Big bore kit?

[black black bird]

What is a big bore kit for ....

whats the pricing like

is it like getting a new engine?

what are its down sides? :?: :?: :?:

[Northman]

It's basically a set of pistons & the corresponding head gasket, that increase the displacement of the engine.

Stock is 1137cc, the most common big bore kit brings the displacement to 1195cc, and some raise the compression as well from 11:1 to 11.5:1.

Cost is about $600US + labor to install + machining costs.

Downside - you have to disassemble your engine, and machine the cylinders to fit it.

Is it like getting a new engine? Yes, a bigger one :grin:

[4U2NV]

Does this procedure cause any future problems for the engine? Do you have to replace or add other parts to strengthen the engine so that it will be able to handle the added pressure and/or stress?

What about adding a turbo - in addition to over-boring?

[Northman]

No need to add anything else to the bottom end to preserve longevity on the XX when installing a big bore kit.

A competent engine builder should be able to perform it for you, and it last just as long as the engine originally would.

There have been some concerns about adding a turbo to the mix when cylinder walls have been bored out that far. Should be fine at moderate (street level) boost levels, but not advised for the high boosts some guys (namely eliXXer) are running, although there are a lot of 1200cc, high hp, turbo'd bikes out there used in dragracing.

The concern is flexing of the cylinder walls under very high pressures, and possible eventual cracking.