YZ250 Woods Build

Discussion in 'Thumpers' started by Auto-X Fil, Jan 2, 2015.

  1. OldManSandman

    OldManSandman Not really old

    Joined:
    Feb 16, 2011
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    I picked up a completely rebuilt 2005. It doesn’t have the sss front fork but the one that’s on there seems good enough for me at the moment. I’ve thought about doing a lot of the mods listed but in the end I didn’t. It’s nice to know I can upgrade the bike over time, if funds allow.
    I did have to lean out the carb settings as the racer before me was a seriously fast rider.

    The front brake certainly doesn’t have a lot of power and I might well upgrade that, if I can. The one other thing I might also change is the rear wheel to an 18” for the fatter side wall or I might just go tubliss with The 19” wheel that’s on there (I think that’s right).

    Any thoughts on the Tubliss system for those that have gone that way? Trail riding involves some sharp rocks. I’ve already ruined a ride with a pinch flat. I’d rather be riding than dicking around with flat tires.
    #21
  2. Dao1

    Dao1 Long timer

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    Mar 17, 2014
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    Austin TX
    On my CR250, I went w/ an 18" rr wheel b/c I wanted a radial trials tire for all the rocks & sharp ledges I like to ride on. If there was a radial trials tire avail in 19", i would have stayed w/ a 19". ONce i got the 18" wheel, I tubliss it so I could run my trials tire at 5psi to get max. grip. This , imo, is the big reason to go w/ tubliss.... so you can air it down to 5-8 psi.

    If you don't have a need for 5-8 low psi, then imo, a h/d tube in the rear at 11-15 psi should be more than enough to avoid pinch flats. On my street legal husaberg FE390, I use tubes b/c it gets partly ridden on street , so to preserve my knobs, it'll never see less than 11 psi in the back, even on technical rocky single tracks. I haven't had a pinch flat on this bike in 5 yrs w tubes, and some of what I ride on this bike is the same rocky stuff I ride on my CR250 w/ a 5 psi trials tire in the back.
    #22
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  3. kawagumby

    kawagumby Long timer Supporter

    Joined:
    Sep 5, 2008
    Oddometer:
    1,438
    I just finished converting my 01 YZ250. I didn't have to do much maintenance as the bike had very little hours, the engine has not been opened yet and it still has good compression. The suspension bearings are still like new.
    I weigh 180 with full gear, and the stock suspension was no good off-road. What I did was modify the fork compression stack by converting to a two-stage type, and drop the spring rate from the stock .43's to .41's (stock yz125). No need for midvalve mods, IMO. I set the fork oil height to 120mm. The stock shock valving was kept (with amsoil light 5 oil) but the spring, similar to the forks, was changed to the stock yz125 coil. The suspension is now very supple, can handle stutter bumps and trail trash well, but still deal with higher speed hits. I found, for my style of riding off-road, that even with the lighter shock spring, the bike works best with very little shock preload - I adjust back from 115mm sag initially to where I like it once on the trails, easily over 120mm.
    To make it easier to dab in rough situations I lowered the rear 3/4" (spacer in the shock) and slid the forks up in the triples to match (there's room for that because I use fatbar conversion mounts which sets the bars higher).
    Engine-wise I'm running a pro-circuit pipe with FMF silencer/SA. I also installed a 13 oz steahly flywheel that I trimmed down to 12 oz. Stock reeds. That's all the engine needed to be where I like it. Loads of low-rpm torque with good run-out.
    The bike is excellent off-road now.
    #23
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  4. dakarchef

    dakarchef Been here awhile

    Joined:
    May 1, 2008
    Oddometer:
    574
    I had the first gen tubliss on a husky wr144 that I raced enduros, Xc and trial rode. I had nothing but troubles with the setup, burped out air when pushing hard, tore knobs off, inner liners lost pressure. Had more flats with this than with tubes. A buddy just pulled his out of his wheels as he too had troubles. Some I ride with love them.... me, not so much.

    The yz is brilliant. I blew the rear shock last week and had it rebuilt. I also ride a 16 beta 390. I’ve been timing myself on a 7km single track loop on both bikes. I’m a full 1.5 minute faster on the yz than on the beta....hard to believe.... 15:30 vs 17:00
    I’m off to a National Enduro next weekend and it looks like the yz will get the nod.
    #24
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  5. husky390

    husky390 Long timer

    Joined:
    Sep 24, 2017
    Oddometer:
    1,139
    Location:
    Colorado
    I’m on an 05 YZ250 that was used for MX by a much smaller and faster rider. Current mods are new heavier springs in the forks and shock, Pro Circuit pipe, RG3 triple clamp, and 51 tooth sprocket. I only did the springs and FWW and it’s decent in the woods.

    This winter I plan to do the following:

    Have the suspension re-valved and sprung since I lost a lot of weight since the last round of springs.

    New chain and sprockets 13/50

    New taller handlebar

    Maxcross Desert Intermediate tires with mouse. I used the first gen Tubliss on a different bike and won’t go back.

    Grease everything

    Ride the piss out of it to get ready for next years Enduro/Harescramble season.

    They’re great bikes, I’ve had guy’s with much newer, nicer bikes want to ride it which I don’t get. I don’t believe I’ll ever go back to a 450 for single track. This is just so much easier to throw around in the corners and a lot of fun. With the way mine is setup now, I’ll typically lug it into a corner and let the mid range hit of the pipe pull me through it. Tons of fun.
    #25
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  6. greasyfatman

    greasyfatman Long timer

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    Oct 18, 2014
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    2,762
    I saw 340 sleeve out there for the yz and woods porting. If I can find the right deal I would put one in the shed.
    #26
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  7. ACR

    ACR 52,015

    Joined:
    Sep 3, 2012
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    1,100
    Location:
    The Flats, MB
    Something to consider for all the YZ owners. Clutch basket fingers on my 01' decided to break off and give the ultimate salute, causing an impressive amount of damage. The wear on the basket appeared acceptable, other than the missing pieces. The mechanic was surprised, said he had not previously seen this sort of failure on a YZ. Probably a rare event, though I'll be taking a closer look at the basket during future clutch service.
    #27
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  8. dakarchef

    dakarchef Been here awhile

    Joined:
    May 1, 2008
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    574
    My buddy who rides a late model ktm200 took the Yz for a ride. He couldn’t believe how well it did in the singletrack. He is now considering selling the Ktm and looking for a Yz. He really felt the Yz was dialed in and had great power.
    I managed a third place at the Zink Ranch national enduro a few weeks ago on the Yz. I was the ugly duckling surrounded by a sea of pretty, blinged out new bikes. Had a great time and turned some heads. Lol
    #28
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  9. jcshew

    jcshew Been here awhile

    Joined:
    Jun 30, 2009
    Oddometer:
    116
    Any of you guys riding the YZ in the woods have a preference between the steel frame vs the aluminum frame? Pros-cons? Any real difference?
    #29
  10. dakarchef

    dakarchef Been here awhile

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    May 1, 2008
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    I’ve ridden both but set up differently. I don’t think the average rider would know the difference. Some swear by the steel frames, some like the alum frame as it’s a few lbs lighter. I think it boils down to buy the best bike you can buy, set up as close to the way you would want it, for the best price. A rekluse and a large tank would be things I’d be looking for.
    #30
  11. tHEtREV

    tHEtREV Encouragement award recipient. tEAM iDIOT.

    Joined:
    Apr 14, 2007
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    12,299
    Location:
    Middle Park, Brisbane, Australia
    I have never ridden an alloy frame YZ, but from what I have read most people can't tell the difference, but the steel frame has smaller frame tubes and it makes engine access a bit easier allegedly.

    I was looking for an alum frame YZ purely because it would be newer but decided if a nice steel frame came along I would get that (I didn't get either because other stuff happened, but then again, I have only ever decided on a bike to get, and then bought that bike once, usually I go searching for a certain bike and end up getting something completely different).
    #31
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  12. husky390

    husky390 Long timer

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    Sep 24, 2017
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    Unless you’re a solid A rider, I don’t think you’d notice a difference and I would recommend buying the newest and cleanest model you can find in your price range.
    I was looking for a clean 06 and newer for the SSS forks but couldn’t find one in my price range that wasn’t beat to death. I stumbled on a guy selling an 05 which is an oddball year as it has an aluminum frame but AOS forks and it was so clean that I couldn’t pass it up. I’m not skilled enough to tell the difference between the two forks and the AOS and I get along pretty well.
    #32
  13. husky390

    husky390 Long timer

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    Tore it up today. The trail had a lot of areas that were ice packed with snow on top which made riding challenging and hill climbs gnarly. Me and the bike are beginning to gel and it was a lot of fun.

    IMG_1930.jpg
    #33
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  14. dakarchef

    dakarchef Been here awhile

    Joined:
    May 1, 2008
    Oddometer:
    574
    I had the crank bolt on the clutch/ water pump side back out and crack my side case. I caught this on the first transfer section of our last Enduro of the year. The bike is now waiting for parts. I found a side cover on ebay.. got to love the yammy for parts availability. I had to clean up the threads on the crank and replace the bolt. The powervalve (governor) gear was chewed up so I’m going to rebuild it with the Yz250x spring and washer mod. Will see how this affects the power delivery. I also have a Yz250 unit coming (eBay) so I can compare the two.
    This arrived today.... jeez this Yz makes me smile!
    image.jpg
    #34
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  15. dakarchef

    dakarchef Been here awhile

    Joined:
    May 1, 2008
    Oddometer:
    574
    The Yz is back together. While I had it apart I started looking at a 36mm lectron carb that I had in the shop. The lectron was from my small bore husky (165). That bike was brilliant with the lectron, always started first kick. The carb really smoothed out the power as well as improved the fuel mileage. I did some initial measurements and the lectron would fit. Lectron recommends a 38 mm carb but others have used the 36. I did need to change the metering rod to a 4-2 (lectron recommendation). Initial startup the bike was very lean so I ended up turning the rod in 3/4of a turn to get it to idle well and have crisp response. The bike was lean on top too with the power jet set at one turn out. I ended up going another 3/4 turn out to get it right on top.
    I’ve only been riding the bike around our property in -2 C weather. Initial impressions With no woods riding, the carb has really softened the hit, the engine has far more linear power but will still pull the front up in 4th if you whack the throttle.
    I’ve also added a yz450 kicker arm to the bike and these two items seem to make the bike easier to start. The old kicker was awkward and you would often hit you foot on the footpegs when kicking. The new kicker moves you foot further away from the side of the bike avoiding the peg. Minus 2 c and the bike starts second kick.
    #35
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  16. Cochese

    Cochese Been here awhile

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    Sep 16, 2017
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    Somewhere near Dallas NC
    Did you put the X power valve spring and washer in or did you put it back together stock for now
    #36
  17. dakarchef

    dakarchef Been here awhile

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    May 1, 2008
    Oddometer:
    574
    36mm Lectron installed. I didn’t have a carb spacer to deal with as the 01 didn’t have it. Apparently the 01’s were one of the hardest hitting bikes. The carb spacer arrived in 02 and tamed them a bit.
    5BBF9A09-5242-4C11-ACAF-2AE6CB4C1A69.jpeg C35F8233-50DD-4BF6-A2D4-FAB4B5B013D0.jpeg 047B9E00-20E4-4941-9115-1A55EABA8074.jpeg As for the powervalve .... Just the stock unit as I’m waiting for the x spring. It is still on backorder. I need to ride the bike more, I have the timing retarded but I might start moving it back to stock.
    I managed a 1 hour ride today. 15 minute loops of single track x 4.
    Snow covered with no studs. The bike worked very very well 3rd gear and it pulled well off the bottom. 2nd was very good in the tight corners. The bike doesn’t come on the pipe near as hard and is very smooth and controllable. I think I can be faster on it now.
    A few pics from today:
    The last photo shows the 450 kick lever. You 79F521FC-8434-4E0C-81FF-33A0EBBD9CC9.jpeg can see where the stock unit would sit on the side of the tank
    Feel free to comment on my weird bike setup ... it works for me.
    89020159-E3DC-4F1A-9276-0EB09652AD4C.jpeg
    #37
  18. Cochese

    Cochese Been here awhile

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    Sep 16, 2017
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    I'm doing one right now as well that's why i ask about the power valve mod thought about knocking a few degrees of timing out as well love the 2 stroke hit but it's going to be my woods bike so thought i might try it not sure yet keep us updated please
    #38
  19. husky390

    husky390 Long timer

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    Sep 24, 2017
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    1,139
    Location:
    Colorado
    What Rekluse setup are you using?
    #39
  20. FenceJumper09

    FenceJumper09 Been here awhile

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    Oct 2, 2014
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    525
    Location:
    Birmingham, AL
    I upgraded my 2002 kick starter shaft to an 01 for the larger diameter, mine snapped, and went with the YZ 426 kicker. Aligns well with my oversized tank!
    #40
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