It seems the YS engines forum is dead so I'm posting this here.....

The used DZ170 I purchased is my second, after a 140DZ, YS fuel injected engine. The 170 has a different fuel injector than the 140 does. What is the purpose of the diaphragm? Is it a check valve of some sort? I'm not seen it listed as a repair item unless it is in a "kit" with other parts. My diaphram looks a bit funky but I believe it is still functional???

My 170 was completely disassembled. It was in reasonably good shape with a few minor issues. I found a bent exhaust valve push rod and a little more varnish than expected. Valve clearance was excessive on the intake and of course on the exhaust. A 140 parts engine donated an exhaust pushrod.

After reassembly I feel the compression is a bit on the low side and can hear compression loss through the crankcase indicating a poor ring seal. The ring has an end gap of about .008. Is this to much? I have to guess it is on the high side of tolerance. Maybe running will improve the compression????

Thanks!

Ken