Friday, December 30, 2016

Rat Racer Returns - Episode #39

By: David L. Morrill
@ Mototique

Updated 12-31-2016

Rat Racer at the Rat's Hole Bike Show at Ocala, FL. Bike Fest
Photo by Julius Williams
Well, it's been about a year since I have given an update on my 1921 Harley-Davidson replica racer, which I call "Rat Racer." It's always a continuing work in progress, with several changes since I last wrote about it in Episode 29. To start with, it made an appearance in the Rat's Hole Bike Show at Ocala Bike Fest this past July. Teddy Smith, and his staff at the Rat's Hole do a first class job, and were great folks to work with.

The day of the show, a photo of me sitting on Rat Racer appeared in the Ocala Star Banner article on Bike Fest. Pretty cool!

We were lucky enough to walk away with a win in the Pre 1935 Antique Bike Class and received a great plaque designed by Teddy Smith.

Rats Hole Bike Show Plaque
By Teddy Smith

With the bike show commitment completed, I could concentrate on converting Rat Racer to ride on the street. There were several problems to solve, including working brakes/clutch, and a better carburetor. I tackled the carburetion problem first. Over the past few years I have tried both period Schebler  & Linkert carburetors. The problem was neither could be leaned out enough to use on a single cylinder bike. I finally decided to go with a 1970s era 34mm Mikuni VM carburetor. Yeah, I know it's blasphemy to use a modern Japanese carburetor on a 95 year old Harley-Davidson. Funny thing is, before switching over to fuel injection, all the modern carbureted Harleys used Japanese carburetors.

The Mikuni, being a much more modern carburetor, has several advantages. First they are relatively cheap, especially compared to period alternatives. Second tuning parts are readily available and reasonably priced. Finally, I am very familiar with tuning these Mikuni carburetors from my AMA road racing days. With a little tuning, the engine ran strong throughout the rev range with the Mikuni.

The next problem was a working brake. The rear wheel assembly with the Free Wheel Clutch assembly I am using, also comes with a period style drum brake on the right side of the hub. The trouble is the hub assembly with the clutch and brake, would no fit my racing frame. I opted to use the hub with the clutch assembly, and find an alternative brake for the front end. This required a pretty significant offset in the lacing of the rear wheel to get the tire aligned with the centerline of the frame, but after a few hours of painstaking adjustment, everything lined up.

Free Wheel Clutch Rear Wheel After Alignment
After some time searching Bay, I located an early 80s Kawasaki dirt bike front wheel with a small drum brake. 

Front Wheel Assembly with Drum Brake

With all the major problems solved, it was time for a road test.

Rat Racer Road Test - November 6, 2016
Lee Merkel Field - Sylacauga, Alabama
The bike ran very well, reaching about 55pmh, tracking straight, the plug reading was good, and the front brake worked superbly. Mission accomplished!

Rat Racer - Road Ready


Deadly Dave's Collection

Ocala Star Banner

Julius Williams

1 comment:

  1. Good Luck for 2017!
    Come over to Bielefeld and let the brake at home... ;-)