There are only seven things that will upset an engine:

1) No fuel. This is usually but not always characterised by running for a few seconds and then stopping.

• Normally this is easy to cure, just a couple more presses on the priming button will do the trick.
• This problem can also be caused by having the needle valve too far shut (it should be 2-3 turns open from fully shut, although it does vary greatly from engine to engine)
• It can also be caused by having a blockage in the fuel line. Blockages in the fuel line generally happen at the needle valve, as this is the smallest aperture in the line (to cure it you must dismantle the needle valve assembly and remove the blockage).
• Depending on the model of the engine in your car it is possible that there are two needle valves, a main and a secondary. Normally you only need to adjust the main needle, and the secondary will be pretty much factory set. If however you have tampered with the secondary needle, this could also be causing your problems. The secondary needle is a lot more sensitive that the main one, and you will need to follow the below procedure to return a rule of thumb setting to the carb:
  • Screw the main needle valve all the way shut, set the secondary needle about half way
  • Open the carb barrel fully
  • Get a spare bit of fuel tubing (preferable unused). Attach one end to the fuel inlet nipple on the carb, and place the other end in your mouth
  • Blow through the tubing, and as you do so unscrew the main needle valve. As you do this it will become easier to blow. At some point the main needle valve will reach a point such that unscrewing it any more will no make any difference as to how easy it is to blow. Leave the main needle valve at this cross over point between making a difference and making no difference.
  • Stop blowing
  • Shut the carb barrel onto the thickness of a sewing pin
  • Start blowing again, but this time screw the secondary needle either in or out, until you can just hear your breath escaping from the carb
  • Stop blowing
  • The carb will now be roughly set.
    

2) Too much Fuel (Flooded). This is usually but not always characterised by the engine being very hard to turn over. It is dangerous to persist in trying to start a flooded engine, you risk damaging it. You can damage pull starts if they are fitted, and even bend conrods.

• This can be caused by over priming (don't use as many presses in the future)
• Can also be caused by having the main needle too far open (see above for details on carb setting)
• To remove the excess fuel follow the procedure below:
  • Disconnect the fuel line from the engine and place it somewhere so it can't leak everywhere
  • Remove the glow plug, you will need an 8mm box spanner
  • Hold the engine upside down over a rag and turn it over quite quickly, most of the excess fuel will be ejected onto the rag.
  • Put the glow plug back in
  • Try to start the engine (leave the fuel line disconnected)
  • The engine will run for 5-10 seconds depending on how flooded it was
  • After it stops, try to restart it, it will run for a shorter time and then stop
  • Keep trying to restart it until it will start no longer
  • Re-connect the fuel line
  • Prime the fuel system until the fuel reaches the carb but no further
  • Start the engine
    

3) No glow. This is usually but not always characterised by the engine being totally unresponsive.

• To check this is the problem:
  • Remove the glow plug from the engine.
  • Attach the glow plug to your glow clip.
  • It should have nice orange/yellow glow.
  • If it doesn't, either your glow plug is broken or your glow start is flat.
  • If you have a spare glow plug try that, if it works put it into the engine, and off you go.
  • If it doesn't work charge you glow supply and try again.
  • If you don't have a spare glow plug all you can do is presume your glow supply if flat, charge it up and try again. If things still don't work after charging your glow supply, I would suggest you come and see us, as either you need a new glow plug or a new glow supply
    

4) Worn out. This is usually but not always characterised by and engine that will run at tick over for a few seconds and then stop, but will run continuously at higher speeds. The engine may also be very hard to start when hot. This can be caused be running with no air filter, with dirty fuel, or with too lean a setting.

• There is only one cure to this problem, you must replace the piston and liner assembly, contact us with the exact make and model of the engine for a price. They range in price from £25.00 to £70.00

5) Disassembled and re-assembled incorrectly. This will be characterised by you having a nagging worry that you didn't re-assembly it properly when curiosity got the better of you and you had to have a look inside. The common things we see are:

• Liner inserted in the wrong orientation.  This is possibly the most  common thing that people get wrong. The holes in the liner must line up with the appropriate ports in the crankcase. The liners usually have a mark on them that will line up with a corresponding line on the crankcase. If not, size up the exhaust opening in the crankcase, then find an identical sized opening in the liner, and align the two.
• Piston inserted in the wrong orientation. Some engines use pistons that have holes in them. This hole must be on the opposite side of the engine to the exhaust side.
• Lose cylinder head or backplate. These must be tightened up as you would a car wheel, across the diagonals, and bit by bit. You should seat each of the screws in one tightening circuit, and then fully nip them up in another. I should also point out that there is no need to tighten them up as far as you can get them, don't get carried away.  
• No glow plug washer. This doesn't normally stop engines running, but it will retard performance. Find one of those easy to lose copper washers and put it back in.
• Lose flywheel. This will stop engines starting, it will fire but it will never actually start. Very easy to fix, just tighten the flywheel up.

6) Something broken. Usually quite obvious, something went with a bang, engine very easy to turn over, or wont turn over at all.

• Most of the engine breakage's we see are down to a snapped conrod. This has only one cause, over revving the engine. It is most common in cars  because it is easier to rev the engine up with out any load. Never rev  the engine up without any load, this includes going over the top of  jumps when all four wheels clear the ground, and huge wheel spins on  ice etc. For above reasons most car engine manufactures do not guarantee conrods at all.
• Other engine breakage's can be very diverse, I would recommend you show us the engine if you suspect a problem

7) Old Fuel. The fuel has a shelf life of between 6 months and 18 months, dependent on where it is stored. Things to avoid in storage are:

• Sunlight: Ultra violet light causes a chemical reaction within the fuel, it will darken in colour, and spoil.
• Dampness: The fuel is miscible with water, as such it will absorb water, as you can imagine this doesn't help combustion.
• Warmth: The fuel consists of methanol, oil, and nitro methane, both the nitro methane and the methanol will evaporate at room  temperatures, and leave you with the oil. Engines don't run too well on just oil!

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