Lawn Boy Score Update

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boraticus

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This morning I got into checking out the old Lawn Boy mowers.

One of them is so old it's before they painted them green. This one is beige and actually has a steel fuel tank.

I can't find anything on it that says Lawn Boy but I can tell it is. Same magnesium deck and engine as one of the other ones I bought last night. The beige one has a round name plate on it that I can't read but it does have a number stamped on the name plate "7215". The nameplate also seems to have a big "M" in the middle of it and the letters "oard" can be made out on the circumference of the nameplate. The plastic engine cowling has "Fingertip Starting" written on it.

The other similar machine has serial no. 903189B and the number 5124 stamped on the left side of the nameplate. The nameplate say the mower is made by Outboard Marine Corporation.

The third mower has a more modern engine and a steel deck. It' serial number is 9385904 and model no. 7050.

Mechanical status:

The old beige 7215 fired up and ran with nothing more than a carb and spark plug cleaning. Compression was showing at 60 psi which seems low.

In order to get the other similar LB running, I had to take the reed plate and carburetor off of the beige one.

It still wouldn't run because it had no spark. I pulled the flywheel, sanded some rust off of the magnets and coil, re-gapped the coil, cleaned and set the points, cleaned and set the spark plug. I poured fuel into the spark plug hole, put the plug in and it fired up after a few pulls. The carb from the beige machine has a plunger built into it for priming rather than a primer bulb. Compression was showing 60 psi on this one too. Strange. I poured some engine oil into the cylinder to seal the rings and compression didn't change much. I'm thinking my compression tester might be screwed. I'll be looking further into that.

Regardless of the low compression reading, it started and ran very well. I let it run for a good ten minutes and it was very steady.

Can't tell you much about the third machine. Engine looks good. Carb is covered in greasy dirt and looks like it might be plastic. Can't test compression because the pull start mechanism is broken off. The shaft that holds the recoil system onto the block broke off at the block. I've got both pieces and will see if I can get them welded together.

So, I've got two machines that run but share a carb. The guy I bought them from says he'll see if he can find the carb for it. In the meantime, I'll start working on no. 3 when I get the recoil fixed in the next day or two.

Anyone out there familiar with these models?
 
The 7215 is a 1965 model, with the D engine.

The 5124 (also with the D engine) is a 1979 model, since the serial number starts with a 9.

The 7050 confuses me. Those with serial numbers starting with 9 were 1959 models (with the C engine). They picked up that model again in 1982, with serial numbers beginning with A. A 1983 model would have a serial number starting with a B, an '84 model with a C, an '85 model with a D, and an '86 model with an E. Are you sure the serial number doesn't start with a letter? Any '80s 7050 has a steel deck with the F engine.
 
the 7125 is a 1965, and the 5124 in that ser. range is a 1979. that is as much as partsmart has. We cant get parts for it. Lawnboy is gone, and now owned by Toro. Don't know if you've ever noticed but lawnboys have the worst coil hands down. We replace more lawnboy coils than b&s and honda combined X10.
 
Originally Posted By: Hokiefyd
One thing you can try for the coils is bake them in the oven at 200 degrees for about 20 minutes. Sometimes that fixes them. No joke.


What's for supper ma? Steaming hot Lawn Boy coils that's what. Mmmmmmm!
 
Thanks for the input guys.

I found the old specs for two of these engines. They are D400 and minimum compression is 65 psi. Normal cold compression is 70 to 85 psi. I went out and tested the 5124 again and the best it does is 60 psi. It starts easy enough and runs great but I'll have to see how it performs under load.

I haven't had any problems with the electrics since I've cleaned them up a bit. The two D400s seem to have plenty of juice.

The serial number for the 7050 is what it shows on the name plate. It also shows being built in Peterborough Ontario. So maybe it has a Canadian ser. no. It does have a steel deck and the engine is definitely newer. It has electronic ignition as well.

Will have to do a bit more research after dinner.
 
Originally Posted By: Hokiefyd
The 7050 definitely has the F engine. Maybe the Canadian numbers were different. Interesting. PICS PLEASE!!!


The machine is partly disassembled. I could get some pics of it tomorrow. What that engine needs is a recoil start assembly. Anyone know where I can get one. I can't do anything with it until I get it.

If you know of one on ebay or elsewhere, please let me know.

I fine tuned the carb on the 5124 (Very adjustable. It's off of the old 1965 model 7215) put the electronic tach on it and it runs at a steady 3290 to 3300 rpm. That's pretty much factory spec. It doesn't smoke at all. With such low compression, I wouldn't expect it to run as good as it does.
 
Last edited:
Did you ever test your compression gauge? Maybe needs a new schrader valve? I rebuilt the carb on an 8 year old Briggs the other day that had a leak down of 35% all into the crankcase. You would have never known by its running characteristics. I tryed to talk the guy out of repairing it. Do you own a cylinder leakdown tester? It really takes a great picture of the c-chamber condition. Well... most of the time anyways.
 
I did as 660mag suggested and tested the compression gauge. I used my air compressor with an output gauge and set it at 80 psi. I put a rubber tipped nozzle on the end of it and secured it in a vice. I tested the air pressure at the nozzle with two high quality air gauges. One electronic and the other mechanical. Both were reading 82 psi. When I put the compression gauge onto the nozzle it read 60 psi. I increased pressure to 100 psi and it read 80 psi.

Bad news is that it looks like the compression gauge is junk. The good news is that the Lawn Boys are healthy with compression well within normal limits. Nice!

Here's a couple pics. The machines don't look the greatest but other than a few missing parts and need of a paint job, they're in pretty good condition. The plastic covering on the coil of the '65 mower is cracked but the coil works fine. I'll probably just fill in the cracks with silicon or epoxy and wrap it with some magic tape.

The two together are the model 7050 on the left and 7215 on the right. The one by itself is the 5124 which is running great.

DSCF6632.jpg



DSCF6641.jpg
 
I had one of those tan L-B mowers years ago. A free-bee from an uncle.
3HP IIRC, Once started ran great. Didn't care for thick grass much though.
Brother took it off my hands and ran it for years after.
 
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