Modifying a Honda NC50 Express/Express II to Rope Start
Disclaimer: This tutorial is to fabricate a working idea. Although it has been reproduced by myself and others, there is no guarantee or warranty of fitness for use and safety. Use of the information in this tutorial is at the user’s own risk and I will not be held responsible for injury or death (in the highly unlikely case of) in conjunction with use of this or any other tutorial derived from this work. Use of this tutorial in modifying the NC50 engine will void any warranty real or implied if such warranty is still valid.
In short, if you hurt yourself, I am not responsible. If all safety procedures are followed while using power tools and common sense prevails, this modification should be successful and all your fingers should be intact.
This tutorial will walk you through the steps of modifying the starting system of the NC50 series of Honda Scooters. There is one precaution that should be followed at all times. When working with the engine, you should always remove the spark plug wire, lest you accidentally start the engine inadvertently.
First off, you will need a few things. Below is a list of items needed to take on this task.
Large screwdriver to hold the flywheel
Socket set that includes metric sockets.
Grinder (bench and/or hand)
Drill and bits
Starter cup for either a Briggs & Stratton or Tecumseh lawnmower engine
Starter Rope kit
Clear Coat Lacquer
Right about now, you’re asking yourself, "Why do I need all this stuff?" This will all be explained as we go along… so read on.
This modification will use a starter cup from a lawn mower to wrap a rope around to spin the crankshaft and thus start the engine. This is by all means a primitive yet effective solution to a broken NC50 wind up starter. We also will be needing a protective shroud that will keep your leg from being caught up into the moving parts. This is where the sheet metal comes in. Each part will be broken down into steps that will include where to get parts.
Pull Rope Preparation
You can Purchase a new pull rope kit from most Lawn & garden stores and/or Small Engine Repair and Parts stores. The kit will include a high quality rope and a pull rope handle. You can also cut the rope off a lawnmower at a junkyard at a cost of about a dollar. Either way, we will need to tie a rather large knot at the very end of the rope. I usually double or triple knot it. Once you have your rope ready, set it aside and we’ll move on.
Starter Cup Preparation
You will first need to obtain a starter cup from a dead lawn mower, a junkyard or a small engine parts store. I myself repair lawnmowers on a regular basis and have these cups lying around as leftovers from blown engines. Check your local junkyard for lawnmowers. Some Small Engine Repair and Parts stores carry these as well.
Here is what you are looking for. Note that there is no notch for the rope to sit in. This is where the modification comes in. Some older minibikes and other side shaft engines had rope start cups with pre-fabricated notches in them. The problem with those is they are designed to spin clockwise. The NC50 engine spins counter-clockwise when looking at it from the right side of the bike. We will have to use a grinder to cut a notch into the cup for the rope to rest in. So get out your grinder and your safety glasses and let’s get to it. With the cup in the upright position (with the wide lip facing up), cut a groove about