RE: Welcome to Club SAITO !
Sorry to bring up and old topic, especially one that has been beat to death in this forum.
Saito 125 vibration. Same old story. I picked up a 125 on ebay, changed the bearings and cleaned the inside of the engine. As far as I can tell the cam is in time, and the valves are set to about .003 or so. New fuel (15% FS Powermaster), new Prop and OS F plug. Set the HS Needle as close as I could and the Engine fired right up and I've ran about a gallon of fuel through it.
Very smooth low end and transition seem to be very crisp. However.... Starting at about 1/2 throttle, the engine begins to shake and at full throttle I can barely focus on the valve covers. Trying to adjust the HS Needle is like trying to grab the end of and engraving pencil. I have tried a couple different props that are balanced to the best of my ability. The last one was a APC 15-8 and the first was a MAS 16-6 wooden.
I changed the bearings again, this time from BOCA. No change.
I did notice the that the rear bearing slid onto the crank with no effort. It didn't feel loose, but it does slide on and off by hand. Do I need a crank?
This is my first 4 stroke and the "good old boys" network ant my local field are less that interested in helping. It seems that if it's not a YS, don't bother....
From what I read in this forum, Horizon Hobbies can be hit and miss with used engine repair and I don't want to throw any more money into this engine if the vibration problem can't be fixed.
I am hopping that I can send the engine to one of you more experienced folks for testing and tuning and tell me if I'm wasting my time and just buy a new engine. I will be happy to Paypal the money or your time.
John