Lawn Boy - Need 2 cycle Engine for 1991 S21ZSM

DanfromNC

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My son put gas with no oil in by mistake and ran the mower til it heated and stopped running. Engine was partly siezed but looks like the ignition module failed before the engine siezed fully. Replaced ignition module. Been able to get the mower running again but motor tends to overheat after running for 10 or 15 minutes. Assume what is needed is a new engine, guessing rebuild would be costly and no guarantee of success.

Anyone know of a source for replacement 2 cycle engine for 1991 4HP Model S21ZSM?

Been a great mower, bought new in 1991 and used a lot every year with only minor issues. New bag, etc. Hate to see it die or go for parts. Thanks
 

Rivets

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Good luck finding any type of replacement. They have not been made for a long time. I would not recommend rebuilding. You could try this to get a little more life out of it. Change your oil/fuel ratio to about 28/1 instead of 32/1. Also, make sure that all the cooling fins are clean. The change in fuel ratio should help a bit with cooling and give you more compression.
 

DanfromNC

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That's what I thought, thanks for the quick response.
 

Two-Stroke

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Sorry to hear about your engine. :mad:

If I were you, I'd look for another similar Lawn-Boy to use as a parts mower. Or maybe make your current mower the "parts mower". I think a lot of the engines around that vintage would bolt on.

You might try posting this question (about interchangeability of engines) in the Lawn-Boy forum. There are some members who could tell you more about that -- assuming you're interested.

I wouldn't be concerned about getting an engine that's 20+ years old -- they last that long and more. :thumbsup:
 

twinfords

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yup two-stroke is correct, craigslist for anothe 2 cycle is your best bet. S21ZSR is what i have and people have no idea how great that mower is.
 

Howard Traucht

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I have 2 good engines sell $50.00 ea = ship. Thank you Howard
 

topless64-455

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I will take one as my girlfriend did the same thing with straight gas. I have a 91 non propelled mower than needs a new engine. I took it apart last fall but I dont think it will go together as its been to long. Can you send pictures?
 
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