dlicata
Member
My 450 readily starts but has a high idle at around 3000 rpm. Revving it causes the engine to rev way high, and not come back down, hangs around 5000-6000 rpms. I need help figuring this out, I've tried everything and can't get the dang thing to run right.
I've been working on this 71 450 for a few years now and had gotten to a finishing point, but have had carb trouble consistently, and the engine eventually stopped firing on the right side. After my limited diagnostic knowledge, I determined the only thing left for the no spark issue was a bad PAMCO electronic ignition. I replaced that with the common motor collective Shockwave system and the bike readily started with spark on both sides. The engine should be perfectly timed, and the valves should be adjusted correctly at about .003 of clearance.
Things I know:
-Carbs totally disassembled and cleaned with ultrasonic
-Felt gaskets in throttle shafts replaced and upgraded
-Throttle plates set with guitar string method, both the same
-New intake manifolds, rtv'ed to the head rather than paper gaskets
-No air leaks that I can tell
-Properly timed and adjusted engine (starts effortlessly)
-Engine slows down/struggles if choke is on
-Mixture screws set to 1.5 turns out
-Throttle cables slacked, not holding the plates open
-Cable not caught on anything
-Vintage hooker 2-into-1 exhaust
-Pod filters
-Mechanical advancer springs replaced with century spring B3-5, extremely similar to stock, but a tad stiffer making for a slightly later advance
If anyone has ideas, please let me know. I can provide any additional information about the bike that's needed, as well as pictures.
Thanks!
I've been working on this 71 450 for a few years now and had gotten to a finishing point, but have had carb trouble consistently, and the engine eventually stopped firing on the right side. After my limited diagnostic knowledge, I determined the only thing left for the no spark issue was a bad PAMCO electronic ignition. I replaced that with the common motor collective Shockwave system and the bike readily started with spark on both sides. The engine should be perfectly timed, and the valves should be adjusted correctly at about .003 of clearance.
Things I know:
-Carbs totally disassembled and cleaned with ultrasonic
-Felt gaskets in throttle shafts replaced and upgraded
-Throttle plates set with guitar string method, both the same
-New intake manifolds, rtv'ed to the head rather than paper gaskets
-No air leaks that I can tell
-Properly timed and adjusted engine (starts effortlessly)
-Engine slows down/struggles if choke is on
-Mixture screws set to 1.5 turns out
-Throttle cables slacked, not holding the plates open
-Cable not caught on anything
-Vintage hooker 2-into-1 exhaust
-Pod filters
-Mechanical advancer springs replaced with century spring B3-5, extremely similar to stock, but a tad stiffer making for a slightly later advance
If anyone has ideas, please let me know. I can provide any additional information about the bike that's needed, as well as pictures.
Thanks!