My Lawnmower Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Hello:

First post here. Purchased this used in 1996 for $50. Retired guy would buy all types of Lawn Boys, piece them together and sell from his garage.

It has run great until about month ago. Compression good, new coil, new plug (every spring), and put new needle and seat in. Downloaded the manual from web and set the float at factory spec. Just could never get to run right.

Carb has the air F-100 series late model with adjustable fuel flow needle valve. It's hard to start, and won't hold RPMs, runs rough. I thought the air vane spring was bad, but couldn't find on line.

Took to local small engine shop and got back today. Runs same. Ugh. They put kit in (needle, seat, gaskets, etc.) and it just won't run right.

Manual says turn needle valve until seats, then back off 2 full turns. Get engine running, then turn needle valve clockwise until runs smooth and even.

I can her up to around 3,000 RPM but still rough. Crazy thing is when i shut off gas the engine smooths out and powers up to 3,400 RPM.

I'm thinking it's running rich and i need to tighten needle valve.

Any suggestions on this one?



 

·
Premium Member
Joined
·
324 Posts
7268

Hi and welcome to the forum! The 7268 Lawnboy as well as it's little brother, the 5247, are some of the most reliable F engine Lawnboy's ever made. I actually have one of each although I have been doing most of my mowing with a mid 70's D engine Lawnboy and a different F engine Lawnboy from 1978.
Just some things to check before you proceed.
Is the air vane free and not binding.
Have you or anyone checked the exhaust ports for carbon build up. When I got my 1978 Lawnboy the ports were almost 100% blocked. This is a common cause of lack of power.
Check muffler for blockage. If you have the muffler off and it feels heavy it may be full of carbon. Bake on a grill for 45 minutes to 1 hour on high heat and the carbon will turn to powder and can be easily shaken out or flushed out with water.
Check the lower seal for signs of leaking.
I will assume the carb was cleaned thoroughly when the new parts were installed.
Air filter cleaned and properly oiled.
You can check the float by placing it in a small dish of fuel but if it is new it should be okay.
These are very simple machines unlike a 4 cycle. Most likely it is something simple that have been overlooked. Let me know if I can be of any further help and keep us posted. Good luck! Bill
:welcome:
:mlf:
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #4 ·
Thanks Bill. You replied to my thread over on MyTractorForum.com.

I responded over there. Thanks again!
 

·
Premium Member
Joined
·
324 Posts
7268

Thanks and no problem. I figured the more guys that could look at the issues the better chance you have of getting it fixed. Bill
 
  • Like
Reactions: DaubsNU1

·
Registered
Joined
·
4 Posts
Discussion Starter · #6 ·
UPDATE: Fixed!

Thanks for the help! It's running constant 3,200 RPMs, holding power, running strong. It's little tough to start again after shutting down, but i'm thinking i need to run a little more rich.

I think it was combination of following:
1. Warped carb, creating gap between carb and head. I used straight file to get it nice and straight.
2. Air needle way to rich. Tightened down, then backed off two turns.

The 7268 has served me well for almost 20 years. Looking forward to another 20+.

Side note: the wife got so fed up with "Franken-Mower," as she call my 7268, that she talked neighbor in to selling us his Lawn Boy 10797. She gave him $200. Research shows Honda engine, built in 2009, and retailed for around $650. I think it will be a good backup for Frank

Thanks again for the help. Not to get Frank fine tuned and ready for next mowing.
 
1 - 7 of 7 Posts
Top