in the transition to a new, much more amazing, frame for the derbi, it was time to case match and do some porting.  i didn’t feel like splitting the cases and doing a full rebuild.  to avoid aluminum shavings all up in my crank and bearings i used some play dough and plastic wrap.  obvserve…

step 1: use the new base gasket to mark the material you want to take away.
stock to 65 metra
step 2: cut a piece of plastic wrap to fit inside the crankcase sleeve. poke a hole for the conrod and slide it in. the plastic wrap makes it easy to pull all the play dough out in one swoop.
case match prep part 1
step 3: play dough time! mash it in and make sure there aren’t any cracks.
case match prep part 2
step 4. grind away. a huge part of successful case matching is making sure you have the right bits. my favorite for aluminum are dremel’s high speed cutting bits. i like to use the largest cylinder one they make (aluminum melts at it’s hands), and a smaller cone shaped one to smooth in the rounded bits.
then i clean up and smooth out with a cone shaped stone bit. finished product!
step 5: clean up time. i used some of the left over play dough to dab at the aluminum shavings so i didn’t have a bunch of floating chunks lying around when i took the play dough out. after that just dig around the edges and grab ahold of the plastic wrap and pull everything out. i did a quick spray of brake parts cleaner just to be sure i got everything out. annnd ship shape!
ship shape!



  1. 1 Metrakittayyy

    case matching upgrade 150 crystals 150 vespene gas. *click*

  2. 2 vic

    frame change huh? sell me your variant brake levers and maybe the chain cover if you’ve got it.

    • 3 gabeb

      hmmm, at this point i think i’m still going to try and sell it complete. i’ll let you know if i decide to part it out.

  3. 4 jeremy bandit

    looks nice and clean, dude. good tips too. I used silly putty, but I think the play dough would be much easier to find.

  4. 5 Derek

    Im getting ready to try this this week!!

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