It’s easy to own a 144cc or 300 cc Two-Stroke!
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
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Comments
By GlennCMcGovern on July 30th, 2010 at 10:03 pm
KTM made a 380 cc and I raced one for years. Always got a holeshot or near without much effort. I cannot come close on a KTM 250SX with works suspension and a Pro-Circuit pipe and the red powervalve spring. 300 cc is great but I think 320-380 cc is what you need to compete with the 450 cc. The 380SX was so powerful I would always seriously over jump jumps as it had the strongest top end I have ever ridden in that size or larger bike. I added a Stealthy flyweight and it made the holeshots even easier but cut the top end rev–but I had more than I could handle at my skill level and over jumps. That 380 cc engine in a new frame will be more than competitive with the 450 four-strokes for the average rider. I made a Ponca and and the AMA LL with that bike in the 45 plus classes. Point is, I think a little more CC is needed than 300 cc and 500 cc is too much to handle for the average guy. I think Rodger D raced a 320 cc bike in Europe against 500 cc on rough tracks and won several world championships in a very light bike. That is the way to go.
GLENN
By 2STROKEREVOLUTION on July 30th, 2010 at 11:40 pm
Glenn
I have 2 380s right now! A working SX and a project EXC. It is a very fast bike indeed.
For AMA Motocross I think 144cc and 300cc is enough to be competitive. A test from MXA compared a 144 and 250F and the 144 was faster. KTM/s current 250SX makes 49hp. That is identical to the 450s. What it lacks is the mid range. The 300XC motor provides just as much top end with a lot more low end. Basically the 300XC has a 450 powerband. On top of that the 300XC is only 293cc, add 6cc more and you could find another horsepower. Combine an equal powerband with the lighter weight of the 2-stroke and you really should be faster. Plus you have many more lines that you can take to pass the 4-strokes as they fight for the same line.
What I think should be added is a reduction in the minimum weight rule. A stock KTM 250SX 2-stroke weighs in at 212lbs. The minimum weight is 212lbs. No room for weight reduction. But a 450 stock weighs 240lbs and the rules allow them to weigh 220lbs. Seems unfair they get to drop 8% of their weight while 2-strokes are stuck at stock weight.
By yz125rider157 on July 31st, 2010 at 3:08 pm
John,
You forgot two other bikes. MXA turned a wr300 into a full race bike. Also husqvarna is coming out with wr150 in 2011 so their are two more bikes you can add to the list.
By yz125rider157 on July 31st, 2010 at 3:12 pm
Also is their any way we can get motocrossactionmag.com to put the petition up on their site, since they support two strokes.
By GlennCMcGovern on August 1st, 2010 at 10:51 am
I think I will keep my eye out for a KTM 380 engine to put in a later KTM 250SX frame. That would be something.
GLENN
By burn1986 on August 3rd, 2010 at 12:52 am
Man, I wish MXA supported 2-strokes, but they have never returned one of my emails. MXA has never published a 2 vs 4 stroke shootout. They are simply opportunists. If the 2-stroke is the trend at the time, then they report on them, vice versa for the 4-strokes. MXA could care less, unless it’s what the factories want, or is the “fad” at the time.
By 125mx.com on August 3rd, 2010 at 2:20 am
We are all 2st fans RIGHT ! Why are we not asking for equal cc ? and looking to except a lesser amount is flawed. There’s no way 144cc is enough, 175cc minimum would be needed to run anywhere near the front. Our trick sx200 struggles when the grounds hard, hey even 250 2sts do. The 250f is a fast bike now with excellent delivery, we need equal cc to even stand a chance ?
By MXDUKE on August 3rd, 2010 at 12:29 pm
I agree with those that suggest a larger displacement. I think a 175cc 2s would be competitve against the 250fs. I also think a 350 2s would be competitive with the 450fs. There is a good chance that you could use the existing bottom ends as well without all the retooling costs.
I acutually think that 350-370cc is about the perfect size for open class 2 strokes…funny, they thought the same thing in the 70s…remember Roger’s RN370, Husky 360s, CZ 360s,RM 370s, YZ 360s…Thats an idea; Yamaha should come out with a 40-year aniversary YZ 360 two-stroke in 2013…in my dreams!
By Chris2T on August 3rd, 2010 at 2:28 pm
a 144 is only 20cc’s more than the 125’s and it brings it to a nearly even footing as the 250F’s. Another 20cc’s and it would be a rout. So i’m thinking 160cc 2stroke versus 250cc 4 stroke = 55% handicap. And i believe 300cc would be enough to take down the 450F’s, but only if the engine was designed from the get-go as a 300. Boring/stroking a 250 usually gives you more horsepower, but the ports/carb/air filter/pipe were not designed for the bigger piston. A 300 mx’er designed and built by the factories would be competitive with the 450’s imo
By Wil on August 3rd, 2010 at 6:18 pm
I just signed the petition.
It would be a great benefit if this could be given to MXA and Dirt Bike to post on their web site. Might really get a lot of signatures.
Great initiative John, as an avid 2-stroke rider I thank you all for this grass roots effort!
Braap!
Wil
By 2STROKEREVOLUTION on August 3rd, 2010 at 10:27 pm
I agree that the best thing to have would be equal displacement; a 250 class and an open class. But that will never pass. The big 5 would never let such a thing happen, they need their expensive 4-strokes to win so they can sell them. They invested too much in them to allow some privateers on 2-strokes beat them.
But there is a possibility that 144s and 300s could pass.
MXA tested a KTM 144 vs a Kawasaki 250F and the 144 beat it. An old tech 144 beat a new 250F. So a new 144, designed with modern technology and designed as a 125 will be more than competitive with a 250F. Same powerband or more peak power (depending on conditions) with a weight advantage.
As Maico’s 250 makes 54hp and all the 450s make 49hp a 300 will easily take out 450s.
By 2STROKEREVOLUTION on August 4th, 2010 at 1:55 am
Correction: That test was done by Dirt Action not MXA. The 144SX beat the KX250F by almost every rider (4/5 and the only one not faster on it was the girl)
http://twostrokemotocross.com/2009/11/dirt-action-magazine-2009-ktm-150sx-vs-kawasaki-kxf250/
By aussie2t on August 4th, 2010 at 3:56 am
Hi all, I recently saw a small clip where a Yamaha exec was sprouting how Yamaha are still a friend of the 2 stroke. I would like to take his rederich and burn it with some of that sweet smelling 2t fuel. Has it been 4 or 5 years since yamaha has changed more than the color of a sticker on the bike, it would be nice to see them stand behind there word and be a friend to the 2t and actually give the bike some 2010 improvements. World wide our bikes are making a huge comeback, mostly at grass roots but it is there. The big 4 can steer ruling commisions there way for now, but one day soon the people will speak a bit louder than dollars. Support the companys that support our cause. Long live the 2T.