Soma-san's Corner

The two-stroke obsession spans across the globe. When I moved to Japan, I met my friend Japanese Soma-san.  He is a fellow two-stoke head like me!!  Like most Japanese, he is crazy into his hobby.  He owns a good amount of bikes.  He has:  two Honda MB5s, a Honda MB8, a Suzuki Z, and Yamaha 250Z.  He has tons of parts.  He even has parts under is desk in the office.  When I say parts, I mean two engines, a frame, a fairing, a exhaust, etc.  This guys is crazy!!  Like me!!  I turned him on to Treatland USA and now he is straight up lost his mind!!

Honda MB5 in its natural habitat

Two-Stroke Tuner's Handbook

Feed Your Brain!!

Anyone who is serious about two-stroke tuning read or came across Gordon Jennings "Two-Stroke Tuner's Handbook".  Although it was originally published in 1973, a lot of the information still pertains today.  It's a extremely technical book.  I felt like I was reading my old college engineering books!!  If you didn't get a chance to read it or a lot of the stuff is just flying over your head as did mines, some section I thought worth reading were:

• Squish Bands
• Expansion Chamber
• Port Timing
• Cylinder Porting (Gorr) p.90
• Reed Valves
• Intake Port Shape
• Cylinder Scavenging
• Port-Edge Chamfers
• Subtleties p.121
• Carburetion, Ignition

Puch ZA50 Motor Case & Transmission Gaskets

Here are scanned copies of a case gasket and transmission cover gasket for the Puch ZA50 motor.  These gaskets are available at Treats or 1977 Mopeds.  If you don't what to any spend money or just too impatient for an order, you can download the PDF file here.  Print it onto your gasket material then cut out using a xacto knife and scissors.  The key to making these types of gaskets is to use the correct size paper hole punchers for the bolt holes.

Mr. Two-Stroke

“…You have to know what you are doing with a two stroke, you don’t with a four stroke.  With a two stroke you are doing it yourself, with a four stroke you buy the pistons, buy the cam shafts and just take it apart and put it back together.  There is less skill, it’s just fitting…”

An quote from an article featuring world renown two-stroke tuner Stan Stephens.  Read the whole article here.

Puch Second Run: Post Disaster

One step backward, two steps forward.  After the epic meltdown of my Powerdynamo stator coil, I installed a new one I ordered from TreatsHq (it came in less than a week).  I re-timed it and tuned the carb a little more.  Still need to continue tuning cause there still some dead spots in the powerband.  But its getting there:

Puch ZA50 Clutch Rebuild Part 2: Second Gear

My second gear clutch was surprisingly in great shape compared to my first gear clutch.  The clutch shoe lining were all intact and not cracked.  I previously lightened the shoes without taking them apart by drilling numerous holes via a drill press.  (Note:  Optimal location to lighten the clutch shoes is along the outer edge as shown below because it has the most "metal mass" that can be removed.  Also, you want to take out the most "metal mass" toward "that side" of the linkage hole pivot point to optimize the "lightening" effect on the clutch.   The outer edge of the pivot point has the most mass that produces the centrifugal force which the clutch shoes needs to generate to overcome the  centripetal force created by the clutch spring.  When this happens the clutch will engage.  Less mass on the shoes means you need more angular velocity to generate the centrifugal force.   Hence, the clutch shoes will engage at a higher RPM giving you that longer "stall".  Anyway, enough physics!!)  As I did with the first gear clutch, I banged out the linkages:

All blown up!!

Puch ZA50 Clutch Rebuild Part 1: First Gear

I was forced to rebuild my clutches after a total destruction of my first gear clutch shoes by my Gilardoni kit.

Puch ZA50 Clutch Installation Tool

Getting springs on a Puch ZA50 stock clutch isn't a walk in the park.  Many of us shy away from cutting or reinstalling new springs onto our clutches because of the difficulty and hassle to get them on.  But by doing either spring modification, it can greatly benefit a ZA50 motor's performance.  For a long time, I've been thinking of a way to easily reinstall springs onto these clutches.  I've been looking for a better way ever since I ruined the elasticity of my first springs by installing them with a bunch of screwdrivers.  In the past, we used a D-sized MagLite flashlights or a worn down skateboard wheel to get them on. But these methods usually meant more than one pair of hands to do it.  I've even saw someone use their bare hands to get them on.  Ouch!!  I just don't have that kind of hands!!  With a design in mind I had for years, I finally decided to try to make life easier for all us ZA50 modders:

Get The Lead Out!

Videos to get the modding juices flowing!!...GET TUNING!!

Island Built Scooters

A few videos I recently saw from Guam and the 808 State that got me excited about scooters again!!  The first set is a Yamaha JOG.  The second one is a SMC Rexy.  And, the third one is a Honda Dio (?).  Unfortunately, the second one is a four-stroker but it still represent.

Moto Champu Zasshi

Living in Japan, I have the luxury of accessing the many scooter magazines (zasshi) this moter-bike crazed country has to offer.  Scooter or moped magazines are a rarity back in the States especially Hawaii.  One of my favorite magazines here is "Moto Champu".  Moto Champu (or Moto Champ) features a lot of bikes like the Honda Monkey, Dio ZX, and Yamaha Jog ZR.  The content is all in Japanese but it's worth buying for the pictures alone.

I can read this.  It's the Kanji for book.

Curtis (Got Rigid?) Rigid Maxi

A short clip of the famous Rigid Maxi in action:

Curtis (Got Rigid?) Rigid Maxi from gza710 on Vimeo.