Posts
102
Joined
6/2/2015
Location
Loretto, TN
US
Edited Date/Time
3/13/2019 5:19am
So I'm looking for a 2006 and up yz250 to get into the two-stroke game. I need some help though because I'm not really familiar with the major differences between the newer and older models. Are there any major differences? Is it basically the same bike just different plastics? Any help is appreciated
The Shop
The only functional difference is the diameter of the fork tubes at the upper triple clamp. That just changes flex slightly. I seriously doubt anyone but the most sensitive test rider could feel such a small change, but I haven't ridden those new fork tubes on a two-stroke model.
I don't think the valve-stack in the forks has been changed since 2006. From 2008 up it's all the same for sure, I've worked on them. In fact, the valving in a 125 is the same as a 250. They change the springs, oil height and the clickers per application.
The rundown on the YZ250 goes like this:
1999 First year of the current engine
2002 First year of the current frame geometry and bodywork through 2014
2003 Exhaust port raised about 0.5mm and h-igher compression head for USA model.
2004 48mm open chamber forks
2005 Aluminum frame (identical geometry and compatible with 2002-2004 parts) 48mm AOSS forks
2006 48mm KYB SSS forks and shock. I believe the swing arm also changed to a stiffer casting
2007 Pro Taper 1-1/8 Handlebars
2008 Smaller fork lugs and shorter lower tubes. Brake calipers also reduced in size + wave rotors
2011 No more US model: Bigger silencer and a neutral switch for sound checks. Low compression head.
2015 New body work (compatible with 2002 - 2014 bikes) Smaller fork tubes (at top clamp) from the four stroke.
The only major issue with any of those years is the bad brakes on the older bikes and the terrible design used on the shift forks in the transmission.
Currently I race my 2002 model with some 2009 SSS forks and shock. My 2010 model needs a 5th gear and the tranny upgrades I've done to the older bike.
My sons '05. I wouldnt rule out an '05 if you run across a good one.
Most guys don't seem to have a problem with them, but I do and a few other guys do as well. I think it depends on how hard you ride and how much you abuse the transmission. If you have issues, you just have to pay Yamaha for more gears and forks each time. Eventually, the cases become worn and the shift forks just get really sloppy.
My fix involves billet shift forks, tool steel guide rods and machine work on both cases to allow the custom forks to be used. Once it's done, the cases cannot accept the original Yamaha forks. That 2002 bike I currently ride has other case modifications in order to use a stronger YZ450F gear set. The YZ250 has only 3 dogs per gear while the 450F has 4 dogs on each.
If you search MXA you can get a pretty good review of each year. You could possibly say the motor lost a teeny bit when they went to the global spec in 2011 with lower compression and the longer silencer.
Come get this one, it's a 05 I bought in December and completely restored it to make it look like a 16. I put 2.5 hours on it and figured out I'm a 4 stroke guy! Haha
Pit Row
The 2010 YZ250F foot pegs fit the older bikes at least as far back as 2002. I believe those are the same height and part number as the 2015 / 2016 two stroke pegs.
Edit: also did the 15+ seat (much softer) and the newer pegs
2013 here. Where do I start? I absolutely love this bike. I race desert and GP's. Do the occasional REM and SRA GP. it was said in this thread the steel frames handle better. I disagree. I do not feel there is any performance difference between the steel and aluminum frames, only rider preference for chassis feel. The steel frame does flex better, and for some riders they feel the flex of the steel frame makes the bike handle better. Again there is only empirical evidence of this at best, and no real world conclusive data.
Things to watch out for. The shifter detent wheel. Yamaha lists it as a stopper wheel. part number is 5CU-18140-01-00 Go ahead and buy a couple. Immediately replace your's. Replace it every 50 hours when you do your top end. Otherwise, this is what will happen:
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img]https://scontent-lax3-1.xx.fbcdn.net/v/t1.0-9/10172579_1020381579501299…]
This happened to my bike around hour 20 from off the show room floor. Look I love Yamaha. However they are not perfect. The shifter detent wheel is a ball bearing design. same as its been for years. Identical on the yz125. However yamaha knows this is a defective design. The race on the inside portion of the wheel gets flared and worn, and then drops 8-9 wonderful little steel ball bearings into your transmission. BOOM. The redesign on the newer 07-up YZ125's is a solid steel wheel, no more bearings. However yamaha has not carried over this design on to the YZ250. My sources tell me that because of the inherent shifting necessary for riding a 125 vs that of a 250, yamaha had to make a change. ive owned three YZ125's. every single one of them has had this part fail. Its also failed on my YZ250. Be aware.
Shift forks arent the strongest either. Im currently splitting my cases to replace my 4th and 5th gear, and the shift forks as Ive started to experience 4th dropping into nuetral on its own, and when in 5th it dropping back down into 4th on its own. Since I race off road these two gears are where I spend most of my time. It happens. It sucks. watch for the signs and dont push your luck. KX500 racers used to replace their transmissions with every top end. So it could be worse!
Run race gas. Dont be stupid. Dont try and think you're smarter than everyone else. Run race gas. This is your warning. I run straight VP C12 @ 32:1 with motul 800. If I'm trail riding, I'll run 50/50 VP C12 and VP 100 unleaded. The bike runs correctly with race gas. They are known to ping on 91/93 octance. Especially when its hot. I personally change my air filter and gear oil after EVERY ride. Not just race, but EVERY ride. its cheap insurance. Dont be lazy.
the 2015/16/17 has different triple clamps, steering stem, and the entire front end is basically different. The performance is the same. however the newer forks are a little larger on the top (as I believe was already mentioned). So if you decide to go the OEM bodywork upgrade like I did, be aware the front number plate will not fit correctly. Its a little too short to work with the older triple clamps. It'll fit but you'll need to finesse it on. also the front fender holes dont line up with the older lower clamps. take your original fender and place it upside down on the new fender. Take a sharpie and mark out the new holes. Drill out new holes on updated fender. Now it fits.
Have fun!!
(1) Front tire: In 2008 the YZ250 came stock with the Dunlop D739 front tire. Then in 2009 it got a Dunlop D742FA (the same tire that is spec'ed on the YZ450F).
(2) Rear tire: Although the rear D756 rear tire looks the same as 2008, it is in fact the 2009 that got the "G" model tire. I liked this tire , they should've kept it! How does the 756G differ from a regular 756. It was 200 grams lighter. How much lighter is 200 grams? About seven ounces.
(3) Front brake hose clamp: Yamaha drop-kicked the previous steel front brake hose clamp in 2009 for a smaller and lighter aluminum clamps. The DR.D-style clamps saves 32 grams (a little more than one ounce).
(4) Chain: The side plates on the new D.I.D. chain have been zinc coated for better rust resistance.
(5) Seat cover: For 2009 the YZ250 seat cover has a woven pattern instead of the old sandpaper-style gripper material on the seat cover. I like the old seat better! Lasted forever!
(6) In 2007 the thickness of the inner and outer fork tubes have been changed to feed more flex into the front end of the YZ250. Additionally, there have been damping changes to improved the feel and lower the overall weight of the fork. If you're a hack of a rider? Stick with the 2006 specs!
(7) Several of the key pieces of the Kayaba shock absorber have been changed from steel or brass to aluminum. The valving has undergone some modest changes. But nothing noticeable if you're slow!
(8) The 7/8-inch Renthal bars were replaced with 1-1/8 inch Protaper Contour bars.
(9) for the USA, In 2007 the YZ250 came with a new jet needle in the 38mm Keihin PWK carburetor boosts bottom-end and mid-range response.
(10) Lighter bolts are used throughout the chassis to reduced weight , again barely noticeable
Furthermore, the 2005 was a good bike , but it suffered from the AOSS ( air oil seperate system) suspension , as mentioned , but slow riders obviously can't feel the difference! If you ride a snails pace ? You don't need works 'like' suspension
And in 2010 Yamaha dropped the titanium springs in the fourstrokes and switched back to steel , but the two-stroke kept it
Listening to Denny on pulp the other night ! He's back riding and he just got a 2006 YZ250! It's virtually unchanged in a decade and with everything listed in this thread you could make your 06' into a 16'quite easily
If I were doing this? I'd get the new-style plastics , new air-box and black rims! Literally - no one would know
According to MXA, Yamaha Japan could not build a better two-stroke. (coming from the same people who brought you the modren 4 stroke lol)
It used to be great race bike (when people raced twostrokes ) and it's still the best dirt bike for the common man!
I've only started hearing problems since 2013! Engine! Tranny! Not sure why ?
Hopefully the YZ250 doesn't get built cheaper , it's built proof , jetted right out of the box & and a shit ton of fun to ride!
Back in the day when people raced tiddlers , this bike was bad ass!
Now that motocross has turned into a sport ! Sadly it doesn't have a place in the pro ranks anymore !
For the weekend warrior ? This is the bike to own
Case huge jumps with the SSS suspension and just roll away , literally hearing KTM riders gasp!..... Like? They will think you jacked yourself up and then you don't pull off , you keep pounding laps like nothing happened !
AOSS? not so much
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