Topic: 74 CB200 - cylinders do not have same spark plug thread diameter

[earth tones]

Is it standard on a 74 CB200 for the two cylinders to have different spark plug thread diameters?  One cylinder has a "B" thread diameter NGK plug while the other has a "D" thread diameter?  Just wondering...seemed strange to me.  Thanks!

[HavocTurbo]

No it isn't normally common for that to happen from the factory.

What is common is for someone to strip out the threads and to drill and tap new threads for a larger diameter plug.

Which seems to be the case here. Maybe.

Got pics?

[Laminar]

Nope, my CB200 had the same plug in both cylinders.

[earth tones]

I don't have pictures at the moment, but can take some tonight.

Like I said, there is a smaller plug hole that fits a 12mm NGK plug (type D) and there is a larger plug hole at 14mm (NGK type B).  So that must be the case, somebody must of bored out a larger hole and tapped it.  So you just find a plug, with the larger thread diameter, that would equal the performance of the stock plug -- a NGK D-8ES-L??

[kirkn]

Yep, my CB200 has NGK D8ES's in it.  Both sides the same.