How much do you think you can deck Kawasaki FD620 heads off the Lxi

[FloryPB505 2]

Had the head gasket go on the thermostat equipped head on my mower a few days ago.

 

I pulled the heads off and I definitely need to mill the surface probably atleast 0.015" in order to clean up the damaged caused and get something flat again.

 

Block is pretty flat, got it trued up with a lapping plate and a little patience.

 

I am going to try and knock the heads down and see how it goes before I buy new ones because I have machinery to handle that in house.

 

If anyone has any experience doing it, advise or cautions would be appreciated.

[Maxwell-8 4,367]

more Powa!

[Achto 29,402]

2 hours ago, FloryPB505 said:

I definitely need to mill the surface probably atleast 0.015"

 

 

I do not believe that .015" will harm anything at all. To make sure you can use modeling clay to measure valve to head clearance after you deck the head. 

 

 

Edited October 11, 2021 by Achto

[FloryPB505 2]

So just want to update people whom might have this question in the future.

 

 

I had a long night after work a long long night since I didnt really get to sleep at all (my own fault)

 

I checked the deck heights on both heads and they are off from one another by 0.011" strangely because the valves and pushrods are not different between heads nor is the rocker mount different. I did not CC the combustion chambers I figured its a lawn mower with 2 cylinders it cant be that crazy.

 

Anyway I had to take 0.028" off the thermostat equipped head to get it flat, I mounted it to a square and flat block, bolted it down through the valves and took 0.005" skims off it until the cavitated aluminum area between the ports cleaned up well enough. I than set my zero and knocked the other cylinder down the same amount and that is where I noticed the deck height difference because I only pulled 0.017" off that head. 

 

I didnt clay pack the cylinder I just did a sanity check  on the max valve travel and the piston dish and it looked like there was still clearance, (not going to lie I was plenty scared I upped the compression ratio way to high by not ccing and calculating the actual compression in the chambers)

 

I than went down the rabbit hole and blended the bowls in a little and cleaned up some of the casting boogers in the intake and exhaust ports, gasket matched the outlets, no crazy polishing but a good 4 hour port job to do both heads, intake, and water pump (there were some serious sharp edges that hurt flow in and out of the new factory kawasucky one I bought)

 

Put the water pump on, the heads, stuck a new thermostat in it (I need a new housing still the original one is degrading but its on there for now) Tossed some gaskets on with copper silicone on both sides of all gaskets. Truthfully the intake could be machined down to match the new heads better but I buttered up the gasket sealer on the new gaskets figuring if I screwed the heads up I wanted to try it before I went ahead and wasted another part.

 

Put some straight water in it and changed the oil since it was chocolate milk.

 

First thing this morning it fired right up and sounded great. Very happy with it, sounds like it is running strong and definitely up on power. Probably running a little rich and IDK if the new kawasucky thermostat isnt awesome or just the thermocoupler is jumpy but my temp gauge was jumping around a bit more than I would like to see. (I ordered a new thermocouple to see if that changes things the original one is pretty crusty) 

 

Long story short, at sea level with 89 octane you can deck around 0.030" off the head without detonating problems or crushing valves. I got to 0.030" by milling 0.028" off the head itself and I probably took a minimum of 0.002" off the block when I was flatting it with the lapping plate.