Questions about big bore kits

Discussion in 'Full Rebuilds' started by joe allen, Sep 15, 2020.

  1. joe allen

    joe allen Member

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    What should I do to my bike? I currently have a Vitos 240 with a 3 mil stroker crank, a mikuni 36mm carb, and a FMF gold series fatty pipe and a powercore 2 muffler. I was thinking about rebuilding my Vitos kit and getting the head ported. I was also pondering getting a Vitos fat bastard pipe. Should I do this or go back to a stock head, get it ported and keep my FMF? Also, if I were to go back to a stock cylinder, could I keep my 3 mil stroker? Lastly could I bore out my Vitos kit and get a custom piston and rings? Which would be the best, and which would be most reliable?
     
  2. Slydog

    Slydog Active Member Technician

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    What's the bore at? It comes new with a 72mm bore. You can get the cylinder ported and head mod done on the big bore for a nice power gain that is not that much$.
    Check out ken occonor racing website
     
  3. Awk08

    Awk08 Administrator Staff Member Technician

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    What bore is your Vito's cylinder on ? has it been bored/honed before and you're on the last bore now ?
    if never bored before, you have 2 or 3 more to go, Call Ken @ http://www.kenoconnorracing.com/ to set up sending it in to get bored to the next size piston, ported and head mod,
    but that FMF is holding the big bore back, especially after porting and head mod, so the Fat Bastard would match that setup better and produce more power, especially top end.
     
  4. joe allen

    joe allen Member

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    to my knowledge it has never been rebuilt in the 6 years the kit has been on it. the casting in the side of the block says 72mm
    also where could i get a fat bastard or a similar flowing exhaust? im not looking to spend too much money on the bike, although i probably will.
    lastly are the pro-circut exhausts better? i haven’t heard anything about them
     
  5. joe allen

    joe allen Member

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    also if anyone was wondering the bore of a vitos 240 with a 3mm stroker crank
     

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  6. Slydog

    Slydog Active Member Technician

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    Yeah thats where im at right now 251
    Vitos performance. Makes the fat basterd pipe the same that made your big bore kit.they are not cheap. But is good
     
  7. joe allen

    joe allen Member

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    is there any option cheaper? they are 500$ on vitos website. also would my fmf constrict my bike too much or could i still get my head ported and bored and get a fat bastard further down the road?
     
  8. Slydog

    Slydog Active Member Technician

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    Like awk mentioned the fat basterd would wake it up. Maybe it comes with a free tube of ky?. I run a B1 Toomey.
     
  9. joe allen

    joe allen Member

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    Are the Toomys better than fat bastards?
     
  10. Awk08

    Awk08 Administrator Staff Member Technician

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    Pipe opinions are subjective, what's good for one guy may not suit another
    FMF, Pro Circuit and DMC are targeted for low to mid range power
    Toomey is mid to high rpm power, the right bends like LRD, DynoPort, CT/Trinity, and all the related power pros made pipes perform best at high rpms
    I'm not sure about the fat bastard but thinking Vitos designed it for their big bore cylinder, for a ported/head mod Vitos cylinder ????
    I always suggest to suit the pipe to your riding .... low/mid rpm track or tight trail riding ? any of the low/mid pipes would be best
    the Toomey seemed to be great at all rpm ranges to me, and I've had most of the right bends over the years, the CT pipe was best for my riding.
    BUT .... any bike can be ridden in the rpm range the pipe on it was designed for by using the throttle and gears to keep it in the rpm range the pipe makes power. and any pipe is better than stock.
    In your case I'd go ahead with the bore/hone, new piston, porting and head mod from KOR and see how you like that paired with the FMF, it may suit your riding style/area ? then upgrade the pipe later if needed.
     
  11. joe allen

    joe allen Member

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    alrighty i am doin mostly trails and track but i like the top end too
    ill probably get a Toomey later on

    Edit: I may have drank a bit last night and I pulled my engine so I’m going to go ahead and send my head and cylinder out
     
    Last edited: Sep 18, 2020
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  12. Slydog

    Slydog Active Member Technician

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    What happened? Woke up and the motor was on the bench:eek:
     
  13. joe allen

    joe allen Member

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    I’ve done it more times than I like to admit...

    Also, when you get you cylinder bored and ported at KOR, will he provide a new piston or do I need to order a separate one? Just wondering how it works
     
  14. Slydog

    Slydog Active Member Technician

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    Print the form out from his website that you will
    Need to send your cylinder in with it asks on it.
    He can ste you up with everything if you want.
    Just open the box. And you have everything you need to install. Might have to ask for intake and exhaust gaskets?
     
  15. joe allen

    joe allen Member

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    good thing i pulled my motor apart [​IMG]
     
  16. joe allen

    joe allen Member

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  17. Slydog

    Slydog Active Member Technician

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  18. joe allen

    joe allen Member

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    That could’ve been bad
    I guess I’m going to be out my bike for a while since KOR is booked for 4 weeks on cylinder porting. Any other companies that you would suggest? Dads a little mad that he came home from Colorado to a shed full of blaster parts.
     
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  19. Larry's Shee

    Larry's Shee Active Member

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