Does anyone here know anything about a YS engine? This is a learning curve for me.

I bought the thing used and in great shape but the guy i bought it from could not get it to run. I found it to be a challenge.

I got it and replaced all of the gaskets, diaphragm, reset the valve clearance to between .004 and .01, and and did a thorough inspection. I then got on the net and found all the settings for the needles and regulator and set up the check valve pressurized fuel system. Used a syringe to check for leaks.

I fueled the tank up and started right up and ran like a dream for a min or two. As the fuel level started to drop the engine began to richen up. I chased the high speed all over the place and I could not get it to run correct. The engine bogged and died. I fueled it up again and again she ran great at first. then back to the same routine. I think that it either is a heat problem or something with the screwy fuel system.

I called a guy over to look at it that has been running YS engines for a while and he could not figure it out.

I just hope this rings a bell with someone.

Thanks to all