I have begun a slow restoration of my Motobecane 40V moped. The ped was built in 1970 and I have owned it since near new. I rode it for several years, before putting it into storage for almost 20 years. It’s all eBay’s fault! I finally found some 6V light globes to fit the indicators, so now there is a real chance of getting them to work again.
The moped has been reluctant to start, requiring a squirt of ‘Aerostart’ straight into the spark plug hole before it even thinks about it. So today I took the points out and filed them and reset the gap, and then dismantled the carburettor and cleaned the jets – and now it starts easily and runs well.
The points are located behind the magneto rotor on the right side.
Here is a short video of that starting procedure – just turn on the fuel, roll the throttle forward to decompress the engine, start pedalling and bring the throttle to idle and the engine starts easily.
If you look carefully you should be able to see the clever expanding pulley “variator” in action on the left side of the moped. This provides an infinitely variable gear enabling the engine to maintain power even on hills (for steep hills some light pedal assistance is required)
Once I have the indicators working, I’ll start work on restoring the engine – notice the seepage from the head gasket – I’ll strip it down and rebuild it as the historic vehicle it is 🙂 Watch this space!
Well I got a bit distracted by St Paddy’s day preparations and fitting the topcase to my own bike, but Eve’s bike fired up today and settled quickly into a steady purr.
What else needed to be done? When I assembled it I aligned the top-dead-centre mark on the crankshaft with the cams leaving the valve tappets just loose enough to move, tightened down all the bolts to the right torque and tried the engine movement without a spark plug and noticed a tight spot and a metallic ticking sound. hmm. Could the valve timing be out? Yup – it could. You see, when I assembled it it was getting dark and what I thought was the dot on the cam sprocket turned out to be a speck of oil.
Today I came at it with a fresh eye and it is the work of only about half an hour to undo the two bolts retaining the cam sprocket and identifying the real dot (actually an engraved small circle) and with the sprocket loose, I was able to flip the cam chain over a few links until the dot was in exactly the right place – aligned with the V mark on the head. It was a quick matter then to replace the relevant covers, give the engine a kick over to hear nothing but smoothly interacting machinery, then change the oil, replace the spark plug, and with two kicks the engine purred into life with a nice quiet smooth new-engine sound. Success!
A few revs and it was apparent that the cam chain was making a little bit of noise, so I adjusted the tension bolt and the engine became even quieter.
First test ride was down to the local service station for fresh fuel and tyre pressure check, and despite the welcome rain the bike performed very well.
And the beauty of it is that it no longer blows smoke, and it has real pulling power. Not bad for my first ever piston change – and it cost only the new piston, rings, gaskets and cylinder machining – you certainly can save a lot by doing it yourself!
The gearsack was more than six years old and lately the zip had started to give way making it difficult to open and close, and the thing was no longer waterproof. It was time for a re-think. Armed with some birthday money I headed off to Joe’s Motorcycles in Fyshwick on the advice of a friend who had told me of some bargain priced hard top-cases to be had.
I looked at replacement bags and then saw a small top-box. It was more lunch box than top box. It may have been cute, but I couldn’t see a helmet AND jacket fitting in the way the gearsack did (oh so THAT’s why the zip gave way!)…
Underneath the small topcases was a larger model – the Rjays Super top box
– a full 45litres and by trying in the shop found it fitted two helmets snugly inside. That’s a good start I thought and after parting with AUS$159.95 I took home the case.
It comes with a mounting plate and a set of four brackets with bolts to attach the mounting plate to the bike. I figured I would just cut down the gearsack rack to provide room for the lid to swing open.
After a bit of research online, it appears that there is a strong recommendation to have a pre-existing FLAT rack on which to mount the topcase. I decided on a different solution. The gearsack rack is built from square section steel, so I lined up the slots on the mounting plate with the non-structural in-fills of the rack and drilled two holes to fit. Then I used some longer bolts to fit the topcase mounting plate. I positioned the other two so the brackets would go between the rack in-fills and bolted the plate firmly down.
When I tried to position the topcase onto the mounting plate I found it was held apart by the uprights on the rack. So a little surgery with an angle grinder brought the rack uprights down to the level of the mounting plate.
I positioned the topcase on the mounting lugs and pushed it home. It felt solid for a second or two then popped off in my hands. Okay so it needs to be pushed home very firmly until there is a definite click.
The case looks neat, and feels secure, and at 45 litres it should hold a fair bit. I shall reserve judgement on whether or not it will need to be mounted more securely – ie whether it needs to be bolted to the mounting plate, but it’s designed to be able to lock securely on the bike, or to be removed quickly to use as a carry case. Good concept – like the BMW panniers. As I say, I hope the plastic clip holds it securely – if not I’ll bolt the thing permanently to the mounting plate.
Anyhow, it looks like a stylish piece of luggage and at one third of the price of some other brands, it’s a bargain! It should look good with the panniers in place for touring too. One nice touch is the elastic hold-down inside the topcase to stop stuff from moving around inside – nice touch.
It weighs a mere 6 kg and measures 40cm front to back and 58cm across and top to bottom is 28cm. Did I mention it has a pillion backrest incorporated? In my case it’s probably mounted too far back for a pillion to use it comfortably, but for safety it’s always better for the pillion to hang on to the rider so the rider knows when the pillion is falling asleep.
Inside the cardboard carton you will find: the top box, the steel mounting plate, four brackets with bolts, a set of keys, and an almost useless sheet of instructions. But it’s easy enough to figure out and over the next few weeks Ill put it through its paces 🙂
[later 21 May 2007] In response to James’ comment below, I have included a couple of photos to show the carrying capacity – the yellow envelope is a standard A4 inter-office envelope – you could probably fit an A3 envelope in without bending it. – [Jerry]
Progress! The Honda CT110 oversize piston kit arrived and the cylinder has now been rebored to fit the new piston.
And with Sharon starting to be on the mend I took the opportunity during her sleep to start reassembly of Eve’s bike. First the new piston went on smoothly – the new piston pin slid neatly onto the connecting rod and the pisoton was secured with the new piston clips.
After fitting the piston rings it was time to start on the barrel – there was a lot of rust and dirt on the barrel so I cleaned the exterior using kero brushed on and then a drill-mounted bronze wire brush.
Then the tricky bit – fitting the cylinder without breaking the piston rings. After fitting a new bottom gasket I tackled the fitting. Not having a piston ring compression tool I used finger pressure to squeeze the rings closed as I gently lowered the barrel over the piston. This requires patience and eventually got it ride smoothly over the piston.
taking care to thread the cam chain through. Then I fitted the cam sprocket to the cam chain and held it all in place with some thin wire.
Now for the head. I cleaned the carbon out of the combustion chamber and the valves, and removed the remnants of the previous gasket, before cleaning the outside of the head thoroughly and fitting a new head gasket.
I lowered this gently in place and then, after making sure the crankshaft was at top dead centre, I installed the cam through the cam chain sprocket and bolted it in place, using a small 10mmsocket wrench. I set the other socket wrench on the timing end of the crankshaft to stop the cranckshaft rotating when I tightened up the sprocket bolts.
Once in place it was a relatively quick process to install the covers with their respective new gaskets, so it looks nearly complete.
Next step was to refit the carburettor inlet manifold – with its new gasket – and then the exhaust.
Looks like a new engine now! And in many ways it is – it will need running in of course. But before I can test start it I want to get the footpegs and bash-plate back on – so more to come on this rebuild 🙂
Roger McGuire has built himself what looks like a steam turbine powered motorbike – using an old (air conditioner?) blower for the engine and a home-built propane burner, and what looks like a gas tank for the boiler – very innovative 🙂
Check out his page
And I couldn’t resist a closer view – especially with the Stanley steam cars in the background
It’s his photo, but I brought up the contrast a little to improve the clarity. I wonder how many other steam bikes are out there?
