.

[thumpinsx]

From what I've read you can't cure the noise problem from a differnet silencer, the problem is the stock ignition doesn't recognize the high RPM with no load sound test situation and doesn't advance the timing to quite the bike down. You may need to switch to a different ignition system. check out www.mtracing.com

[grunkthump]

The Q2 is the ticket for noise on this bike.

[rmx250rider]

ok what if your runnin with the stock right outta the factory? and there is no way u can get a quiter pipe?