TOPIC:

A question for the more experienced, could my kawasaki kz1000 A1 reach around 83 horsepower (hp)?

The only changes it has are some RS34 carburettors, original 72mm pistons and a Delkevis exhaust.

Assuming everything worked correctly of course, since I don't have access to a dynamometer.

What is the compression? The higher the number the more HP potential.

Is the 83 HP at the crank or the wheel? I believe Kawasaki quoted HP is at the crank (not sure)

I believe the carbs are probably good for at least 5-7 HP over stock, the pipe probably worth 2-3 HP (just a guess) so maybe your right there anyways.

All Dyno's read different but I believe the difference between crank HP and wheel HP is somewhere around 8-10% (again not sure) Its been a long time since I looked it up.

I should hope so.
Stock 1000 was booked at 83 and the later  Z1R etc another 7 hp at 90 just because of the 2mm bigger carbs
Measured at the crank..

Original pistons were 70 mm.  Are you saying yours are oversize?  

I think with a 1075 motor (10:1 comp) with RS34's and a pipe you should be around +90HP at the wheel. It just depends on where the cranking compression is (worn rings) if your down on compression it could be a lot less.

The losses incurred from crank to wheel vary between 12-15% (just looked it up) Most people quote wheel HP as that would be the number from the majority of Dyno's out there (not too many set up to take a engine on its own)

hardrockminer wrote:

Original pistons were 70 mm.  Are you saying yours are oversize?  



 

Yes, they are 72mm, but they are in the old original format, not like the modern Wiseco ones, for example.

Here I don't know which piston the Japanese put in his Z1 but the acceleration it has surprises me.

 

Will someone please explain what the relationship is between cranking compression and horsepower?
My compression gauge readings were 165 psi in each cylinder the last time I checked, and I don't know much what that means.



 

MLMG wrote:

hardrockminer wrote:

Original pistons were 70 mm.  Are you saying yours are oversize?  




 

Yes, they are 72mm, but they are in the old original format, not like the modern Wiseco ones, for example.

Here I don't know which piston the Japanese put in his Z1 but the acceleration it has surprises me.


 

What does this video have to do with your post. As HRM says stock 1015 bore is 70mm. 72mm would be 1075. It would be useless to go to that bore without increasing CR, unless it was a budget issue

A good cyl. head porting and bigger IN/EX valves is needed to remove the main bottle neck = less resticted airflow = more air/fuel = more power.

Like I said before, the higher the cranking compression is the more HP potential there will be - pretty simple. This has nothing to do with your aftermarket 10:1 comp pistons, but a lot of other factors such as cam duration and cam timing, combustion chamber volume/piston dome volume, ring seal, etc.

If you go crazy trying to get maximum PSI you will find that pump gas will no longer be useable to keep knock at bay.

You can't quantify PSI with HP on a individual basis, it has to be measured on a Dyno because no two engines are tuned alike.

Dyno's are more plentiful than 20 years ago, one hour booked is pretty reasonable as long as you don't have to make any tuning changes.

Here is one from my KZ650 street bike taken in 2015 :



831cc 10.5:1 comp MTC, big valve head, Stage 3 port, 400 lift WebCams, 33 mm Flatslides = 89 HP at the wheel (second run 836.002)

Stop trying to guess and measure it, its not a lot of $.

 

daveo wrote:

Will someone please explain what the relationship is between cranking compression and horsepower?
My compression gauge readings were 165 psi in each cylinder the last time I checked, and I don't know much what that means.

 

The more you compress the intake charge (squeeze it into a smaller space) the greater the rate of expansion will be when it fires causing increased thrust on the piston ( more horsepower) this is why if you over do it the intake charge "explodes" rather than "burns" which is what causing knock and destroys motors