Problem with Victa (powertorque) mower moter - can't start it

[Normanj]

Hello,

MY trusty Victa mower died on me recently and I removed the engine to access the ignition circuit. I found and fixed the problem so I now have a spark.

However, when I replaced the engine I found I could not start it because when I pull the starter cord it comes to a halt at some part of the engine cycle. If I pull the cord slowly I can get past this point, but obviously this will not start the engine.

In some ways this seems to be a compression issue, and if I remove the spark plug the engine turns happily. I've checked the decompressor unit and it seems seviceable.

What puzzles me is that in the days when the thing was working I could start it with the throttle in the "run" position when, I believe, the decompressor would not be operating. Also, the manual says the purpose of the decompressor is to make starting easier, whereas in my case there is sufficient resistance to bring the starter to a complete halt.

Any thoughts?

[Normanj]

I should have mentioned that I've checked that the vacuum tube from the carburettor to the flywheel port is in place.

[Acco]

Check the muffler, possibly blocked by a wasp nest

[Normanj]

Thanks Acco, though after the rebuild I removed the muffler again. I assume that not having the muffler in place would not cause the problem I'm seeing now?

[rrich]

Thanks Acco, though after the rebuild I removed the muffler again. I assume that not having the muffler in place would not cause the problem I'm seeing now?

Maybe not enough back pressure???

[Normanj]

Thanks for the suggestion rrich. I've replaced the muffler and that has made no difference. The resistance is felt when the piston is at the top of the stroke, and so I wouldn't expect the exhaust to play a part in this.