Dan105 said:To Eric, Rich and the likes- Is it possible to down size a 250 motor to a 200 or 220? I ride in nasty terrian. Nasty rock and root sections. The races are 3 hr harescrambles. Now that I have finally got the suspension working right, I want to tackle the motor issue.
I have a 05 YZ 250 two stroke with low hours on it. I did a powervalve mod and added a washer to smooth the bike out. Put a 13oz fww on it and the bike is still too much. I just rode a 08 KTM200 and liked the motor. Now I know Eric does a ton of big bores, ever done a small bore :)
The KTM is 193cc and shows a bore and stroke of 64 x 60mm (2.52 x 2.36").
The YZ is 249cc and shows a bore and stroke of 66.4 x 72.0mm (2.6 x 2.8")
I was hoping someone wouldnt say that. Just wanted to throw it out there and see if it was possible to get the same characteristics out of the yz motor.Rotorranch said:You won't be able to get the same power characteristics out of that long stroke 250 as you would with the short stroke 200. If you like the 200's power, you should get the KTM. :nod: :cool: :)
Rotor
2hours into a harescramble i dont want to aciddently blip the throttle and see god. The bike is great when I am full of energy but when you get tired it can get hairy in tight races. Maybe the porting will be enough but I doubt it.76GMC1500 said:What exactly do you want to gain by reducing the size of the bore? If you want to smooth out the power, have it ported for smoother power.
Dan105 said:I was hoping someone wouldnt say that. Just wanted to throw it out there and see if it was possible to get the same characteristics out of the yz motor.
2 strokes for life said:Rotorranch, well at least you corrected youself. Its like telling you or myself to buy a new bike. Just not happening.
What type of conditions were you riding it in? Might have to give the 265 a try.Lorin said:I had my 98 yz bored to 265 with the "mo-better" all-around porting done by Gore. That, along with a 11 oz flywheel weight made the bike very smooth. Power was smooth like a kdx with 10 extra horsepower when needed. Worked well for me.
I added a spacer (thick smooth washer) to the powervalve. The mod is from Team Green and how they make their KX more tracable. The powervalve in the kx and yz are pretty much the same. The mod worked well and smoothed things out a bit. I would reccomend itSpDyKen said:I would suggest that you send an e-mail directly to Eric. I suspect that he will be able to advise you of a good alternative; perhaps one not suggested here.
BTW, exactly what did you do to modify your power valve, and what were the results you experienced?
Please keep us posted here! KW
Got a pic or diagram?Dan105 said:I added a spacer (thick smooth washer) to the powervalve. The mod is from Team Green and how they make their KX more tracable. The powervalve in the kx and yz are pretty much the same. The mod worked well and smoothed things out a bit. I would reccomend it
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