Question shimming?

Kray-Z wrote:

daveo wrote:

swest wrote: Shim under is the way to go with hot cams.
Steve

I like the :kiss: method, so the 84 GPZ cams will be it for me.
:lol:

You should be using the shim under and GPz retainers and springsfor those cams! I would keep the revs below 8500, then....

Good advice, thanks
Maybe luck, but no issues since spring 2015 when the top-end was done, and engine will eat 8500 like a snack. I have the rev limiter set at 9500, but will rarely go there. Here's a link to my low-budget build, which I went into with 100% confidence:
www.kzrider.com/forum/2-engine/596933-ca...-engine?limitstart=0

...and I read this awhile back:
www.kzrider.com/forum/2-engine/602634-83...n-and-buckets#727930

Ha!

On that second one - Kawasaki's reason for shim under on the later GPz - note the factory redline on the '82 GPz1100 vs. the '83 GPz1100....or the KZ650 /750 (also SUB) for that matter.

Ever seen what happens when an engine spits a shim (SOB) at high RPM (due to valve float)? That would be a nice "window" in the engine, then? And valve float is more severe with big valve two valve heads and valve train components because all the parts are bigger and heavier than four valve heads...so unless you are running 250 lbs seated pressure on the springs....

Just a note - we were running 800 lbs seated triple springs on our Yates / Roush heads on our shop's 332 cubic inch, titanium valve NASCAR head 845 HP small block Ford rail dragster years ago, and we still got valve float at 10,500 rpm.....and often some pretty badly burnt valve springs from harmonic vibration....

Kray-Z wrote: Ha!

On that second one - Kawasaki's reason for shim under on the later GPz - note the factory redline on the '82 GPz1100 vs. the '83 GPz1100....or the KZ650 /750 (also SUB) for that matter....

Sorry, but you left me in the dust there... :dry:
I appreciate this particular investment of effort too much to abuse it, being a BOTM and all...
Had some well-respected forum members advise me with the top-end assembly last year, and no one mentioned concern about the valve-shims being over or under, so I dismissed it.

BTW, what rpm limit should I consider safe if using shim-under buckets?
Some other forum member previously wrote, "I'm a woodworker, not a mechanic", so I'm in good company here.

I'd say 10,000 routinely. Daveo, I 'm just saying for longevity, and to [play it on the safe side, I wouldn't rev SOB with GPz cams over 8500...but that doesn't mean the first time you take it to 9500 it's going to blow sky high, either...

Here is another bunch of observations and food for thought.....

My stock engine '81 CBX (SOB) went tach needle straight down once because my attention got diverted from looking straight ahead for about half a second on a street race (the other guy's nitrous 750 engine had just locked up beside me), and when I looked forward again the tacho needle was completely off the numbers scale, pointing straight down. Lucky there was no engine damage. I later extrapolated 14,000 rpm from where I saw the needle - redline is 9300....Engine still runs great today, now with 7000 more miles on it, and is the smoothest and quietest running six I ever had (I have owned 22 CBX's so far), and it doesn't burn any noticeable amount of oil at 45,000 miles.

When racing my '79 CBX, I can't even imagine how many times it popped out of gear on the first - second shift, sending the tach soaring past redline, and that was shim over bucket, too. That bike went 11.00 1/4 mile with a professional drag racer riding it, after some extensive modifications, but it still had SOB it's entire racing career.

Three years ago I took my 100% stock "Beater I" '81 KZ1000CSR (SOB) to the drag strip, with 35,000 miles on it. I had originally bought the junk pile just for spare parts; I only paid $500. I had fully expected to bring it back home in pieces. I beat the hell out of it that day - 11 or 12 full on passes, sometimes crossing the finish line in third at 11,000 rpm (redline 8500). I even matched time with a 2004 V-Max at the 1000' mark on one pass. To my amazement, at the end of the day the idle dropped about 100 rpm and it sounded rough - that's it???? Not quite - when I dumped the oil at home, a 1/2" long piece of clutch fiber plate came out of the oil pan. The filter and oil had a fair amount of silver in them, and oil consumption went from a quart every 1000 miles to a quart every 300 miles, so, yes I "hurt the motor", but all the shims stayed put....and it still ran.

And yet - I have talked with other CBX and KZ1000 owners who spit shims at 9500, and while watching road races, I've seen stock class racers blow up spectacularly at just a few hundred over the redline....

I'd keep the max rpm at 9500. although an occasional trip to 10,000 probably won't cause immediate harm. Keep in mind that the KZ1100 makes its maximum horsepower at 8,500 rpm and max torque at 7,000 rpm, so over revving it, even with some mods, isn't going to make more power. If you rev it too high you can cause other non-shim related problems. A guy on another forum used to routinely rev his KZ650 up to 11k rpm. This was really dumb since the power generated by that engine drops off sharply after 8,500 rpm. It wasn't long before it blew up. He suspected the con rods may have stretched a little and caused piston/head crash but he had no real evidence showing that. All he knew for sure was that the engine was trashed - so he sold it as is. Ed

These old Kaw's are simply amazing.

My Z1 makes max power at 9000 but will pull way past that without any more noticable power. I lost to a family car because I didn't shift early enough. I was pulling on him but I held it open too long. SOB, Kibblewhite springs and 1X drop in cams.
Steve