RE: Welcome to Club SAITO !
Hello Club Saito. I need help in figuring out what is going on with a Saito FA-91S I bought on RCU. I was told by the seller that the engine was "in very good condition, never been in a crash and runs great, plenty of grunt!" When I got it, I put it on a test stand to run it and get it tuned. But it absolutely WOULD NOT START and there didn't seem to be much compression. Finally after much frustration, I pulled the valve covers and observed what they were doing while turning over the crank. When the piston was approaching TDC, the INTAKE valve was wide open.
So I retimed it by aligning the dot on the bottom of the cam gear down while the piston was at TDC (as has been described in a few RCU forums). When I put it back together, it fired right up! At first I was pleased but noticed that it was making a terrible sound. From idle to WOT, there was a knocking sound coming from somewhere inside. I could get it to idle at about 2100 and WOT was around 9500 RPM (I live at about 3,000 feet above sea level). But it didn't sound good at all. So I removed the side cover and noticed that there were scrape marks on the inside of the side cover (see photo)! I could also notice that at the bottom of the cylinder walls there were deep grooves. I pulled the head off the case and after I slid the piston out I could see grooves in the piston on one side and what appeared to be gaulding marks on the other side.
My questions are these:
1. It appeared that the fit between the connecting rod and crank journal was so loose that it was striking the side cover. Could that be causing that much noise?
2. I found a bunch of blue sealant on the gaskets that had gotten into the inner workings- could that have contributed to the damage?
3. Historically, were there variations in the length of the threaded prop shaft between FA-91S models over the years? (I'm thinking this is an older engine)
4. Were there variations in muffler size and styles for the muffler? (the muffler doesn't match a new FA-91S that I have).
5. Is there any way this engine could have been described as "used, excellent", "in very good condition" or "runs great" when it had all of these problems?
6. Did I get ripped off, or what (paid over $160)?
Your comments are most welcome. Thank you very much.