I have a 150st quad, purchased via JAYS BEST DEALS on Ebay, The seller is no longer on EBAY so I cant ask him for help!!,

The bike is very hard to start, I have replaced the spark plug and this appeared to fix the problem, however, it has again gone back to the old way of not starting, the plug is only about 4 weeks old. Can anyone suggest what the problem might be??

Once the bike is started it runs beautifully,

Cheers!!

 

Adjust the valves. They tighten with wear, and also when the engine cools. Hard starting (or no starting) when cold, and then running fine once it starts is the classic symptom.