Disconnect the cable from the carb, then run the engine. If it goes back to a normal idle after a rev, it’s a cable problem. If it still revs high, it’s carb / linkage problem
With the EMPI/Redline basic linkage there is a kink in the throttle cable in normal operation there . And the spindle bearings are tormented by larger than necessary side forces because the cable pulls sideways .. I ended up having to drill out the primary throttle spindle "bearings" in the carb. body and insert some bushings, and carefully file down a "step" in the side of the throttle bore cut by the throttle plate, where the spindle had worked its way sideways.. I also had grief with the choke assembly throttle opening wire wearing and then jamming itself in strange positions. One of the reasons for my linkage upgrade, to something like the proper manifold and linkage also sold for the progressive. My version has a strong spring pulling on the throttle cable, but not pulling across the throttle spindle. ..
When your glamorous assistant presses the pedal (engine off) and you are watching the carb you see it opening and closing smoothly and fully? Or is the cable getting snagged as it comes through into the engine bay holding the throttle open? There should be minimal slack in the cable; just sufficient to allow the throttle to close against the stop.
visual inspection Spray bottle of water - will change revs when sprayed on leak Hose to ear - listen for leak Check spark plugs for colour The brake booster circuit is a prime suspect. The elbows off the manifolds for twin carbs is a typical culprit. Not sure how this works with a modification to the single carb Other culprits are - Manifold boots to end castings. Manifold gaskets
I'm at a loss, out of my depth now. In the morning, when cold it's fine. Then when warm it revs like hell. Disconnected throttle and started it, same, revs like hell.?? I've tried looking for vacuum leaks but I just don't know really what I'm doing, looking at. I don't wNt to take it to garage, I havent yet... Any other tips, help, suggestions.
Can you post a video of you running the engine with the cable disconnected, showing the throttle mechanism etc? That might give us a clue if it’s the mech, or an air leak.
Here's a bid, this is running a bit slower, mostly its faster. //cloud.tapatalk.com/s/61e0180315dc0/VID_20220113_131531.mp4 Sent from my MAR-LX1A using Tapatalk
Cant really tell a lot from that vid. Can you do it again, camera in your left hand, pointing at the linkage, while you rev it up and let it snap back with your other hand?
