cmego

Does anyone know if you can put a 9 port piston sleeve & rod into a seven port case.
I have a 721p that the piston and sleeve got damaged through my own stupidity (TOO LEAN) ,and I was wondering if you could put a 35 plus 21 race assembly in that crankcase?

German Muscle

iTrader: (8)

If the case is the same dimensions as far as sleeve fitement and height it will. and as far as the rod if its the same length. Also is the stroke the same as the 35+21?

If all that is yes then yes it will work, although some ports will be blocked and unmatched to the case also your powerband will change as i bet the port timings arent the same.

quietstorm76

iTrader: (12)

It will probably cost you $300.00 or so for the P/S for the 35 plus 21. You could just buy another 721p.

GHETTOTEACHER

First of all, are the engines Rossi (Axel) or Novarossi?

Second, check the inside of the block and see if the venturi cuts match up with the cuts on the other sleve. If they don't, you will burn up a expensive motor rather quickly!

Roelof

Do not get fooled by the fact a 9-port sleeve is faster, it is all about the combination of the timing of the crankshaft and the poorts. The 721P is a nice engine but I think you can better buy 2 sets 721 for the same price as one 35-plus set.

German Muscle

iTrader: (8)

Novarossi
VERY true! Almost everyone now goes by the mis conception that more ports=top end, and less ports=bottom end. The truth is the engine timings have everything to do with this. More ports just means more velocity.

cmego

Thanks for the help.
I opened both motors up to see what the difference was and they are both very similiar except the 721 crankcase has some internal fins that are removed from the 35 plus, stroke & bore are the same, crank is different.

German Muscle

iTrader: (8)

rod length the same?