kz750-4 camshaft for low-end torque

wrote:

My 82 GPZ had around 18 more HP than a 650, stock...

Thanks. yes, I knew the turbo hp was going to be higher & looked up the numbers beforehand. was thinking Kawasaki went w the 650 cams to get more torque. but that was guessing based on fewer degrees of duration. I'm not that knowledgeable on the topic.

wrote:

I miss a "multi-quote" option to answer all of you lovely people answering. So I will just try to reply with your names instead:

750 R1: It has standard airbox and CV34 carbs. It runs smooth as hell, so there is nothing to be found in jetting. But I have however considered fitting smaller carbs and to be honest the only thing that really makes me hesitate is how well-jetted I have it currently. That being said 30mm carbs or something around that size could perhaps be the solution to more low end grunt.

Injected: No my suspicion would also be that all aftermarket cams would be tuned for the opposite scenario. So it should have been if the bigger 1000cc bikes had milder cams perhaps to make up for the added volume.

Nessim: Very valid point! I have my eyes set on a 810cc kit once I decide to rebuild the engine or it decides for me But of course you are right, that would help low end torque.

650ed: I do not have a tachometer, so I have no real way of saying exactly. But my guess is that it is somewhere from 2500-3000 and up that I want some more grunt. Which is perhaps asking for something another type of engine entirely would be better at. But just asking for suggestions for making what is already a bike I love more suited to my driving style.

zed1015: Adjusting the cams could be a solution, yes. I might have to consult my 4-stroke performance tuning book and look a bit more into that. With regards to the gearing I have actually raised the gearing which makes it a lot more pleasant to ride on highways. So I think I am more in the smaller carb or cam-adjustment camp at the moment.


 

All aftermarket cams for these motors (650/750) have more lift and duration, there are none that are ground to have less. With more duration you would be making less torque, these aftermarket cams also raise the RPM level the motor can make peak power/torque. The 900/1000/1100 version of this motor has about the same thing going on with the cams as stock, same thing with aftermarket cam selection. The only time this would differ is a "Turbo" cam which is much like the stock cam (lower lift and duration)
The stock cams for the 650 are almost the same grind they used for the GPZ750 Turbo. Kawasaki used a 650 motor to prototype the GPZ750 Turbo package.

 

wrote:

wrote:

My 82 GPZ had around 18 more HP than a 650, stock...

Thanks. yes, I knew the turbo hp was going to be higher & looked up the numbers beforehand. was thinking Kawasaki went w the 650 cams to get more torque. but that was guessing based on fewer degrees of duration. I'm not that knowledgeable on the topic.

Mine wasn't a  turbo....  I'm not up to date on turbo's either but the always seem to use milder cams and lower compression, not really comparable to a naturally aspirated engine..

wrote:

Mine wasn't a  turbo....  I'm not up to date on turbo's either but the always seem to use milder cams and lower compression, not really comparable to a naturally aspirated engine..

Okay, thanks for the clarification. I did not know the GPz's hp was that high. every other 750 air cooled I checked was in the 75 hp range, including the ZR7s.  I was guessing Kawasaki went w the 650 camshafts for more low rpm torque since the turbo was getting them so much more power, around 112 hp. was thinking otherwise the turbo power would spin the engine like crazy & hit the redline too easily. ha ha.

the turbo got small cams to improve low end during off boost situations along with low compression ratio.