ORIGINAL: Sport_Pilot
OS plugs are overpriced. Fox, K&B, McCoy, and others make plugs that are as good (unless the heat range is wrong) and cost a bunch less. Not saying OS plugs are bad, just overpriced. For example a Fox Gold will replace an OS #8 in most engines. K&B 1L or Fox RC if a slightly cooler plug is needed. Might want to try the Thunderbolt plugs from Hobby People as well. The Thunderbolt four stroke plug is hotter than an OS F.
At the moment I'm testing the Thunderbolt four stroke and I have already tested out the Horizon four stroke. The H plugs I had were a mistake in an order and I was sent a sheet of 12 instead of just one plug. I was just filling in an order for shipping. I gave some out to friends to test too. They are great, don't seem to last as long as the F but at half the price?? The Thunderbolt cured a idle problem I was having with my YS 1.20. Again, at half the price?? I want to order a few of the YS plugs, I have a feeling OS makes them for YS and again, half the price. YS only recommends the YS or OS type F plug. Go figure.