can air cooled 250r be bored out? and questions

[demonband2000]

Are these nikasil coated?
Can they be bored out without resleeving? or re nikasilled?
If its possible to bore,how big can I go without resleeving and still be reliable?
What cc would this end up?
what piston would I have to get?

Whats the boring out going to give me powerwise?

milling head -- how far can I go?

I'll be running stock carb and pipe --- Looking for extra torque more than revs, but the more overall power the better.

I have an old extra motor I was going to take the top end off off and see if I can bore it, and redo the top on my atc. If they are nikasil, and hhave to be recoated, or sleeved I probably wont do it. And just freshen up what I got on there when it needs it.

[D-dub]

Yes they have an iron liner and can be bored,and honed with multiple oversizes. They can also be resleeved to almost 300cc's

[fabiodriven]

There is no gain in you boring that cylinder to its maximum. I'm guessing maximum is .080 over, and that' not going to gain you more than a couple of cc's. It's not worth doing, it's a waste.

[ktmbk]

Yea, maximum is 80 over, unless you go with a big boar kit of some type. No you don't get much extra power from doing it, and you usually don't jump up as big as you can unless there is that much damage to your cylinder. It's mainly used to restore lost power, however if you go to someone who knows what they are doing and get a good porting job with the boar process it can make a world of difference. I don't know what the cc difference is from boring but it's usually negligible at best. Usually you end up with a wiseco piston, although you can find others in the smaller sizes if you look (i usually try for the oem honda). Best bet for power is a pipe, porting, reeds, and a good air filter for power. A larger carb can also help if you set it up correct, but it's not something iv'e done.

[Yamaha_Rules69]

^ With what it says above, boring that small will not be worth it powerwise. Send your jug in to get ported, along with a few bolt on mods, and it will be a whole new machine. The standard piston size is 70mm, and it can be bored up to 72mm, so after 2mm of boring, and it needs to be bored again at a later date, a sleeve will have to be installed. Dont waste the cylinder by boring it if it dosnt need to be done. Good luck!

[D-dub]

Ya definatly only bore as needed