I want to bore stock cyl. whats the max size?

[lassek]

Hi.

I want to bore out my stock cylinder. I want it to be maximum size and still reliable and runing great. What do you guys recommend in bore size? 68mm? 70mm? BTW: I am also getting it ported and polished along the way. My plan is to get the stock carb bored up to 28mm to go with this.

And another thing: Please recommend and link a piston to go with the new bore.

BEST regards ...

Lasse

 

[Blaster#55]

You do know that boring out ur stock cylinder wont give you any more power? It just looses the life span of the top end.

 

[Vootie]

Does your top end need rebuilding, or are you just trying to make it more powerful? Boring you're cylinder out isn't gonna give a noticeable increase in power, basically all you're gonna do is shorten the life of your cylinder.

 

[screamin2stroke]

i would just bore to the next size and have it ported..

 

[blasterman87]

yup just get it ported your wasting time/engine life

 

[b_russell_82]

best thing to do is take your cylender to someone who can bore it. Let them measure it and see what size the bore is right now. Then let them see if it even needs boreing or if you can just hone it. Don't bore it any biger then it needs to be. After seing what size you need the order a Wiesco piston in that size and take the jug and piston to have it bored.

 

[electricguitarlover21]

Yeah boring it out only brings it out 1/100 of a millimeter at a time. i recently rebuilt mine and had it bored out to .04 over, but that was only because i put a gash in the sidewall, these guys are right it shortens the life span of the jug, and you can't really bore out a carb, you'd be best off just getting a bigger one, like a bigger keihin or a bigger mikuni carb, rather than trying to modify the stock one, because regardless of how big you make the inlet and outlet, the slide will still be the same size. so you're better off just buying a new one to match an aftermarket pipe.

 

[DUALSTROKE]

If you want to bore it that much just make sure you got another cylinder for the next blow up.lol Just go as least as needed.

 

[wrench man]

Yeah boring it out only brings it out 1/100 of a millimeter at a time. i recently rebuilt mine and had it bored out to .04 over,

Do you pay attention in math class?

 

[electricguitarlover21]

haha, yeah, when it's bored out you take it out .01mm at a time till it fits the piston size then you smooth it out, hone it, then you're good to rebuild. haha

 

[lassek]

Hmmmmm i am really surprised over your answers? I am not a master mechanic! .. but i do know from my scooter days that if I ran a 46mm cylinder kit... a 48 mm cylinder kit would be more powerful / faster. Otherwise why go big bore?!?! The bigger piston - the bigger explosion? or am I completly wrong????? So if my stock cylinder i 66mm i really dont understand why not a 70mm cylinder kit would not be more powerfull? Specially if ported and polished also.

And what if the head is shaved along? for higher compression?... all theese things together wont they give any power???????

The reason why I am thinking about this is an alternative to buy VITOs big bore.. i live outside US and is is terrible expensive in shipping and VAT to import.. i want to get maximum power of the parts i already have instead.

Regarding the bore of the carb, that was because i saw PROJECT BLASTER on ATV SCENE... they do it? They bored it out to 28mm for no money, i guess it is possible to tweak it just a litte before the need for a bigger carb.

 

[DUALSTROKE]

Hmmmmm i am really surprised over your answers? I am not a master mechanic! .. but i do know from my scooter days that if I ran a 46mm cylinder kit... a 48 mm cylinder kit would be more powerful / faster. Otherwise why go big bore?!?! The bigger piston - the bigger explosion? or am I completly wrong????? So if my stock cylinder i 66mm i really dont understand why not a 70mm cylinder kit would not be more powerfull? Specially if ported and polished also.

And what if the head is shaved along? for higher compression?... all theese things together wont they give any power???????

The reason why I am thinking about this is an alternative to buy VITOs big bore.. i live outside US and is is terrible expensive in shipping and VAT to import.. i want to get maximum power of the parts i already have instead.

Regarding the bore of the carb, that was because i saw PROJECT BLASTER on ATV SCENE... they do it? They bored it out to 28mm for no money, i guess it is possible to tweak it just a litte before the need for a bigger carb.

Your best bet is to just go as little as possible on the bore/hone and send it out for some port work.That will really wake it up for sure.

 

[FLOTEK]

well you could bore it over and make 1 more hp on lowend and drasticly lose the life of the jug or you could have it ported along with some accompany mods and make 10 -15hp more everywhere ,your pick