AV7 cylinder installation

Taylor Trotter /

I took the head and cylinder off of my AV7 recently to replace the gaskets because of various air leaks.

I was told to try and use the same rings if they looked fine. I thought they looked fine so I decided to keep them.

When I was going to put the cylinder over the piston no matter how much I compress them the cylinder will not slide on. I have read that you should be able to use your hands to compress them.

Does this mean that the rings have too much of a gap? And if I have to buy new rings which do I buy? It is a 79 50v 30MPH model and I know they use different pistons.

Thanks,

Taylor

Re: AV7 cylinder installation

Is the ring gap lined up with the little nub in the piston groove when you compress the ring?

Re: AV7 cylinder installation

Taylor Trotter /

When you say piston groove do you mean the grooves in the actual cylinder itself. If so, then yes.

Re: AV7 cylinder installation

As said above, there is a little nub in groove that the rings are installed in, and that nub is to line up with the gap in the ring. There's material missing behind the gap in the ring to allow clearance for the nub.

Re: AV7 cylinder installation

No I mean the grooves in the side of the piston.

Read this:

http://www.scooterhelp.com/tips/engine/piston.sf.vespa.html

You probably just don't have it centered correctly. You shouldn't have to force it.

Re: AV7 cylinder installation

Are you trying to put piston In from top or bottom?

Re: AV7 cylinder installation

Brent Bublitz /

Make sure you spread some 2 stroke oil on the rings before you try to install them. It not as easy as you would think on some motors. I have had to use at least 5-8 fingernails to compress a ring into a bore before.

Re: AV7 cylinder installation

Taylor Trotter /

I haven't noticed any grooves in the piston itself. I will take a closer look when I get a chance tonight.

Re: AV7 cylinder installation

Brent Bublitz /

These are what we are talking about. Your piston has pins in the ring groves. The pins should line up with the gap in your rings.

(edited)

19_27_lambretta_main.jpg

Re: AV7 cylinder installation

Taylor Trotter /

Appreciate the picture. I will take a look tonight and report back if I get I get it installed.

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