Originally Posted by sm4100
Hi Roelof, does it work if I put a 9 port PS instead of originally designed 7 port?.
It looks like a PS from RB Circuit 9 will fit and have the same bore and stroke (16.22 X 16.80). and I found the kit at reasonable price too.
Yes and no. First of all you do need a matching buttonhead as well because the 9 poort sleeve has a thicker upper edge (3mm instead of 2mm).
Last I fixed a 9 poort sleeve in a N21-5T basic engine but the sleeve was placed an half milimeter to high so I needed to modify the sleeve on my lathe to fix the right depth of the sleeve in the crankcase.
Again, the 9 poort set is an expensive investment if you can not get the full potential out of it with the original clasico crankshaft. Then it is better to get a 35-plus-21 enginge fo a few bucks more.