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Hello everyone, new to the forum... Looked for this subject already, but could not find it.

I'm trying to fix my friends TB240 Self Propelled mower that is having kick back issues.

Honda Engine

1. Visually inspected flywheel and key.
a. No obvious sign of being out of alignment
2. Pulled and inspected spark plug.
a. Plug used, but dry, minor corrosion, Spark plug does spark.
3. Checked top dead center of piston and Magnet alignment.
a. Piston at Top Dead Center, Magnet on flywheel is just leaving coil magnets
4. Pulled the flywheel to check for position and key problems.
a. Flywheel broke from pressure of the pulley.
b. Drive shaft Key is seated and does not appear to be out of alignment.
c. Some minor play on the flywheel and the Key, but this looks normal. Can not get feeler gauge in to check tolerance
5. Purchased brand new flywheel and installed
a. During installation noticed same play between the fly wheel and the Alignment key. The key is set firmly on the shaft and is square.
b. Did my best during installation to keep pulling with same gap on each side of the alignment key. This play is so small I doubt most people would notice it. Of Coarse it doesn't move once pressed onto the shaft.
6. Same Kickback
7. Recheck top dead center and magnets.
a. same results as above
8. Check Blade and shaft for straightness.
a. Blade installed correctly and tight.
b. No obvious sign of blade damage
c. pull cord with no sparkplug and no obvious sign of alignment or bent shaft.
9. Check for carb leakage
a. Turned off fuel supply and removed feed line.
b. pulled spark plug.. still dry... pulled cord several times and burned out cylinder (No sign of fuel in the cylinder)
c. Put the spark plug back in and it still has kick back. I don't believe this is a cylinder filling up with a leaking fuel valve

This thing kicks back on the first pull and every pull. It does it weather it's trying to start or not trying to start. I've read a lot of threads on this subject and can't figure this thing out. The only thing I can think of is that the play in the alignment key is really that important. If I had to guess it less that 1/2 a millimeter.

The engine has an automatic decompressor.
Honda have the best by far and rarely give any problems.
To work properly the valve lash must be correct and in particular must not be excessively large.
So remove the rocker cover and check the valve lash.
If it is correct then it is new cam shaft time.
Also note that some of the domestic grade engines have a thin pressed tin rocker cover that will warp when removed.
So it might need to be replaced .
Also some are glued down with Honda bond ( silicon ) and every bit of it must be removed.I always fit gaskets, even if I have to cut one where there was none one.
A little weeping at the surface is a lot better than 2 hours cleaning the crud off.

If it is a old engine the breather hose should also get renewed.

bertsmobile1 said:

The engine has an automatic decompressor.
Honda have the best by far and rarely give any problems.
To work properly the valve lash must be correct and in particular must not be excessively large.
So remove the rocker cover and check the valve lash.
If it is correct then it is new cam shaft time.
Also note that some of the domestic grade engines have a thin pressed tin rocker cover that will warp when removed.
So it might need to be replaced .
Also some are glued down with Honda bond ( silicon ) and every bit of it must be removed.I always fit gaskets, even if I have to cut one where there was none one.
A little weeping at the surface is a lot better than 2 hours cleaning the crud off.

If it is a old engine the breather hose should also get renewed.

Click to expand...

Okay! excellent advise! I pulled the valve cover (without damaging it, what a pain). One hand turn and noticed the exhaust valve did not move. Looked closer and the rocker arm was bent and cracked. I was able to squeeze it back together and weld up the cracks and it came out perfectly straight. Valve was stuck, but with a small tap from a rubber mallet, it broke loose and actuated smoothly and easily. put it back together and did a hand adjustment based on similar movement on intake side. slapped the cover back on and it pulled and started right away. No kick at all!

Now I will order a new rocker arm as the protective coating was removed during welding and there were other stress cracks in it.
Can I use high temp black silicone to put that valve cover back on?

Also, after putting the new flywheel on the stop spring wasn't' strong enough to kill the motor. and theirs no adjustment on the cable. Is this just because it's a new flywheel?

If this is a pushrod engine, pull the rod our and check it for bends.
If it is overhead cam don't worry.
Good chance you will have to adjust the valve lash again at the end of the season so put a gasket in there.
Some sort of compound on the rocker cover side and axel grease on the other so it strips clean.

Also note the most common cause for a valve to stick is overheating.
The second most common is rusting between seasons.
So if the cause is not addressed then you will become really good at doing rocker swaps.

As for those idiot engine brakes, it is up to you.
In reality they do absoluely nothing of any benefit to man or mower