FMF Muffler Silencer - The Woodpecker Mod - 20 bucks 4quiet

FMF Muffler Silencer - The Woodpecker Mod - Twenty Dollars for a quiet FMF muffler on a WR250R/X.

This is one way to make a silencer for FMF Mufflers that requires no permanent modification to the muffler.
It can be installed or removed in 60 seconds and costs less than 20 dollars to build.
This mod (known as the Woodpecker Mod) makes your FMF muffler only slightly louder than
the OEM exhast system. It is made from commonly available plumbing parts from Lowes or Home Depot.
It makes the bike quiet so I can listen to my favorite MP3 tunes while riding. It has been tested
for 1500 miles and seems to work just fine for me. Make your own at your own risk. I don't know
anything about muffler design other than what little I could find on the internet. I put a temperature
sticker on the outside of my FMF Muffler and it reads the same with or without this modification.

https://s1360.photobucket.com/user/Harold_Woodpecker/library/Facebook/Untitled%20Album?sort=3&page=2

https://s1360.photobucket.com/user/Harold_Woodpecker/library/Facebook/Untitled%20Album?sort=3&page=1

When designing this mod I assumed a few things. These are listed here.

The output hole should not be smaller than the hole on other existing OEM mufflers on quiet cycles.
Compared to the exhast hole on the Kawasaki KLX 450R this output hole is a larger diameter.
The hole on the PEX plumbing connector worked good enough for me so I stopped playing with hole diameters.
If someone wants to experiment further please let us know what you learn.


There might be some power loss at high rpm.
I do not have any way to measure the power loss (if any) from this mod.
I have been unable to notice any difference other than a lot less noise.
Low end torque actually seemed to increase a very small amount. This might
be because it makes the bike run slightly richer. The internet said that
backpressure makes the engine run richer. This seems to be what happens.
I have not yet gotten around to replacing the spark plug so I can not be sure.
I wanted the bike to run richer and changed the stock setting of the fuel injection
system by jumpering the connector under the seat and reprogramming the injection.

If someone would like to measure the before and after differences, go for it,
and post the results. I will be out riding. You probably will not hear me leaving.

I made this thing out of plumbing parts and some old galvanized fence pipe from a chain
link fence. Welding galvanized pipe produces toxic fumes that can kill you if you breathe
them. Be warned. Proper ventilation and holding my breath outside while welding a little at a time
is how I completed the welding using a wire welder from harbor freight tools.
A fan directed at the weld is a good idea. Do not inhale the fumes of welding galvanized fence pipe
or you may die or suffer severe permanent injury.  You could breathe from a SCUBA tank while welding
or use non galvanized steel pipe or fab the part from alluminum. A fan directed at the welding is a
good idea to keep toxic fumes away.

So here is how it is made. Try to stick the 3/4 inch elbow into the quiet insert of the FMF muffler
and you see it is too large. Grind it down till it fits just right. This was an outside diameter
of 1.4 inches on the elbow.


I figured out which way the elbow will need to face on the motorcycle so exhaust gas is directed
downward to the ground and away from the motorcycle.
Obviously I did not want to melt anything on the motorcycle by directing the hot exhaust gas
near turn signals or rear tires. Understand where the hot exhaust will go. I used
a Dremel tool to smooth the inside of the elbow so gas would flow smoothly with minimal resistance.

Cutting a slot in the elbow the screw head that holds the quiet insert in the FMF muffler will
slide into the slot, rotate and be held in place. I was shocked to find that the elbow would stay
in place while riding without the additional retainer. Some high temp Silicon seal around the elbow
might have been enough to keep it from falling out while riding but I wanted something better.

The retainer system I came up with is a piece of pipe that fits over the elbow and is held by the
PEX connector. When final assembly is performed the PEX connector needs blue thread sealer applied
so it will not vibrate loose. I cut the fence pipe at a 45 degree angle with a hacksaw. The fence
pipe was 1.7 inches outside diameter and 1.5 inch inner diameter. I used a large washer to go over
the threads of the elbow.

The hole on the washer had to be enlarged to fit the elbow threads. This took about an hour and
was not fun because the washer was pretty thick. A thinner washer would be easier to work with.

When welding the washer onto the end of the fence pipe I used great care to avoid the toxic fumes.
As stated earlier, welding galvaized pipe is very dangerous due to deadly fumes.

Then I removed the excess washer and weld material on the outside edge of the retainer with a grinder.

If the size of the fence pipe retainer is just right, the adjustment of the PEX connector on the
threads of the elbow is sufficent to cinch everything up just right.
I misjudged the distance and made a spacer to fill the gap.
The spacer was another piece of fence scrap that I cut off with a pipe cutter.
The spacer has an inside diameter of 1 inch.

I prefer the OEM exhaust over an FMF muffler with this mod but I have a pair of used WR250R
motorcycles that the previous owner changed to an FMF muffler. It is a lighter muffler but any
power improvements seem only to be at high RPM even with a power bomb. I do not like repacking
any muffler and consider it a waste of money. Good for the aftermarket muffler manufacturer but
bad for the consumer. I repacked the muffler before installing this mod 1500 miles ago. When the
weather warms up I will repack it again and inspect the spark plug. I rarely post anything on the
internet so don't be surprised if you never hear from me again.  

I decided to try this before going to the OEM muffler only because Yamaha wanted 1400 dollars
for the muffler and heat shields. The FMF muffler is too loud for me even with the quiet insert.
After trying this mod I was delighted with it and decided to share my discovery with the world
because its cold outside and I have nothing else to do.
I know nothing about muffler design. Try this at your own risk. If you set your turn signals on
fire or have engine failure or run over a moose in the road because it did not hear
you coming then don't blame me.

Parts List

3/4" Galvanized Street Elbow  Lowes #22151  
3/4 x 3/4  Female PEX Adapter
Big Flat washer with large hole about 3/4 inch in center
Chain link Fence post pipe

So generally, you're severely restricting the flow of the exhaust and redirecting the sound down?

You might be much quieter, but I'd bet you're also making quiet a few less ponies too.

Not having acess to dyno I can not tell how many hp are lost, if any.
I expected to be able to see a difference but can not.
This is why I decided to put it out there for the whole world to critique.

I have 3 WR250R bikes. One is basically stock with OEM muffler. All have
13/49  or 13/52 sprockets. I like the OEM muffler bike best of all. The weight
reduction of 10-15 pounds means little or nothing to me because I am an
athelete and use cycle riding to stay in shape. I like to ride parts of T1 and T2
etc. so must have bike so suited to purpose. Otherwise I would just wrestle my
pig of a KLR.

It is my opinion that the cost of an FMF pipe, power bomb, and programmer is
wasted cash when for a new chain and some sprockets off a WR250F you
can get all the power needed for most situations. But what do I know, I have
only logged almost 40,000 miles on 5 different machines across Utah, Idaho, Wyoming,
Montana,Nevada and Oregon in the last 3 years. Top speed is not critical to me
because I avoid the freeway like the plague. I also like to start off in second gear
leaving 1st for grunt work on uphill switchbacks like those found on Ben Lomond peak
that is near my house.

Oh and while I am expressing my opinion, the edge tail light is a piece of junk that
leaks water and dirt and corrodes within months. It does not have any agency
approvals for this reason I am sure. The brackets it came with are some of the
softest steel material I have ever seen, easily bent by hand.

   

Seems like you took a perfectly good aftermarket pipe and modified it to be a nearly as restrictive as the stock pipe.

Interesting mod, and I appreciate a thorough write up.  I understand the conditions that led to this decision, as I too frequently find myself with a particular objective, an overpriced route (if available at all), and a cheap/readily available DIY route.  I sometimes wish my exhaust was quieter but certainly not enough to replace the FMF that the bike came with.  If the silencing results are as drastic as claimed, I would definitely install this before riding where I shouldn't be riding.  

The ability to quickly and easily configure my bike for different roles is important to me.  I have added it to the list of possible future projects.  Thank you for sharing!

How did you happen to come up with the name  'Woodpecker mod'?   Just curious.

I can see where this might be a useful mod for some folks, those who may want to stay on good terms with their neighbors or the local LEOs/Forest Rangers.  Certainly noise fatigue on a long ride can be a real nuisance as well.  Can't beat the price or the convenience either.  Thanks for posting.  

I don't see much use for it personally however, as I find the FMF pipe combo only slightly louder than the stocker, and not obtrusive at all.

Why not just put the stock pipe back on and sell the FMF?

If you don't have the stock I am sure you can find one pretty cheap or be able to swap for one and a few $$.

user888 wrote:

One is basically stock with OEM muffler.

I like the OEM muffler bike best of all.

rsteiger wrote:

Why not just put the stock pipe back on and sell the FMF?

If you don't have the stock I am sure you can find one pretty cheap or be able to swap for one and a few $$.

Yeah...ummm....this     

Here you go:

http://www.ebay.com/itm/Yamaha-WR250R-Silencer-Muffler-WR-250R-250-R-2008-/350753706127?pt=Motorcycles_Parts_Accessories&hash=item51aa8cd08f&vxp=mtr

I would say you could probably get $200 or $250 for your FMF or trade it for a stock one plus $100 in cash.

rsteiger wrote:

Here you go:

http://www.ebay.com/itm/Yamaha-WR250R-Silencer-Muffler-WR-250R-250-R-2008-/350753706127?pt=Motorcycles_Parts_Accessories&hash=item51aa8cd08f&vxp=mtr

I would say you could probably get $200 or $250 for your FMF or trade it for a stock one plus $100 in cash.

If his FMF pipe is in good condition I bet he could find someone who would swap him even...

But like the man said, it was cold outside, and he had nothing else to do.  Some of the best stuff has come from tinkerers with time on their hands.   I know I've spent stupid amounts of time trying to mod something on the cheap, and ended up tossing it in the bin.  I don't find much use for this thing, but -someone- might.

Woodpecker is a nickname I have had since childhood.

The previous owner put on the FMF and did not keep the OEM pipe.

I am in the process of obtaining an original muffler for 1 of the 2 bikes
that has this mod. I can tell the difference between the OEM and this mod
but it is not very much. I am a wildlife photographer and I see more animals
with a quiet exhaust system by a hundred fold. My stock DRZ exhaust was
too loud also and I could find many more animals on the OEM muffled WR250R
than on the DRZ. The OEM muffler on the KLR however seems louder than the
WR250R but does not disturb the wildlife. I came within inches of touching the
testicles of a moose with my front fender once because it didn't hear the KLR
coming around a mountain corner. I was amazed to realize that the moose's
antlers were twice the lenth of my handlebars when viewed from that distance.
Strange but true.

I welded a washer over the end of the stock quiet core in my fmf q4 to make it quieter, it made a big difference, I was able to do this for free.

I can drill the hole in the washer larger to adjust the noise level or grind it off to go back to the way it was but have no plans to mess with it as the way it is now its quieter than a unmodded q4 and just as powerfull.

user888 wrote:

Woodpecker is a nickname I have had since childhood.

The previous owner put on the FMF and did not keep the OEM pipe.

I am in the process of obtaining an original muffler for 1 of the 2 bikes
that has this mod. I can tell the difference between the OEM and this mod
but it is not very much. I am a wildlife photographer and I see more animals
with a quiet exhaust system by a hundred fold. My stock DRZ exhaust was
too loud also and I could find many more animals on the OEM muffled WR250R
than on the DRZ. The OEM muffler on the KLR however seems louder than the
WR250R but does not disturb the wildlife. I came within inches of touching the
testicles of a moose with my front fender once because it didn't hear the KLR
coming around a mountain corner. I was amazed to realize that the moose's
antlers were twice the lenth of my handlebars when viewed from that distance.
Strange but true.

Nothing like a good moose testicle story to keep things interesting, I always say...

Years ago I had a college friend who was from the Middle East, and every joke he ever told was about camel's balls.  Just the culture, I guess.