I doubted if that was true...thats just what I've been led to believe about his lobes. So I didn't know for sure.
Thats why your the expert on this stuff and I'm not Which is why I have one of your cams...

 

you don't want k-motion.

 

If you are going to turn your motor that high rpm ,You need to check your installed valve height. and have your spring pressure checked .you may have weak springs. after you know your valve height than check to make sure you don't have coil bind on your springs.

 

what ayers said....

Colin, I haven't cam dr'ed a Joe O/Erson lobe, but with the beehives setup right the most aggressive stuff I have used will work TO A POINT. The key is just to not run them too that point so you can get the RPM out of the motors.

Bret

 

I wonder if they are the crane 99893's. I have them on my hotcammed motor and it does the exact same thing at the exact same spot. I can also hear some clack which tells me there is a loss of valve control.

 

I had the 99893's with my 846 cam and it pulled to 6500 without any problems.

 

How do we know what that point is? Are there any guidelines or general rules.
-b

 

Not really.... when the SOB will not turn any more RPM because of valve float, your over the line.

Bret

 

Ive been thinking and why do you want to turn your motor so high rpm? Ive never had a motor that is to be driven on the street that ever made any power over 6000 rpm .I think whats happening is your over your cams power peak. and your floating the valves.If you keep turning your motor that high I have three words for tic tic tic.

 

Stock bottom ends can handle more than 6000 RPM's...

 

Here's another vote for valve float. The 918s solved the problem, although my cam is smaller than yours. My dyno graph looked the same as yours, the rpm just fell off the table.
And ayers1967, I had a stock 5hp Briggs kart motor with a few tricks done to it that turned 6200rpm. You might what to do a little a little research on cams, valvetrain components, harmonics, etc, ect.

 

Sure you can rev a stock bottom end motor over 6000. The question is how many times before it goes pop.

 

i've been doing it since 1999...still runs great over 600 passes on it with 6700 shifts

 

I raced karts in the briggs class, it must have been a long time ago if you were only revin to 6200, I was turning my motors 7,000. And they actually set those motors up to float the valves since they limit the lift so low.

 

I built the motor to hand rpm like that. Use the heads and cam that I have and only rev it to 6k and you're not going to see the full potential of the combination.

I really appreciate all the help guys. How do I check my installed valve height? I'll be doing this spring swap after it starts to get a little warmer, so the results may take a little while.