When i kick my scooter(vespa 125cc) off its ok if i stop and it cools down it wont kick off but if i bump it off it fires up ok

Since the problem seems to be heat related (you said that after you rode it for a while then shut it off it won't restart), I'd be inclined to suspect either a fuel problem or an ignition problem.



This sounds like one of those problems that you are going to have to troubleshoot while the problem is there. In other words, it there isn't a problem, you can't find it. You have to wait until it presents itself.



Ride your bike and go somewhere that you can work on it. After you turn the bike off, see if it will restart. If not, pull the spark plug out and ground it to the engine. Kick the engine over and see if you have spark at the plug. If not, your problem is ignition related. Maybe the coil is overheating and shorting out or a wire is shorting somewhere.



If you have spark, the only two things left is compression and fuel. When you kick the engine over, does it feel the same way as it does when it's cold? If so, the compression is probably alright. If it kicks over much easier, then you need to run a compression test on the engine. I'd do that anyway. It's not difficult to do. Find someone that will either loan you a compression tester or have it done. It only takes a minute and shouldn't cost that much if you have to pay someone to do it for you.



If the compression is good, the spark is good, the only thing left is fuel. It could be that heat from the engine is boiling the fuel in the float bowl of the carburator. This is an unusual situation as the manufacturers design their bikes so that the carburator usually stays cool enough to avoid this problem. However, if you or anyone else has added something to the machine that would reduce the air flow around the engine, this could be the problem. After you turn the bike off, touch the float bowl of the carburator. If it's too hot to hold your finger to it for more than a few seconds, it may be boiling the fuel in the float bowl. If you remove the air filter immediately after you stop the engine, sometimes you can see the fuel bubble up into the throat of the carb. Then it will evaporate and your carb is empty of fuel.



If you live in an extremely high altitude or the bike was owned by someone that lived in an extremely high altitude, the carburator may need rejetting. At extreme altitudes, the oxygen level in the air is lower. therefore, the carburator would have to be jetted leaner. With the carb jetted for high altitude and the bike operated at a much lower altitude, the mixture would be too lean and the bike won't run well. This is a very rare case however. If you know the history of the machine, you'll know if this might be a problem.



Like I said originally, I'm no expert on Vespa scooters but an internal combustion engine is the same whether it's in a Vespa or a Harley. They all work on the same principles. I am making an assumption that your machine is equipped with a four cycle engine. But, in the event the engine is two cycle, the same advice applies other than the valve adjustment recommendation. You will have to troubleshoot the problem when it manifests itself. You can't find a problem that isn't there. Good Luck! Since the problem seems to be heat related (you said that after you rode it for a while then shut it off it won't restart), I'd be inclined to suspect either a fuel problem or an ignition problem.

This sounds like one of those problems that you are going to have to troubleshoot while the problem is there. In other words, it there isn't a problem, you can't find it. You have to wait until it presents itself.

Ride your bike and go somewhere that you can work on it. After you turn the bike off, see if it will restart. If not, pull the spark plug out and ground it to the engine. Kick the engine over and see if you have spark at the plug. If not, your problem is ignition related. Maybe the coil is overheating and shorting out or a wire is shorting somewhere.

If you have spark, the only two things left is compression and fuel. When you kick the engine over, does it feel the same way as it does when it's cold? If so, the compression is probably alright. If it kicks over much easier, then you need to run a compression test on the engine. I'd do that anyway. It's not difficult to do. Find someone that will either loan you a compression tester or have it done. It only takes a minute and shouldn't cost that much if you have to pay someone to do it for you.

If the compression is good, the spark is good, the only thing left is fuel. It could be that heat from the engine is boiling the fuel in the float bowl of the carburator. This is an unusual situation as the manufacturers design their bikes so that the carburator usually stays cool enough to avoid this problem. However, if you or anyone else has added something to the machine that would reduce the air flow around the engine, this could be the problem. After you turn the bike off, touch the float bowl of the carburator. If it's too hot to hold your finger to it for more than a few seconds, it may be boiling the fuel in the float bowl. If you remove the air filter immediately after you stop the engine, sometimes you can see the fuel bubble up into the throat of the carb. Then it will evaporate and your carb is empty of fuel.

If you live in an extremely high altitude or the bike was owned by someone that lived in an extremely high altitude, the carburator may need rejetting. At extreme altitudes, the oxygen level in the air is lower. therefore, the carburator would have to be jetted leaner. With the carb jetted for high altitude and the bike operated at a much lower altitude, the mixture would be too lean and the bike won't run well. This is a very rare case however. If you know the history of the machine, you'll know if this might be a problem.

Like I said originally, I'm no expert on Vespa scooters but an internal combustion engine is the same whether it's in a Vespa or a Harley. They all work on the same principles. I am making an assumption that your machine is equipped with a four cycle engine. But, in the event the engine is two cycle, the same advice applies other than the valve adjustment recommendation. You will have to troubleshoot the problem when it manifests itself. You can't find a problem that isn't there. Good Luck!