Z1OwnersClub GB

Just thinking about big bore kit wiseco piston 1075cc or 1105cc I would like to end up with 125 horsepower could this be possible with bigger carbs and cams or what engine spec would you need

I think to have something street rideable, you're looking more at 100HP with a big bore, mild cams, head work and some decent carbs and exhaust.

1075 is really the only safe bet on a standard block.... boring out to 73mm (1105cc) leaves the liners too thin and they can move and distort under high heat, meaning you'll lose your oil control.
Anything biiger is fine but a total engine strip to have the crankcase mouths opened up to take the bigger liners.
As already stated, 100+ bhp from 1075cc is asking a tad too much me thinks, though it is possible you'd have to lose some reciprocating weight first.
Rather than big bore, the best results would come from breathing (head work), cams and carbs. I used to run .435" lift cams in a Phil Manzano head at 1105cc with Keihin CR35 carbs which gave 123 rwhp on the dyno back in 1989.

I have a spare engine so I could go bigger which I might use

I'd go for a Wossner 1075cc piston kit, very good quality semi slippers pistons, lighter, gudgeon pins are shorter and lighter, a very good piece of kit. Done a couple of engine builds this year using these pistons, customer well pleased. Buzzard@ the buzzworkz.

1075 is besterest option all round me thinks.
My old Z1000 was 1075 Wiseco - 10,25:1 comp, flowed headm std cams! RS36 carbs and ran great with measured 90bhp.
Slot some 395 cams in you'll be near 100bhp - I ran 11.5/120mph 1/4's easy enough & did 1000's mile on it with no problems!



Loved that old beasty

Pigford wrote:1075 is besterest option all round me thinks.
My old Z1000 was 1075 Wiseco - 10,25:1 comp, flowed headm std cams! RS36 carbs and ran great with measured 90bhp.
Slot some 395 cams in you'll be near 100bhp - I ran 11.5/120mph 1/4's easy enough & did 1000's mile on it with no problems!

Photo0546.jpg

Loved that old beasty

That's gorgeous

The GPZ1100 unitrack achieved around 145/150mph at around 104 to 120 HP (depending on what you read) in what was a fairly mild state of tune.
A motor with 1075 @10.25 -1 with a decent flowed head and/or some fast road cams (or UNI cams), 28 to 31mm carbs and a decent 4-1 pipe will get you something similar.
My Z1R with 1075 Wiseco's, proper flowed (Manzano) head with 1mm o's valves ,stock dialled in cams and 28mm mikunis would piss all over my mates stock unitrack and see 160 mph and still does ( the power is in the flowed head/bigger valves ).
My alloy cafe is 1075 but with stock valves , flowed head, Norris 407 fast road cams and bored out VM26mm to 30mm mikunis and gives similar results with a slightly different power delivery (the power is mostly in the cams).
I have never had either dynoed and don't need to as they go well enough.
The Z1R is a nicer everyday ride with the stock cams giving a wide, smooth spread of power all the way through with the bigger valves assisting the flow whereas the café with stock size valves probably flows about the same due to the higher lift cams but their spec makes for a peakier motor with the same top end.
The next motor on the bench is Wiseco 1075cc at 12-1 comp with a 'J' head knocking it down to around 10 and either Kent kaw16 comp cams or 1100 uni cams.
Carbs will be either 26 bored to 30 or the VM32 katana smoothies i currently have on the Z1R and i expect similar but meatier performance to the others.
Swings and roundabouts to achieve nearly the same results.
A reliable combo would be something like 1045/1075cc, flowed head, bigger valves or hairier cams or both, 28mm to 31mm carbs and a decent 4-1 pipe.
I wouldn't bother going any bigger on the capacity as it's more expense for diminishing returns and reliability.

Rob what do you think the z1r bhp is making

paulmceleney wrote:Rob what do you think the z1r bhp is making

To be honest I haven't a clue and don't really care about hp figures and knowing what it produces won't make it any faster.
As long as the motor runs clean and smooth i'm happy but if pushed i'd say it's got to be over 100hp compared to my stock 90hp Z1R.
Having big HP doesn't necessarily mean a faster bike if you can't get the power down or have handling to match .
Apart from on the straights the Supercharged Drouin is actually a slower bike from A to B than the Z1R or cafe because if i grab a handfull in the twisties the the back end just spins and steps out and a split second after my arse nips i'm rolling off the throttle.
Better to have a motor you can ring the neck out of and decent handling to maintain corner speed.

Thanks to all that replied , some useful imformation I shall go for a 1075 kit

What sort of increase would you expect to get by just fitting the big bore kit on it's own ?

zed1015 wrote:

paulmceleney wrote:Rob what do you think the z1r bhp is making

To be honest I haven't a clue and don't really care about hp figures and knowing what it produces won't make it any faster.
As long as the motor runs clean and smooth i'm happy but if pushed i'd say it's got to be over 100hp compared to my stock 90hp Z1R.
Having big HP doesn't necessarily mean a faster bike if you can't get the power down or have handling to match .
Apart from on the straights the Supercharged Drouin is actually a slower bike from A to B than the Z1R or cafe because if i grab a handfull in the twisties the the back end just spins and steps out and a split second after my arse nips i'm rolling off the throttle.
Better to have a motor you can ring the neck out of and decent handling to maintain corner speed.

What sort of horse power do you think I will be running, 1045 wossner pistons, welded and balanced crank, Andrews x2 cams, ported head 28mm z1r carbs

Swirl wrote:What sort of horse power do you think I will be running, 1045 wossner pistons, welded and balanced crank, Andrews x2 cams, ported head 28mm z1r carbs

I wouldn't get hung up on HP figures but set up right i recon that spec should produce performance about on par with my Z1R .

zed1015 wrote:

Swirl wrote:What sort of horse power do you think I will be running, 1045 wossner pistons, welded and balanced crank, Andrews x2 cams, ported head 28mm z1r carbs

I wouldn't get hung up on HP figures but set up right i recon that spec should produce performance about on par with my Z1R .

Hopefully be back in after Xmas so we shall see