dtitzer

i am getting ready to rebuild a saito 72 and os 120 4 stroke pump looking for info on intalling cams , timing marks thanks dave

rccrazedman

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I'm fixing one of my own saito .72s . when it comes to cam timing its very easy. All you have to do is rotate the craknshaft to where the piston is at top dead center. The camshaft has a dot on the casting near its gears. All you have to do is install the cam with the dot at the 6 o'clock position. Now I don't know about the OS > But I don't see why it wouldn't be the same.

logair

Let me jump in with my two cents worth. I just yesterday was able to run my OS FS-61 four banger after sitting in storage for a few years. History is that it was involved in a crash a few years back, and it was low on compression from lots of running. So I installed a new ring, bearings, new rocker, etc. After that I could not get it to run much at all. Last week I thought I should dive into the problem since I liked that engine and hated to see it sitting. I tried the internet for any info on cam timing and finally found one relating to a ASP four stroke witch appeared to be a copy of the OS. The cam timing was explained as follows. With the piston at TDC install the cam gear with the timing dot at the 12 O'clock postion. After doing this compresstion was stronger, and it runs great. It is hard to find any overhaul info on these engines for some reason. Hope this post will help someone with the same problem as I had. Logair

rccrazedman

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ok fair enough each engine is different.

dtitzer

thanks i am going to do the os this week i bought it at a swapmeet it looks new but the bearings feel rough hopefully thats all it needs thanks again dave