# Old Lawn Boy-no start



## walmel (Feb 17, 2009)

Greetings... I have a 30 year old 2 stroke Lawn Boy model 8070. It has compression-flywheel rebound, spark-working used coil. I have to hook up the old fuel line. My question is-shouldn't it start and run for a second if I put gas or carb cleaner in the spark plug hole. Thanks for any help.


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## 30yearTech (Sep 14, 2006)

It should probably pop off and run a second or two off a prime. There are other considerations with a 2 cycle though. You have to have a good crankcase seal and with this engine the reed valves need to be good as well.


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## Deathrite (May 21, 2009)

that sounds like a real project there. 

good luck


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## geogrubb (Jul 28, 2006)

You really need to make sure you have spark at the plug some old LB's ignition modules always failed at the wrong time. Rather that put fuel in the sparkplug put it thru the carb or use some starter fluid thru the carb. Some times if you put it in the plug hole it will spit most of it out on the exhaust portion of the cycle. I love LB's, if it has spark it will run. Have a good one. Geo


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## pyro_maniac69 (Aug 12, 2007)

exhaust plugged? what kind've compression do you have? any scratches or scores in the cylinder? muffler clogged?


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## manalone44 (Jun 10, 2009)

pyro_maniac69 said:


> exhaust plugged? what kind've compression do you have? any scratches or scores in the cylinder? muffler clogged?


that would be my guess , lawn boys are notorious for this ... cheep mix oil ...


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## Pepo (Apr 29, 2008)

Hi, well here goes another story about a Lawn Boy engine not starting. It is a model 10252, serial 9906332. It belongs to a neighbor and he told me that it was stopped after mowing and when he wanted to start again it did not. On pulling the starter cord it will push fuel out of the muffler. Compression not much to write home about. Pulled flywheel as there was something dragging (It was the shut-down brake - didn't know about that). But found that the flywheel key is steel, that I don't think is right, need some advice on that. 
Am thinking about taking off the the muffler to check for clogging. Pulled the head and the piston looks good, cylinder walls have cross-hatching, there are no vertical score marks. Still have not pulled the carburetor. Crankshaft seals look good. I plan to do the following:
1. Take engine off the deck to take off the muffler and check for clogging.
2. Take carb off, clean and reset.
3. Replace the steel Woodruff key with aluminum one.
4. Reassemble all, replace fuel and see what happens.

Need to know what is the torque value for head bolts. What do I need to do if muffler is clogged. What is the clearance of the coil to flywheel magnet?

Thanks for any help. My motto is: "If it ran once, it can run again"


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## geogrubb (Jul 28, 2006)

Did you check to see if you had spark before you started taking things apart? If not you are doing a lot of work that may not have been necessary, you must have spark. Fuel, Compression, Spark = Smoke and Noise. Have a good one. Geo


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## 30yearTech (Sep 14, 2006)

Flywheel key on Lawnboy engine is steel not aluminum. 

Does it have spark?

Bad or broken reed plate can also cause a no start, even with a prime.

I will see if I can find torque settings for head and post back.


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## Pepo (Apr 29, 2008)

Hi guys, thanks for the quick response. Yes, there was spark with smoke. Right after that there was a bunch of raw fuel coming from the muffler. I don't know what the history of this mower exactly is. I stuck my finger into the tank and it seemed like pure gasoline, but, what came out from the muffler had oil mixed with it. It is quite possible that it also was over-primed. I will still take the carb off and clean it. I will eventually let you know how it turns out. So far its not all that much work and at least we know that the crankshaft seals are good. Thanks for the help so far.
By the way, I don't think this engine has any reed valves. I might find them though when I take the carb off.


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## 30yearTech (Sep 14, 2006)

Pepo said:


> By the way, I don't think this engine has any reed valves. I might find them though when I take the carb off.


You should, if you don't that's why it won't start.


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## Pepo (Apr 29, 2008)

Hello guys, well I found the reed valves and they are nice and clean. If you ever had to get to them, you would have to split the block, wow. We took the whole engine off the mower deck and turned it upside down. We took the cover plate off that covers the muffler U tube. There was at least an inch of fuel in there. We took the muffler off as well and it had raw fuel in it. We also took the carburetor off and cleaned it with 'Engine Brite" and then washed it with water and dried it with compressed air. Assembled everything, including the steel Woodruff key (amazing). Set the gap of the coil to the flywheel to 
.010", gapped the cleaned spark plug to .030" and got everything back together nicely. Also used the torque wrench for the head bolts at 
23 ft/lbs. Told my neighbor that when we took it down from the sawhorse bench that it would start at the first pull. He and the other guys looked at me funny, I wish I had a hundred bucks of bet on it.......but it did!
Many thanks for your collective help. Its just fun for an old man to put things back right and have it humming...Like I said: "If it ever ran before, it can run again!"


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## geogrubb (Jul 28, 2006)

There is nothing like an old 2-cycle LB, the older one were made by OMC, however yours(from my lookup) is a Duraforce 6.5, are/were they made by OMC. Nothing like the Blubber of a LB. Have a good one. Geo


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## Pepo (Apr 29, 2008)

Well here I am again. Pulled an old LB out of the shed that was destined for the junk heap some years agao and I had the itch to see if it still had life. First, no spark. Pulled the top cover and starter coil. By the way it is a 7729 model. No idea when it was built. Found that mice had built a nest under there and their P usually shortens things out. Took the magneto off and cleaned everything up including the corrosion on the magneto and the flywheel. Put it back together with 0.010" gap. Got a spark. Still no start. Took the carburetor off and apart. Oh boy! Could smell the old gas. Like turpentine. Needle valve totally stuck with rust and corrosion. Carfully got it out and cleaned it. Float still looked ok. Took the mixture screw out and it also had corrosion on it. Cleaned all these parts with Engine Brite and much rubbing with a cloth. Put it all together and in two pulls ran great! Took it to the lawn, put the bag on, pulled the cord and.........nothing. Cover back off and there was the small wire off the magneto. Crimped it carefully a bit tighter and pushed it back onto the little spade, it is tight now. Ordered a new needle valve and seat and a new primer bulb that seems to be leaking and not giving any resistance when pumping. Well, I think my neighbor who originally threw it out will use it again because his replacement mower from one of the big houses has gained a lot of four letter words and he wants to get rid of it now. In any case, I juts love those LBs, especially when everybody says that it will not run anymore. Love to prove them wrong.
Hope this helps somebody, sorry for the long-windedness. Take care and have fun


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## Pepo (Apr 29, 2008)

Once more with my LB 7229. Gave it to the neighbor and it ran great. Then it started to do the same thing from years ago, it would not start when hot. Now I installed the new needle valve and the new primer bulb. The kit for the needle valve hat a small gasket that fits the seat fitting. The old one did not have this gasket, what will that do with the float setting? I also wanted to take the muffler off and clean it, but...........That little square plate that locates the mower blade will not allow the muffler to come off. I tried to pull the plate with a puller but it will not budge. I don't see a key slot but I think there should be one. The question is: Does this 3" x 3" plate come off the engine shaft with the sleeve and is it just stuck or rusted on? Right now I will run the mower as is and see what happens. Any ideas are welcome. Take care and have fun


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## 30yearTech (Sep 14, 2006)

If your carburetor is composite (plastic) then you do not need to use the gasket.

The blade adapter is not keyed to the crankshaft, it's just a taper fit and they get pressed on pretty tight. I use an air impact hammer to knock them loose.

Best of Luck....


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## Yukkel (Jan 23, 2010)

i got shop manual for lawnboy's 1955-1988 on my site in the forums if needed.


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## Pepo (Apr 29, 2008)

Some time down the way I will try to get that thing loose. However, right now I would like to understand the logic behind that primer bulb. I installed a new one and at first I felt some reistance when pumping. Then that reistance left and now it does not want to start again. Yes, it is one of those plastic carbs and sure seems to be the simplest thing there is but this Simpleton is missing something. Maybe somebody can educate me. Thanks


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## 30yearTech (Sep 14, 2006)

Pepo said:


> Some time down the way I will try to get that thing loose. However, right now I would like to understand the logic behind that primer bulb. I installed a new one and at first I felt some reistance when pumping. Then that reistance left and now it does not want to start again. Yes, it is one of those plastic carbs and sure seems to be the simplest thing there is but this Simpleton is missing something. Maybe somebody can educate me. Thanks


The primer just forces a small amount of air pressure into the carburetor. This pressure pushes some fuel up the main jet to prime the engine. Check the hose from the primer to the carburetor, it may have come off the carburetor, pinched or may have a crack or hole in it.


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## luckyclover4u2 (Apr 15, 2010)

I am working on a couple of lb's as well...I have one that is surging and I can't seem to get it to even out..been through the carb twice...any suggestions?


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## 30yearTech (Sep 14, 2006)

luckyclover4u2 said:


> I am working on a couple of lb's as well...I have one that is surging and I can't seem to get it to even out..been through the carb twice...any suggestions?


What is the model number of the unit that you are having issues with??


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## luckyclover4u2 (Apr 15, 2010)

I'll have to get back to you on that...It's over at the shop....


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## Pepo (Apr 29, 2008)

*Old Lawn Boy - no start*

Well I have used that Lawn Boy a few times now and it starts fine when cold. I did get the low and high speed about right and it cuts great! I did go back into the carb the other day when it would not start for h.ll or high water. I took that little filter screen off the pick-up tube in the bowl and blew it out with air, as well as the tube itself. I thought that maybe the little screen got pinched shut when you tighten the bowl back down. It started fine after that maneuver and I mowed some more. Tried to start it hot and it became defiant and did not. Could it be possible that with heat that tube expands and closes the fuel against the bottom of the bowl? 
So far I have not pulled the muffler yet. I did check the fuel cap and it does not seem to be stopped up. The fuel shut-off valve in different intermediate positions seems to be alreicht too. So....The only two things that I still supect is the magneto coil and the "altitude adjustment." The altitude adjustment is right now at one half turn out as that is the way I found it. The coil baffles me though because if it got hot I think it would quit while running but it does not. All in all, it is just a challenge for me and I will mess with it until I figure it out, of course some help would be appreciated. By the way, the model number is a 7229, the other number that I quoted was wrong. Well, if you can point me in the right direction, I appreciate it. Take care and have fun


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## Katmandu (Jun 14, 2010)

Yukkel said:


> i got shop manual for lawnboy's 1955-1988 on my site in the forums if needed.


Do you have manuals for newer Lawnboy's w/Duraforce engines ?

If so, do you have a URL (Link) ??


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