Many years ago I has a Montgomery Wards rebranded Lawn Boy but sadly lent it out and it never came back. 10 years ago I brought a 5021 home and forgot it in a shed. A few weeks ago I brought a 7623 home. I need something to trim around the yard and yesterday pulled them both out. Both tanks were empty and looked to have been run dry. I first filled the 7623 up with gas and when I pushed on the drain spring on the float bowl nasty smelly varnish came out and then nothing, ok the needle and float are probably stuck. I moved on to the 5021, primed it 3 times and it fired on the first pull and started on the 2nd. It ran just above idle, I added seafoam and let it run. After about 20 minutes it started smoking up a storm, still loping along at a rough idle like it could die at any time. I wasn't timing it but it sucked the tank dry really fast. I filled it up again and it continued as before and that tank emptied quickly also. When I filled it up for the 3rd time it roared to life seemingly much faster than I remember my old one running and the smoke was largely reduced. I think I have a keeper.
A couple of questions the 5021 looks to be totally original, even has green wheels. Should this have some sort of throttle control? It only has the on/off primer control. It has an outer air cleaner housing but no element or cover, is there an illustrated parts list to find p/n or an alternative? Does the 5021 and 7623 share the same engine family? Are these engines with the good crank bearings?
Thanks I found the schematic and the parts on ebay. I had the numbers wrong on one of my mowers, one is a 5021 and the other a 7263. From what I can tell I have D433 and D600 engines, Are these bushing crank engines or bearings? Is the 600 an improvement over the 433? I run Amsoil Saber at 75 to 1 in all my other 2 strokes, Amsoil recommends it at 100 to 1 in all 2 stroke engines. Are you guys leaning the oil mixture out using modern synthetic oils?
I used to run everything at the 100:1 even on my 1977 7024 (D433) and my 80's "F" engine mowers and never had an issue. My Amzoil dealer always said running richer than 100:1 was just wasting good oil !!
A few years after 2-cycle engines left the new lawnmower & snowblower world, I decided to be a bit more conservative and started mixing my Amzoil at 64:1 for all my 2-cycle equipment.
The 1998-2004 Lawnboy Duraforce / Toro R-Tek engine was designed to operate at 50:1, but Lawnboy still marketed it at 32:1 and Toro marketed theirs at 50:1.
My Duraforce mowers and my R-Tek snowblower are the main 2-cycle equipment I run today, so running a 100:1 synthetic oil at 64:1 is pretty safe / not much leaner than the factory recommended 50:1 non-synthetic mix.
