Tdc... Hiding somewhere

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dunnes2002
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Tdc... Hiding somewhere

Good evening, 

I'm struggling to get a spark on my Atco light as I'm unable to find any markings on the shaft to align to the magneto casing. Could anyone tell me where I'm not looking? 

Thanks mike

 

 

wristpin
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Before you do anything, fit the  flywheel  and clean and set the points gap. At this point the relationship between the flywheel and the piston is unimportant . Then remove the flywheel.

Possibly best to work from basics. Cylinder head off and determine the tdc position of the piston. The only 100% accurate way is the “ positive stop” and timing disc method ( more accurate even than using a dti)  but “ eying and feeling” the piston position is probably adequate for the job.  

Then making sure that the crank does not move, refit the flywheel and turn it to the position where the points just start to open. Determining that point can be done either by the “ fag paper” method or using the continuity setting on a digital multimeter.

At that position tighten the flywheel.

EDIT Spot the error!  See my next post.

 

 

dunnes2002
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Excellent advice, although I

Excellent advice, although I have never taken off a cylinder head before. I guess I will need to replace a gasket once I put it all back together?

Many many firsts, but that's why I started to play with lawn mowers, to learn about engines. 

wristpin
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Well, it would have been good

Well, it would have been good advice if, in editing it before posting, I managed to lose the instruction to lower the piston the specified amount Before Top Dead Centre.  Then refit the flywheel to the position where the points are just opening.!

Head gasket. It may separate cleanly and be reusable but the book will say  - fit new.

Just glad that I spotted the error before either you were totally misled or someone else corrected me.

This may be useful

https://www.dropbox.com/s/sa8ft3j7khj4nla/Villiers%20Lightweight%20timin...

dunnes2002
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Thanks for the handbook. Do

Thanks for the handbook. Do you know if this is a 50cc engine. Just need to know for the head gasket, surprisingly it disintegrated on separation. That may be one of the issues it was hibernated in the first place.

 

 

Otherwise is it easy to make your own gasket? 

Thanks

Mike

wristpin
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I would guess 150cc but I'll

I would guess 150cc but I'll do some research. You could make a head gasket but they are a bit more substantial than normal paper gasket material and buying just one bit may be difficult as many sellers do packs of several sheets and grades.

PM  sent.