A Hodaka Mini-Bike?

They never made a Mini-Rat, did they?

Aug. 05, 2009 By Rick Sieman
Custom Hodaka Mini Rat
The only Mini Rat in existence.

The concept of the project came during the return trip from an AHRMA vintage motocross in Arizona some ten years ago. A superb motorcycle mechanic friend of mine, Paul Duchene, and I were discussing possible "unique" bikes to build. We contemplated the usual dream bikes of every vintage enthusiast you know, like a TM-400 or KX-250 powered Bonanza mini-bike, or a Pro-Fab Yamaha 125cc twin motocrosser, or the bike that Hodaka should have but never built: a 50cc entry-level mini-sized Super Rat!

The "what if's" helped pass the time getting home to So-Cal, but the crazy ideas didn't end with the drive. A few years later, Paul surprised me with a gift - his latest Ebay find: a 55cc Hodaka engine. A what? A 55cc four-speed oval-cased little jewel that we, a couple of long time Hodaka freaks, had never seen or heard of! That settled it - time to create a complete bike around the little engine.

Fast-forward a few more years and the day arrived to actually get started, having assembled all the parts and pieces necessary. My original vision was to build a proportionately scaled-down Super Rat. In comparison the little engine was maybe 30% to 35% smaller than the 100cc Hodaka mill.

If a project doesn't excite you it can be hard to maintain momentum, or even finish it. I wanted to achieve the fit and finish that looked "factory" and not fabricated. I wanted people to see it and say "Wow, I never knew Hodaka made that."

Custom Fab Work
Attention to detail is staggering.

I took parts from five different Hodakas to make it. First an Ace 90 frame was altered to match the exact particulars of a correct model 93A Super Rat by removing the mounts for the horn, tire pump, battery tray and coil.

I then took three-inch sections out of the four down-tubes and another three inches out of the backbone under the fuel tank.A 93A swing arm was shortened by three inches. The 27mm fork tubes came also from an Ace100, although they were still too long, so I machined internal travel limiters to reduce overall height. The fork tubes were mated to 1978 Dirt Squirt 80 Hodaka fork legs, which when chromed, look exactly like Super Rats, only smaller and shorter.

The shocks are 10 inches eye-to-eye, and are dead-ringers for the Super Rat suspension and were sourced on Ebay.

Wheels are from donor Dirt Squirt 80; 16" front and 14" rear, with Cheng Shin Nitto copies for rubber.

Fenders are NOS (New Original Stock) Ace 90 inner rear for the front of the bike and NOS Wombat 125 front for the rear, both cut and radiused to suit.

Number plates and brackets are proportionately reduced in size by approximately 35%. Even the fender and number plate hardware is five mm instead of six.

The saddle was narrowed two inches and shortened three inches. I layered the foam in one-inch increments and hand shaped it on a belt sander to match the 93ARat.

Custom Hodaka Mini Rat
Superb example of the bike builders art; for example, the metal tank was reduced in size to fit the concept.

The fuel tank was the "key" to the whole package and had to be perfect. Knowing I wasn't capable of quartering a steel tank, welding, stretching and shrinking the metal without filler to be straight enough for chrome plating, I contacted Cole Foster of Salinas, Ca.

Cole is a good friend and the best chopper / hot rod fabricator I've ever known. He narrowed a stock Super Rat tank by two inches, shortened it by three inches length-wise and one inch in height. He is a master - there is ZERO filler in the tank!

He advised that I have my chromer copper plate it three times and block sand it between, which I did. The end result was amazing - although very expensive - but worth every penny.

Custom Mini Rat Bars
Special bars from an early Husqvarna were fabricated to fit the package.

I cut down two sets of handlebars until I was happy with the bend and width. The silver cables I fabricated from NOS early Husqvarna examples, since they were of smaller diameter than stock. I took stock control levers, shift lever and brake pedal and shortened them all one inch to one inches.

The expansion chamber is an AT1 NOS down pipe piecut to reduce cone diameters, with a Super Rat heat shield added. Stinger diameter is inch O.D.

The air cleaner is from a Wombat 125, as it had the smaller outside diameter I wanted. I shortened the depth by one and inches and molded in a bumped outer panel to replicate the 93A Rat. The air boot is from a SL-100 Honda.

Hodaka Mini Rat
Everything is in perfect proportion.

The engine is a 55cc Hodaka prototype (transition) piece from Yamaguchi to Hodaka, circa 1963. It has Hodaka cast into the shifter inspection cover and also into many internal engine parts, including the con-rod and primary gear. The bore is 42mm, it has a whopping 3-disc clutch (two fiber, one steel) a four-speed tranny and a 16mm Mikuni.

Final wheelbase is 43", seat height is 26", and weight is 125lbs dry.

As for finish, the frame and swing arm are powder coated to exactly match the 93A Super Rat.

The air cleaner and chain guard are painted a slight variation from the chassis color per original spec.

All bare aluminum was polished, then ball-burnished to tone it down to that "NOS" sheen. I probably invested 100 to 120 hours in it over four months.

It starts and runs quite well, with a typical peakiness of most early two-strokes. Since completion, it's been shown twice; first at the Bator International Classic in Hanford, Ca., where it took 1st place, and finally at Hodaka Days 2009, in Athena, Oregon, where it won Best Custom, Best of Show, and the Henry Koepke award for design excellence.

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