Common Problems For Budget Scooters

Chinese scooters suffer from some of the worst press ever imagined. Most of it is undeserved and propagated by those unwilling to take the time to figure out whats going on. Here, we’ll detail a couple of the oddities and what you can do to work with these affordable and fun vehicles.

Some of the most common problems with these are listed here. Unless you’re mechanically inclined, you shouldn’t be working on the bike in the first place. More scooters have died because the wrong people ‘fixed’ them than anything else.

  • Spark Plugs – they’re garbage, usually Torch or LD, and they are to be replaced as soon as they get out of the box with quality NGK plugs. Most of the two strokes seem to come with decent plugs, so this is mostly a 4 stroke affliction.
  • Fuel Filters – the Chinese don’t add Ethanol to their gas, because they’re not crazy and driven by oil politics. The fuel filters shipped with some scooters are paper element type and fall apart with ethanol gas, and the goopy bits of paper end up in your carb. Better choice is ethanol friendly metal core filters.
  • Valve Clearances – often set poorly at the factory, these tend to go out of adjustment in the early miles (under 500) of many of these bikes. This has lead to the premature death of many a good bike when people don’t properly understand this very basic problem. It’s sometimes a time consuming job to do, but once done, rarely needs doing again for a long while. The trick is knowing what to set these to, which a skilled repair shop can do for you.
  • Carburetors – they’re usually copies of Keihin designs and sometimes Walbro’s (50cc). The auto chokes crap out occasionally, but not nearly as often as people will tell you, it’s often a misdiagnoses of something else. The jets in these tend to block up with our volatile and fast to evaporate ethanol containing gas. The previously mentioned fuel filter problems don’t help one bit. 
  • Gas Tanks – More ethanol bashing. Being as ethanol absorbs water over time, when it sits in your gas tank for more than a few months it can cause rust problems. Bikes with external gas caps suffer most because people leave them in the rain and water gets in through the key hole and seals. Gas treatments like Stabil can help, especially if you’re not using your ride regularly (once a week at least). The petcocks (fuel valve) can also cause problems. They can stick open, possibly flooding your motor or they can stick closed, obviously stopping fuel getting to the engine. Or worst of all, the lines can crack and allow a vacuum leak to your engine.
  • Tires & Wheels – Generally, these are problem free, but the alloy wheels on some are easily cracked and bent, but this goes for all scooters and motorcycles. Hit a curb or big pot hole and it’ll cost you. A bigger problem is valve stems; they dry rot (at least here in the south) and either leak or can pop out at speed! This mostly happens through neglect, being left outside on unused for long periods.
  • Oil Leaks – The engines need oil! Four strokes need it inside the engine, not on your driveway. Check this regularly, it takes five seconds and we’re happy to show you how to check it. Two strokes need oil in their oil tanks – and not lawn mower, marine, engine oil, vegetable oil or any other garbage you find – they need motorcycle specific two-stroke oil ! We have it. Some even smells like Strawberries, I kid you not. Put the wrong stuff in here and your engine will not last long.
  • Engines – Most chinese scooters use a few basic engines; lets start with the 50cc class and work up from there. 50cc four-stroke: 99% of these are based on an engine called a QMB139 GY6. Reputed to be an old Honda design from the 80’s that was stolen and cloned, it is possibly one of the most popular motors in the world. The story of how it came to be cloned is well documented in industrial engineering circles. The easiest way to identify if you’ve got one of these is to look for a raised area on the bottom left of your engine with the 139 number somewhere. The 39 portion is the bore size of the motor in mm. These motors can easily be improved on by upping capacity to 80cc – a kit skilled repair shop will be happy to fit to your scooter.

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