engine knock on '61 10 hp QD-22

Hi all. Just got my my '61 10 hp QD-22 running a few weeks ago thanks to the forums. Finally got a stand built today and put the motor on. Fired up on the first pull! Sweet! BUT I noticed a bit of a knock in the engine approx. every 2-3 seconds when idling in neutral in the test tank. I was wondering what the most likely cause(s) might be.
I've done all the usual tune up stuff like new water pump, carb kit, lower unit lube, point, plugs, etc... She went from stone dead when I got her to starting on the first pull. Sounds silly, but aside from the knock, she runs very smooth, quiet, and pumps tons of water, and shifts into/out of gear easily. However, I'm not getting into forward, but I think I just need to adjust the shift linkage in the side window properly. I've heard they're tricky and it seemed way too easy when I was putting it back together after installing the water pump, etc... Unless y'all think the two issues are related? I'm gonna get mix a new batch of gas at 24:1 tomorrow to see it that helps a bit, and double check the shift linkage too. Would it help to sea foam/deep creep it or something while I'm at it? thanks for any help.

Re: engine knock on '61 10 hp QD-22

I don't know what all that stuff about the shift is all about, but I think you are hearing a "lean sneeze". It happens when fuel catches fire in the crankcase. Sort of a sneeze, snort, backfire, whatever you want to call it. Try setting the slow speed mixture a bit richer.

Re: engine knock on '61 10 hp QD-22

Thanks F R. I'll do some more carb tweaking tomorrow to see if I can get rid of the "sneeze". I think my shift rod connector is not conncected to the lower shift rod correctly either which is why it's not going into FWD. I'm gonna check that tomorrow too.

Re: engine knock on '61 10 hp QD-22

If it's not a lean sneeze, perhaps it's something in the recoil. You can pull the recoil and rope start it from the flywheel to confirm.