Lawnboy -- 2 Cycle Question..


Lawnboy 2Cycle question.
I have a very old Lawnboy that has been a great mower. Lately it loses power after awhile, and I notice that gas is dripping from where the two haves of the crank case are bolted together. (Would it still be considered a crank case on a 2 stroke) I have a feeling that there is a seal between the halves that has failed and now I am losing compression. Does this sound correct? Can I still get seals for an ancient Lawnboy? I believe this one is from 1982.
I have searched the net and have found Carb gaskets for it. I have also found drive parts. Actually I bought a new drive shaft for it last year.
Is there a change that the two halves don't use a gasket but rather some kind of sealent?
I really do not want to give this one up. I love mowing the lawn with it. I have used the new Lawnboys, Toros, MTDS, and Hondas. I still like the old Lawnboy
Jeff P
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Try ebay (lots of used and new old stock parts avail)
Try Yahoo (just do a search for lawnboy parts)
Lots of parts are avail, just harder to get sometimes. I found a local small engine guy here in NY that carries alot of parts. (lucky for me!)
Tom
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A crankcase leak should not affect compression but that would be a thing to test with a compression tester to see if it is worth fixing. It should not be to difficult to replace the rings if it is low.
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The thing about 2-strokes - at least the ones on which I've worked - is that the crankcase must hold pressure to run properly. The air/fuel mixture is sucked into the crankcase as the piston is on its way up to TDC and is compressed by the downward moving piston so that when the transfer ports are uncovered, the air/fuel mixture is forced into the combustion chamber. When the crank seals or crankcase gaskets leak, that transfer pressure is reduced or lost and fuel is, instead, forced out of the engine.
mark pepperell, ma
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100% correct.
======
The thing about 2-strokes - at least the ones on which I've worked - is that the crankcase must hold pressure to run properly. The air/fuel mixture is sucked into the crankcase as the piston is on its way up to TDC and is compressed by the downward moving piston so that when the transfer ports are uncovered, the air/fuel mixture is forced into the combustion chamber. When the crank seals or crankcase gaskets leak, that transfer pressure is reduced or lost and fuel is, instead, forced out of the engine.
mark pepperell, ma
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I know.. Thanks for the advice.. I have bought from MFG Supply for my lawnboy
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the crankcase halves dont use a gasket. i would try tightening all the bolts and nuts, ive had several with loose bolts/nuts.crank seals popping out is common also. i allways take a compression reading and take muffler off to see if cylinger is scored before i put much time in a lawnboy. the ex ports on the cylinder and the muffler can close off/clogg causing the problem your seeing... the gasket set can be had for about 8.00 from stens if you can find a stens dealer,lucas
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That is the Exact case.. the Gas will be forced out of the seam between the crank case halves.. I have seen on diagrams a mention of a crank case seal.. So that is incorrect? I don't see anything popping out.. I will have to look at this closer.
Under load ever more gas spits out.. I will check the muffler.. I am guessing it is not clogged due to the fact that it puffs smoke when it starts running crazy.
I have bought Lawnboy parts from MFG Supply with great luck.. I might try them again if I need parts..
Am I nutts for liking my old LawnBoy? There us just something magical about the thing..
Jeff
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wrote:

No your not nuts. I have a lawnboy myself, although not as old as yours, and i also love it. Best running and most reliable mower I have ever had.
Steve B.
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Not to be negative but increased crankcase leaking under load could be due to blowby of the rings. Might check with manufacturer as to what type of reading you should expect with a compression gauge if tightening bolts the hold the crankcase together seals the leak but doesn't restore power.

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nope... back then , they made good lawnmowers.......
my dad had a 1967, and a 1977..... in 1987, when the 77 started getting tired, I went out and bought an electric start Lawn boy for 500 something bucks....
the lawn boy delaer warned me I wouldn't like it, and it would require much more maintainance that I was used to giving one....... bou, was he right!!!
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1982? Old Lawn Boy? Old is late 50's, early 60'S! Parts for a '82 Lawn Boy should not be any problem at all to get. There must be a local Toro dealer that can get them for you. Toro bought LB about 10 years ago.
The crankcase halves do not use a gasket, LB recommends a Locktite product, but I don't have the specifics handy. I have never seen a LB crankcase leak, not saying it couldn't, just not likely. More likely is that the crankshaft seals are shot. They should be easy to get as LB used the same seal for decades. Power problems with a LB or typically plugged exhaust ports, leaky seals, governor adjustment, or bad reed valves.
I love LB mowers. I was using on that was made in the early 70's until my neighbor ruined his later model mower. I grabbed it, and with parts I had laying around I rebuilt the engine. I plan on running it for years. My old 70's model I gave to my other neighbor for use at his rental house. I tuned up a friends LB that his dad gave him that was built in the early 60's. He uses it for his yard. LB painted everything a pukey brown/beige color back then. Greg
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Hmm.. I thought maybe the cranshact seal but not.. It is misting out of the flat seam in the front
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I took the Blade Off... Took the Muffler off.
Look at the Port, and only one was open, and only 50% open... I cleared out the three ports and it is running like a champ now.
I noticed that the side pf the piston look terrible. It has brown slunk on it.. Is this common on a two cycle?
It is running great now. No loss of power when hitting the tall patches or using the sell propelled feature.
Thanks All!!
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It is not unusual to see some carbon build up on the piston. As long as the piston looked smooth it probably is ok. I highly recommend running Lawn boy's oil. It is a bit more expensive, but you mower will thank you in running for years! When I had my repair shop I often had to rebuild LB's that had been running cheap oil. The oil would carbon up the cylinder and piston so bad that the engine would loose compression. Disassemble, de-carbon everything, slap in a set of rings and all was well again. For most people the added cost of using LB oil would only be about to a buck or to a year, so why chance it?! Greg
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to clarify, a clogged exhaust causes excess presure in the crankcase. lucas
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I will check this out..
I see that the Exhaust exits from the bottom... Is it a huge pain to check if it is clogged?
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Ok... I have seen by looking on the net that Lawnboy actually stresses keeping the muffler clean..
Can I clean the muffler or do I need to buy a new one?
I should use a wooden dowl to clean the ports?
Thanks, Jeff P
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