One of our passionate readers started circulating a petition to the AMA to allow two-stroke race machines into the Pro ranks. His suggestion was to allow a 144cc two-stroke to compete in the 250F class and a 300cc two-stroke to compete in the 450F class.

While it’s not the ideal many two-stroke fans would choose, it is a step in the right direction.

It’s important to keep one thought in mind, this is a step for the Pro Racing ranks. Many journeyman Pros have to pay for their own race efforts and spend quite a bit of cash in order to make their machines competive with the best in the world.

Of course when 144 and 300cc two-strokes are brought up the first question to come up is who makes machines in those sizes. This is a guide to point you in the right direction. It’s not as difficult as you would imagine.

Let’s start with the simplest, easiest path and move to the more labor and cash intensive.

Which manufacturers provide machines in these sizes?

TM Racing a small manufacturer in Italy builds purpose built machines in both a 144 and 300 size for motocross racing. These machines have been talked about for years, but have had spotty distribution in the USA for many years.

That has now changed since Barker Bros Cycles has taken over distribution rights for the US. In the first year of being US distributor, Dan Barker has placed machines in different parts of the country to allow potential customers to see and test the machines for themselves. In addition he provided Dirt Rider and Dirt Bike with a TM 144 MX for testing. Check out the current issue (August) of Dirt Bike magazine.

For 2011 look for TM Racing and Barker Bros Cycles to make bigger waves in the US market.

For those that don’t know much about these machines, they are hand built, works style machines. The best way to describe them is to say TM Racing is the Ferrari of dirt bikes. Don’t take anyone’s word for it, try one and decide yourself.

Purpose built 144 engine from TM Racing. These machines are super fast!

What other manufacturer build a 300cc two stroke motocross machine? The TM Racing 300 MX

Of course we can not leave the bright Orange machines of KTM out of a discussion of machines with different displacements. KTM builds bikes in many different sizes.

Over the past few years KTM has begun to make inroads into the sales strangle hold that the Japanese had enjoyed for many years. More folks are buying them, liking them and recommending them to others.

The 2011 KTM 150 (actually a 144) has taken accolades from every quarter with this machine.

While KTM does not build a Motocross specific 300cc motocross machine, they offer a 300cc kit for their 250SX. While it is an option it’s more expensive than buying on direct from the manufacturer.

Take the 250 SX and add the $800.00 300cc kit and you have a 300cc MXer.

These are all the parts included with the KTM 300cc kit.

MXA did a test using this kit on a 250SX. MXA KTM 300SX Big Bore

The lone Japanese manufacturer to still build and import two-strokes into the USA is Yamaha, with the YZ125 and YZ250. Unfortunately these machines have seen few updates since 2005.

While they are great machines, they are dated looking and have not had updates applied to them like the four-stroke line-up has.

Still they are good handling machines that can still be bought new from a dealer. That is if you can find a dealer that has any in stock! There seems to be very few of these machines built and made available to the buying public.

Even with these short comings, the Yamaha is a great platform to race in the Pro ranks.

To bring the little YZ125 up to the proposed 144 size there is a few options available. Probably the easiest is the GYTR 144 kit available directly from Yamaha.

The video below is of Pro Racer Max Anstie testing the GYTR kit…

While it’s not an inexpensive option, it certainly is one way of owning a YZ144.

MXA did a test on the GYTR 144 kit. MXA YZ144

With the YZ250 you could also build a 300cc racer using the L.A. Sleeve 270 kit. While this kit is built by using a steel sleeve, it seems to work quite well as the MXA test below shows.
MXA YZ 270 Build

In addition to the solutions listed above there are many companies that perform Big Bore surgery to your 125 and 250 two-stroke machines. Any one of these companies will take your bike and turn it into a 144 or 300.

My suggestion before trying any of these builders, is to ask others that have had work done by them and see what their experience was like. Then if you can talk them into it, try to take a test ride to see what you think.

Athena – Builds big bore cylinders for two-strokes. Available through larger distributors and your local dealer.

Eric Gorr / Forward Motion – Eric has been building 144 kits since 1976! He has tons of experience with big bore two-strokes. There is also some great advice to be found on his site.
http://www.eric-gorr.com/international144kits.html

Eric Gorr big bore kit.

Millennium Technologies – Well-known for there plating services, they also offer big bore services as well.
http://www.mt-llc.com/bigBoreKit.html

Kustom Kraft Performance – Another shop that has been in business for many years.
http://kustom-kraft.com/big-bore-kits.html

MAX Power – Builds big bore kits for all Japanese two-strokes
http://www.maxrpms.net/shop/index.php/motorcycle-kits/mk-yamaha/yz250.html?SID=078130f90c171feaf15eaa36f74c0d72

If you are determined enough to get something done, it can be done. There are machines available or that can be built that will fit into this proposed rule. Next up is to work to get this new rule passed!

If you have not done it, please sign this petition. http://www.gopetition.com/petition/38076.html