Get Immediate Silence From The FMF Turbine Core Spark Arrestor – Review

I love to ride my dirt bikes, and the thing that I would hate the most is to be shut down by some no-fun, party poopin’, selfish brat because they think my bike is too loud. It’s pretty sad considering how quiet most dirt bikes are compared to trains, jets, and, of course, harley’s. This is what has come down to in the sport of motocross though, so if you want to continue riding then you better do something about it! A simple and inexpensive way to do this is by slapping a spark arrestor silencer on your dirt bike. In fact, you need a spark arrestor to ride at most state trails, as well as enduro and harescramble racing.

Turbine Core 2 Silencer Off Road Series
FMF Turbine Core Spark Arrestor

Even worse…. public tracks, riding parks, and popular trails are being shut down because of noise issues. I’m not a big fan of putting a spark arrestor on my bike just because I don’t think dirt bikes can start fires very easily. That is, unless you literally pour gasoline on a tree and stick the exhaust right up to it. I DO feel more comfortable using one at certain riding places though, because I don’t want to get in trouble because some grouchy neighbor tattled on me. So, I got me an FMF Turbinecore Spark Arrestor to quiet my lovely 2-strokes down.

I used this spark arrestor on my KTM 144SX and, YZ125, and CR125, and the results were all very similar. One of the first things that comes to mind when thinking of a spark arrestor might be that it would take away power from your bike. I thought it would, but I had to use it if I wanted to ride in certain areas.

How Loud?

The first thing I noticed when I put the FMF Turbinecore on was that the bikes idled a lot quieter. I could actually talk to someone next to me with it on instead of having to shut my bike off. I used it for trail riding (a great combination with Bark Buster Handguards), motocross racing, and just for playing around. When I raced with it on my KTM I asked my dad, who was watching the race, how loud my bike was, and he said it was probably the quietest bike on the track. This was surprising to me because KTM’s are usually loud, especially when they have aftermarket exhausts on. FMF states that this silencer lowers the sound output to about 92 decibels. I didn’t have a sound meter, but can definitely say it was close to 90 db.

My YZ125 on the other hand, was a little bit different. It idled quieter, but it still had a little bit of that 125 snarl once it got on the pipe. When I was riding in the woods you would barely be able to hear it. The exhaust had to be directly pointed at you for it to be loud. The result was the same for my Honda 125.

What About Power Loss?

This is the biggest question when deciding whether to buy an aftermarket spark arrestor or not. I was scared that it would take away some needed power from my bikes, especially with what little power these 125’s had. From all the riding I did, I didn’t notice any power loss on the bottom-end. The mid-range still felt the same as before on all of the dirt bikes I tried. For the top-end power, I will say that it felt like I lost a little bit of power up top. It really didn’t feel like much though, and it might just be in my head because the bike was quieter. So all in all the power surprisingly did not really change. You would have to use a dyno to see the actual difference in numbers.

Is It Really Worth The Money?

Well lets look at what you will be able to do with this silencer on your bike… You will be able to ride on state trails because it has a spark arrestor and is USFS Approved, you can race enduro’s and harescrambles, it will make your neighbors happy, and most importantly it will help keep more riding areas open. Plus, the FMF Spark Arrestor is a whole lot cheaper than any four-stroke exhaust. If you are riding in noise-conscience riding areas then this is the part to get if you want to continue riding your dirt bike. Good luck!

Buy My Dirt Bike An FMF Spark Arrestor Here

-Tom Stark

1996 KX250 Rebuild A Junkyard Wildabeast


In this rebuild project a 1996 KX250 was bought for $200, the only parts that appeared to be missing were the silencer, some plastic body components, and  the front brake reservoir. 1996 KX250


As I began the tear-down i began realizing just like Tom in many of his rebuilds, that many of the parts were discreetly missing. I first noticed that the Carburetor slide was missing after I took off the sub frame, air box, and carburetor. I had already known that the bike needed a new crank, crank bearings, and a top-end; and there was no telling about how bad the motor damage would truly be knowing that the bike sat outside in the rain, sleet, and hail throughout winter. 1996 KX250Of course I knew I was going to have to strip all of the bike down to the frame and replace and grease every bearing and moving part, especially the swing-arm and shock bearings.

Unexpected Problems

After I began the dis-assembly and long restoration process for the bike I en-countered a major problem, the swing-arm was severely busted up and every bolt you could think on the entire rear end of the bike was stripped, rounded, or cross-threaded. So I then began the process of looking on eBay for a swing-arm in decent shape.

I observed the characteristics of the 1996 swing-arm and discovered that the 1994-1998 model KX125s and KX250s were very similar,  so I ordered a very nice or at least decent shape 1998 KX125 swing-arm. Along with just being in better shape, the 1998 swing-arm offers better handling than the 1996 swing-arm. The 1996 swing-arm is about is about one inch shorter and about one inch less in width. Another advantage of using the 1998 swing-arm is that it is made out of aluminum so it is lighter, and the longer length provides better cornering and less front wheel pop in the straights.

Frame Repair

The frame was badly rusted and the sub-frame needed a new mount re-welded. First, for the main frame assembly I treated the rust and primed the frame. The main frame was then painted “alloy silver”.

Motor Tear down

The top end only took about 5-minutes to tear down, I could tell I was definitely going to need a cylinder sleeve and piston. Once the top end was disassembled I removed the clutch cover and removed the clutch plates, clutch springs, clutch inner and outer basket, and clutch actuator rod. Next, the kick starter assembly was removed and the water pump was removed, good thing the water pump was removed because the impeller was  froze. For the final dis-assembly part, which was splitting the cases, I used a Tusk Crank Case Splitter from This made taking out the crank and transmission easy. Here are some pictures of the dis-assembly…

Motor Assembly

The cylinder needed a new sleeve or to be chromed by a shop such as U.S. Chrome. I realized that for slightly $30 more I could buy a very nice cylinder off of eBay with a new cylinder sleeve, a slightly used piston, a KIPS cover, and carbon fiber reeds; All of which I was going to buy anyways. With all the new tools I bought I was slightly out of my budget, which was why the project got put on hold for several weeks, thanks to finding great buys on eBay I was able to jump right back on track with this project!

First off, since the motor was already disassembled there was no delay to install parts. I installed some new All Balls Racing crank bearings, although All Balls Racing products are cheaper they are not cheaply made, and they have been proven in amateur racing. Next, the crank was installed using a Tusk Crank Case Installer tool, due to the way the threads are on the crank of older KX250’s I had to buy a dye to use the tool. You may think why doesn’t he just use a mallet? But the answer is simple enough, if I was to use a mallet the Crank would no longer be balanced due to beating on the crank with the mallet. After the crank bearings and Crank were installed the transmission was installed. The bottom end of the motor also received some new shifter forks due to the severe beating it took from the last owner. Next, the crank cases were put together using the Tusk Racing Crank Installer again. Finally, the top-end was installed along with a new Athena gasket kit.

More Unexpected Problems

As I began to disassemble the rear wheel I realized that the rear hub was cracked, It’s hard to believe how mistreated a bike can be, especially when you take into consideration that it was once a brand new bike of a proud owner.Due to the hub being cracked I decided to go ahead and buy some nice aftermarket wheels. I decided to go with RAD MFG. Econo Wheels because they offer a great price for the package and the only issues i’ve heard of them have been about the wheel spacers. Not to mention the offer a trick look, thanks to RAD MFG.’s in-house anodizing, so i went with a Lime colored hub and a Black rim with Silver spokes and nipples.

Trying to Finish the Project

I had a very nice 2004 KX125 loaded with ProCircuit goodies, but unfortunately I had to be willing to sacrifice one my bikes to finish the rebuild. So after about a one month break from the project, and  after selling my 04′ I decided I mind as well dump some more money into this bike and just keep it. Since I now had $2100 in my pocket I decided to get the rear shock spring, frame, and swingarm powdercoated matte black. I also had to buy some forks along the way since mine were corroded. I bought 3 sets of forks of ebay, all of which were damaged just as bad as mine. So I finally decided to start browsing on Craigslist, and I finally found a set of 96′ kx250 forks two days later. Come to find out I also had to spend $35 on some tripple clamps because I later figured out I had a 96′ frame and motor with 95′ forks, which are 2mm.s smaller in fork tube diameter. So after  I figured all of that out I began assembling the frame, I’ve also been waiting for some parts so I decided to make some brackets and trim so older plastics so I could use the newer style (03-05) style plastics. Here are some pictures…

Rad Mfg. Wheel

Powdercoated Parts

Assembly and Plastic Conversion

Just When I Thought I Was Almost Done Buying Parts!!!

My new plastics finally arrived, so I began making the adjustments to make them fit. I also ordered OEM levers, swingarm hardware for the chain slider, and new pistons for the front brake caliper. All of which was around $140. Later on I ordered some black side panels, which I found out are very hard to find for this year and model, and some wave disc rotors for front and rear. I also bought a new rear Dunlop tire from  a local dirtbike shop. I was about to install the motor but I found a very small crack on the connecting rod, so now I must also buy a connecting rod or complete crank. It’s kinda bad, yet good at the same time that I found the crack because it probably would have messed up my cylinder wall plating and new piston. Although it seems i’m back to square one I’m really not. Now that I have to save up some more money, since my parents put  $1900 of my money savings Arrrgggghhhh!!! I mind as well spend about $35 at local shop to get the cylinder (The plating was beginning to wear away.) bored out 1 mm. so I will know that the bike will be race ready and run good for years to come, along with buying a new crank assembly so the crank doesn’t need to be balanced after the new connecting rod is installed. Here’s some more pics…

The Final Assembly… (yep, the third complete assembly of the bike!)

After I recieved the parts I began re-assembling the motor. I installed a new crank-shaft assembly and Wiseco piston I also replaced the water pump impeller. After I assembled the motor I installed the rest of the electrical system and put the motor in the bike. Everything on the new subframe lined up perfectly, although at first I didn’t think it did because the UFO side panels didn’t fit. The rest of the bike went together fairly smooth except I spent several months ordering the rest of the ‘odds-and-ends’ when ever I had the money…  Below are the final pictures of the bike and further down on the page is a complete parts list with the total cost. The only thing the bike is still lacking are some nice graphics…

I made the pictures big so all the details are easier to see…

All Done!!!!

Parts List

Used Parts

  • New airbox
  • Cylinder (replated)
  • Swingarm
  • Carburetor
  • Forks (newer and larger diameter)
  • Radiators (sprayed with paint remover to remove stock black paint)
  • 98′ electrical system with TPS sensor for carburetor

New Parts

  • 94′-98′ style rear fender, side number plates, and radiator shrouds made by UFO plastics
  • 03′-07′ style front fender and front number plate
  • Renthal handlebars
  • ProTaper pillow top grips
  • Anodized works connection brake covers and assorted hardware
  • Factory Effex seat cover
  • FMF Gnarly
  • FMF Powercore II
  • ProCircuit Linkage
  • UFO gas cap
  • Motohose colored hose kit
  • Tusk racing Chain
  • JT rear steel sprocket
  • JT front steel sprocket
  • Renthal Brake pads front and rear
  • Galfer brake lines
  • Cyrca Handguards
  • Off brand wide footpegs
  • Turner performance chaing guard and roller wheel (red)
  • Tusk Racing Wave rotors front and Rear
  • Acerbis chain slid plate (rubber)
  • Topar Racing billet clutch cover and case saver
  • MotionPro clutch and throttle cables
  • Wiseco piston and Crankshaft assembly
  • Koyo crank bearing and water pump impeller bearings
  • Rad MFG. Econo series Hubs (green)
  • Rad MFG. Rims (black)
  • Heavy duty spokes
  • Heavy duty tire tubes
  • Aluminum rim locks
  • Dunlop tires front and rear
  • And approximately $450 in specialized OEM hardware (bolts)

And the running total is… $4,327.73

I’m very sorry for the long delay in updates and slow progress, but unfortunately I ran into some family and money problems along the way. I also had to stop spending money on the bike for about 3 months because I had to purchase my own truck when my father bought my step-sister a BRAND new Volkswagen Jetta. Although my problems aren’t your problems I just felt as though I should explain why the build took such a long time ….

As of 11/2/2013 the bike is still running strong and is 100% completed now!





Suspension Tips – Adjusting Your Spring Rate

Suspension depends on spring rate, valve shim stacks, and clicker adjustments. First, If you want to have good suspension you have to install springs that are the correct rate for your size. Depending on your weight and riding style you might need to get some aftermarket springs.

Shock Spring
Shock Spring

After you have purchased your springs you may want to re-valve your front forks for better characteristics for the new spring rates. For older or worn out dirt bikes, Race-Tech Gold Valves work great because they give the feeling of newer and more modern suspension. If you own a newer or mid 90s KX 2-stroke I suggest installing washers below the springs to lower the rear end and offer better cornering on tight tracks. For bikes such as the Yamaha or Honda I would suggest an aftermarket rear linkage to help them in straight-away stability and jumping.

Oil weight can also affect dampening, or the rate at which the suspension bottoms out. A 5-weight oil is usually used on trail riding applications, for MX style jumps a 7.5 weight oil (if available) would be better preferred. for large MX jumps, arenacross tracks, and supercross tracks 10 to 15 weight oil should be used. By using the correct oil weight you can avoid spending $200 on Gold-Valves and Shims although they are highly recommended. Next, set your rear sag on your shock.

Race Tech Gold Valves
Race-Tech Gold Valves

Once you have set your sag you can now play around with your dampening and clicker adjustments to create a soft and plush feeling or a racy type firm feeling that offers more comfort when jumping larger jumps and cornering at higher speeds than what your stock settings are intended for. You can’t forget that stock settings performed by the manufacturer’s are for the average adult rider, not an A-class or B-class racer. If you need any help post a comment regarding your question for suspension.


Free Mods For A WR250F Dirt Bike??

It’s always fun to make your dirt bike more powerful and go faster. But, it’s difficult for many riders to choose what they want to buy for their bike because money is tight. If you own a Yamaha WR250F though, then you’re just in luck, because I would like to share a few mods that you can do to make it faster. Oh, and did I mention, they’re FREE!! So if you want to get that extra kick out of your almost-motocross-bike-but-still-a-trail-bike, then you’re in the right spot. These modifications consist of altering the air-box, exhaust, CDI wires, and the throttle stop.

Air-box Mod

The stock air-box on your WR250F dirt bike has a snorkel/shield that helps protect the air filter from water, sand, and other foreign materials. Although it is safer on your filter, it also robs usable horsepower because it blocks air-flow. To change this you just unscrew it and pull the screen out. This mod will make it more like the YZ250F because it doesn’t have the screen in it. If you go out to the desert or a dusty track and want to protect the air filter, simply screw back in the screen. Doing this will make more of a difference on the 2001 and 2002 models because the newer ones have a battery in the air-box that restrict air-flow.

WR250F Mods


The exhaust baffle on the WR250F is very restrictive because it has to be quieter and have a spark arrestor for trail riding. The exhaust hole is very small, taking away a lot of power from your dirt bike. To remove the baffle you must take off the ten-millimeter bolt on the end of the muffler that keeps it there. Then just slide out the baffle and you will have instant power gains. Although doing this give the bike more power, it will be much louder, so keep that in mind if you ride close to crabby people that don’t want people to have fun these days. If you want to buy a silencer with a spark arrestor that keeps the bike quiet, yet still gains power, an FMF Q4 slip-on exhaust is an excellent choice.

CDI Gray Wire

The gray wire on a WR250F from the CD ignition box connects to the ground. The gray wire is what makes the WR250F’s timing differ from the YZ250F. It retards the timing on the mid-to-top-end of the RPM range, thus making it a slower and more poky ride. To give it more power in the upper RPM range you simply have to get rid of the gray wire. You can either cut it, or take it off and cover it with some tape.

To get the the wire you have to take off  the seat, the tank, and the radiator shrouds. Find the CDI, which is a black box (on the right side of the steering stem for ’01-’02 models).  There should be two different groups of two wires coming out of the CDI. The kill switch has a black wire and a black wire with a gray stripe. You want the other group with a black wire and a gray wire. It should be under the frame where the gas tank is. Then just unplug the connector and pull of the dust ring. Plug the connector back in and tape up the wire you just took off to the connector. Then you just slap the tank, shrouds, and gas tank back on and you’re good to go!

Throttle Stop

Throttle Stop

Who wants to be restricted, especially on a dirt bike?? I know I don’t, and that’s why one of the first things I’d do on a WR250F is get rid of the ridiculous throttle stop that limits it to 3/4 throttle. To get rid of this you must go to the right side of the carburetor and take off the throttle cover that has a couple of allen bolts. The throttle is a screw on the bottom of the throttle disk, as shown in the picture. To modify it to the length of the YZF throttle stop, take it out and cut it with a saw. The original size is in between 30 and 35mm, so cut it to about 25mm. Put the throttle stop back in and that’s it.

After you do these mods your bike will be about as close to a YZF motocross bike as you can get. There are a couple more modifications you can do to your WR250F, but they require some special tools and a little extra cash. If you take out the exhaust baffle and decide that it’s too loud where you ride, you can just get a Silencer Insert for it to lower the decibels while still keeping almost all of the power. Good luck, and ride safe!

Carry your WR250F with a Motorcycle Hitch Mount.

-Tom Stark

Is The KTM 350 SXF For Real??

There have been many rumors going around that the Austrian-based company, KTM, has been testing out a new 350cc motocross weapon. Well for once, the rumors were true, and KTM recently announced it like they weren’t hiding anything. The reason they are building a 350cc production bike is because they wanted a bike that had the power close to a 450cc motocross bike, but the weight and handling to that of a 250F.

KTM 350 SXF Motocross Bike

The 2011 350 SXF is an all new bike from the ground up. It has a new 350cc engine, a new frame, fuel-injection, and new-to-KTM linkage rear-suspension! The bike also has electric start for those lazy and physically challenged riders out there. It also seems to have a spot to put a kick starter, but there isn’t one currently on the bike. It is said to be released to the public this summer (2010). The price may be high, but it will most likely be worth it for the amount of work KTM has put into this bike.

This project-bike-no-more has been in the works since 2007, with KTM doing testing to see what works best on the bike. The 350 SXF was made with the help of World Motocross Champion Stefan Everts. He said the thought of a 350cc was to make up the needed power that a 250F was missing so it would be almost as powerful as a 450. The combination of a bigger and lighter engine than a 250F with the weight still similar will make this the perfect motocross bike….. Or will it? Find out this summer when KTM releases their 350SXF motocross weapon!

MSRP of the 2011 KTM 350SXF is $8500.

Instead of Telling Your Friends Riding Stories, SHOW Them in HD With VHoldR’s ContourHD Helmet Camera

Here are the promoted specs of the 350 SXF motocross bike:

Engine: 349cc, single-cylinder four-stroke; approximately 58 HP

Transmission: 5-speed, 1-down 4-up

Fueling System: Keihin EMS with EFI

Cooling System: Liquid/water-cooled

Ignition: Kokusan

Clutch: Wet multi-disc, hydraulic

Frame: Chromium Molybdenum

Front Suspension: WP USD 52 MA – 11.8 in./300mm of travel

Rear Suspension: WP with all-new linkage – 13.2 in./335mm of travel

Brakes: Front 260mm/Rear 220mm

Seat Height: 36.4 in./925mm

Fuel Capacity: approx. 2 gallons/7.5 liters

Weight: approx. 220 lbs/100 kg

-Tom Stark