As far as routine maintenance goes, no one is ever in a mad hurry to check and adjust valve clearances. It’s as involved as mechanical tasks get, short of a top-end or engine rebuild. However, you ignore them at your peril. Incorrect valve clearances lead to lumpy running, poor starting and, in extreme cases, burnt-out valves.
Everyone knows someone whose valve clearances have been rigorously checked, but adjustment has never been required. The brand name ‘Honda’ usually figures in such tales. Far be it from us to doubt the veracity of these legends, but the fact is that valves can and do go out of adjustment and motorcycle brands and usage really don’t seem to have much bearing on matters.
Most motorcycle owners are not really sure what would be a good baseline static sag setting for the suspension. Static sag is how much your motorcycle settles on its suspension with you or the rider in the seat.
A good amount of motorcycles sold in Thailand are not set-up for the average European or American rider, which results in a suspension that works less correct.
Even when you think your two-wheeled best friend is running without issues, it might be time to put a new battery in your motorcycle. But what type of battery should you buy? Life was simpler a couple of decades ago, when only conventional batteries were available. Several years ago, absorbed glass mat (AGM) batteries became available, and more recently, lithium iron phosphate batteries have hit the market.
Conventional batteries are also known as lead-acid, or flooded electrolyte, batteries. These batteries contain several series of positive and negative plates of different materials (including lead); each series of plates is contained within a sealed cell. The plates are immersed in electrolyte, which is a mixture of sulfuric acid and water. It is the chemical reaction between the electrolyte and the plates that produces electricity, at a rate of roughly two volts per cell, which is why there are six cells (and six filler caps) on 12-volt batteries.
Note that 12 volts is a nominal value, and batteries are actually designed to work ideally between 13.5 and 14.5 volts, with a static voltage of at least 13.2 volts. That means that if your voltmeter reads just 12 volts, it's time to put your battery on a charger.
Most owners of old two-stroke motorcycles know that they're harder to store long-term compared with four-strokes because the engine internals are more exposed to the atmosphere. With some understanding of the engine you can with a single-cylinder turn it in the top-dead-center which will close the intake and exhaust ports.
With a two-stroke engine the crankshaft bearings are only being lubricated by the two-stroke oil in the fuel mixture when the engine is running and any moisture in the air will settle on cooler metal. A capful of oil down the bore may keep the piston and rings coated, but it won't touch those crankshaft bearings, and if there's a spot of corrosion on the faces that's about the most costly repair on any two-stroke engine.
It's not a glamorous component, but you're stuck without it. Your motorcycle's regulator-rectifier turns alternating current (AC) produced by the charging system into direct current (DC) and also controls the charge going into the battery. That's vital because enough power at idle to run the engine and any accessories, which is about 20 volt AC, jumping to 100 volt AC when revved.
Any excess current is converted into heat, which is why a regulator-rectifier needs to be mounted in an exposed position to use airflow to keep it cool – and why it's kitted out with fins, as you can see in the picture. But that means it's also exposed to dirt and moisture and the block connectors can get grimy and increase resistance and heat.
If your motorcycle is a few years old it's worth checking the condition of those connectors as 80 percent of the time it's increased resistance there that starts to stress the regulator-rectifier itself. Cleaning them, then sealing them with non-water-based grease is good preventative maintenance.
Most times when your motorcycle is having problems or has quit running, the problem is traced back to a poor electrical connection. It takes time to trace where that problem is located and could have easily been fixed. Over the years I have seen all kinds of wires connected together using wire nuts and just twisted together with black tape wrapped around them. Many use crimp connector which works fine, but over time the wire can oxidize which will fail in time. Especially in a tropical climate like Thailand…
The soldering method, if done correctly, will be a permanent connection. It is not that hard to do, if you follow these steps for proper joining and soldering.
The tools and supplies needed, are easily found and cost little:
Thankfully it's rare that anyone has to pull an engine apart after some catastrophic issue these days. Modern motorcycle engines are generally reliable and hardly ever give major trouble. Routine maintenance and replacing ancillaries should be all that is needed, with valve clearances usually the only time we have to delve inside.
But occasionally something breaks, or hits something else, or wears out and the first we know is a nasty noise, loss of power, a bad smell or – worse – the rear locking up and bits escaping. When this happens, what is the best course of action?
The first step is simple. Diagnosis: see what went wrong and work out if it's something you can repair. If you can peek inside the engine through a hole made where a part escaped, then the whole engine is very likely ruined. Otherwise, does it turn over on the starter? Will it select neutral and change gear if you move the rear wheel? Is there oil and water? It so, is there metal swarf in the oil? Could it be chain, brakes or gearbox? All these questions will help isolate the problem, so that you can then decide if it's economical to fix or replace.
Production lines have all necessary controls and inspections engineered into them, but an individual building an engine must take responsibility for fits and tolerances. This is the case in a race shop or for a home builder. The basics are in the available manuals for all to see, and you begin, as one man put it, ‘By just getting into it.’ We all begin with just the desire to do it and w willingness to learn from mistakes. Experience causes the unfamiliar to become familiar.
I got a call from two club racers who’d decided to change the crank in their Yamaha, Honda or a Kawasaki. They basically wanted someone to tell them they could do it. They had the manual, some tools, a new crank, and desire. It took them weeks of evenings, and we spoke on the phone often. They found and removed fasteners, pulled the heads and cylinders, and then the pistons.
The parts began to look less scary and more familiar to them. Engine features began to make sense. Each step was in the manual – pulling the ignition rotor and crank primary primary gear. Storing, even labeling, the parts as they came off. They gradually became their own experts.
Gearbox problems are very rare nowadays, but normally only affect first-to-second upshift. The reason for this is that gearbox ratios are not evenly spaced but are widest apart at the bottom and become closer at the top. As a result, the speed difference and the shift impact are greatest on the first-to-second upshift.
That's why quick shifters normally work better from third upwards. This engagement impact from first to second gear is also transmitted through the gear teeth and then through the gear itself to the shaft. You can imagine what forces act on these gears when you are playing rough with 200 horsepower at the rear wheel. To make the gearboxes last and survive the high tooth-to-tooth pressure, gear surfaces are hardened by a nitride coating.