Honda C90 - putting it back together

Honda C90 - putting it back together

Intro If you have dismantled your bike in order to refurbish it then, once you have finished reassembling the engine, you will be faced with a large pile of bits that need putting back together. In the immortal words of the old Honda manuals: "Perform the reassembly in the reverse procedure of disassembly."...
Intro If you have dismantled your bike in order to refurbish it then, once you have finished reassembling the engine,...
Honda C90 - carburettor - cleaning and replacement parts

Honda C90 - carburettor - cleaning and replacement parts

There are only a few things that can go wrong with the simple carburettors used on the Honda c90 and – once you have a rough idea of how these parts work – the fixes are straight forward and largely common sense. A note of warning from the early workshop manuals: Engine trouble during acceleration is caused...
There are only a few things that can go wrong with the simple carburettors used on the Honda c90 and...
Honda C90 - carburettor choke

Honda C90 - carburettor choke

Fuel evaporates poorly at lower temperatures and, when the engine is cold, tends to condense on the walls of the intake manifold and cylinder making the engine hard to start. The solution is to make the mixture richer, either by temporarily adding more fuel or by restricting the amount of air. The mechanism used on...
Fuel evaporates poorly at lower temperatures and, when the engine is cold, tends to condense on the walls of the...
Honda C90 - carburettor idle circuit

Honda C90 - carburettor idle circuit

The idle circuit, sometimes called the pilot or slow circuit, controls the mixture of fuel and air at low throttle speeds. There are not many components involved, read on to see how they work together to ensure the engine ticks over smoothly at low revs. Pilot jet The orifice in the pilot jet is tiny...
The idle circuit, sometimes called the pilot or slow circuit, controls the mixture of fuel and air at low throttle...
Honda C90 - carburettor main circuit

Honda C90 - carburettor main circuit

The carburettors fitted to the C90 super cub have two independent systems for metering fuel and air, the main circuit and the idle circuit. The idle circuit is designed to control the mixture of fuel and air at low throttle speeds and the main circuit determines the mixture at higher engine speeds (you can get...
The carburettors fitted to the C90 super cub have two independent systems for metering fuel and air, the main circuit...
Honda C90 - carburettor fuel supply

Honda C90 - carburettor fuel supply

Parts The engine needs a constant supply of fuel – the parts involved are marked on this picture of the dismantled carburettor: * fuel tap * float bowl * float * float valve Fuel supply The fuel is fed to the tap by gravity from the tank where: 1. It passes through a filter and up through the hole marked...
Parts The engine needs a constant supply of fuel – the parts involved are marked on this picture of the dismantled...
Honda C90 - carburettor overview

Honda C90 - carburettor overview

One of the first things I did when trying to get my old Honda C90 to run was to clean the carburettor, having read that it might have become clogged up with old fuel while it was in storage. I did eventually get it to run but it didn’t idle well and was hard...
One of the first things I did when trying to get my old Honda C90 to run was to clean...
Honda c90 z2 - introduction

Honda c90 z2 - introduction

Introduction Honda’s Super Cub step-through motorcycle is the most successful motor vehicle ever built and a staggering number – well over 100 million – have been sold. I was lucky enough to find a low mileage 1978 C90 for sale a few miles from where I live. It ran for about half a mile before conking...
Introduction Honda’s Super Cub step-through motorcycle is the most successful motor vehicle ever built and a staggering number – well...