Posted by Jerry on February 25th, 2007 — Posted in Journal, Motorcycling
Well, after about six years faithful service, my daughter’s postie bike (Honda CT110) began getting hard to start, and when it did, it started blowing smoke. I checked the compression and realised that the engine was down to about one-third the compression it should have. The dial read about 32 psi, when it should have been over 100. With a couple of weeks to go before my daughter was due to head overseas we just poured in some treacle-like ‘smoke free’ which brought the compression up to about 42 psi – still very low.
With the bike in storage I decided it was time to find out what the problem really was. My suspicion was a broken oil ring on the piston. I spent one evening last week removing the footpegs, bash-plate sub-frame and the exhaust pipe.
And today I set to work in earnest. It took less time than I expected. I began by removing the carby (two 10mm bolts) then followed the Clymer manual beginning with ensuring the piston was at top dead centre on the compression stroke.
I had also previously made a ‘piston holding fixture’ which you can buy as a special tool or make one from wood. The instructions were in the manual – for info you need a piece of wood 1/2inch x 1-1/4inch x 4 inches. and you just drill a 1/2inch hole in the centre and then cut away from one end until you have a fork – like this
And it worked perfectly.
But I digress… After removing the camshaft and with care to ensure that the cam chain did not slide down into the crankcase the head was removed. I used wire threaded through the cam chain to ensure it remained above the cylinder.
There was some carbon on the piston crown, and some deposits on the valves. The piston holding tool worked very well, but I needed to explore further. On removing the cylinder I found that the piston rings were quite worn, and that the oil ring was in three parts – clearly that is where the problem lies.
So it was time to remove the piston. This is secured to the connecting rod by two spring clips – not easy to see, but observing a small cutaway on the side of the piston, I noted a hint of a clip. With a pair of needle-nosed pliers it was a brief job to remove the clip from each side. I used a short piece of 1/2inch dowel to push out the piston pin and the piston was free.
After cleaning the worst of the carbon with a wire brush and fine emory paper I saw another issue – the top compression ring had at some point worn so thin that it had gouged the groove in which it sat, allowing for movement.
So it is likely we will need a new piston. But the bore seems unscratched and with luck I will be able to find a new piston to match. And that is a story for later in the week.
Meanwhile, there is a rather sad looking Honda CT110, with rags to prevent the entry of dust, sitting in my garage awaiting some new parts.
And the rest awaits reassembly on a nearby table
In the meantime, you can read more about this wonderful bike People actually race these things, and every year there is a Postie Bike Challenge in Australia where people ride these things from Brisbane to Adelaide (2005), or Ayre’s Rock (Ulluru)(2006). And this year 16-27 October the Postie Bike Challenge is from Brisbane to Cairns (over 3000kms) on some of the roughest and most beautiful country in Australia
And here is an online owner’s manual 🙂
Cheers
Jerry
4 Comments »
Posted by Jerry on February 18th, 2007 — Posted in Journal, Motorcycling, Technology
The Wheelsurf is an amazing machine – part 50cc motor scooter, part German wheel (circus wheel) 🙂 And it looks like a load of fun! – Click on the image to see how it goes 🙂
I can see my daughter coming up with a whole new circus act coming up with these…
Cheers
Jerry
Comments Off on Wheelsurf – Unicycle with motor!
Posted by Jerry on February 10th, 2007 — Posted in DIY, Journal, Motorcycling, Steam, Technology
There have been a number of projects over the years to convert internal combustion engines (petrol engines) to work on steam, either for vehicles or, more widely, for small generators.
Some use a bash valve, welded onto the piston of a small two-stroke motor, such as this steam conversion of a Motobecane moped.
But Lynx Steam Engines discuss in detail how to convert a small four-stroke motor to work on steam or compressed air, to run electricity generators, mowers ec – perhaps even small karts. Their approach is a good one, keeping it simple, and making minimal modifications. This one requires modification to the cam by smoothing the cams to round, and adding a valve lift lobe to the correct timing (90 degrees between inlet and exhaust) by adding round-headed screws 90 degrees apart on the cam. And there is some discussion on the site on making a steam generator that complies with various laws on pressure vessels (best to get it made by a certified boilermaker) to produce a near silent engine that won’t disturb the neighbours. These would not be self-starting motors, but seem like a good beginners project using off-the-shelf components.
The 90 degree valve timing is consistent with the model steam engines I have previous tried making, and seems to be a good standard – with teh main variation being in the cut-off or ‘dwell’ of the valves – ie how long they stay open once opened. The beauty of this design is it uses low temparature, low pressure saturated steam, making it no more dangerous than a kettle, and able to operate without having to worry about separating the oil from the steam when you re-use it.
I also like the way Lynx engines have put their concept into practices as an apporpriate technology project to power a coffee producing firm in Nigeria, using waste biomass as fuel, rather than expensive petrol.
Cheers
Jerry
2 Comments »
Posted by Jerry on August 20th, 2006 — Posted in Journal, Motorcycling
Last year when I last replaced my motorcycle drive chain it came with a spring-clip split link – which I have found quite safe for the past thirty years of riding. This time the new chain came with a rivet link.
Sure it seemed like a good idea, until I realised that I would require a new $200 tool to fit it. Moreover, I found that very few bike shops sold such a tool. The obvious inference is that replacing a bike chain has now become a specialist job.
Of course my bike was already at home, and I don’t have a bike trailer, and I had already removed the old chain in anticipation of fitting the new one.
Finally, I went to a bike shop that did sell the tool – but the mechanic said ‘of course that’s not how we fit them…’ My curiosity was aroused – could there be a simple solution? Sure – it just requires two hammers – one to brace behind the link, the other to pein it home.
So how does it work in practice? With the chain guard removed and the axle nut loosened and the chain tensioners slackened off I lined up the chain on the rear sprocket (having already fed it over the front sprocket). Having found the amount of overlap (about ten links) I used a dremel-like tool with a grinding wheel to grind down the rivets on the crossover link, then used a chain breaker to drive out the pins.
Now here’s the trick – I found that by then I had some grease on my hands and that when I fed the joining link through, I kept losing the side plate because it would stick to the grease on my hand. The answer was a small rubber band fed around the link to act as the third hand – one to support a small lump hammer behind the sprocket (an anvil) and a small ball-pein hammer in the other. I first drove the side plate on by peining in the centre of the plate with the ball end of the hammer.
Then, once the rivet heads protruded, I peined the rivet heads until they expanded over the plate to hold it in place. Remember there will be no side force on the plate, so you just need enough to ensure the plate won’t come off.
And within minutes I had the chain fitted and the bike ready to ride (after ensuring the wheel was straight and the chain had the correct play, and the axle tightened and a new split pin through the nut, and the chain guard re-fitted.
The result? a nice quiet chain, and no chain snatch 🙂
And the tools? Two hammers and one chain breaker!
Cheers
Jerry
17 Comments »
Posted by Jerry on August 24th, 2005 — Posted in Journal, Motorcycling
Sunday was not quite perfect for riding – the drizzle threatened, but held off for the most part as I headed off up the Cotter Road to the Cotter reserve where the Canberra Veteran and Vintage Motorcycle Club was having a gathering.
They were a welcoming lot and there was a good selection of interesting machines. I was too slow in getting the camera out to catch the Brough Superior, but I managed to photograph some good bikes. Here is a selection:
Vincent Rapide
Vincent Rapide
Triumph speed twin
Norton Commando 850cc
Norton Commando 850cc
Royal Enfield 1923
Ducati 750cc Sport
AJS 18S
AJS Model 20
Cheers
Jerry
2 Comments »
