OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines B&S 20hp hunts through the rev range.

G'day everyone,
I have a Husky ride-on with Briggs 20 hp engine on it, 2016 model 40N877 in the workshop. It hunts from idle through to top no load revs. I have changed the plugs, removed and clean out the carby btw it was clean inside no debris or blocked holes(Nikki single throat carby). I checked to see if there was a sheared key in the keyway but that was fine, it has fresh fuel in it and there is no blockage in the filter and the fuel pump pumps fuel. Spark is good from both coils jumped across my spark tester nice blue spark. But one thing I noticed when I gave it a compression test, right hand cylinder had 100psi but left hand cylinder had 150psi, I tested both cylinders twice and got the same readings engine oil is still clean and at proper level.I also pulled the connector block off the back of the press button start assembly, cleaned all the contacts with contact cleaner. So after doing all these things it stills hunts while running, I have both Briggs V Twin engine workshop manuals but they don't do this one, the carby linkage set up is different to the older V twin set up this only single throat carby not dual throat. So I don't know if Briggs have brought out a updated workshop manual? So any help or suggestions from fellow small mechanics please let me know or if someone has come across the problem I have described please let me know how you fixed the problem. cheers Mike

Hunting is a carby problem. Difference in compression will give lumpy running maybe

I think you have an Intek V twin but need the type number.

Now if it is an Intek the compression numbers are too high for a cranking engine as this engine has an ACR system that limits the compression. With Intek engines that usually means the rockers are out of adjustment. So check the clearances. .004-.006 in.

It does sounds like a lean burn issue. Have you tried applying a little choke to see if it will smooth ou? Note some has an air vane auto choke system.

As being the Nikki make sure the main jet is not loose. And it is clean.

And the SM doesn't cover the single barrel carb set up. Briggs should update their manual but they apparently too darn lazy or too cheap.

G'day,
Yes, it has an air vane choke system, I had the carby apart and the jet is tight and clean. But I will check the rocker adjustment and get back to you.

G'day,
I removed the rocker covers on both cylinders, checked the rockers for cracks, checked to see if there were bent or damaged push rods(all good). Then checked tappet gap both sets were in spec. I had couple of spare Nikki carbies so I swap over the internals and it still hunted but it ran better, then I had a thought I have had a Briggs V twin in for repairs a while ago it wasn't running right a bit like this one. So I removed the "sump" and found the " paddle" had come off the govenor shaft, replaced it new new governor shaft and it fixed the problem. But i think I will get a new carby first before I pull the engine out and strip it down.