hi guys really need some help as I’m new to scooter tuning. My problem is the other day my speedfighter 2 cut out on me as I pulled away from the traffic lights the over day pushed her home checked her over nothing so removed the cylinder head to find one of the piston rings had gone and mad a mess so replaced it with a cast iron 70 kit I had on my shelf got it back together and started it in the garden but don’t run right with a 62 main jet so I put a 72 main jet in and seam to run ok as long as I don’t fit the air box so would I need a bigger jet if I’m wanting to run it with the air box
That's because the main jet is too big. You need to balance the air and fuel ratio. By taking the airbox off you are allowing more air into the carb, put the airbox on and it's less air.
Hi and thanks for your reply I’ve taken your advice and dropped the main jet from a 72 to a 68 main jet and now it seams to run ok with the air box on but the engine temperature is getting hot quicker than normal I’ve checked for a air lock I’ve checked my thermostat everything is working fine I’ve even left the thermostat out and the temperature is still increasing is it to do with the metra 70cc kit
Make sure the radiator fan is working when the engine gets to tempreture. Some bikes, the fan doesn't kick in until the gauge says it's really hot, bit scary at first but you get used to it. Alternatively, fit a switch into the fan circuit
