Scooterotica

Just in the process of putting my Avantti TT3 back together after changing the bearings and seals and there a couple of issues I would appreciate comments on.

First, I checked the ring gap after squaring them in the bore with the piston and get 14 thou, the old ones were 45 thou I seem to recall that there is a ratio for calculating the ring gap, can anyone confirm that 14 though is an acceptable gap?

Second, I originally put it together with a 58mm 110mm crank and used a 3mm packer, the best squish I can get (using the plastacine method) is 1.5mm with no gaskets fitted. Would a 2.5mm packer be better as it would allow some degree of adjustment using different thickness base gaskets

Cheers

colin

Instructions I got were to gap to 0.0012" (0.03mm) and explicitly MUST not be to tight so 0.0014" ought to be ok I'd guess.

With a 2.5 packer you'd be right down at 1mm on the squish which is the absolute minimum. I might be inclined to try that with a 2.5 and a thin gasket.

rosscla wrote:Instructions I got were to gap to 0.0012" (0.03mm) and explicitly MUST not be to tight so 0.0014" ought to be ok I'd guess.

With a 2.5 packer you'd be right down at 1mm on the squish which is the absolute minimum. I might be inclined to try that with a 2.5 and a thin gasket.

Yes, that's what I was thinking Ross, it was running ok before but was very thirsty and the piston showed signs of uneven combustion. I don't know how much if at all the 2 issues might have had on it but if I don't try getting the squish a bit tighter, I'll never know I suppose