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Thread: Tri-z 250 race bike build

  1. #1
    Join Date
    Sep 2009
    Location
    peoria az
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    34

    Tri-z 250 race bike build

    Hey guys I'm going to build a tri-z race bike kinda I'm thinkin of bumping up the compression some boyseen power reeds and a 38mm pj carb off a cr500 rejet the carb port and polish done by madman eng and plan on some suspension upgrades not sure what tho cld u guys give me some tips on any mods that work good let me know what u think

  2. #2
    Join Date
    Feb 2006
    Location
    Texas
    --
    738
    What type of racing will you be doing? Moto-X, Flattrack, Enduro? What year is your Z? Some of the mods will depend on the type of racing you'll be doing. Will you also trail ride the bike?

    TORKER.
    THOSE WHO SAY IT CANNOT BE DONE, SHOULD NOT GET IN THE WAY OF THOSE BUSY DOING IT...

  3. #3
    Join Date
    Sep 2009
    Location
    peoria az
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    34
    It's a 85 and I ride trails just wanted a tight setup that'll scare me when I hit the throttle

  4. #4
    Join Date
    Aug 2009
    Location
    Newfoundland, Canada
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    915
    just ride that 88mph 175! seriously though, it shouldnt be too hard to find the right set up for your type of riding. I dont think you would need anything on the bottom end
    "Beauty is in the eye of the beerholder"

  5. #5
    Join Date
    Feb 2006
    Location
    Texas
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    738
    This is what I would do personally.
    1. Stage one Yamaha wrench report, dont wanna ruin the Z great trail characteristics, it's the best in my opinion. Don't forget to spend as much time as nessesary tunning your bike, this is the most important step.
    2. Warrior Elka/Axis/Fox etc. Rear shock, they pop-up once in a while on e-bay for a good price. Set-up as nessesary.
    3. ATC 250r front suspension (you'll need the 86 Z tripples) with progressive rate springs (these are fairly inexpensive) and heavier weight susp. oil. If keeping the stock front susp. try playing with 83-84 suspension internal parts (search the forums, not sure if it works for the Z). Make sure all your bushings and bearings are in top condition. All of them.
    This should give you more than you're looking for suspension wise. Don't forget the all important tires !!! Withouth good tires the suspension cannot work at its best.
    20" in the back and 23" in the front. Hope this helps a bit. Now spend some money and go do it !!

    TORKER.
    Last edited by torker; 02-28-2010 at 06:35 PM.
    THOSE WHO SAY IT CANNOT BE DONE, SHOULD NOT GET IN THE WAY OF THOSE BUSY DOING IT...

  6. #6
    Join Date
    Sep 2009
    Location
    peoria az
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    34
    A how did u know bout my 175 and be sounds good for those mods I do keep the bushings clean and I'm thinkin about rebuilding my shock and money is very tight right now so cld it be possible to build the forks to hold a 260lbs person? what about the boost bottle is bigger better or is smaller? and has annyone ever ran the the pj carb?

  7. #7
    Join Date
    Feb 2006
    Location
    Texas
    --
    738
    Well, you can re-build the front forks. The Z forks can use motor oil. For 260# rider I would use 30 weight motor oil. Get a service manual It will tell you all you need to know about the suspension, including the amount and type of oil needed for your aplication.
    The PJ carb is very good, provided is in good condition. I would not go more than 36mm for trail riding. The boos bottle is not a big help.

    TORKER.
    THOSE WHO SAY IT CANNOT BE DONE, SHOULD NOT GET IN THE WAY OF THOSE BUSY DOING IT...

  8. #8
    Join Date
    May 2006
    Location
    N.E. Ohio
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    2,005
    I'd go coolhead, water pump impeller by Sprock, full DG pipe/silencer, Gforce, or other aftermarket banshee axle +4" A large carb really isn't needed if the Z's-tunned in. You can port the other window into the head; and thats what I'd do if you really going large carb route/open air filter. As mentioned suspension in the rear comes by at a large $price tag(well worth it) but a Custon Axis new is $850(ebay one for $200-350: re spring and recondition will run $225). You can use pvc(1"-3") to stiffen the old fork springs. Rumor has it there is a knock off brand that has a 23" holeshot style front tire for the Z...keep your eyes open for that. Out back traction depends on rim&size and personal feel.
    Last edited by Tri-Z 250; 03-04-2010 at 01:34 AM.

  9. #9
    Join Date
    Sep 2009
    Location
    peoria az
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    34
    Is it possible to get close to 50hp out of this bike

  10. #10
    audioworks04's Avatar
    audioworks04 is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    Oct 2008
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    Kansas City, KS
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    332
    It would be possible, but it probably wouldn't make for a very nice trail bike more of a duner or drag bike. In order to make 50 your looking at high compression, portwork and timing along with a large carb and lots of fuel and possibly big bore. Personally if I was building a tri z trail bike I would do like others have said and up grade suspension first, then possibly light portwork, but nothing extreme as to raise powerband or make less reliable. HP doesnt really mean a whole lot in the trails, its about ride-ability and a machine that can be lugged around without fouling plugs but get right back with it.

    2005 CRF450R Alum Frame build done, switching to inverts.
    86 trx250r fmf fatty fmf q k&n v force reeds gold valve rear shock with eibach spring.
    86 atc250r stock sand only
    88 NX250 mint rainy day
    85 kawi js550 stand up basicly stock
    87 kawi js550 scary fast for a stand up

  11. #11
    Join Date
    Sep 2009
    Location
    peoria az
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    34
    Ok I was justwondern if I cld get close to the horsepowr as the 09 yz250

  12. #12
    Join Date
    Feb 2006
    Location
    Texas
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    738
    H.P. / Speed is money...How fast you wanna go ???
    Now, money does NOT necessarily means H.P. / Speed !!!
    TORKER.
    Last edited by torker; 03-04-2010 at 01:09 AM.
    THOSE WHO SAY IT CANNOT BE DONE, SHOULD NOT GET IN THE WAY OF THOSE BUSY DOING IT...

  13. #13
    Join Date
    Sep 2009
    Location
    peoria az
    --
    34
    Well i want a reliable motor I'm going to increase compression on one of my hEads and get the cyclinder ported and polished maybe have it niksil coated and have swain tec coat my piston

  14. #14
    Join Date
    Sep 2009
    Location
    peoria az
    --
    34
    What about pipes I have the full stock setup and dg both are dent free where do the pipes range ie low to mid
    mid to top wich muffler works best stock with dg or dg with stock
    pipe or is it better to keep them together Ps when I say trail
    I'm talkin open areas where there's enough room to do 100mph on my cr500 so the 75mph that cooked this thing at is a little behind my dads and brothers 250s and I'm gettin suspion takin care of so it's down to
    tire motor and gears I'm goin to run a 22in Itp holeshot with current gears and see how it does

  15. #15
    Join Date
    Sep 2009
    Location
    peoria az
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    34
    New update Iv got the forks off a 1985 cr500 cld it be possible to shortin them to use on my tri-z

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