982 engine surge

[jcrews]

Hello
I am having a little trouble getting my Linamar LX790. It was really surging and I tried to clean it with carb cleaner and it made no difference so I went out Sunday afternoon and removed the Nikki carb and removed all the jets and cleaned them with wire strands, carb cleaner and compressed air and finally figured out where the breather filter was and cleaned it, and then reassembled it. When I tried it cranked instantly and ran perfectly. After an hour of cutting grass the engine started to occasionally act like it was going to cut out and stop, but would run on and slightly start to surge temporarily for a few moments and then run normally. My question is would replacing the carburetor diaphram correct this problem or should I look for something else.
Thanks

[deputyrpa]

I hope I can help with general engine knowledge. Engine surging can be due to either running lean, sucking air, or mal-functioning governor. I'd troubleshoot in this order. This is how I diagnosed my 982.

When you sprayed the carb cleaner, did the rpms climb? Does it run better when choked? If so, you're sucking air. That could be anywhere from the carb to the intake manifold gaskets. Spray carb cleaner on the manifold and man gasket areas, and see if you get revs.

If that's good, or you get no response, try adjusting the high speed needle out an 8th of a turn to richen the mix. Wait a while after you adjust it.

If a no-go, re-adjust the governor and/or replace the spring. If it bogs under load, then recovers late, that might be the issue.

Good luck.

[jcrews]

Thanks for the advice deputyrpa.
Unfortunately the carburetor only has an idle speed adjustment, I'll see if I can adjust the governor, I can't find a service manual for that engine anywhere, onky engine specs and owner manual.