Piston stopper (Make your own)

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Though it was time I make myself a piston stopper. I tried doing it like I have seen before and found it much too vague. Thought I would elaborate as I did mine for those who may also want to make one. You can use pull start rope, tubing or other items to stop the piston before top dead center and myself and many of us have for some time now without any problems but, there is a slight chance you may bite off a small part of the tubing or rope when the piston goes by the ports. We also all know we can buy a piston stopper that is made just for the job but hey this is the chance to be creative and save some money.

You will need the following:
Spark plug
Dremel with cut off disk
File or you can use Dremel
Vise grip or a vise
Spark plug wrench
(1) 5mm x 22mm or longer allen bolt. (I used an exhaust bolt.)
(1) 5mm nut
(3) Washers

Find yourself a new or old spark.

Cut off the side electrode from the bottom of the plug.

We need to remove the top seal from the plug. With the cut off wheel grind all the way around the top of the plug and through the metal case until you hit the ceramic insulator. This will allow the removal of the top seal. The ceramic insulator will now be flush with the sides of the metal case.


Now clamp your vise grip on or install the plug in a vise so that there is enough pressure that the insulator will not spin. Take your plug wrench and twist back and forth until the insulator breaks free from the metal case.


File or Dremel the bottom of the sleeve where the side electrode was until it is flat. Now take your bolt, washers and nut and assemble your stopper. Use the proper amount of washers for the stopper to hit your piston.


Spark plug terms:

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Terrific idea.....Thanks! Might just try adding a piece of fuel tubing extending barely over the bolt to protect the piston myself. Why spend $10 plus shipping on a piston stopper when theres great guys like you around. :rock-on:
You come up with the best DIY projects. I made a flywheel puller for one of your tuts. saved me 30.00.

Im just wondering....
Does the screw need to be a softer metal so it doesn't scratch the piston?
I have no clue if its an issue or not.
I may have an easier idea which will cost you much less time and $$$.

The threaded shaft you get in household lighting which the wires are put through uses the same threading! I work for a lighting company and when I was building my 30.5CC I needed this tool. I had a bunch of these lying around and found they work very well. I'm sure Home Depot or Lowes carries them. There are various lenghts and some are threaded on both ends.

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Pisto n stopper improvement.

I would suggest using an aluminum bolt instead of the steel one pictured, because the chances of gouging the piston would be less. even better would be brass since it is softer than the aluminum of the piston.
I've punctured a piston in a nitro with a commercial stopper. I used rope on motorcycles and cars... take that lighting thing Selwa showed and stuff a rubber stopper in the end. The more surface area on the piston the better. Not to knock your idea btb cuz you always have the coolest tricks and will say I am using a few of your ideas.
If you have access to a lathe you could turn down a small piece of PTFE to fit and epoxy it in either the modified spark plug or the lamp rod.
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