1932 Sloper spark plug

[oilman]

I need to buy a plug for my bike and I can't read the number on the old one.  What is recommended.

[mark quinney]

 Hi can't help you with what modern plug would be needed the parts book gives a number of 15–1300  for the overhead valve models . In the  engine that I have somebody has put an insert in the plug hole to reduce it down so it will take 14 mm spark plugs which are more already available I haven't actually run  this engine but the plug looks a nice colour and it is a Bosch super RO 562 . Hopefully you'll get a few more replies from people actually running them at the moment and will give you a better idea of a plug to use ,  hope this has been of some use regards Mark

[Dean Southall]

I'm running my '29 Sloper on a Champion D16.