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To bore, or not to bore...that is the question.

Discussion in 'General Tech' started by mxracer_0141, Mar 3, 2011.

  1. mxracer_0141

    mxracer_0141 PR Member

    Grafton, OH
    Racing Number:
    so ive got a 2005 yz125 that im tryin to get some more horses outta to keep up with these 250 four and two strokes this season. the first option i stumbled upon was the 144 kit. i have never bored any of my bikes (and have never blown a single bike up nor had any problems with any of my bikes) so i honestly dont know how reliable this process is. any input on it? my second option is porting and polishing it, putting a v force 3 reed cage in it and changing the gearing on it. how much would that help me? ive already got a fmf sst with a titanium 2 silencer on it. im just trying to get a little more power outta my little 125 to keep up a little more instead of spending 6 grand on a ktm150 or buy a 250 2 stroke that will ride me more than i will ride it. any input on this would help me out alot!
  2. jfalat

    jfalat PR Addict

    brimfield ohio
    Racing Number:
    Have a 09.. stock bore with vforce reeds and doma pipe/silencer with 2 teeth added to rear sprocket and one step richer from stock on jetting and the bike runs very good with this set up. had a 06 139yz and a 08 144sx and have to say there is not that much between them all. just a blast to ride!!!!
  3. Google Eric Gorr, 640 bucks for the bore, port and polish, set up to the power band you want, piston, rings, cir-clips, wrist pin, bearing and gaskets. He is arguably the best around for two stokes?
  4. mxracer_0141

    mxracer_0141 PR Member

    Grafton, OH
    Racing Number:
    yeah i looked him up already and was looking into that. 640 bucks for all that, plus labor? or 640 bucks and its ready to go?
  5. PitRacer

    PitRacer PR Founding Father

    Medina, Ohio
    $640? Where did you get that number?

    I just paid Gorr $425 for the RM144 job a month ago. I got a discount as a returning customer, normal price is $500 for 144cc.

  6. MarctheSharc

    MarctheSharc PR Founding Father

    I just hammered on my Eric Gorr YZ-144 ... Rock Solid and added some kick.
  7. sdjclevland

    sdjclevland PR Addict

    Yeah send if to gorr. I have the same bike as you with same pipe but a 144 and love it. My crank went out but I think is was going bad when I bought it.

    Still put the vforce on it and 13 50 gearing. It still won't be as fast as a 250f. But not far off
  8. My bad, I was looking at the price to make my yz 250 a 300 and the 144 thing, I got it mixed up.
  9. MXracn746

    MXracn746 PR Addict

    Obetz, Ohio
    Racing Number:
    LA Sleeve offers a 540cc kit for your KX500! In case your interested. I am.
  10. hershey

    hershey PR Elite

    Ozone Layer
    Racing Number:
    Trust me the 144 kit makes a HUGE difference. And yes it will keep up with a 250 4stk. I have the athena 144 kit and it rips.
  11. sdjclevland

    sdjclevland PR Addict

    i have both bikes 144 and 250f stock and yeah the 144 can keep up but there is no doubt the four stroke is faster. No by that much though.
  12. shaffstall721

    shaffstall721 PR Member

    Andrew if it wasnt a yamaha and it was a KTM 125 it would keep on STOCK! lol. but no i honestly think the 125s are pretty darn close stock to a 250f? with the 144 kit it should be faster, but i been gone a while so idk anymore.
  13. GeorgiePorgie

    GeorgiePorgie PR Founding Father

    Ohio the 440
    Racing Number:
    What about a small stroker kit? Maybe more reliable in the long run, or not...

    What would you guys say is more reliable bore or stroking?

    My buddy slapped an athena kit on his kx 125 and when he fired it up that thing just sounded mean as hell. Can't go wrong with the Athena kit...
  14. six6seven

    six6seven PR Member

    Pleasantville, Oh
    Honestly, it'd probably be easier to sell it to someone with a kid that needs a 125 and buy a 250 2 stroke, since your allowed to run in the same class its like cheating but no really and its kinda like a 450 with more speed and sounds alot cooler when your bouncing around a corner 3rd gear pinned on the rev limiter. I'd just sell the bike, and take the money you were gonna invest in amping up the motor which isnt always a safe bet, and buying a newer 250 2 stroke and getting some suspension and brake work done.

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