Posts
402
Joined
4/1/2008
Location
Uppsala
SE
Edited Date/Time
11/19/2020 1:10pm
I’m curios how much difference there is between, say, an YZ250-96 (”SuperEvo”) engine, a -02 and the -05 (I’ve owned a -06 myself, and feelt it hit to hard for my fast novice/slow intermediate, 48yr old, 155lbs featerwheight)?
The same goes for the 2001-2008 RM250’s, any differences in HP and ”rideability”?
I never tried a heavier flywheel on the -06, does it really tame it down that much?
I had an -89 ”Evo-prepped” YZ250 this summer, with a ported cylinder, VForce3 and PC-system and loved the engine! Just the right amount of power and low end-grunt so I could ride long motos (and still be ”aggressive”), but still way more exciting engine-character than my sons FC250-19.
Sure, the brakes weren’t the best and the suspension weren’t always up to par (depending on the track), but still ALOT of fun!
So I would love to build me a bit more modern 250 twostroke, and that’s why I’m hoping some of you guys could help me out here.
Sure, the easiest would be an 06< YZ250 again, with the KYB SSS-suspension, but as I said, get tired to fast with that engine-character.
The same goes for the 2001-2008 RM250’s, any differences in HP and ”rideability”?
I never tried a heavier flywheel on the -06, does it really tame it down that much?
I had an -89 ”Evo-prepped” YZ250 this summer, with a ported cylinder, VForce3 and PC-system and loved the engine! Just the right amount of power and low end-grunt so I could ride long motos (and still be ”aggressive”), but still way more exciting engine-character than my sons FC250-19.
Sure, the brakes weren’t the best and the suspension weren’t always up to par (depending on the track), but still ALOT of fun!
So I would love to build me a bit more modern 250 twostroke, and that’s why I’m hoping some of you guys could help me out here.
Sure, the easiest would be an 06< YZ250 again, with the KYB SSS-suspension, but as I said, get tired to fast with that engine-character.
Very similar engine character but I guess the 2000 was more mellow.
This 2000 had the newer SSS stuff as well, it was a sweet bike and I never felt like my 06+ was really any better.
The trend has been toward smoother power all these years, so older versions will likely hit harder ('98 and previous, although I've never ridden one of those.) Late '80s and early '90s bikes probably have even more hit but less power.
EDIT: PS, yes a flywheel weight will tame the power considerably. It would help you to not light up the rear tire as quickly.
The Shop
I recently bought an 03 Honda CR250R and it is more powerful than both of those previously mentioned bikes.
I also recently rode a 20 YZ 250 and was disappointed with the motor. My 03 CR is stronger mid to top, closer to new KTM power.
Lastly, I rode a 20 KTM and man that thing had a great motor. It is the best of the bunch..
I have not dyno'd any of them but that's my seat of the pants comparison for what its worth.
The smoothest setup I've had was a YZ250 with DEP pipe with standard length DEP silencer and a 9oz flywheel weight. There was almost no hit compared to stock and it pulled forever. On really slick tracks an 11oz flywheel weight would probably have been even better.
I now have a YZ250 with HGS exhaust and HGS shorty silencer and no flywheel weight. It hits hard but signs off earlier. I find I can short shift this set up though as it has more torque to pull the higher gears
The yz hits harder and rips more on top. The Suzuki is quicker to turn over. Stock for stock.
I had a 2019 Ktm 250 and it didn’t have the immediate snappy throttle response of my Rm.
It had good smooth bottom and mid and fell on its face on top.
In my opinion all the last gen Japanese 250s run better and are more rider friendly. Just my opinion though.
Sounds like you may want a yz250x. I think that would be a very smooth engine.
Pictures for proof of opinion. Lol
But you have to get the setup right or it can be a handful. Recently at Glen Helen the rm just wanted to kill me the entire time. By the time I got a decent setup the weekend was over. But that was my fault and not the bike really.
Keep the CR.
As you mentioned with the old school bikes the engines can be made to run quite well, it's the suspension, brakes, and ergos that hold the bike back.
Kawasaki designed the '05-07 engines for Bubba to be able to compete against the 450s at the time. I had a custom head insert made by Phathead, and threw on a 11oz flywheel weight to tame the power a bit. It's perfect for me now, it was almost unrideable when I got it.
Rode a brand new '16 YZ250 smoker and couldn't believe how mellow the powerband was.
Pit Row
The magazines also criticized the '07 KX250 for having a violent powerband (and shit forks but that's separate)
Bands. At least thats how I remember them.
Peak numbers aside (which are close btw), the KTMs make all their power through the mid range, making something like 3.5-4hp more over the YZ250 in that area. The YZs make that same amount more than the KTM in the top end.
The YZ power is broader and easier to ride imo, though that is subjective. I've yet to meet anyone who has ridden both that prefers the KTM power, but that doesn't necessarily mean anything. The power valve is easily tunable on the KTM, which is a big plus.
The KTM is more advanced in other areas (chassis/geometry).
As an aside, I'm not sure that either the KTM or YZ engines can be modded enough to make more hp than a well tuned last gen CR250 engine. That case reed design was a monster. It had its own flaws though.
I've done quite a bit of experimentation between X and regular YZ engine parts in general over the past few years and have a hybrid of sorts that runs beautifully for my needs/skill level. It's nice having all the options for parts between both bikes.
Thinking of getting a 2T 125 /250 sounds like you have a bit of experience with both...
Thanks for your input!
1992 cr 250: rocket fast, not tractable violent hit no mods.
1994 cr 250 not as exciting as the 92 more effective.
then went to 125s
2003 ktm sx 250 great engine attached to a shopping cart. nevr came to grips with the hydro clutch. put a stock exc silencer and heavier silencer made the engine super tractable.
went to 125s then 250 f and quit riding.
in 2015 restored a 2004 cr 250 with lowered cylinder and tightened squish. super powerful but turned over really quick. the gears were short.
2018 yz 250x felt slow after getting of the cr. after riding it along with my buddies i noticed it was deceitively fast. but smooth. it vibrates a bit, switched to pro taper evo with pillow top grips to calm down the vibes.
might get a brp top clamp or a mako 360 to further reduce handlebar vibration.
now i have in sight a sherco two stroke enduro.
"When the MXA test crew ran the ’05 Honda on the dyno it blew our socks off. All kidding aside, the 2005 CR250 produced the most low-to-mid power of any deuce-and-a-half that we’ve ever run on the dyno. It made two more horsepower than the class leading 2005 YZ250 at 6000 rpm, three more at 7000 rpm and one more at 8000 rpm."
Both the YZ and CR are fast motorcycles. I have not ridden the RM and KX but have raced against them -- they're also fast. Faster than most of us can ride them controllably.
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