bore kit

DoubleDub wrote:

Those kind of HP numbers aren't very usable unless you're drag racing on these motors. Maybe if you did some form of force induction, but there is still a ton of heat created when you increase performance which will reduce longevity, blah, blah, blah, blah. I think the general consensus is that a drivable motor can do something in the high 80's to 90's and still be reliable for everyday riding?

But again, it all depends on what you are wanting to do.

Don't get me wrong, anything is possible - if you're just wanting to make the engine hit a number and don't care how it drives, the more power to you, just post pics!

Edit: I would think that bigger carbs will be mandatory if you are pushing to get >100HP

Popular opinion is it takes a 10.25:1 1075, ported head, and your choice of aftermarket carbs to make 130- 150 hp at the crank which is about 110- 120 at the wheel. If you want things to be bulletproof then you have to weld the crank and back cut the tranny and put in studs. Hell I just want to give the young guys fits stop light to stop light on their "race bikes"

FWIW, it costs a lot of nickels and dimes to get 150 horsepower. Going quick isn't cheap.

andy9802gt wrote:

Popular opinion is it takes a 10.25:1 1075, ported head, and your choice of aftermarket carbs to make 130- 150 hp at the crank which is about 110- 120 at the wheel. If you want things to be bulletproof then you have to weld the crank and back cut the tranny and put in studs. Hell I just want to give the young guys fits stop light to stop light on their "race bikes"

FWIW, it costs a lot of nickels and dimes to get 150 horsepower. Going quick isn't cheap.

Hmm...more optimistic than I've seen, but I'll defer to the more experienced. Not my realm of expertise!

ok its a 1979 kz1000 ltd it has 32,000 on it never rebuilt i just want a fast bike for the street so what would be my best kit for that

Stay at 10.25:1 compression max. Over that you won't be able to use anything but race fuel.

Key is to match the components. It's not necessarily the biggest that is the fastest, just the best matched.

Lots of others on this site have more experience than me and can give you pointers. The 1075@10.25:1 piston kits are popular/common. Head will need porting. Carbs will need to be bigger. Larger cams will be needed, I just can't tell you how large to go. And a pipe, dyno time to tune, and paint, maintenance components (seals, gaskets, cables, etc). It turns into a big project pretty fast.

Welcome to the disease! :laugh:

You'll likely need something from any of these places as well:

www.z1enterprises.com/
kzzone.com/
www.flowbenchtech.com/porting/CRH/
www.pitstopperformance.com/

I believe they all sponsor the forum as well....bonus.
Carbs will be Sudco or Dynoman.net, I believe, unless you go with RS34's which APE has.

Just my 2 cents worth.

I've built a few engines similar to what you're talking about for street and for dragracing, like others on the thread have said, "weld the crank" and don't forget to install a heavy duty cam chain and main bearing support.

Just a thought.
I've had very good luck with street engines using a larger bore kit with lower compression.
One of the best street combo's I've had was a stock block 1200cc 10.5 to 1 kit with a KZ900 head with stock valves and running the APE 410 cams and 36mm round slide carbs.(the 410 cams are find with shim on the top followers but you'll have to clearance the head and valve cover).

In my current race bike I'm running a 998cc low compression engine with Engle 410 cams, J model head (SOT)KZ pistons, and Mikuni 29mm smoothbores. The head is stock except for being clearanced for the cams. The crank is welded, There's a main bearing support installed and there are HD cylinder and case studs installed. The clutch is stock and the tranny is stock also. The clutch basket is modified (welded)and I run a HD cam chain and an APE cam chain tensioner. In October the engine made over 93 rear wheel horsepower.

I'm building a new engine for the upcoming season with a KZ style head (ported), higher compression pistons (10.5 to 1 and APE 410 cams. I expect to see at least 115 rear wheel HP.

Have fun with your build but remember to get the basic lower end finished before you start putting a lot of compression in the engine. I've seen stock KZ1000 engines twist unwelded cranks on the dragstrip.

Good luck,

Buzz

so if i just bore it to a 1075 kit with 10.25:1 compression, get a vance and hince exhaust, and rejet the carbs will i notice a big diffrents in the response and power

kzgeary wrote:

ok its a 1979 kz1000 ltd it has 32,000 on it never rebuilt i just want a fast bike for the street so what would be my best kit for that

Rebuild it to stock and drop 1 or 2 teeth on the front sprocket. That'll put a little pep in your step. If you really want to go 1075 it's gonna cost money.

piston kit - @$500
cams- @$400
porting your head- @$1500
carbs- @$1000
welding your crank- @$500
all new gaskets and seals- @$400
backcut tranny- @$300
labor if you don't do it- ?????
total- @$4600+/-

alright bec now its only got about 65hp and stock new it had 87hp so i will notice a differents then.

so if i got

365 cams

1075 10.25:1 pistons

RS34 carbs

what do u think that would put me at in hp

kzgeary wrote:

so if i got

365 cams

1075 10.25:1 pistons

RS34 carbs

what do u think that would put me at in hp

if youre not going to port the head save your money and just run a set of 28-29mm carbs.
omrs motor runs 10.25:1 1015 pistons with 365 cams and a street ported head and 29 carbs.
i guessed around 95hp at rear wheel,after some tuning he got 96hp at the rear wheel on local dyno.
id say your 1075 with a stock head with same cams and carbs would make around 90 real world hp at the rear wheel,same head porting as his would put you right around 100hp at rear wheel.
that is a real world motor that will run everyday and not require a lot of constant upkeep,and should be plenty to keep you entertained for a while.

my 1075 with stock head, stock cams and vm28's made 76hp at the wheel with an 8" over arm according to the dyno sheet I got with the bike.