Z1OwnersClub GB

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.

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

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

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

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.

stubby wrote: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.

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.