I only set these up for optimal road usage. Funny thing is, by doing this, everything else pretty much falls into place, including gearing. The lone exception is ultra-low-speed use, such as a swap meets. For that, I drop-down 3 teeth at the C/S, well within the range of chain tension adjustment and you can virtually drop the clutch at idle...the bike will lurch away without stalling.
Sooner, or later, every rider is going to want to push a machine to its limits, or at least flex its muscles a bit. That's a universal trait among true gearheads. Your bike has enough motorvation in its boiler room to sustain mid-50s all day long, without breaking a sweat let alone hurting anything. Setting it up so that it can do so sacrifices nothing. I get it with the KZ comparison, it's like comparing a `60s era car with an equivalent from the EFI era...in a number of ways. The further one goes back with vehicle technology, the more rider/driver skill is required to get the most out of it. We're talking about 1960s-era vacuum-operated carburetion tech here and setup such that every throttle position is virtually the same as 1.6x that of stock. At the big end, you get completely unrestricted breathing, at the low end, airflow velocity is lower than stock.
anotherct said:
So I have done some testing, have #150, #160, #170 mains, #20, #22.5 and #25 pilots available and tried most combinations. Here is what I found. Main jet does not have as much of an impact as needle clip. With the clip in the leanest (or second leanest) position, engine revs out fine, however there is some stumble with throttle response at low-mid rpm, especially when yanking the throttle open. The larger pilot seems to help a bit, but it still comes down to the needle, if I want responsiveness at low end have to sacrifice high rpm.
Currently at #25 pilot, #160 main and second leanest position on clip.
anotherct said:
With the #160 main, needle needs to be in the leanest position and even then it doesn't rev out well, with the #150 main (current set-up), the richest I can go is the 2nd leanest position (2nd clip from top).
Between those last two posts, I'm confused; they're contradictory. I'm unsure what you meant by "doesn't rev-out well". The motor will either rev to redline, or go into rich misfire before it can reach peak power, at WOT, if it's overrich. Under that scenario, throttle response should be crisp, below the misfire threshold.
Let's go back to basics. At the very beginning, I baselined the VM22 as-delivered (#30 pilot, #100 main). This gave very easy starting and EFI-like low-speed throttle response. Unfortunately, the idle turned pig-rich once everything was up-to-temp and the main circuit was more than lean enough to burn a piston. It's always been a coin toss between #20 & #22.5 for the pilot jet. The pilot airbleed screw can cover ~one jet size. Where you're going to get into trouble, with an oversized pilot jet, is carbon buildup. Even if you're "lucky" enough to not get fouled plugs, heavy carbon deposits inside the combustion chamber can eventually cause problems...like hot-spot-induced pre-ignition.
When yours was setup, it ran best with #150 and the needle near its richest setting + high float level. That was unique, at the time...8 or 9 years ago, as best I can recall. Going by the rotted O-ring in the main jet well, I have to assume that it sat for a long time with bad fuel inside. Thus, something may have changed, in addition to pump gas, during the intervening years. Pump gas is a moving target. What's available depends upon location & time of year. If that O-ring isn't sealing completely, all bets are off. A substantial leak, at that junction, would be the same as running the biggest main available (and they go into the 400s if I remember correctly).
Assuming a proper O-ring seal, I'd try #145, maybe #140 + the highest jet needle position (clip in the lowest groove) working back, one position at a time, toward the lean side if it still won't rev-out...until you find the point at which it will. Get that sorted first, only then can the driveability be addressed.