The rattle from the kickstarter turned out to be due to a crack in the support bush in the side casing that was letting the kickstart ratchet to float around and rub against the variator. Without buying a new engine side cover (surprisingly rather expensive), the best way to deal with this is to remove the entire kickstart mechanism, and get the electric start working.
Seat bin out, then I can get to the engine and wiring to check things over with my voltmeter. It confirms that there's voltage getting to the starter motor when the button's pushed, so there's a fault inside the starter. It's easy to take off of the engine, then the starter cover is held on the starter motor by two long screws. I should have marked the cover how it was assembled to the motor body, as it can go on in one of two ways. If you get it wrong, the starter runs backwards when you push the button, and the bendix doesn't engage with the starter gear on the variator. Guess how I know this....
Inside the starter motor, I find a wire that's fallen off of one of the brushes. The threads it should screw into have been partially stripped on assembly, and so won't tighten up properly. A small stainless self tapper does the job, and the motor goes back together with some assistance from a second pair of hands to help lining the brushes and springs up with the commutator. The least said about putting the cover on upside down, the better. There's a birds nest of insulating tape on the earth strap going to one of the starter motor bolts. Removing that reveals a corroded cable with missing insulation, so I trim it back to clean copper and solder a new ring terminal on the end.
Stabbing the starter button now has the motor spinning nicely, and after some head scratching resulting in me spinning the cover of the starter around 180 degrees, the motor is turning over. It starts easily with a whiff of throttle. Nice.
I take off the now redundant kickstart assembly and plug the resultant hole with a bicycle handlebar end plug that I had lying around. It fitted perfectly, and you'd not know the kickstarter was missing unless you'd seen the bike with it fitted.
Getting that sorted coincided with a spell of wet weather, enough to make my normal commute by bicycle uncomfortable. Taking the car would be madness because of the amount of roadworks being carried out on my route - five miles could take an hour on a bad day - so the scooter was pressed into service.
First impressions are that it's perfectly adequate for my commute. I can pootle up between the traffic, getting to the head of every traffic light queue. The small size of the bike makes it easier than on my larger, faster, bikes, and a pair of light overtrousers combined with the effective leg shields keeps my dry in downpours. Commute time is a rather good 15 minutes each way.
What is apparent is that the rear tyre is a little too low on tread to inspire confidence on wet roads. The internet finds me a Michelin City Grip Winter delivered to my door for £28, only a little more than the cheapest no-name nylon tyres. Bikes need their best tyres fitted to the front wheel, even more so with the tiny 10 inch tyres fitted to these bikes, so I move the front tyre onto the back wheel, and put the new one on the front. These are tubeless tyres, but they fit easily with some tyre lube and a ratchet strap around the outside of the tread to get the beads to seat enough to start pumping air into the tyres. Once they're started seating, remove the strap and pump them up until the beads seat evenly all round the rim, then adjust the pressures to what they should be.
That makes a massive difference to how the bike handles, with much more feedback from the tyres.
Filling up the fuel tank after a week and a half's commuting and pottering around reveals that I'm getting just under 110 MPG. I'm rather pleased with that.
Sunday, 23 November 2014
Tuesday, 4 November 2014
Back on the Road
One day the dog will work out that sleeping underneath the letterbox isn't a good idea. I've got all of the bits to put the scooter back on the road, and the dog's got a bump on his head.
The new speedo cable's dry, so I greased it lightly and fitted it. A quick spin of the front wheel and the speedo needle moves, that's all it needed. I've also ordered a replacement front brake lever which bolts straight on. That lets me push new fluid through the front brake system as it was a little discoloured and of unknown origin.
All that's left to do is sort out the non-functioning horn, then bolt the plastics back on the bike. A quick check with the volt meter shows that nothing is getting through to the horn when the button's pushed. Taking the switch apart is simple enough and reveals that it's fallen apart internally, fortunately nothing's broken so I reassemble it and the horn springs back to life. Back on with the panels and I'm ready for a test drive.
A couple of prods on the kickstart and the engine's burbling away. On with the riding gear and we're off up the hill.
Gawd it's slow....
It crawls up to the top of my hill onto the flatter road and off it goes. At speeds up to 31mph, when the limiter kicks in and performance hits a brick wall. I'd noticed a sensor next to the clutch bell when I had the covers off. That's what senses the speed of the bike and when it reaches the preset speed limit the CDI retards the ignition preventing the bike from going any faster.
This is dangerous. At 31mph, you don't pick up enough momentum going downhill to give you enough oomph to get up the other side so you end up with a queue of impatient traffic behind you as you struggle uphill at 15mph. Allowing the bike to run to its real top speed downhill will reduce this problem, so I removed the sensor from the belt cover. This is the "pink wire" mod you'll find described on the internet without having to butcher the loom.
That's better. A 50cc scooter isn't ever going to be fast, but it'll pull 43mph on the flat and doesn't struggle uphill so much.
I'm going to ride it to work for a few weeks to see if anything breaks. Worryingly, the kickstart's making odd noises already....
The new speedo cable's dry, so I greased it lightly and fitted it. A quick spin of the front wheel and the speedo needle moves, that's all it needed. I've also ordered a replacement front brake lever which bolts straight on. That lets me push new fluid through the front brake system as it was a little discoloured and of unknown origin.
All that's left to do is sort out the non-functioning horn, then bolt the plastics back on the bike. A quick check with the volt meter shows that nothing is getting through to the horn when the button's pushed. Taking the switch apart is simple enough and reveals that it's fallen apart internally, fortunately nothing's broken so I reassemble it and the horn springs back to life. Back on with the panels and I'm ready for a test drive.
A couple of prods on the kickstart and the engine's burbling away. On with the riding gear and we're off up the hill.
Gawd it's slow....
It crawls up to the top of my hill onto the flatter road and off it goes. At speeds up to 31mph, when the limiter kicks in and performance hits a brick wall. I'd noticed a sensor next to the clutch bell when I had the covers off. That's what senses the speed of the bike and when it reaches the preset speed limit the CDI retards the ignition preventing the bike from going any faster.
This is dangerous. At 31mph, you don't pick up enough momentum going downhill to give you enough oomph to get up the other side so you end up with a queue of impatient traffic behind you as you struggle uphill at 15mph. Allowing the bike to run to its real top speed downhill will reduce this problem, so I removed the sensor from the belt cover. This is the "pink wire" mod you'll find described on the internet without having to butcher the loom.
That's better. A 50cc scooter isn't ever going to be fast, but it'll pull 43mph on the flat and doesn't struggle uphill so much.
I'm going to ride it to work for a few weeks to see if anything breaks. Worryingly, the kickstart's making odd noises already....
Thursday, 2 October 2014
A good once over - Part two.
Panels off, new mudguard in hand, its time to look at the front end. I've already ordered a new speedo cable as the one fitted came out in two pieces.
With the rear of the bike weighted down so the front wheel is in the air, the front wheel comes out easily after removing the spindle. The speedo drive is very stiff, filled with a mixture of dried grease and corrosion. Not brilliant for a two year old bike, but it'll be OK after a clean and lube session. Surprisingly, the brake caliper comes apart easily. It shows signs of partial seizure, as the pads are worn unevenly, although the pistons both move. Again, a clean and lube session should sort that out.
There's a lot of rusty staining around the lower headstock, but the forks are still in good condition with no leaks and no pitting to the stanchions. Where's the rust coming from? Pulling and pushing on the fork ends produces a good half inch of free play. A torch and a good squint under the panels reveals a completely collapsed lower headstock bearing.
Bummer.
That's really rather poor so it's bars off to dismantle the bicycle style cup and cone bearings. The top bearing is still fine, with traces of the original grease. The bottom one is a different story. It's a caged bearing, the cage has rusted and most of the balls are missing. There's slight marking and light rust on both the crown race and the lower cup, but with some wire wool, those clean up enough to be reused. Instead of caged bearings, I fit loose balls. This provides more support to the lower headstock and will reduce the chances of the bearings falling into any small indents in the lower races. With the bearings packed full of good grease and the bars refitted smooth, play-free operation is restored.
The painted metalwork on the front is the same as on the back - pretty poor. There seems to be little corrosion resistance provided by the frame paint. As already mentioned, a can of Waxoyl would be a good investment if you want one of these to last.
The new mudguard clips in at the top and secures with two bolts at the bottom. I wasn't expecting much for £14, but the new 'guard fits perfectly.
Time to wait for the postman with my new £6 speedo cable, then I can carry on with the reassembly.
With the rear of the bike weighted down so the front wheel is in the air, the front wheel comes out easily after removing the spindle. The speedo drive is very stiff, filled with a mixture of dried grease and corrosion. Not brilliant for a two year old bike, but it'll be OK after a clean and lube session. Surprisingly, the brake caliper comes apart easily. It shows signs of partial seizure, as the pads are worn unevenly, although the pistons both move. Again, a clean and lube session should sort that out.
There's a lot of rusty staining around the lower headstock, but the forks are still in good condition with no leaks and no pitting to the stanchions. Where's the rust coming from? Pulling and pushing on the fork ends produces a good half inch of free play. A torch and a good squint under the panels reveals a completely collapsed lower headstock bearing.
Bummer.
That's really rather poor so it's bars off to dismantle the bicycle style cup and cone bearings. The top bearing is still fine, with traces of the original grease. The bottom one is a different story. It's a caged bearing, the cage has rusted and most of the balls are missing. There's slight marking and light rust on both the crown race and the lower cup, but with some wire wool, those clean up enough to be reused. Instead of caged bearings, I fit loose balls. This provides more support to the lower headstock and will reduce the chances of the bearings falling into any small indents in the lower races. With the bearings packed full of good grease and the bars refitted smooth, play-free operation is restored.
The painted metalwork on the front is the same as on the back - pretty poor. There seems to be little corrosion resistance provided by the frame paint. As already mentioned, a can of Waxoyl would be a good investment if you want one of these to last.
The new mudguard clips in at the top and secures with two bolts at the bottom. I wasn't expecting much for £14, but the new 'guard fits perfectly.
Time to wait for the postman with my new £6 speedo cable, then I can carry on with the reassembly.
Friday, 26 September 2014
A good once over - Part one.
Now the scooter's running, it's time to give it a once over and a service. Warned by their reputation, I expect to find low quality parts in some places and poor quality finish to, well, almost everything,
With the engine running, I can check all of the electrics. With the exception of the horn and the electric start, everything seems to work. That's better than I expected.
The brakes need a coat of looking at. The rear drum is fine, although the lever travel is on the long side. The front disk has very little travel and seems poor, so will need a looking at, and the end of the lever is snapped off. That'll go on the list of parts to buy, along with a new speedo cable.
Bodywork wise, apart from the broken section of the front mudguard, the panels aren't too bad. There's the odd scrape which may respond to T-cut, and some sticky patches from where the L-plates have been taped on which will clean off. Some of the panels are lightly cracked in places, but they're firmly attached and not massively noticeable. I'll ignore these for now.
I've already checked that someone's changed the plug for an NGK so that's one thing off of the list, but I need to change the oils and take a look under the belt cover to see what state that's all in. The Chinese belts fitted from new have a poor reputation.
Out with the gearbox drain plug, and I'l surprised to find good quality clean oil. Has someone been here already? I pop the plugs back in and refill with new EP80 gear oil from my squirty oil can.
It's engine oil next. That comes out black, but the strainer is nice and clean. After it's drained, I replace the drain plug with a new O-ring and fill up with 5w40 Castrol Magnatec that I had on the shelf. These bikes won't need bike specific oil, as they don't have wet clutches, so don't waste your cash on motorcycle oil for one of these.
The belt cover is held on with 8mm headed bolts. They all come out, but all look very dry. I'll put them back in with copper grease on the threads later. The cover looks rather corroded on the outside, the paint is flaking off in places - this is poorly finished from new. Inside, it looks fine though. The belt itself is.... a Contitech. Someone's replaced the original belt with the best one available. Result! The clutch bell as a small amount of run out on the outside, but as the clutch engages smoothly and doesn't judder I'm going to assume it's OK on the inside where it matters and add it to the ignore list.
I clean the air filter, housing and pipework while I'm in the area, then screw it all back together and fire the bike up on the kick start to check it's OK. It's fine.
While I've been working on the bike, it's given me a chance to look an under the panels at the overall finish. Some bits look as good as any other scooter I've worked on, the electrics for example. Other bits are very poor. The frame paint would fall into this category, for a two year old bike. It's shockingly thin and appears to have been applied with little or no primer. Anyone looking at keeping one of these on the road long term would do well to invest in a can of Waxoyl or a similar rust preventative.
That'll do for now while I wait for my new mudguard to arrive, then I can tackle the front end.
With the engine running, I can check all of the electrics. With the exception of the horn and the electric start, everything seems to work. That's better than I expected.
The brakes need a coat of looking at. The rear drum is fine, although the lever travel is on the long side. The front disk has very little travel and seems poor, so will need a looking at, and the end of the lever is snapped off. That'll go on the list of parts to buy, along with a new speedo cable.
Bodywork wise, apart from the broken section of the front mudguard, the panels aren't too bad. There's the odd scrape which may respond to T-cut, and some sticky patches from where the L-plates have been taped on which will clean off. Some of the panels are lightly cracked in places, but they're firmly attached and not massively noticeable. I'll ignore these for now.
I've already checked that someone's changed the plug for an NGK so that's one thing off of the list, but I need to change the oils and take a look under the belt cover to see what state that's all in. The Chinese belts fitted from new have a poor reputation.
Out with the gearbox drain plug, and I'l surprised to find good quality clean oil. Has someone been here already? I pop the plugs back in and refill with new EP80 gear oil from my squirty oil can.
It's engine oil next. That comes out black, but the strainer is nice and clean. After it's drained, I replace the drain plug with a new O-ring and fill up with 5w40 Castrol Magnatec that I had on the shelf. These bikes won't need bike specific oil, as they don't have wet clutches, so don't waste your cash on motorcycle oil for one of these.
The belt cover is held on with 8mm headed bolts. They all come out, but all look very dry. I'll put them back in with copper grease on the threads later. The cover looks rather corroded on the outside, the paint is flaking off in places - this is poorly finished from new. Inside, it looks fine though. The belt itself is.... a Contitech. Someone's replaced the original belt with the best one available. Result! The clutch bell as a small amount of run out on the outside, but as the clutch engages smoothly and doesn't judder I'm going to assume it's OK on the inside where it matters and add it to the ignore list.
I clean the air filter, housing and pipework while I'm in the area, then screw it all back together and fire the bike up on the kick start to check it's OK. It's fine.
While I've been working on the bike, it's given me a chance to look an under the panels at the overall finish. Some bits look as good as any other scooter I've worked on, the electrics for example. Other bits are very poor. The frame paint would fall into this category, for a two year old bike. It's shockingly thin and appears to have been applied with little or no primer. Anyone looking at keeping one of these on the road long term would do well to invest in a can of Waxoyl or a similar rust preventative.
That'll do for now while I wait for my new mudguard to arrive, then I can tackle the front end.
Sunday, 21 September 2014
Time to take a look and see what's wrong.
The Chinese scooter is home and in the garage. It's a Direct Bikes DB50QT-11. Romantic name eh?
These are as generic as they come, they're made in various factories in China to a vague specification and sold by the container load to dealers who get them badged up with whatever brand they sell them as. The exact same machine can be bought as a Baotian, a Lexmoto, a Longjia, a Znen - you get the idea. What you're actually getting in all of these cases is a scooter chassis with the 139QMB engine fitted.
There are some decent workshop manuals available to download from the internet relating to these machines and so long as you remember that what's fitted to your machine may vary a little from what's in the manual, then there's plenty of information available to help you undertake looking after or repairing one of these bikes.
Now it's time to take a look and see what I've bought.
First, the bodywork.
It's obviously been ridden by the ubiquitous impoverished teen. With balance issues. The front mudguard has the front snapped off. There is the odd scrape down either side and the seat has a torn cover. The glass is broken in one of the mirrors, and the front brake lever has the end snapped off. Overall, it's in poor cosmetic condition for something just over two years old. However, none of that can be blamed on the fact that it's a cheap Chinese bike - the finger of blame points at the previous owner and how they'd looked after it.
Mechanically, the electric start doesn't turn the engine, although it turns over on the kickstart fine. All of the locks are a little stiff, although they do work. The electrics mostly work, apart from the horn. The brakes aren't dragging, and stop the bike when rolled along. Giving the bike a good shake produces no ominous noises, and the suspension moves freely at both ends. Front and rear tyres are both legal and are a brand that I've at least heard of, Duro. Overall, better that expected.
As the bike's stood for a couple of months, I put the battery on charge. Surprisingly, it's a branded battery (Lucas), rather than the un-named one I was expecting. It's in good condition and takes a charge. Unfortunately, there's still no action from the starter motor, apart from the click of the starter relay.
Back to first principles - if you've got fuel, compression and a spark at the correct time, the engine should at least fire. Whipping off the seat and under seat storage box, I can now get to the engine to check for the presence of all three.
Running down from the tank to the carburettor is the fuel line with a big fuel filter in it. It's dry inside. It can't be that simple can it? With the starter out of action, the vacuum operated fuel tap won't get enough suction to open when the engine's turned over on the kick start, so I remove the vacuum pipe from the inlet manifold and suck on it enough to open the fuel tap. The filter fills, could this be all that it needed?
No.
Many kicks later with no signs of life at all, I move onto the next thing to check and remove the plug. It's a brand new NGK. Someone's been down this path before, apparently unsuccessfully. There's a nice big spark when it's turned over on the kickstart, so let's park that one for now.
Compression. I know it's only a tiny engine, so the kick start won't put up much of a fight, but if I put my finger over the plug hole, it struggles to blow my finger off. Compression is low, why? With a four stroke engine, low compression can be due to bore, piston or ring wear, a blowing head gasket or valve problems. Checking the valves is the easiest and first thing to check. Off with the valve cover (noting that the engine seems spotlessly clean inside, and that the valve cover uses a reusable neoprene gasket, rather than a one shot paper one) I rotate the engine until both valves are closed on the compression stroke and check the clearances.
Inlet - fine. Exhaust - there is no clearance. We have a smoking gun, if not a running engine. If the exhaust valve has no clearance it'll not be closing properly so the engine will be losing compression. This will be worse when the engine is hot, so the performance must have been very poor when it actually did run.
A quick adjustment, so that the exhaust valve has the required clearance, and a few prods on the kick start and the engine is attempting to start. Time to put the valve cover back on, this time with a little copper grease on the bolts to make future maintenance easier. This done, and a few more prods on the start lever, and the bike bursts into life, burbling away at a slightly high tick over.
It lives!
These are as generic as they come, they're made in various factories in China to a vague specification and sold by the container load to dealers who get them badged up with whatever brand they sell them as. The exact same machine can be bought as a Baotian, a Lexmoto, a Longjia, a Znen - you get the idea. What you're actually getting in all of these cases is a scooter chassis with the 139QMB engine fitted.
There are some decent workshop manuals available to download from the internet relating to these machines and so long as you remember that what's fitted to your machine may vary a little from what's in the manual, then there's plenty of information available to help you undertake looking after or repairing one of these bikes.
Now it's time to take a look and see what I've bought.
First, the bodywork.
It's obviously been ridden by the ubiquitous impoverished teen. With balance issues. The front mudguard has the front snapped off. There is the odd scrape down either side and the seat has a torn cover. The glass is broken in one of the mirrors, and the front brake lever has the end snapped off. Overall, it's in poor cosmetic condition for something just over two years old. However, none of that can be blamed on the fact that it's a cheap Chinese bike - the finger of blame points at the previous owner and how they'd looked after it.
Mechanically, the electric start doesn't turn the engine, although it turns over on the kickstart fine. All of the locks are a little stiff, although they do work. The electrics mostly work, apart from the horn. The brakes aren't dragging, and stop the bike when rolled along. Giving the bike a good shake produces no ominous noises, and the suspension moves freely at both ends. Front and rear tyres are both legal and are a brand that I've at least heard of, Duro. Overall, better that expected.
As the bike's stood for a couple of months, I put the battery on charge. Surprisingly, it's a branded battery (Lucas), rather than the un-named one I was expecting. It's in good condition and takes a charge. Unfortunately, there's still no action from the starter motor, apart from the click of the starter relay.
Back to first principles - if you've got fuel, compression and a spark at the correct time, the engine should at least fire. Whipping off the seat and under seat storage box, I can now get to the engine to check for the presence of all three.
Running down from the tank to the carburettor is the fuel line with a big fuel filter in it. It's dry inside. It can't be that simple can it? With the starter out of action, the vacuum operated fuel tap won't get enough suction to open when the engine's turned over on the kick start, so I remove the vacuum pipe from the inlet manifold and suck on it enough to open the fuel tap. The filter fills, could this be all that it needed?
No.
Many kicks later with no signs of life at all, I move onto the next thing to check and remove the plug. It's a brand new NGK. Someone's been down this path before, apparently unsuccessfully. There's a nice big spark when it's turned over on the kickstart, so let's park that one for now.
Compression. I know it's only a tiny engine, so the kick start won't put up much of a fight, but if I put my finger over the plug hole, it struggles to blow my finger off. Compression is low, why? With a four stroke engine, low compression can be due to bore, piston or ring wear, a blowing head gasket or valve problems. Checking the valves is the easiest and first thing to check. Off with the valve cover (noting that the engine seems spotlessly clean inside, and that the valve cover uses a reusable neoprene gasket, rather than a one shot paper one) I rotate the engine until both valves are closed on the compression stroke and check the clearances.
Inlet - fine. Exhaust - there is no clearance. We have a smoking gun, if not a running engine. If the exhaust valve has no clearance it'll not be closing properly so the engine will be losing compression. This will be worse when the engine is hot, so the performance must have been very poor when it actually did run.
A quick adjustment, so that the exhaust valve has the required clearance, and a few prods on the kick start and the engine is attempting to start. Time to put the valve cover back on, this time with a little copper grease on the bolts to make future maintenance easier. This done, and a few more prods on the start lever, and the bike bursts into life, burbling away at a slightly high tick over.
It lives!
Saturday, 20 September 2014
Can a Chinese Scooter be any good?
Direct Bikes DB50QT-11 Scooter.
These bikes, along with most Chinese bikes, get a slating online and in the press earning an unenviable reputation for unreliability, low quality and just being a bit rubbish. They tend to be chosen because they seem to be an extremely cheap way of getting on the road as a teenager.
However, their cheapness tends to lead a situation where their invariably impoverished teenage owners are reluctant to spend a large portion of the bike's purchase price on maintenance and upkeep at a dealer, if you can find one that will work on your bike in the first place. Servicing gets done by a "mate who knows about bikes", if at all. Little problems get ignored until they become big problems or so much goes wrong with the bike that it becomes uneconomic to repair. By then, the owner has given up on bikes and moved onto a car. The scooter gets left in the garden under a tarpaulin or, better, at the back of a garage until, fed up of it getting in the way, the disappointed owner puts it up on Gumtree or eBay.
For those of us who've been around a while, this is a familiar story. A lot of the cheap bikes bought in the 70s or 80s, Minsks, MZs, CZs or Jawas for example, got ran into the ground in exactly the same way. Some of these were good bikes let down by their owners, while others were just bad bikes.
Via Gumtree, enter one two year old Direct Bikes DB50QT-11, advertised as a non-runner since the fuel ran out for £70 including a full tank of fuel, a new top box and new screen. One quick trip across town in the back of an estate car, and it's mine.
So, can this be returned to the road as a reliable vehicle, or is their poor reputation deserved?
These bikes, along with most Chinese bikes, get a slating online and in the press earning an unenviable reputation for unreliability, low quality and just being a bit rubbish. They tend to be chosen because they seem to be an extremely cheap way of getting on the road as a teenager.
However, their cheapness tends to lead a situation where their invariably impoverished teenage owners are reluctant to spend a large portion of the bike's purchase price on maintenance and upkeep at a dealer, if you can find one that will work on your bike in the first place. Servicing gets done by a "mate who knows about bikes", if at all. Little problems get ignored until they become big problems or so much goes wrong with the bike that it becomes uneconomic to repair. By then, the owner has given up on bikes and moved onto a car. The scooter gets left in the garden under a tarpaulin or, better, at the back of a garage until, fed up of it getting in the way, the disappointed owner puts it up on Gumtree or eBay.
For those of us who've been around a while, this is a familiar story. A lot of the cheap bikes bought in the 70s or 80s, Minsks, MZs, CZs or Jawas for example, got ran into the ground in exactly the same way. Some of these were good bikes let down by their owners, while others were just bad bikes.
Via Gumtree, enter one two year old Direct Bikes DB50QT-11, advertised as a non-runner since the fuel ran out for £70 including a full tank of fuel, a new top box and new screen. One quick trip across town in the back of an estate car, and it's mine.
So, can this be returned to the road as a reliable vehicle, or is their poor reputation deserved?
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