Nitroaddicts

iTrader: (8)

I got a ReX P5 i am gonna buy a new sleeve to drop in but was thinking that a 421 piston sleeve might fit and give me a new 421B?? Any know if this will work?

SpeedBump57

Should be a drop in.

o.s. power

iTrader: (14)

it might drop in, but have you actually looked at a 421 and p5 next to each other? They are completely different motors. Look where the carb is positioned on the crankcase, the timing of the crank I'm sure is different as with many other numerous details. This might be a bigger headache than what you think. Get your sleeve ported if you want more power.

Davidka

iTrader: (86)

I have heard of guys doing this in the past with good results but os power has some good advice there. Compare the port heights of your P5 sellve with the port heights of the 421 sleeve (from the bottom edge of the squish band at the top of the sleeve) before commiting. The Novarossi line have been changing little by little and the newer stuff might not be the same.

Nitroaddicts

iTrader: (8)

Good points... I looked at some shops where they sell the sleeves and the say they all drop in the long stroke cases p5 p5x 421b and even 821! All fit.. I liked the p5 so i still may just to the normal sleeve.