5247 (1980) won't restart. Carb adjustment problems?

[Fireman 123]

Buy a mechanics handbook from eBay. It's very useful if you're planning on keeping the old mowers going.

 

[Gene123]

Buy a mechanics handbook from eBay. It's very useful if you're planning on keeping the old mowers going.

I'll look for one. ..... Sure wish I'd had one a few days ago. It would have made my Lawn Boy repair adventure a lot easier and less time consuming. I've learned a lot.

 

[Gene123]

1 preset altitude needle 1/2 turn from seat
2 start and let warm for 3-5 min.
3 place speed control to low
4 slowly turn needle CCW until engine running smoothly
5 place control to high, if not running smoothly turn CCW 1/8 turns at time till smooth
6 shut-off and immediately try to restart, DO NOT PRIME, should start within a couple pulls at both
low and high settings, if not contitnue turning needle 1/8 turns CCW to obtain easy starting.

This is from manual, good luck, looks like everyone pretty much have it covered. Fuel+ Air+Combustion+Ignition=VROOOOOM.

Thanks, Hankthecrank. ..... Great to get such precise information. You mention an altitude needle. My carb doesn't have one. That confused me. Instead, it has an "adjustable fuel flow needle valve" on the top. Finally, I ferreted out information on the internet saying Lawn Boy made the model 5247 from 1978 - 1982. During that time, they used three different carbs on the F100 engine. The first two had the altitude adjustment screw. The third carb (mine) has the "adjustable fuel flow needle valve."
I'm going to fiddle with adjusting it as soon as it stops raining. ..... Got the feeling I may get lucky and "get 'er done." :laughing:

 

[Two-Stroke]

1 preset altitude needle 1/2 turn from seat
2 start and let warm for 3-5 min.
3 place speed control to low
4 slowly turn needle CCW until engine running smoothly
5 place control to high, if not running smoothly turn CCW 1/8 turns at time till smooth
6 shut-off and immediately try to restart, DO NOT PRIME, should start within a couple pulls at both
low and high settings, if not contitnue turning needle 1/8 turns CCW to obtain easy starting.

This is from manual, good luck, looks like everyone pretty much have it covered. Fuel+ Air+Combustion+Ignition=VROOOOOM.

Thanks, hankthecrank, it's always good to know how to do things by the book. :biggrin:

But I have always tuned two-cycle engines under full load (in this case that would be cutting grass.) Maybe the spinning blade is like an airplane propeller which puts enough drag on the engine to approximate a full load.

 

[Two-Stroke]

Thanks, Hankthecrank. ..... Great to get such precise information. You mention an altitude needle. My carb doesn't have one. That confused me. Instead, it has an "adjustable fuel flow needle valve" on the top. Finally, I ferreted out information on the internet saying Lawn Boy made the model 5247 from 1978 - 1982. During that time, they used three different carbs on the F100 engine. The first two had the altitude adjustment screw. The third carb (mine) has the "adjustable fuel flow needle valve."
I'm going to fiddle with adjusting it as soon as it stops raining. ..... Got the feeling I may get lucky and "get 'er done." :laughing:

I think all of the carbs we're talking about have only one needle valve which adjusts the fuel/air mixture. So don't worry about the different terms -- they're talking about the same thing.

As hankthecrank said (quoting the manual), start 1/2 turn out from the seat -- so cancel what I said about starting one full turn out from the seat. :ashamed:

 

[Fireman 123]

Maybe I'm missing the concept, but I can't imagine adjusting the carb while mowing at the same time. My arm isn't that long haha?

 

[Two-Stroke]

Maybe I'm missing the concept, but I can't imagine adjusting the carb while mowing at the same time. My arm isn't that long haha?

It's trial and error. Try one setting and cut some grass... then turn the screw in 1/8 of a turn and cut some more... see if it improves or gets worse. Repeat until you find the best setting.

The point is that a two-cycle engine needs to be tuned fully warmed up and under load -- and I might add that the propeller effect of the blade might provide enough drag so it's not really necessary to test the mower on grass.

:laughing: I can't tell for sure if your question was meant as a joke. The internet is like that. :laughing:

 

[Gene123]

I'll look for one. ..... Sure wish I'd had one a few days ago. It would have made my Lawn Boy repair adventure a lot easier and less time consuming. I've learned a lot.

Fireman, I checked eBay. There are 135 manuals about Lawn Boys. Since you have a model similar to mine, I'm wondering if you know the title of a manual like you mentioned. For my cars, I've always bought the oem service manual. Is there an oem service manual for just about any Lawn Boy? I'd sure like to find one for my model 5247, a 19" push model made in 1980. As I mentioned, I've got two 5247's ----- one on the verge of running right (thanks to the guys on the forum :thumbsup and one that has only 35 lbs compression and needs lots of help.

 

[Fireman 123]

There's one that covers the older d400-600 series, f-series, and the then new compliance mowers. That's what I have, and what you need. Good luck!

 

[Two-Stroke]

About manuals.. here's a link to a page with links to lots of LB manuals available for free download:

LAWN-BOY SERVICE MANUAL 1950-88 (FORM 492-4608, INTERNET REVISION)