Cylinder Boring Up...Car Related (Kinda!)...BenR Maybe?

[u33db]

Might be a daft question but hopefully someone can answer this for me (as it kinda applies to cars too);

i'm away to build a relatively hi spec 2stroke motor to drop into my scooter as a bit of a fun project. The bore up kits i've seen only go as far as 70cc (mines a 50 as std) - ideally i'd like more though (i've heard of a 90 but am having difficulty locating who makes it) since theres no substitute for cc's;

Now, the questions i have is what are the limiting factors in boring up and how much would it cost to have a custom cylinder/cylinder head/rings constructed and who could do it?

Bear in mind the engine in question will be reviing to about 12000rpm...if its not going to be reliable going >70cc on a 50cc BE then someone tell me!

Appreciate any help! :D

[j3ned]

When i used to race Moto X i had a few lumps done with these guys

http://www.beedspeed.com/vespatuning.html

They do everything !!!

[BenR]

Dont know much about scooter engines, only played with crosser single piston engines.

Your limited to whatever available pistons are about and how large your cylinder is before you run out of meat/stiffness. Also if its an iron liner or if your using a nikasil lining.

larger pistons are heavier pistons and will put more force on the crank/rods at the same rpm. Do the kits include a new rod/crank?

[u33db]

j3ned - yep, got some other bits on order from beedspeed atm...70cc is the max they go though.

Ben - The 70cc ones use the existing crank. The larger ones ive heard of but can't locate all seem to be accross in the US where they're called 'stroker' kits. AFAIK they include a new piston/cylinder head and longer crank and are usually 90 or 105cc. Information is a very spares tho!

Just wondering if its worth the effort...as you said a larger piston will put more force on the crank...guess it might just be easier to build the engine to 70cc spec but so that it can run a massively higher rpm? I know mine is good for 12000rpm as std but i can get a lightened/balanced crank to handle more and 2 stoke is bombproof anyway...