Kz900: Stock Bore - High Compression Pistons

kawasaki mike wrote: Les I have a question for you as you seem very knowledgable on these kz's. Checking valve clearances is it better or more accurate to check the clearance 180 degrees opposite peak lobe hight or about 45 degrees after the valve comes back in its upward rotation? Some say check at opposite position from deepest position. What is your take on this. I am running 6 thousanths and 4 thousanths exhaust and intake. Figure it is better to hear them than smell them.

I check them at 180 myself

I use a dial indicator and make sure I am on the base circle. It doesn't matter where on the base circle you are, as long as you are on it. Just my .02

Cory

Thanks Corey. I figured as soon as the lobe passed,the critical gap should be immediately after that because if that clearance isn't in spec a spit shim would happen right there. The rest of the ramp is of no matter as you are past the point of spitting the shim. I have stock cams so there is no worry anyway unless I had 8 or 10 thousands anyway. Does this sound mechanically coherent to you? I have run as much a 7 thousandths on exhaust in Las Vegas where the engine runs alot warmer than other parts of the country. I am anal about such stuff. Thanks for your input.

I owe alot of that to Scott from S&K racing in Dayton, Ohio. He is anal about the right x patern in the cylinders,the right grit, the proper boring plate and the exact ring gaps. He even said taht 105 hp is the most I could possibly get with a perfect tune-up and everything perfect. So, I am pleased as hell. Thanks for your input.

kawasaki mike wrote: I owe alot of that to Scott from S&K racing in Dayton, Ohio. He is anal about the right x patern in the cylinders,the right grit, the proper boring plate and the exact ring gaps. He even said taht 105 hp is the most I could possibly get with a perfect tune-up and everything perfect. So, I am pleased as hell. Thanks for your input.

Do you know what dyno you were running? 105 seems very good for a 1015!

That sounds "sound" to me. Air cooled engines are more susceptible to increased heat saturation of the metal components from ambient temps. This means the expansion of the components is greater than a more temperature stable liquid cooled engine. Now this isn't a huge difference, but might warrant someone who mostly rides in very high temps to give a thou or so in the exhaust lash. When you look at the lash range from the factory, they most likely (don't know for sure) have a safety factor built in to account for tolerance and owner neglect to prevent shim spitting on shim over bucket configurations. I think your OK if you opened it up a thousandth or so, but I would be careful to not go too far. When in doubt, follow the factory guidelines. Just my .02, but what the H#&^ do I know!

Cory

Hi, K Mike, just read this section (I'm slowly catching up with the forums), 105 sounds good you have a great engine. Previously I mentioned I ride with a guy the has hot Web cams (underbucket shims) huge sunk into the head valves, 1200 MTC pistons 38mm racing carbs, porting etc and he is getting 98 at the wheel. My scoot doesn't have anywhere the mods (and I'm porkier) and we're pretty level on go (I didn't / won't dyno mine).
How does your bike compare to some new hardware - just curious.

Sorry if this is off the topic guys.

Dyno comparisons are a waste of time.

I have to agree, since no dyno test is the same. As you might've noticed I wrote "didn't/ won't dyno mine" for that very reason, I prefer the seat of pants approach (drag your mate).
That said if you use the same dyno for tuning you can monitor gains/ loses better.

Bozo wrote: I have to agree, since no dyno test is the same. As you might've noticed I wrote "didn't/ won't dyno mine" for that very reason, I prefer the seat of pants approach (drag your mate).
That said if you use the same dyno for tuning you can monitor gains/ loses better.

That and you can tune to make a dyno happy and loose ET & MPH at the drag strip. It's neat to have a number to look at but it's better when the number is reflective of something meaningful and comparable to the real world.