KartDen

Looking for baseline jetting data and sanity checks on a TM R1. I know these motors are picky about the whole package, so I am trying to gather some real-world ranges before I spend half a season chasing symptoms that might just be compression or timing related. Timing and dome volume seem to move the target more than I expected. Advancing the ignition or going to a smaller chamber volume both raise cylinder pressure, and that usually wants a richer main to keep the mixture from going lean under load. Squish tightness plays into the same thing. A tighter pack can make the engine feel sharper but it also changes how the fuel charge behaves near TDC, so the jetting that was fine last month suddenly reads different. I am not locked into one combination yet and would rather start from known-good ballparks than guess. On the mixture-reading side I keep seeing dark, sooty chambers even when the piston crown itself does not look nearly as bad. Is that a common pattern with these, or does it usually point to too much oil in the premix versus an oversized main? I am running a fairly rich oil ratio on pump premium with a little booster when the air is hot, and I am never sure how much of the residue is just two-stroke reality versus actual over-jetting. Cold response and midrange feel okay on the pilot, but temperature swings still throw the low-speed circuit around. What mains and pilots are people using on R1s in moderate temps near sea level, and how far do you typically move the main when you change timing a couple of degrees or swap domes? Any reliable way to separate “rich from jetting” from “rich from oil” without leaning it straight into detonation? Also curious what tends to go wrong first when the setup is marginal, so I know what to watch on the plugs and piston. Ballpark numbers or just the logic you use would help a lot.