| CORRECTIVE STEPS: 1. Plane flat the mating surface for head and cylinder by grinding them onto sandpaper on glass. These are always warped which allows loss of compression. Upon reassembly use Copper Coat or High Temp Silicone Sealant, just a little, on both sides of the aluminum gasket. 2. Make sure the spark plug isn't gapped larger than 0.8mm (.031"). The easiest plug to allow spark is the platinum or iridium plugs. The stock setup for generating a spark is very weak which is OK for the stock low compression engine but when you increase the compression too much (over 135psi cranking pressure) with a high compression head then you're asking for problems. If you insist on keeping the head then at least use a 2nd head gasket to aleviate the compression a bit. 3. Electricity flows in a circular route and in this case needs good ground connection at the stator coil. The current flows from the spark plug tip to the ground electrode, thru the metal engine parts to the left side case where the stator coil is, then into the stator coil but only if there is no insulating shellac there (which was put on during putting together all the metal plates) and no corrosion. 4. Make sure all electrical connections aren't being hampered by corrosion. I don't use connectors. I solder everything together. 5. The stock carb doesn't supply enough fuel at low slide opening if the float in the carb isn't adjusted correctly and I doubt the lazy chinese ever do it correctly. Take the bowl off and adjust the valve actuating tab so that it closes with the float just almost hitting metal. 6. Make damn sure the connection of carb to intake manifold isn't letting any air in. I had to cut back the connector on the Speed carb and flatten the end of the intake manifold to get it to seal correctly. (It's been too many years since I had a stock carb so I don't remember about it.) [link] 7. Once it's running right the turn the screw at the left side of the carb for acceptable no-throttle idle RPM. 8. If there's no spark then click here. Be aware that it might spark with the plug held onto the side of the head but not spark inside the engine if you have a high compression head. More psi requires more spark voltage to spark. 9. Old gasoline loses its volatility and is harder to ignite, so make sure you only use fresh gasoline. Also the crank seals aren't ethanol resistant and so you need to use non-ethanol gas. Look up a gas station that sells pure gas or just remove the ethanol yourself. [link] 10. If you keep on trying to start a bike with problems then you could get too much gasoline in the engine crankcase and even after you fix the problem you may have to find a steep hill to go down to get it started.  Drawbacks of High Compression Heads: A. They greatly increase the pressure on the bearings during peak combustion pressure, and that reduces the life of the bearings. B. They greatly increase the piston temperature, also that of the cylinder. When those temps get too high then the oil on the upper cylinder evaporates off which increases friction until the piston seizes. C. They make it harder for a spark to happen due to the increased compression pressure. This can only be overcome with aftermarket CDI such as the Jaguar High Performance CDI with motorcycle high voltage coil. D. Buying one puts money in the pocket of someone who cares only about profit, completely ignoring these facts. I've never bought one. When I want more compression I just take the cylinder or head to the machine shop and have them take off 1 or 2mm from the mating surface. |