Well, I won't be able to check this until the weekend, but, I did have the carb off the machine twice during my trouble shooting a couple of weeks ago - perhaps I goofed when re attaching it. OTOH, it's probably been years since I started that mower using just the choke. I always attributed the problem to old gas in the fuel line. Now, I'm thinking that some little thing may have gone bad over the years that, with correction, will solve this problem. It's not a biggie to me, but, now that I have her running so well, I'd like to cure this if possible. Thanks for the replies. Caruso

Doug, I checked out that small engine manual I spoke of last night and there still may be some possibility that you're short block could have been for marine use. The diagram shows nothing but it is also very small. There are some interesting aspects to the engines in the manual such as they are definatelly D-400 blocks and cylinder jugs. They are air cooled and the crank looks like any other for mower aplications except the crank bolts up to some sort of compressor. These engines were made by O.M.C for the Einrude "Aquanaut" and the Johnson "Air-Buoy". I have never seen either in real life but the interesting part is this compressor has all kinds of relief valves and air intake tubes etc. Mabe one of these relief valves had some sort of tube that ran too the crankcase. Otherwise the starter, armature plate, carburetor, reed plate all look like the same as any D-400. The exhaust is interesting as there is some kind of wacky inlet hose and an exhaust pipe and an L shaped muffler. Its only a possibility but thought you should know. You can try to locate this manual. Its called "Small engine service manual" 10th edition published by Technical publications div. Intertec publishingcorp. Kansas City, MO P.S. You might want to try going to M.T.F and going to the small engine forum and mabe someone there may be able to help also. Good luck, Neal

Hey folks I have good news! I resolved the issue and I wish I would have done this about twenty five flywheel removals ago. The stinking flyweight is malfunctioning to not allow the running leg to kick in. It must have been stuck or something Its hard to say when you cant see it in action. Luckily I have spare parts for these things. I put a different one on and off she went. So looking at the bad one it really looks identical to the other, I just don't know if it was the flyweight or the cam. I had it installed with the smaller end toward the key way and the movement was free of grease and dirt. I just don't get it. Anyway its running good and I took an old gov spring, streched it out about half an inch and I have now achieved 3000 RPM on this machine finally. Alot of trial and error but a great learning experience. I realize most people don't care too much about these old point ignition engines but they sure are fun to restore and work on. Thanks again, Walt ,Jim in VT, and Mike for the help, I know we would have found something Jim, you were on the right path. Thanks, Neal in Kansas

An out of balance blade was one of the things I ruled out- two back up blades were put on- one freshly sharpened/balanced at the shop, and one brand new blade were tried, w/ no change in vibration. Muffler bolts are not the problem- the heads can be seen on the upper surface of the deck, and the ends/bolts are seen secure on the muffler plate bottomside. The 1st repair I noted from 2001 were described as replacing the 'lower seal bolts' on the receipt. The shop manager said there are 4 of them. In looking at the LB parts blowup on https://lookup2.toro.com/partdex/index.cfm?xCaller=lawnboy There are four bolts (part #314576-'40' on the diagram) These come up from the bottom of the crank, where there is a crankshaft end cover. The bolt threads pass up thru the top of the muffler plate, thru the lower crankcase seal, and into the lower part of the crankcase. I do not see nuts on the diagram, it is not clear where the ends of the bolts go. I am fairly sure these are the origin of the problem. That all said, QUESTION- I am wondering if the rod and piston are degraded by a bent crank? I should note I still have to perform Walt's 'wiggle' test as note in his original post to see if the crank is bent, or if we are just dealing w. loose lower crank bolts. Walt- can you clarify your statement- 'These engines routinely wore out the bottom bushing which is not a replacement item although several guys have bored them out and installed an "F" series engine needle bearing.' What is this bottom bushing? Is that integral to the crankshaft- and that is where the shaft has an hourglass shaped 'bulge'? Thanks again everyone!