raise compression ratio

[muppet]

Hi All, i want to raise the compression ratio to around 12.5:1 as i will be using high octane vp race fuel on my drag only bike, this will be done using the standrd pistons so want to know if anybody has done this and by how much was the head decked,also if any of the members can help getting this done.

[tony.mon]

Not sure if you'll have valve to piston crown clearance, I measured it roughly at 3mm, so there's some room, but I don't know if that'll be enough to get to 12.5:1.

I will have a set of JE high compression (11.5:1) standard bore size ones for sale in the next few weeks, as I will be stripping mine down and reboring it, and will then have to buy the 1st overbore ones.
You could deck it then, to get to where you want to be.


Search on Superhawk forum, for "decking" which is what those ornery overseas fellas call it.

[mik_str]

I am running JE high-comp pistons (0.5mm OS) and have the head decked by 0.015". By my calculation, my compression ratio now sits at @ 12.2:1. Personally, I don't think that it is realistic to get to 12.5:1 without switching to high compression pistons (although I have been wrong before, this is just one "ornary overseas fella's" response, lol....)

[muppet]

Hi Tony did you get my pm ?

[tony.mon]

Yes, thanks.
A deal my be possible......