I had a similar problem recently with my Saito 100 See this thread:

http://www.rcuniverse.com/forum/m_73...tm.htm#7697624

At Joe Nall this year I was talking to a "Senior Product Development Mgr." at Horizon Hobbies, who was supposed to be the Saito Guru, about my problem and Saito engines in general. He stated that any Saito engines sizes 100 and above should be mounted on a glass filled mount and anything smaller you could use aluminum. He did not recommend vibration dampening mounts. Pease take this with a grain of salt since this individual never replied to my email that he promised to do. My problem was a vibration issue that was fixed with a rebuild that included new bearings. The thread will explain it. Good luck.