saito fg-20 well kinda
 

hi all i am about neck deep in my first conversion project. i decided that i wanted to convert my stock saito 125 to run on gasoline. so i made a sleeve that i mounted to the prop hub to mount my magnet to. then i made a band out of brass that wraps around the bottom of the engine and attaches to the top front two cam cover screws. to this band i mounted the hall sensor for my rcexl ignition unit. i ran the engine off of the stock glow carb and i got some very impressive numbers. spinning an apc 16X7 i was getting 8200 rpm running 32:1 lawnboy. the only thing was i could not get a very good idle and the needle was very touchy one click either way and i was out of tune. so i decided that i would solve this problem by changing the carb to a walbro wt340. i found this carb mentioned on another conversion of a 120 size two stroke so i decided it should work for my project. so that brings you up to today.

i am working on the mount for the new carb. i am making it out of some 1/8" aluminum "L" bracket. i took a section of tubing that the stock intake tube fits into and attached it to this "L" bracket. i then took and turned the engine back plate 90* so that the stock carb mount was out of the way and i am using the top two screw to attach my new carb mount to the engine. now i am waiting for my carb to come then i will drill the mount screw holes. my next task is to decide how to operate the pump. i have two options the crank case vent or the to use intake pulses. i want to try it on intake pulses first that way i dont get all that oil into the carb. what are your thoughts on my project?

note: the carb shown is not the one i will be using it is a walbro but is not the right one. it is just a stand in for the real one for these pics. also it is not a complete carb as you can see

RE: saito fg-20 well kinda
 

32:1 is not enough oil. The FG-20 uses 20:1

You are running a 125A cylinder. The bigger cooling fins on the 125B cylinder are the same as on a FG-20.

Horizon wants less money for a FG-20 cylinder than they do for a 125B cylinder.

The FG-20 cylinder has a higher compression ratio than the 125 cylinders.

The FG-20 cylinder has a smaller intake manifold than a 125.

They changed the 125 rod for the FG-20. They now use the FG-20 rod in the new 125's

RE: saito fg-20 well kinda
 

i will be running 20 to 1 when i get done with the carb mod that was just what i had on hand at the time of the first tests

will the fg-20 rod work for this engine?

RE: saito fg-20 well kinda
 

I didn't change anything on my rod when I converted my Saito 91 and 180 and have never had a problem but I run 22:1 Fuel/Oil. I have not raised the C/R on my four stokes but I have on my two stroke conversions and the HP goes up with no adverse effects. All of my conversions are running fine and the Supertigre 90 gets used every weekend. Runs like a top and swings 14X6 lumber 9800 pulling my Goldberg Tiger 60 around nicely. I am using 16:1 Fuel/Oil in the two strokers.