KDXRIDER.NET

So I'm badly needing to go quieter on my exhaust system after 27+ out of my 40 years being abusive to my eardrums. I'm now permanently suffering from pretty bad tinnitus (constant loud ringing in my ears).

I absolutely do not want to swap out my 99 KDX220's FMF Turbine Core 2 back to the stock spark arrestor silencer, as it feels like it is lined with fire bricks!!!
I was wondering perhaps if my FMF TC2 just needed re-packed. It has maybe 2.5 seasons on it, riding maybe 14 times a year, 5-6 hours a ride.

It seems pretty loud to me, even earlier last year (2017 season) when it had half the hours on it, I recall firing it up at home in the city and thinking "WOW...You don't realize how LOUD it is when you're out in the middle of a national forest riding area away from any residences or anyone who would care!"



My main question is this - is the Pro Circuit 296 going to be noticeably quieter than an FMF Turbine Core 2?




If so, I've GOT to order one. And go see an audiologist about my hearing...
And yes, I do wear ear plugs every time I ride nowadays.

Thanks,

Chuck in Ohio
99 KDX220

I read from searching on here of people saying they were running the FMF Q version spark arrestor (lots of posts from 2007-2011), the real long one that is just a little louder than stock.
Apparently FMF do not offer that anymore for any KDX models. I emailed them about it just now, but it is not on their website and I cannot find any for sale on the internet. If it really was THAT long as to extend way past the taillight, I'd probably trash it on failed hill climb attempts anyway. They advertise a perhaps newer Q Stealth model for the KX 250 etc, but no KDX.



I looked up the Pro Circuit Nature Friendly spark arrestor, as I'd love to have one of those, BUT...only available for KX's & the 89-94 KDX200!!!!!! Really?!? The woods friendly S/A silencer, only available for the motocross bikes and the less common of the kdx200 models, but not the most common 200-220 woods bikes!?! What gives?!? I feel an email to pro circuit is necessary based on that argument.

And I love the tinny, metallic sounds from the single walled expansion chamber, and my stock chamber had lots of dents already when i acquired the bike 3.5 years ago, so i won't be swapping back to stock on those.
I actually will probably be cutting open a 77-78 RM250 or 77-79 PE250 Suzuki chamber to do surgery on it to make it a single walled chamber to lighten up the old 240lb goliath AND obtain that tinny metallic exhaust tone that I love. I have an old extended length Answer S/A for an 80's CR250 application that I'll be using on that bike.

WOW. Yes, it is WAY past needing to be repacked. You can get the FMF offical brand packing for about $10. Your ears may thank you.

https://www.procircuit.com/type-296-kdx200-95-06.html

Pro Circuit has the "Type 296" for some newer models. The 1995+ KDX's have a Type 296. The KDX250 and 1989 - 1994 KDX200 has the "Nature Friendly".

Is the Pro Circuit type 296 going to be quieter than a freshly packed or brand new FMF Turbine Core 2?

I'm really trying to dial back the volume to preserve my ears, not piss off my buddy's neighbors when we ride on his 80-acre farm, and not get a ticket if I ever run across any Rangers in Wayne National Forest, which we have yet to ever.


Is repacking of the muffler something that is typically done annually? Does this differ on a 2-stroke vs. a 4-stroke? I never bother with my street bikes because I always am forced to wear earplugs due to the wind noise alone, even with a quieter helmet. I started out riding dirt bikes a few years ago not wearing earplugs at all because I figured we don't go much more than 40 mph through the woods, so I didn't need to worry about it.

I'll see if I can pick up some packing tomorrow if we get to ride this weekend. Huge rain front coming up from Louisiana towards Ohio though, last day of National Forest Trail season here on Saturday :-(
After that, a few sporadic private property trail rides only, until April 15th...

I would go more by hours ridden than years.

https://www.fmfracing.com/?Content=http ... -repacking

http://www.fmfracing.com/instructionfiles/000672.pdf

There was a product on the market a few years ago called the DB snorkel , it was made of rubber & would slip over the rear silencer & was attached by a couple of cable ties ... It kinda looked like the letter S ....when the bike ran the noise was noticeably quieter ....there was a video on YouTube ....not sure if the product is still in production but might be worth a look .

They have not been made in over 5 years.

I have both...the FMF Q on my KDX and the 296 (actually it’s a nature friendly for a KX 250, but I don’t think there is much difference) on the hybrid. Really can’t tell much difference between the two. Just re-pack the one you have and save a few bucks.

B737driver wrote: ↑12:19 am Dec 15 2018 I have both...the FMF Q on my KDX and the 296 (actually it’s a nature friendly for a KX 250, but I don’t think there is much difference) on the hybrid. Really can’t tell much difference between the two. Just re-pack the one you have and save a few bucks.

But I have the FMF Turbine Core 2, not the FMF Q...
I'm guessing that there is a good bit of difference between a fresh/re-packed Turbine Core 2, vs the two you have, as far as volume...

So the Q & the PC Type 296 are very similar in volume level, sound, and length?

Do you run the air box lid and snorkel? They make a BIG difference in quieting the bike down. A repack should definitely help. My Turbine Core gets louder after about 20 hours.

Fast Forward nearly 2 years, my permanent hearing damage has worsened, and I finally was able to track down both an FMF Q and a Pro Circuit Type 296... FMF and Pro Circuit are both out of almost every item they make due to the Covid pandemic and wildfires both affecting production and supply, but I found some used. FMF has not made the Q for several years. I thought I could get a new Type 296 as my wife said their wholesale distributor had 3 estimated to be arriving Nov 13th, but they have not arrived yet and Pro Circuit themselves still say they are totally out of stock...

I have been in awe of the quietness of my wife's 2007 KTM 200 XC-W, as well as it's blistering performance even after trying to tame it wtih a 13oz flywheel weight added... She has an FMF Gnarly 18 guage steel pipe on her KTM, same as my bike, but she has the stock KTM silencer, which is VERY LONG and very nice and quiet. No airbox lid on either bike. Mine is loud as heck even after fully repacking the FMF Turbine Core 2 including drilling the rivets out to clean the last 2 inches of inaccessible perforated baffle, and cleaning the Krizman turbine spark arrestor.

I really was ready to buy a used KTM silencer for $60 and fab up some custom mounts for it and chop the pipe off and weld on the end from my stock KDX spark arrestor...but them I realized that almost NONE of the KTM silencers were legal spark arrestors, and verified by sticking a metal rod down hers all the way into the pipe on the other end!

The only aftermarket add-on spark arrestors for KTM 2-strokes are all 4-stroke screen types that need cleaned after EVERY DARN RIDE!!!! Forget that... I am super envious of the sound of hers though, STEALTH QUIET, you only hear the ring ding ding of the expansion chamber, perfect in my opinion. My bike is obnoxiously loud so much that you really have to raise your voice to talk to someone nearby, even after re-pack...at least as perceived by my damaged eardrums...

I still may go the modded KTM silencer, but will have to get an Enduro Engineering screen style spark arrestor end cap just for the USFS approved stamp for visual inspections, and then retrofit a Krizman bullet type spark arrestor into the end of it for performance and legality reasons...
Too bad FMF won't make a Q Stealth for our bikes...

Thanks for the follow up.

Have you tried wrapping the exhaust pipe with head wrap tape?

I think one has to give up a bit of performance to get a quieter sound. For example, the stock spark arrestor / boat anchor is the quietest way to go.

I do wish they made a Q Stealth for KDX's (and other models). I have one on my 2005 KX250.

No I have not tried the heat insulation tape on the expansion chamber pipes...
I was really looking for a quieter silencer / muffler / spark arrestor, since my wife's is whisper quiet and she has the exact same pipe as mine but different model bike, same construction tho, 18 gauge steel single wall.
But I do realize that the KTM's quietness is due in part to the extra length of her silencer, including the additional length of perforated baffle tube and packing that is occupying space that is not filled by a spark arrestor...

I do have a phone request in with Pro Circuit, nearly everything they make is backordered same as FMF, but Pro Circuit said if they get more than 20 people requesting any certain item over the phone that give their name and contact info, it gets bumped ahead in production priority.

I also am in contact with two guys who have to sell a used FMF Q and Pro Circuit Type 296 spark arrestor silencers, trying to buy one or probably both of those and compare them.

Another thing with the extra long nin-S/A KTM silencer that I noted is the holes in the perforated baffle are much larger and as such, there are less of them, so at least they are less likely to get clogged up with oil immediately, this might have some effect on the sound short-term (more insulation effectively exposed????) or long-term (stays quieter longer?).

If the KTM models are still longer than either of those, I might buy one and retrofit a spark arrester into it.
Or pick up a 2003 KX250 2-stroke FMF Q Stealth and extensively modify it's mounting points or my frame, to fit the inlet piping from expansion chamber to the muffler can off of my existing FMF Turbine Core 2.

Unfortunately it's difficult to do a product search and get an actual picture of the product which fits the item which you are searching for otherwise I would search eBay or Google for Q Stealth photos of a model that looked to have the mid canister frame mount hanger in the same place or similar as the kdx. Most are just generic photos not representative of the actual model you are buying unfortunately, makes it tougher.

I understand the tinnitus problem as I live with it as well. People who don't live with it have no clue how it affects your life and I hope they never do. You'd think in today's age they would have found a fix for it. Ugh.

Anyway, probably the best way to quiet down our KDX's that run aftermarket pipes and silencers is to use exhaust wrap on the expansion chamber (and all the negatives that come with that) and making your own DB Snorkel for the silencer.

A buddy had the DB Snorkel on his KTM and I was actually shocked how well it worked. I wish I had purchased one when they were still available. It would take a little ingenuity but a homemade DB Snorkel could be made. I have considered making one but my bike has always tested no louder than 92dB (normally 88-90dB) so never been pushed to make one. BTW, I run the FMF TC silencer and repack, at a minimum, twice a year using Lexx 2T packing available from RMATV. Much cheaper and easier to work with than the FMF branded stuff.

Speaking of packing, another thing I might suggest is to make sure you're not packing your silencer too tight. The packing material needs to breath a bit to work most effectively. I've seen way too many people that think cramming more packing in will make it quieter and it's normally the exact opposite. I run just enough packing that it fills the silencer but isn't compressed. BTW, running the Lexx packing I can install it without having to run tape around it which normally compresses the packing.

Sadly, lengthening the silencer itself isn't really an option due to it's position on the bike unless you really enjoy fabrication and have the necessary welding skills.

Not compressing the packing makes a lot of sense when you think about it. You need some air space there for the insulation to work properly.

Yep. compressing insulation a in a house wall is a big no no.