Re: Carb jets for 150 Yamaha
Stock would be 124's. To my knowledge that is the smallest available from Yamaha. While that may be a little on the rich side, you would have to solder them up and redrill to get leaner as theory would suggest for altitude adjustment.<br /> An increase in one degree in timing would be equal to a jet size decrease of about 4 mms. This brings on the problem of detonation if the fuel is not up to snuff.<br /> Unless you are having extreme richness as shown by spark plug and piston readings, best you not consider it. You will not regain all HP lost due to poorer air quality through rejetting and likely destroy an engine.<br /> Air quality is not all altitude. We use guages at the races which measure barometric pressure. humidity and temperature to give us an estimate of what jetting or ECU setting to use. This may change drastically during the day.
