Boring +2.5 oversize

[vinze187]

as worked out on other thread (started this one as that ones turned funny lol) boring +2.5 oversize would give 375cc
Is there any drawbacks too doing this?
unrealiablity?
Weak crank?

If it was okay to do are there any other mods that can be done to compliment it?

[hooligan]

Hi Vinze

If its on a Valve your pistons will hit the powervalve and you would need to mod the head gasket. Mine are .2 over size and only just miss the valve.

[vinze187]

Cheers guess ill not do that then lol

have you come across any other problems with your size rebore?

Is it noticably different than from standard size?

[Norbo]

The liner gets very thin and is more prone to sezurs becourse the barrel can and does go a little ovel ater time and more so when you are on a very big over size.

[vinze187]

Right i shant risk it! if i cant afford a big bor kit i'll not do it cheapy and end up with a load more problems

[gazmo]

???Ive just picked up an engine with barrels that have been bored to 2.5 O/S and like you say the liners are very thin and the power valve is very close to the piston but my barrels have had some porting done to them before i got them and the valves have been modded well thats how it looks all that needs doing to them now is a little tidying up on some of the lower tansfer ports as they to are close to the pistons and they all need chamfered.Still along way off being complete but iam going to take the chance as i have all the bits but what i was wondering was if i should use the oil pump or go to premix and if so at what ratio and how much do i increase the main jets in the carbs to allow for premix.Failing this ive heard that these barrels can be re linered is that the case and who does them?