I've got a late D-series engine mower. It is an International, but it was made by Lawnboy, and is Lawnboy thru and thru. I have replaced the rings, new seals, gaskets, new reeds. It has good compression, and it has spark. The darn thing won't start. I'm tearing my hear out. It is an early electronic (pointless) ignition..much longer coil than later ones. (if that matters). It gets spark when I hand rotate the flywheel, holding the spark-plug against the head. Sparks every revolution. The carb is clean, new needle and seat, it's getting fuel.
Very frustrated with D-engine mower
- Thread starter Phototone
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beg
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what kind of spark?:is it snappy or just sparking a weak blue?you done replaced everything so I assume it has great compression.Is the plug wet?I would pop for a new coil if you can find one otherwise you have to use the newer one with is ***** backwards on the on off switch wiring Is it the cool looking International with the cub cadet style shroud?
This coil on this mower is NOT LIKE any other later lawnboy coils. It has three pole ends, and 3 magnets on flywheel. In other words, on all later coils, there are 2 end pieces that you gap with flywheel, this has 3. The later coil would not work, nor mount. Yes, it is the one with the cub cadet style shroud. This has a mechanical governor also, like the older models with points. Not the vane-style later carb. The spark appears to be the same quality as my later Lawnboys which run. It doesn't take much speed when hand-turning the flywheel to make spark.
dewguy1999
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This may be a stupid idea but I'm going to throw it out there anyway in case it does have merit. Is it possible it's not sparking after the plug is installed?
Photo, Visible spark may still be weak under compression and not fire. Try using a spare or discarded plug as a test . Open the gap up to 1/8" or so and try. (Cut off the side electrode even with the top of the center one). I tried this on a trimmer which was failing. A new trimmer would fire the 1/8", not the failing one.
Did you have the mower running before the rebuild?
What was wrong with the mower before the rebuild? Just because the rings are new doesn't mean that the compression is good. How many lbs compression does it have? Too low and it will not start or run. The rings may not be seating well and or how much taper in the cyl?. Is the cyl round ? Is there any scoring on the cyl wall? Did you deglaze the cyl? Low compression will also cause poor fuel delivery to the combustion chamber. First things first. What did you get for your compression test reading?
What was wrong with the mower before the rebuild? Just because the rings are new doesn't mean that the compression is good. How many lbs compression does it have? Too low and it will not start or run. The rings may not be seating well and or how much taper in the cyl?. Is the cyl round ? Is there any scoring on the cyl wall? Did you deglaze the cyl? Low compression will also cause poor fuel delivery to the combustion chamber. First things first. What did you get for your compression test reading?
Two-Stroke
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I tend to trust a solid-state coil if it sparks at all. I've heard of ones that will spark visibly but not spark good enough to fire -- but I've never seen that personally.
Here's another possibility that nobody has mentioned:
Is the crankcase sealing properly? If not, the cause could be crankshaft seals or the gasket between the reed plate and the crankcase.
Don't forget that a two-cycle engine must have a good sealing crankcase so that, on the downstroke, the fuel-air mixture will compress and at the right moment, shoot up into the combustion chamber.
Good luck.
Here's another possibility that nobody has mentioned:
Is the crankcase sealing properly? If not, the cause could be crankshaft seals or the gasket between the reed plate and the crankcase.
Don't forget that a two-cycle engine must have a good sealing crankcase so that, on the downstroke, the fuel-air mixture will compress and at the right moment, shoot up into the combustion chamber.
Good luck.
I have new crankcase seals
I have new gasket between reedplate and crankcase
I have new reeds, adjusted correctly
I have new gaskets for top and bottom plates.
I have new gasket between cylinder and crankcase
Last spring (2013) after a clean-up and carb rebuilding it ran quite good, with easy starting, until one day it just wouldn't start. I put it away until this week, to do refurbishment.