I'm currently using the Hobby People's 4stroke and big bore engine plug which is a special amalgam plug that doesn't have an idle bar and it works great same as the O.S.4 stroke one but is less expensive ($5.50 vs $7.99) than O.S. I think it can also run good with a regular R/C long plug with Idle bar try it, I used one before on my echo 25 that got stolen and it worked great>