The mower appears affected by Ethanol

I have a Toro ride-on mower which ran out of fuel when it was just a couple of years old, perhaps 50 hours on it. Okay, so that is going to happen with failure to check fuel level before starting… but the problem was that when the tank was filled, it would not start, the petrol pump would not self prime even though the suction head was very small with a full fuel tank.

Mindful that long cranking is very hard on batteries, I used the starter sparingly in short bursts with cooling off time. Nevertheless, the battery went open circuit.

So I replaced the battery and primed the pump by hand… and all has gone well for some years… until last week, I ran it out of fuel, duh!

Same problem, when the tank was filled, the pump would not self prime.

The machine has a problem that needs to be fixed.

The inline filter was checked, and fuel flowed though it quite well by gravity. This time, I primed it by hand early in the process and got on with mowing. This was probably not a vapor lock problem, everything was quite cool by the time I fueled the machine. Continue reading The mower appears affected by Ethanol

The mulcher appears affected by Ethanol

I have a chipper / shredder that has a Briggs and Stratton 6.5hp (~5kW) Intek I/C 206cc engine on it.

On a recent routing maintenance inspection, I dropped the carburettor bowl to look for signs of Ethanol damage (mainly corrosion). During that inspection I noted that the bowl gasket was hardened even though the engine is only 13 years old, and that a stain on the mulcher body hinted a fuel leak even though the bowl exterior seemed dry on test..

The machine is usually stored with the petrol cock off, so the opportunity for a needle / seat leak would be during a day’s yard work where the petrol cock is on for hours but the machine is run for a lesser time.

A pressure test might provide a firm diagnosis.

A piece of silicone tube was connected to the carburettor in place of the normal fuel hose, a little petrol added to the hose with a pipette, and then a sphygmamometer used to pressurise the hose.

Above, the test in progress. The fuel level in the hose can be seen about 30mm from the end. The pressure is leaking down quite slowly, the leak is not fast enough to upset engine operation (by flooding or even an over rich mixture) but it might well result in dilution of the crankcase oil when the engine is left standing. It needs repair. Continue reading The mulcher appears affected by Ethanol

Chinese chainsaw review – SX25 #1

When we moved to this place in 2009, I could see the utility of a ‘aborist chainsaw’, or ‘top handle chainsaw’.

I bought a cheap Chinese 25cc jobbie, in fact it was so good I bought a second for spares.


This saw had seen off 6 chains by 2021 and forced by some reliability issues, I decided to replace it with the spare and repair it at my leisure (parts from China are real slow). It has had a good life, usually warmed up before being gunned up to WOT to avoid cold seizure. Continue reading Chinese chainsaw review – SX25 #1

Small 2-stroke engines and popoff pressure

This article explores the physics of fuel metering in a typical small diaphragm carburettor (carburetor to some) as used on small 2-stroke chainsaws, leaf blowers, brushcutters etc.

The discussion following is in terms of absolute pressure, and it is assumed that atmospheric pressure is 100kPa. ALL pressures are absolute unless stated otherwise, to find gauge pressure, subtract 100kPa.

Above from Zama is a cross section view of the metering chamber of a typical butterfly carburettor. The metering lever pivots on an axle (1), the distance from the axle to the needle (2) is 3.5mm, to the spring (3) is 3.5mm, and to the contact to the metering diaphragm (4) is 8mm. The needle seat is 0.55mm diameter. Continue reading Small 2-stroke engines and popoff pressure

Small engines and green fraud

Recent weeks have seen some catch up work on maintenance of small engine yard equipment. There are 22 engines in all, 6 4-stroke and 16 2-stroke.

For some years, ‘green’ measures implemented by government meant that ordinary unleaded petrol (ULP) was not available retail, one had to use E10 (ULP with 10% Ethanol).

Greens claimed that at such low Ethanol, that the fuel was compatible with all existing and new engine equipment.

Diaphragm carburettors

Most of my 2-stroke small engines use so called diaphragm carburettors. These ‘all position’ carburettors are common on yard equipment like brushcutters, leaf blowers, chainsaws etc.

Above is a Chinese after market clone of a Zama ‘butterfly’ type (note the throttle butterfly) diaphragm carburettor that suits a Stihl BG85 and similar leaf blower. (This cost $15 inc shipping on Aliexpress.) Continue reading Small engines and green fraud

Replacing the crystal in a Seiko V158-0AD0 watch

I have a Seiko V158-0AD0 which works very well, and I recently noticed the crystal was scratched more than the case… so a strong hint that it is an ordinary mineral glass crystal.

Searching the net, I could find that the Seiko part number for the original crystal is 310P03HN0 which indicates a diameter of 31.0mm but it does not have the thickness encoded simply. I could not find any articles giving the thickness of the part… so measurement was needed.

Above, the original crystal measures 1.6mm. A ‘standard’ 1.5mm sapphire crystal should be just fine. Continue reading Replacing the crystal in a Seiko V158-0AD0 watch

Reassembling a certain common chainsaw clutch

I managed to drop a chainsaw clutch and it separated into its component parts.

Thinking there would be a simple trick to this, I consulted Youtube. It turns out that reassembling these has proved a challenge for many people, and their online posts informed as to what approaches don’t work well, describing the many hours spent trying to reassemble. One online expert advised buy another, they are so cheap.

Above is a clutch of the type I will discuss, mine is from a 45-58cc Chinese chainsaw. There are variants, and the technique may be adaptable to them. Continue reading Reassembling a certain common chainsaw clutch

Sydney harbour is a beautiful place

One of the trips I am known to take is to Manly for lunch.

Above is a pic taken whilst waiting for the train home at Circular Quay. On the right is the ferry Freshwater arriving from Manly. The Opera House is just visible on the right north of the ‘toaster’ (one of the eyesores on the harbour).

It was a sparkling day on the harbour (Port Jackson) which bought back memories of many happy days boating and sailing, it is a beautiful waterway.

Manly is about 30min north east, 12km over the water, just on the north side of Sydney heads.

It is challenging to get pics on the ferry as tourists push their phone in front of your face to take videos, 5 to 10 minutes as a time.

Above, the route is from home to Bowral station by car, diesel train (Endeavor railcar) to Central, electric train on the Sydney underground to Circular Quay, and ferry to Manly. The return journey was similar but electric train from Circular Quay to Campbelltown then diesel train to Bowral. The round trip is just on 300km and nearly three hours for each direction of travel.

An interactive zoomable map is available. Zooming in around Sydney and a little south will show track jumps due to underground rail.

The track was captured with a Holux RCV-3000 GPS logger, logs downloaded with BT747 (Chinese firm Holux is defunct and so is their application which is now locked out of its maps provider).

Holux web site missing / offline, Holux ezTour crippled

I have had a couple of Holux GPS loggers for some time, a RCV3000 and GPS245+.

They come with a neat little application called Holux ezTour for Logger.

Over time, the application has been unreliable, mostly knock on effects of Google Maps licencing and Holux’s failure to obtain and distribute the appropriate licence keys. Continue reading Holux web site missing / offline, Holux ezTour crippled