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#1
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KX 250 2T in a KX250f Aluminum Frame
A lot of folks think about installing a 2 stroke motor into a modern 4 stroke aluminum frame and I have been wondering about this for many years. I recently had to chance to buy a 2007 KX250f frame with a mid nineties KX250 2T motor (bored out to 299cc) installed. I was also very lucky in early July to find a 2003 KX144 that is close enough to a 2007 KX250 to make a rough comparison in ergonomic "feel". Ideally, I would have preferred a '13 or newer KX chassis as that is the year when the KX frames were upgraded to more ergonomically narrow and forgiving ride characteristics.
My initial thoughts on the bike without having ridden it, yet, is that it feels more bulky across the pegs, midsection, and in the rear where the right side number plate bulges outward for the 4T exhaust cannister. It is bulkier than my '14 GG 300 and substantially more bulky than the steel framed '03 KX144. The steel framed 2007 KX 250 (2T) is listed as 214 pounds dry (97kg dry, 226 pounds wet with no gas) and the AF framed 2T weighs 238 pounds (108.2kg) with all fluids, 1 gallon of gas, FMF Turbine Core II, and Maxxis Desert IT tires). If someone is looking to drop some weight by doing this conversion, I don't think it will save you much. It is possible that it weighs more than the equivalent steel 2T frame from the same year KX. What is the advantage that I see at this time? It really looks good!! That's about all I can say before having a chance to ride it on some real trails (coming soon). If the ride quality is not there, then I won't bother to try and put a GG motor into it. For now, I will have to be content with just how good this bike looks! Eric
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2018 GG 300 GP 2014 GG 300 Racing E 2002 ATK 605 Dual Sport 2003 KX/KDX 220 hybrid 2021 Kawasaki KRX 1000 Trail Edition 1974-86 Vintage Can Ams, SWMs, Puchs, etc. Last edited by coopernicus; 09-06-2016 at 09:08 PM. Reason: embedded a picture |
#2
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Cool bike. Thanks for sharing.
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#3
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Wonder if it will feel less top heavy, not that the gasser particularly does. Lighter is always nice. Top lightness makes it feel lighter than it is
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'07 EC300 GG '14 TXT250 GG '? 496 CPI Cheetah RZ/RGV hybrid '22 765 Street Triple RS '21 XTrainer '69 Stinger T125 Suzuki '23 TRS 250RR (it's a Trials thing) |
#4
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I had the chance to ride this bike extensively this past Saturday and have concluded that I would not bother to make the 4T AF conversion to a 2T motor. The bike had a slightly less top heavy feeling than me 2014 300 Racing E but the width from the pegs to the seat made it more cumbersome. The main drawback compared to a standard KX 250 2T and a GG 300 is the lack of steering precision. It feels a little vague in the turns and does not give the best feedback to the rider as to how far you can "push" the traction on the front tire (which, although new, is a CST brand tire...ewww!). Frankly, this did not surprise me too much given past test reports of the 07 KX250F and the less weight of the KX 2T motor. As for the suspension, this bike has a Race Tech components installed and the suspension is good. However, it is not as good as the bone stock Marzocchi/Reiger combo on my GG. What did I like about the bike besides the 299cc KX motor? The feel of the aluminum frame was far better than anticipated. It was not overly stiff and it did not feel harsh at all. It also had an excellent turning radius compared to my GG (big surprise). I must add, if anyone has a KX 250 that they want to keep, making it a 300 made the motor very nice. I've ridden extensively a big bore YZ and the KX big bore motor is much better for trail and race speeds. The big bore was done by Kustom Kraft but can be done by most other places (Powerseal did the YZ conversion). I don't know if I will keep this bike but I will test it some more after I make some mods to get more "bite" in the front end and I will replace the front tire, too. Feel free to ask my any questions if you are interested in an AF conversion!
Eric
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2018 GG 300 GP 2014 GG 300 Racing E 2002 ATK 605 Dual Sport 2003 KX/KDX 220 hybrid 2021 Kawasaki KRX 1000 Trail Edition 1974-86 Vintage Can Ams, SWMs, Puchs, etc. |
#5
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Quote:
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Steven Beane #275 PlusOnePerformance - Superior Service the World Over - Dearborn MI AMA District 14 (Michigan) Officer afterhourscycle.com Michigan's Beta and TM Race Headquarters |
#6
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Bike looks great, but I always thought the conversion to do for extreme riding was to fit a Kdx motor in the 250f frame
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2003 txt250 Pro 2013 Ossa 280i |
#7
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The kdx motor in a 125 chassis is a very common hybrid. But for less money you could just buy a gg200. I looked into it and had the kdx motor and was going to put it in a CR250 AF, because that is what I had. Was just going to be more money than I wanted to spendZ
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Matt 1999 GG EC 250 Six Days 1999 Cagiva Gran Canyon 2001 Aprilia Falco 2001 Triumph Speed Triple for my 20 year old 2000 GG XC250 for my 20 year old 2003 Honda Rancher 350 for the wife |
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