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Discussion Starter · #1 ·
I have a mc43 tiller. In decent shape, needs a gas tank which is typical for this unit. It has good spark and compression. I cannot even get it to fire?? I have put gas in cylinder and still no go. Any Thoughts? It should fire with gas in cylinder. Could it be a sheared off keyway on flywheel and it is out of time? That is not a easy fix taking it apart to get at flywheel. Appreciate your hlep
 

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Cylinder compression isn't the end-all where 2-strokes are concerned, you have to have a well-sealed crankcase for the fuel-oil mix to first suck into before it's sucked into the cylinder, compressed and ignited too. Check your head gasket mounting bolts. However, you need good cylinder compression too. It should be in the vicinity of 100 psi.

Typically, these 2-strokes develop hardened carb diaphragms and brittle fuel lines in only a couple of years of using ethanol gas too. Carb kits generally cost more than replacement carbs, which are only $15 or so. Most of these come with fuel lines and gaskets too. As with the crankcase, bad carb gaskets that let in air can also prevent the engine from starting.

If you are getting a good spark then the ignition module isn't likely the problem. However, you are right that timing might be.

 

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Discussion Starter · #3 ·
Cylinder compression isn't the end-all where 2-strokes are concerned, you have to have a well-sealed crankcase for the fuel-oil mix to first suck into before it's sucked into the cylinder, compressed and ignited too. Check your head gasket mounting bolts. However, you need good cylinder compression too. It should be in the vicinity of 100 psi.

Typically, these 2-strokes develop hardened carb diaphragms and brittle fuel lines in only a couple of years of using ethanol gas too. Carb kits generally cost more than replacement carbs, which are only $15 or so. Most of these come with fuel lines and gaskets too. As with the crankcase, bad carb gaskets that let in air can also prevent the engine from starting.

If you are getting a good spark then the ignition module isn't likely the problem. However, you are right that timing might be.

Hi Thanks for the reply, I did replace gaskets in carb and new fuel lines. It still should fire with gas in cylinder. My compression tester in not real accurate but I did get 80 on it. I have runs some 2 cycles when my tester read 60 and they have run good. Just hate to tear the thing apart to check flywheel.
 

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How old is your gas? Old gas, especially oil:gas mixture that's sat around and evaporated will be hard to vaporize, especially if it's cold. Also, make sure to mix up your mix as the oil can settle out over time. Are you spraying the fuel into the carb or directly into the cylinder? Try a squirt directly into the cylinder.

Are you really sure that you have good spark? Sometimes you can see a faint spark or a light on a spark tester when there isn't enough spark to actually ignite the mixture. The first thing I'd replace would be the spark plug, then check to see if the flywheel key was sheared, then test the coil. Unfortunately, I couldn't find any specs for your specific coil but it should read in the low single-ohm range on the primary winding side and in the ten kilo-ohm range on the secondary winding side, plus or minus. If you read zero or infinite ohms anywhere then you have a bad coil.


Amazon.com : 300472 ignition coil
 

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Discussion Starter · #5 ·
How old is your gas? Old gas, especially oil:gas mixture that's sat around and evaporated will be hard to vaporize, especially if it's cold. Also, make sure to mix up your mix as the oil can settle out over time. Are you spraying the fuel into the carb or directly into the cylinder? Try a squirt directly into the cylinder.

Are you really sure that you have good spark? Sometimes you can see a faint spark or a light on a spark tester when there isn't enough spark to actually ignite the mixture. The first thing I'd replace would be the spark plug, then check to see if the flywheel key was sheared, then test the coil. Unfortunately, I couldn't find any specs for your specific coil but it should read in the low single-ohm range on the primary winding side and in the ten kilo-ohm range on the secondary winding side, plus or minus. If you read zero or infinite ohms anywhere then you have a bad coil.


Amazon.com : 300472 ignition coil
Thank You for the info, will check out the coil hopefully today, have more snow coming. :cry: Will keep this updated.
 

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Discussion Starter · #6 ·
Thank You for the info, will check out the coil hopefully today, have more snow coming. :cry: Will keep this updated.
I always drain and use fresh non oxy gas. I really think it is the coil, when I put an ohm meter on it as shown in the video both were zero??? so my guess it is the coil. I have tried a new plug and still the same. I tried the spark again and it was faint and would not fires I could not get the flywheel off to check keyway just do not think that is the problem. The question is to put the money in a tank and coil would be about 80 bucks? Not sure the tiller is worth that? Will keep you posted
 

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It's hard to decide when and when not to put money into an older implement. My rear-tine tiller stripped its brass transmission gears a few years back. The brass gears were $90 each. Add seals and oil and it cost $250 to repair the transmission. An equivalent replacement tiller was $900 though so I figured that it was worth repairing.
 
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