Kawasaki FH500v engine rpm's surging

[mikefamig]

I am struggling with an engine that is surging at all rpm's. It can be made to run smoothly by adjusting the choke almost all of the way closed. The engine as a 17hp kawasaki FH500V twin with 450 hours on the meter..

The first thing that I looked for is a vacuum leak in the intake and found none in the gasket surfaces but the engine does smooth out when I spray some carb cleaner at the throttle shaft. Seeing this I removed the float bowl and blew out the carb as well as I could with the carb still on the engine. I reassembled and still the same.

Then I inspected the governor and the linkages and throttle shaft spring all looks good and everything is moving smoothly. I made the static adjustment to the control arm on the governor and still the same.

At that point i spent $40 on a chinese carb for it on Amazon and installed that and still exactly the same.

Next (should have thought of this first) I tried new gasoline and still the same.

I am out of ideas and wouldl appreciate any help,

Mike.

**EDIT - I left out that I also installed new spark plugs, ran with the gas caps removed, added sea foam to the gas, and tested the fuel pump and it has good flow. There is plenty of fuel being delivered to the float bowl.

 

[mikefamig]

I just had at it again and got the engine running smoothly after three days of trying.

This time I had the OEM Mikuni car b on the bench so I had a chance to blow it out with carb cleaner. Then I removed the Chinese carb and also the governor control panel. I cleaned and inspected the panel, performed the static adjustment on the governor control arm, reassembled with the original carb and the machine is running normally.

It bothers me that I still can't say for sure what the problem was but now I can mow the lawn which is a victory in my book.

Mike.

 

[tomplum]

More commonly on these the low speed passage of the carb begin to plug. I see this more on those that run with plugged air filters. They can be a bugger to service depending on the carb. Of course, the float valve can be worn too. +1 for you to have the foresight to check the governor adjustment.

 

[tibadoe]

How long did you leave the Seafoam in for? When I have a surging engine I added seafoam and let the fun for a bit to get it through the entire fuel system. Then let it sit overnight or longer if possible. Seafoam will dissolve the gum an varnish and clean up the carb & fuel system nicely.