new reeds and pro tips


On my old Polini setup I was getting some reed fluttering at the top end when I would let off the throttle at high speeds. This was only going to get worse with the porting and reed mod that I did, so I bought some thicker reed material. Stock Polini reeds are .30mm, I bought a sheet of .35mm Polini reed material. An entire sheet costs less than a set of precut reeds, and I can get about 10 sets out of it. SCORE.

I got good advice from some gurus on how to cut reeds. I used a reinforced dremel cutoff wheel (the regular one would probably work fine), with painters tape over top of the reeds to help prevent fraying. The biggest danger when cutting reeds is fraying, so you don’t want to try and cut it with a blade or sheers. Graham mentioned the best thing would be a CNC engraving tool…you know, for putting that CNC you have laying around to use.

Traced and ready to go.

When I looked everything over i noticed the bottom of the Polini intake and reed block didn’t quite line up. The reed block is straight across and the intake has a slight swoop to it. So I busted out a hand file and got everything line up properly.

more filing

With that done I cut the reeds a little longer than stock so they still completely covered the reed block.

new reeds

After some painstakingly precise lining up, this little duder was ready to go.


Peter has been hibernating, so I’ll leave you with a PRO TIP: When installing your Polini cylinder, do it with the intake and reed block off. This way you can make sure your cylinder/piston intake/boost ports all line up. There’s a surprising amount of rotational cylinder play (unless you have some fancy brass case stud bushings) that can cause things to not line up and steal performance. This should give you a decent idea of what I’m talking about. You want it to look like this…

little things

Then bolt everything up with a thin layer of RTV on each side of the intake and reed block gaskets so you don’t have to torque your intake down wicked tight.

I made a bunch of progress on lil busey last night. Need to work out a fork bearing issue (this has been the bain of my existence), then finish up a few little things and it’ll be time for tuning and tweakin. Really antsy to get this duder back on the road.

almost done


9 Responses to “new reeds and pro tips”

  1. Mopeds/Musical instruments. Excellent stach, by the way.

  2. did you just drill the holes for the mounting screws?

  3. man nostalgias look great with aftermarket forks, i gotta do that to mine..

  4. 6 franta

    So for the midwest polini e50 race is the limit a 15mm bing?

    • 7 gabeb

      nope, here are the rules for the 70cc e50 class (not limited to just polinis)

      70cc e50 class
      1) must use e50 cases and transmission
      2) must use any 70cc or less PUCH cylinder
      must use 2 or 3 shoe type PUCH clutch with unlimited modifications (different springs, re-enforcement plate, cutting shoes, adding clutch material) but clutch must maintain pivot type engagement arms
      any crank ok, but must maintain stoke stroke
      3) no exhaust restrictions
      4) no intake or carb restrictions
      5) no ignition restrictions
      6) no limitations on braking or suspension systems
      7) wheels must be 14 or larger
      8) twist and go only no more than 2 speed automatic (no manual shifters allowed)

  5. 9 kevin kelley

    A jewlery saw will cut reeds with super clean edges.

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