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I've got a 5247 (serial 8892550) that only has 30lbs compression. Is this enough compression to run? If not, what am i in store for if i want to get it running?

Probably not. Squirt a little oil in the cylinder and retake test. If the compression goes up you have bad rings. Is this a LB?

Rivets said:

Probably not. Squirt a little oil in the cylinder and retake test. If the compression goes up you have bad rings. Is this a LB?

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Yes, it is a lawn Boy, ... a 19" push mower. It was given to me for parts. But, I'd like to fix it so I can have a back-up Lawn Boy. The Lawn boy I'm using is also a model 5247 .

I have a '76 model 7264. It has about 25lbs compression. The cool checked good, but I can spray fuel mix into the cylinder and it still won't try to start. If I want to get it running again, I'll have to put new crank seals/bearings, and a new set of rings in it. It prob wouldn't hurt to lightly hone the cylinder walls either.

Fireman 123 said:

I have a '76 model 7264. It has about 25lbs compression. The cool checked good, but I can spray fuel mix into the cylinder and it still won't try to start. If I want to get it running again, I'll have to put new crank seals/bearings, and a new set of rings in it. It prob wouldn't hurt to lightly hone the cylinder walls either.

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Thanks, again, Fireman. You've been great help the last few days. Can I hone the cylinder wall myself, or should I take it to a machine shop? So, I might be able to use the same piston? ..... Just put new rings on it?

Regarding your 1976 model with 25 lbs compression --- are you going to purchase the parts and get it running again? If so, I'd like to hear how that goes. Is it easy or difficult to put in the crank seals? I'd love to get my second model 5247 running for a back up. Like my other 5247, it's a 19" push model also. I imagine it will need the same things your 1976 model needs.

I'm working the bugs out of my good 5247 that I recently got from a buddy who passed away. Advice from fellows on the forum has gone a long way. A new needle & seat stopped gas from leaking into the foam filter. I think I may still need to tweak the adjustment of the carb. I got rained out yesterday. I'm sure happy to have it running. Hopefully, it will last a long, long time. The pic for my avator is it.

When my 1973 model 5241 gave up a few days ago, it was like a death in the family. Ha! Genuine grieving! :frown: I'm hoping a new coil might bring it back to life. Its still got 95 lbs compression after all these years.

To answer your questions, I've never rebuilt an engine so it'll be a good learning process if I decide to do it. I looked up all the parts I need online and it came to right at $100 bucks! I only gave $10 for the whole mower, lol. If I decide to do it, I'll definitely post my progress. I hope you get your bricktop running again. I have a '72 model 7021 with the green wheels & handle. Not much to look at, but it runs great and cuts as good as any new one

Fireman 123 said:

To answer your questions, I've never rebuilt an engine so it'll be a good learning process if I decide to do it. I looked up all the parts I need online and it came to right at $100 bucks! I only gave $10 for the whole mower, lol. If I decide to do it, I'll definitely post my progress. I hope you get your bricktop running again. I have a '72 model 7021 with the green wheels & handle. Not much to look at, but it runs great and cuts as good as any new one

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$100 for all the parts you need? Hey, that's not bad ! I imagine a few of us on the forum hope you will rebuild it and post pics and notes as you go. A lot of us would enjoy that and learn a great deal from it.

Thanks for the encouragement, but I'm not sinking that kind of money into it. If I can for half, maybe. I have a '01 Duraforce with the alum deck, ele start, and easy stride self propel, but it has a broken rod. That's the one I'll be more willing to pay to fix.

It doesn't seem logical to me to spend $100 on parts to fix one of these, given that they are routinely offered for sale for $20 to $30 on CraigsList.

When I have one that needs something major, I just wait until an suitable "parts mower" comes along and then spend the $20 or $30. And that way you have all the extra parts that came with it.

I might add that a high percentage of these LBs that I find have basically good engines -- only minor repairs needed.

Two-Stroke said:

It doesn't seem logical to me to spend $100 on parts to fix one of these, given that they are routinely offered for sale for $20 to $30 on CraigsList.

When I have one that needs something major, I just wait until an suitable "parts mower" comes along and then spend the $20 or $30. And that way you have all the extra parts that came with it.

I might add that a high percentage of these LBs that I find have basically good engines -- only minor repairs needed.

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Totally agreed

Fireman 123 said:

Thanks for the encouragement, but I'm not sinking that kind of money into it. If I can for half, maybe. I have a '01 Duraforce with the alum deck, ele start, and easy stride self propel, but it has a broken rod. That's the one I'll be more willing to pay to fix.

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What is "easy stride?" How do you figure the rod got broken?

Before putting any money and or time into an older two stroke Lawn Boy check the deck underside for corrosion. I used Lawn Boys for years, but years back, and never had an engine problem but retired a few machines due to corrosion of the decks. Remove the blade and the muffler, check the exhaust port for blockage from carbon and inspect for corrosion.
Also these engines do not have a removable cylinder head or cylinder and need to be completely dissassembled to do any cylinder/piston rework.
Mad Mackie in CT

Gene123 said:

What is "easy stride?" How do you figure the rod got broken?

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Yes. My bet it someone put wrong gas in it and seized the engine, and then tried to start it and broke the rod cap. I removed the engine and tore it down to find that was the issue. However, yesterday I secured another standard push model with the 6.5 duraforce for $40! I'll be putting the engine on the easy-stride today

There it is, ready to go back to work thanks to the proud organ donor on the right. It took about 3.5 hr to do the job. Had to re-use the back half of the original short block since it was machined to accept the ele start motor. Had to cut out part of the front half manually as well. I also had to make a new head gasket since the old one was gone and someone didn't do a very good job with silicone sealing it back (tells me someone's had it apart before). It seems to run really good, although I'm a bigger fan of the tried and true F engines. Will have to get used to the easy stride.

Fireman 123 said:

There it is, ready to go back to work thanks to the proud organ donor on the right. It took about 3.5 hr to do the job. Had to re-use the back half of the original short block since it was machined to accept the ele start motor. Had to cut out part of the front half manually as well. I also had to make a new head gasket since the old one was gone and someone didn't do a very good job with silicone sealing it back (tells me someone's had it apart before). It seems to run really good, although I'm a bigger fan of the tried and true F engines. Will have to get used to the easy stride.

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That's interesting. You did very well to accomplish all that in 3.5 hours. :thumbsup:

I never owned a Dura-force engine and haven't had any experience with them. I take note that you prefer the F-series.

Thanks. Having the tools to work with makes a huge difference in time. I've had a couple duraforce mowers, and it seems like they aren't quite as smooth as the F engines. Maybe its the above deck muffler making it seem that way. Now they are very powerful, I give them that. I finished mowing at church awhile ago, and it didn't take long to decide I like the 3-speed trans better than the easy-stride.

I like the below-deck mufflers on the D-series and F-series. That design has some disadvantages but, overall, I prefer it.

I would buy a Dura-force if I saw a really good deal.