Honda Spree and Elite 50 Forums

what are the advantages of doing the boost porting when doing a bbk? and what are the disadvantages of not doing the boost porting when you install a bbk? Just questioning to determine if I should go thru the extra work doing this or not.

I believe that it is most important to match up the case to the cylinder boost port. Case in point; I had cut a boost port into my block to match a malossi cast iron cylinder and then when I went to install a polini corsa on to that block, it would not rev or perform well because of that mis-match boost port. I had to use that block for another cylinder that had a larger boost port that I could match it up with. The only one I know of that would perform well without cutting the block boost port is the polini corsa/contessa cast iron cylinders on to a "virgin" block. Those cylinders have a small enough boost port to not have any significant effect with being "dropped" on to a "virgin" block. Cylinders are designed a certain way to perform properly the way the come. You will have to almost always match up the boost ports on any cylinder or risk poor performance. That's my experience/opinion. I am sure there are others with far more experience than myself and will be along soon enough with their replies. I see you have other posts in search of a block. Best of luck finding one, I know they are becoming rare and careful cutting one up for a stroker or even just a boost port as once it's done you can't easily go back.

Yeah and I am looking for another block exactly for that reason and thanks for your input on this