kenh3497

I've purchased a used DZ170. After a complete tear down and cleaning it is in fair shape. The bearings are not perfect but very serviceable.

The compression seems a bit on the low side. The piston ring gap is about .008. Is this a bit wide or OK? Will compression improve after running a bit?

It it needs a new diaphragm in the pump regulator and the diaphragm in the fuel injector looks a little funky. I've looked but do not see a injector diaphragm listed. How critical is that diaphragm?

Thank you

Ken

kenh3497

Posted an January 6th. Not one answer or even a comment. Not much help here.........

Dave Harmon

I have one of those engines.......008 sounds a bit wide to me....
This is how I measure the ring gap.
Remove the ring from the piston.
Insert ring into the sleeve.
Bring the piston up from the bottom of the sleeve to square up the ring in the sleeve.
Remove the piston and measure the gap with a feeler gauge.

I would replace it anyway.

The injector diaphragm is sold as a unit....I don't think you can get the separate pieces.
Try running it....I doubt the injector has a problem.

Likely the valves are leaking more than the ring so use some toothpaste (not the gel kind) and a piece of fuel line on the valve stem.
Chuck the fuel line in a drill and spin the valve.
This will help a lot.
I have also used fine rubbing compound as well with good results.

Dave

kenh3497

Thanks Dave. I was afraid of the injector being a unit only thing. I have new unused old carb kit parts with some of the very thin material. I may sacrifice one of them as an experiment after I have the engine running. The valves seal tight, With the back plate off you can hear the ring leaking. I've been using your method to check ring gap since about 1975. The ONLY way to do it!

Ken