KZ1075 red line

I'm putting in APE K410 cams and valve springs. The crank is stock 1979. What should I set my rev limiter at?

carbs,head,ignition,gearing,what kind of riding do you normally do?you can rev these things to stars,but no sense in winding it past where it stops making power.take it out and see where you spend most of your time,and go just a little over on limiter!:evil:

Wireman that is how I would ride, shift when the power drops off. I guess I should have asked aproximate valve float rpm. I want to set the limiter just under valve float for protection in case of a missed shift. Doesn't mean I'm going to wind it to the limit every time.

check with who you bought valve springs and cams from they should have a good idea of what your springs can take.

It would be way better to put the bike on the dyno and see where the powerband starts to fall off and make that your shift point. Set your rev limiter a couple hundred RPM above that. There is absolutly no reason to rev the motor up into an rpm range where it is not doing anything.

What the racers do is figure out the RPM drop for each gear change, and set the shift point to where the RPM will not fall out of the power band on each shift.

Jay

I can only say that what Jay has said is right on. I don't have a dyno, but I have experimented a whole lot at the drag strip with different shift points and my times only got slower if I shifted at 10K or above. I found my quickest times were shifting around 9K or so. I have my limiter set at 10K just in case. If you're revving beyond the peak power curve, there's no sense in it at all. I'd love to put the bike on a dyno some day, but quarter mile times will have to do for now. Good Luck.

79MKII wrote:

I can only say that what Jay has said is right on. I don't have a dyno, but I have experimented a whole lot at the drag strip with different shift points and my times only got slower if I shifted at 10K or above. I found my quickest times were shifting around 9K or so. I have my limiter set at 10K just in case. If you're revving beyond the peak power curve, there's no sense in it at all. I'd love to put the bike on a dyno some day, but quarter mile times will have to do for now. Good Luck.

i agree with 79mkii, after taking my bike to the track last week i turned my drl red line point to ten and a half grand. you can tell that i started droping off after that. your motor is just used up at that point and is wanting to be be shifted up. a lot of factors pay a roll in were to set the revlimiter. grearing being one. i run a 16f 45r so my rpms realy get up there quick at low speeds. it all depends on the bikes set up.

by the way 79mkII what kind of time you throwing down in the 1/8 and the 1/4?


i was mad last week. it was so cold the night i ran, 50 degrees. i couldnt hook up. i would brake loose till i hit the tree every time. started of launching a 5000rpm and droped to 3500 and still woulnt bite. best i could get was a 7.60 in the 1/8

rattler. what is your best 1/4 mile time? just curious.I'l like to take mine to the track next summer.Are you running stock tires and swingarm?

So 10500 is still below valve float? I'll just set it at 10K just in case I miss a shift.

What's the total configuration of the engine?

Is the head ported? What's the CR? valve sizez?