big bore motors

[stubby]

have just bought a big bore kit for my z1000 work in progress .
spec as follows mtc big bore o ring block. 1463cc arias 13.5:1 pistons.
have read on the oldskool performance site that there may be problems with oil leaks on such a set up for road bikes.
Have i shot myself in the foot , again....!!!!!!
any insites from people who are using big bore kits on their motors.
i know the compression ratio is probably too high for a road motor on the kit i have bought but again what compressions are other folk running without too many problems.

[Al]

13.5:1 is a little high for pump fuel so expect it to pink noticeably which is destructive.
Heat is the big enemy here and i would guess at the ambient temperatures that the bike is likely to see it will overheat before the sub sonic kills the top end.

Sub see super!

AL

[Mark Tiller]

You might need Avgas for that compression, you could use thicker base or head gaskets which would drop compression.

[mattc]

Nothing like your cap/comp but at 1170cc and 10:25:1 (Wiseco) I use super unleaded to stop pinking.

[big green bus]

I am running a gpz1260 and due to communication problems regarding barrel skimming I ended with 280 PSI per cylinder. I burned my starter out it ran like a diesel taxi. The other issue was the crankcases had been bored more than needed so the oil pissed out from the base. I sorted the problem with a 1mm turbo barrel spacer to drop the compression and got a set of replacement crankcases machined by a less trigger happy machinist and to date has been spot on.

[zed1015]

have read on the oldskool performance site that there may be problems with oil leaks on such a set up for road bikes.
Have i shot myself in the foot , again....!!!!!!
any insites from people who are using big bore kits on their motors.
i know the compression ratio is probably too high for a road motor on the kit i have bought but again what compressions are other folk running without too many problems.

You'll need to dry block the motor and fit external oil feeds to the cams .
(see my Drouin project for details )
That will eliminate oil seepage from the base gasket.


As for comp ratio i'd drop it to around 10 or 11 to 1 - ish.

[FreddaAbborre]

As for the heating issue you can use 1 or 2 size bigger jetting on the middle cylinders. Will still be a problem with heating, but would help some of it.

Had the same thougts for modification so this is what I heard, but I cannot confirm the correctness.