piston to exhaust port?

[DaveTomo]

Just looking for some advice, how much of the piston do I want showing above the exhaust port/outlet.Haven't fitted any gaskets just having a "dry" run to get it set up correctly.If you look at the picture you can just see the top of the ring, with approx 1.3 mm of the piston side ,not the crown showing above the port.Ordinarily I have when I've put it back together concentrated more on the top end with getting the squish right,now with a decent head I want to get it all bob on.Any advice much appreciated. Rapido 225 with Gori exhaust.

[rosscla]

What's the piston like at the top? Is there scope to pack it up a bit?

It's bit of a balancing act to get the squish / timings right.

Has the barrel been shortened at all? What's the distance between the gasket faces?

[Minority]

Ideally none, but that will depend a bit on what version of Rapido you have.
I'm presuming you have a crank with a longer rod and will need the approriate base packer, maybe you can give us a bit more info on the rest of the specs (piston, crank, any porting done etc).
On my Rapido 225 "Classic" the piston crown lined up perfectly with the bottom of the exhaust port at BDC and everything else "standard".
With a longer rod it does you the option of playing with the port timings a bit more by using different thickness base packers

[DaveTomo]

thank you chaps, Indian webs RB conrod 58X107, 1.5mm off the base of the barrel, race rapido 225.Had a 1mm packer plate on it last year, it went Ok, this year after reading plenty of articles on here want to try and get a better understanding of the port timings and get it set up the best I can

[rosscla]

A 60mm stroke would drop the piston 1mm lower at BDC, longer rod as suggested would give a bit more flexibility.

How close to the top is the crown now?