Re: Motor will not run wide open
I would tend to agree that it is running lean, but If at WOT, you are getting 4000 rpm, and the motor is not surgeing up and down, then I would rule out the fuel pump, and lines for now. The lines and pump deliver fuel to the bowl. As the bowl fills, the needle seals the chamber, and no more fuel enters. At fast speeds, an equilibrium is established where the float and needle may look like they are constantly open. If you are not getting enough fuel to the bowl, the engine starts to starve, drop in speed, and suck less fuel, the pump is still pumping, fills the bowl to the proper level, then engine speed picks back up. In sever cases then engine may die before this happens, and you need to pump the primer bulb. More than likely, you have a blockage in one of the high speed jets. Most mixture or pilot screws control the mixture for low speed only, so I doubt that it could be that. Find out if the jets were replaced, and if so, if the correct (same as previous) were installed. It may also be possible that the linkage(s) between the carbs (if multiple) are not synced to each other (less likely) or not synced to the timing (more likely) meaning that the throttle opens up much more than it should for the given timing position, creating a super retarded situation. This can be visually inspected without running the engine.<br /><br />If all the above is fine then continue moving up the fuel system to find the problem. <br /><br />My $.02<br />Good luck.<br /><br />P.S., in any event, don't run extensively until you solve this problem.
