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Collection, Preservation and Display of Old Lawn Mowers

Villiers Midget Engine

Hello

I have villiers midget engine that backfires through the carburettor after starting up.

It seems to run ok once warmed up.

I am going to check the timing but am a little unsure as to how to set the piston to 5/32 btdc?

If I use a vernier depth gauge to check this will I need to subtract the thickness of the cylinder top?

Any suggestions of advice would be gracefully received.

Thank you

 

 

Forums

wristpin Thu, 06/06/2019

With the plug being immediately over the piston it is possibly easier to just use a piece of rod or a thin screwdriver  with a lump of Plasticine pressed into the fins as a reference point. You are just measuring piston movement regardless of what’s in between.

Series3boy Thu, 06/06/2019

Thank you

I will give it a try and will see how I get on. 

Should the points be fully open when I set the position of the fly wheel?

 

 

wristpin Thu, 06/06/2019

No!  They should just start to open at the specified measurement before top dead centre. First clean the points and set the gap to the specified gap. Then, with the piston held in that position and the flywheel loosely fitted to the crank, turn the flywheel until the points just start to open. At that position one of the “ windows” in the flywheel probably gives access to and visibility of the points . The traditional way of ascertaining when the points are starting to open is to place a piece of thin paper between them and holding it with a little tension. As soon as the tension is released, that is the position to lock the flywheel to the crank.  It can be a bit hit and miss so you will probably need a couple of dry runs before you are satisfied with the result.

The flywheel nut has to be very tight.  Villiers supplied a spanner designed to be hit with a hammer to ensure that it was!