Q: Hi guys. I’ve just written this message late at night because I’m really getting annoyed and, asking for help.
I’ve just bought a used Big Boy pit bike (125cc), that didn’t run when I bought it. I’ve replaced the spark plug, installed a new air-filter and changed the engine oil. The plug does have a ‘spark’ when I kick over the engine, so it’s not that. I’ve also taken off the carb and cleaned it to perfection as the jets were blocked with old, and sticky, petrol.
But it still won’t start and the engine seems to have good compression. Have you any ideas what I could look for next?
Kyle.
A: Yes we can advise and it’s an easy thing to check. Take off the two small valve covers on top of the engine and check the tappets for free play. They’re easy to adjust and you only need a 9mm spanner and pliers to hold the top of tappet.
You’ll need to find ‘feeler-gauges’ as well and set the clearance to 0.15mm between the tappet and the top of the valve stem. Once set turn the engine over a full cycle and check again.
This is a common fault if those bikes don’t start. So that should take away your anxiety.
