People often ask me why I need some 13,000+ valve shims on hand and so many of each size.
Well, I just got done doing the second bike in a row with shims in the same range (both Kawasaki's) and if you look at the attached picture you can see how 14 of the needed shims are all 2.925mm
Well I had 23 of them on hand before the first bike which required 12 - 2.925 and now this bike needed 14 of them. Well last I counted 12 + 14 is more than 23, so I ordered another couple hundred dollars of them and this bike can go together with the proper adjustments made. Yes being picky and having one desired clearance number is that important!
Now for many, you simply do not care and will seek out anyone to give you the easy answer that they are fine, no need to check/adjust them etc.......
For those people, this thread clearly is not for you !! Move along and keep your head buried in the sand!
For others, I will update something new sporadically and you can follow me on facebook or on my website
That same pic posted up fine (upside correctly) on the facebook page... WTF--I blame the mods, it had to be the mods fucking with my post. :hmm2:
After 5 months of what has been a weird winter, 2 weeks of sub zero, then 2 weeks of above freezing rotating basically since October. And virtually no snow to speak of, I am not even sure we got 20" total all winter, it seems we are about to finally see 50* come mid week next week. woohoo- only 6 more weeks until the first trackday event !!!
Looking forward to that, and to warmer weather to ride again.
For sure brother, summer started today with our 37 degree high, then low forties tomorrow ... I'll be starting the bikes and riding around the block. Will be hard to stay off the main roads but I'm always afraid of salt-corrosion in the early season.
Yep ... the temps have been up and down, and the last three weeks of February were brutal.
Why be so precise on these simple adjustments?
In a nutshell; balance, performance and longevity. lets just assume for a second that with perfect machining practices and a zero tolerance level of assembly your 120hp machine is getting that 120hp equally from each cylinder. It would run very smoothly, produce power equally from each cylinder, every power pulse would be exactly the same so acceleration/deceleration forces would be identical; ie the depicted pic it would be 30hp per cylinder. If the balance is thrown off by having some of the valves at the bottom of clearance, some in the middle and some at the top (but all within the clearance spec as allowed by all manufacturers) you could end up with a distribution of say; 31,28,29,28.... Now if you could measure crank harmonics and acceleration/deceleration pulses, heat generation, efficiency and tons of other data it would show an engine that will wear out sooner, produce less overall power and not run as smoothly. Cam timing will be slightly changed, valve lift slightly changed, combustion efficiency slightly changed, it also affects throttle body sync and exhaust scavenging pulses... Now we all know there are tolerances and it is highly unlikely your 120hp engine is so balanced, as each individual part has a tolerance at the manufacturer, each combustion chamber may be slightly different in overall size and more.... But those you nor I can control without pulling the engine apart and going through great efforts to make everything perfectly sized and balanced.... But-- Don't you suppose it makes a big difference to keep those assembly differences to a minimum and not add to the problem by not doing what is possible and easy when one is already in doing the valve adjustment?--This is one performance improvement that costs you nothing extra, just requires a little more effort than "close enough" when doing the valve adjustment service. That is the condensed version; in a nutshell because this discussion could really go on and into much more technical science of how the engine works which would be hard to articulate effectively without diagrams, actual demonstrations and hands on with some engines.
I deal with this sort of stuff every day. Holding one tolerance specififation to the tightest possible center of the allowance only makes sense if everything else is dead center..... that's where the term 'double nuts' comes from -- held to .00 of whatever the spec is.
In electronics, it's easy to get the timing of things ridiculously accurate. GPS works because the atomic clocks in all of the satellites are accurate to such a fine point that they have to be compensated for due to the difference in time as a result of the gravity gradient between the surface of the planet and the 100+ miles up that they operate at.
It all comes down to what is 'good enough', for a given situation. It's easy to fall in love with the number of digits past the decimal point, but it's usually an excercise in bragging rights.
How accurate does a wrist watch need to be? Wouldn't within a 10th of a second suffice on a daily basis? How about a timing device at a track? Is 1/100th of a second good?
Instrumentation error from one measuring system to the next is really the maximum accuracy any measurement can claim. That always results in tossing out the least significant digit in a measurement.
I'm sure you are extremely precise in your measurements; and can repeat the same measurement to the same value with great consistency. I'd be very surprised if you couldn't use feeler gauges and torque wrenches to attain a more consistent value every time you made a measurement with the same instrument - practice and experience are in play.
A theoretical excercise:
I'd think that if you personally took a motor and set the valave lash 'double nuts' to the ideal, ran it on a dyno, and then set the same motor up with the valve lashes randomly set all accross the mfg's allowed spec (narrow and wide) and re-ran it on the same dyno in exactly the same conditions.... you could see an extremely small difference in HP.
I'm curious how precisely close each injector squirts fuel in relation to the other injectors? I know there are certain tests you can do on injectors but I've still wondered do they all squirt exactly the same throughout the RPM range. Similarly is the volume of air that is injested exactly the same based on the shape of the air box, spark, etc. I do understand what rivers is getting at though. Why not be as precise as you can with the tools you have on the things you can control? I wish I had a set of feeler gauges with more granularity but I haven't been able to come up with a set so I can only get "close" with the set I have, and that's only if I am using them correctly. Measuring tolerances definitely takes some accurate measuring tools, knowledge, experience, practice, and repeatability.
A buddy of mine was talking about how the difference in how you adjust within the tolerances between the intake and the exhaust valves effects performance. For example setting the intake valves to the tight side of center will cause them to open a little sooner and close a little later, and setting the exhaust valves to the loose side of center will causing them to open a little later and close a little sooner, and was telling me how that can effect performance and why. I like learning about this stuff so Rivers, if you have any more detail to add in that area please do.