Exhaust ports on 2 cycle Lawn Boy mowers.

[mrsilv04]

I'm already starting to realize the benefit of knowing how easily the exhaust ports can be cleaned on a 2 cycle Lawn Boy mower.

I bought a 2 cycle Commercial series Lawn Boy off of Craigslist for $40. It was a 1990 model, but it looked like new. The owner was selling it because "it was all stoved up", and he had stopped using it several years back. With only some fresh gas/oil mix, it started on the second pull, but it only ran at about 1/2 power. I knew what the problem was, and bought it on the spot.

Once I got it home and the muffler off, of the three exhaust ports, one was completely plugged with carbon, one was about 70% plugged and the third was about 50% plugged. The carbon was in the ports like cement. A 3/8" diameter dowel rod is perfect for cleaning out the ports.

After 30 minutes of work, it runs as good as it looks.

After it was able to breathe freely again, I shot a little SeaFoam into the intake while it was running using a syringe, and added two ounces of SF into a fresh gallon of pre-mix to clean the entire fuel system.

I appear to have ended up with a nice little bargain to go along with my 1983 Lawn Boy that I bought new with my own money when I was 13.

After seeing what the carbon build up will do to a Lawn Boy, and after studying much of the conversation here, I've decided to switch over to a synthetic 2 cycle oil, and try it at a 40:1 ratio. If I don't go full synthetic, I may try some of the Pennzoil Semi-synthetic Premium Plus 2 cycle oil that I buy in the gallon jugs ($10/gallon) for the 2 jet skis that I own. I'm going to hit two Advance Auto Parts locations this afternoon and see if I can find a quart (or two) of the discontinued Mobil 1 two cycle oil.

In the past, I've used Quaker State 2 cycle oil, but I don't plan on using it in the newer mower.

 

[dwendt44]

If you go with synthetic, you can run it at 50:1.

With a quality air cooled 2 cycle oil, you can run at 40:1.
My Lawn Boy dealer says the 32:1 is only really needed on a couple of self propelled LB models. (after break-in).
My 2¢

 

[Pablo]

You might want to try:

Saber

or

Interceptor

 

[mrsilv04]

Originally Posted By: dwendt44
My Lawn Boy dealer says the 32:1 is only really needed on a couple of self propelled LB models. (after break-in).


Why do those few self propelled models need the extra lubrication?

 

[wileyE]

Sometimes and engine design will have a far end or drip fed crank bearing that doesn't get lubed good from normal oil migration, so they crank up the ratio. Also could be a bandaid for known problem like an undersized pto end bearing. Whatever the reason, syn is no substitute for lack. IMHO. Nobody could ever tell the difference between 32 or 50 on most engines because the detriment (if any) would take so long somehting else would get blamed.


Also the diffence between syn and min with regard to carbon or port blockage, from what I've seen. Min makes hard carbon, syn it's gummier and easier to clean, Both do it. I use high pressure water to blow it off parts fwiw.

 

[dwendt44]

What Wiley said.
The drip oil lubes parts of the 'self propelled' system.

 

[mrsilv04]

Thanks guys. I've never had a self propelled Lawn Boy, so the reason why was a little lost on me.

I'm leaning towards going with synthetic because the carbon build up that I had to clean out of the exhaust ports was as hard as brick mortar. I'm also going to lean out the oil as well, and go to 40:1, and see how it goes.

 

[Kestas]

I almost threw away my 2-cycle LawnBoy 15 years ago until I realized the exhaust was packed with soot. I'm still presently using it.

 

[Cmarti]

I have a 2000 siver pro series 6.5 hp. Every year I take it apart to clean the exaust port, it is almost spotless. 32:1 with valvoline multi purpose 2 cycle oil. I mix seafoam in the gas before mixing with oil. I am actually starting to wonder if I am doing something wrong to not have any buildup. My kid use to abuse this mower with his lawncare "business"