Boring

[92blaster]

ok my stuiped friend is boring his blaster and thinks its gonna be faster than my other friends blaster they are both bone stock and one is just having his bored and they both belive that just because of the boring its gonna be faster. he is going one size up 66.25 i belive he said. i said simply just boring your motor is not gonna give you any power and if any you wont feel it and i said the main purpose for boring a clyinder is to create a better seal and i said if you want alittle more power,to have your motor ported and polished. so someone out there please end this on going battle at my school its getting anoyying.

 

[McBrenner]

Whats he boring it out too? It all makes the difference. Is he going from 200 to the 240cc kit or what?

 

[245stroker]

boring his cylinder one or two over isn't going to do anything. It may run better for a little while but that will be due to the fact that he'll have a new set of rings making a better seal in the cylinder.

 

[specialized7]

.............

 

[92blaster]

if you read what i posted it says how much its being bored. ok good im right, now i have to tell my shop teacher that same thing, he said boring the cylinder will make more power because it will be a bigger piston and more cc's but .25 mm aint gonna make it really that much bigger. anybody know how much HP a vito's 240 is making with out the porting?

 

[specialized7]

apparently 30 or something but i dont belive it

 

[92blaster]

ya thats with porting though i dont belive it either. hey specialized you putting raptor 700 rear fenders on your blaster

 

[RobJ]

Theoritically boring an engine bigger should make more power, because of the larger displacement. The real question, is this increase in power significant? Since the increase in displacement is so small, the change in power will be likewise, and any change in power resulting from the increased displacement won't even be noticed. If you want more power, you need to change the way the engine breathes, by installing a new pipe, porting, reeds, etc. Probably one of the easiest things is to remove the airbox lid. You will however need to change your jetting, but you will notice the difference.

Boring an engine should only be to restore worn cylinder walls. Boring a cylinder any larger than what is required is a waste of $$ since it shortens the life of the cylinder. They can only be bored out so big then they are scrap.

 

[hickskateboarder]

well said stroker and rob. the bored cylinder will most likely be faster, because it has less blowby b/c of new rings and fresh cylinder walls. a stock cylinder is 195.007 cc's, a cylinder that is bored .25mm is 196.448. thats a difference of 1.441 cc's which is a 0.738% increase. if displacement were directly proportional to horsepower, it would make about .118 more horsepower.

yeah. i'm a dork.

 

[FLOTEK]

i agree with the above only thing id add is a drastic over bore can change the port timing in a negative way and also will add heat ,the bigger bore would require more port area resulting in it being choked out ,the iron sleeve will be thing losing rigidity/strength which can cause wear and a seizure ,the gain of 1 horsepower to only lose 3 hp and reliability doesnt make much sense to me....bottom line >porting is where the power is at