mkaser81cb750c
CB750 Member
1981 CB750C DOHC
The bike revs fine in neutral but on the road it runs fine until you get to 5k RPM and it dies. I have to get off the throttle and then it is okay. Does this in every gear except neutral. Also once it is warm the bike overall runs terrible at all rpm (maybe because the power is even lower at that point?). Also battery never struggles or dies always starts up first try. Headlight gets brighter and dimmer depending on rpm... I assume this is normal? When warm it only goes about 25mph power constantly kicking in and out but mostly out. When warm barely makes it up a hill but picks back up going down a hill.
I believe it must be electrical since the bike acts fine in neutral (i'm assuming it draws much more power in gear and can't keep up?).
Carbs have been ultrasonically cleaned and synced, timing set, fuel flows freely from tank to carbs, SOS taken off, advance timing checked on 2 and 3 (figured 1 and 4 would be okay if 2 and 3 were, couldn't check 1 and 4 because their plugs were already fowled and I couldn't get a reading on the light), spark advancer is in great condition and works, 4 to 1 exhaust, stock air box, no vacuum leaks, new regulator/rectifier, air/fuel screw 3 turns out, tried dr8, dr7 and dr8 iridium ngk's, stock jetting (108, 68).
Whats confusing is trying to determine electrical or fuel issue here.
I'm thinking new point plate? Also when I open the cover for the point plate everything is covered in like a frothy oil... I guess this is normal and will not affect the spark? Help!
The bike revs fine in neutral but on the road it runs fine until you get to 5k RPM and it dies. I have to get off the throttle and then it is okay. Does this in every gear except neutral. Also once it is warm the bike overall runs terrible at all rpm (maybe because the power is even lower at that point?). Also battery never struggles or dies always starts up first try. Headlight gets brighter and dimmer depending on rpm... I assume this is normal? When warm it only goes about 25mph power constantly kicking in and out but mostly out. When warm barely makes it up a hill but picks back up going down a hill.
I believe it must be electrical since the bike acts fine in neutral (i'm assuming it draws much more power in gear and can't keep up?).
Carbs have been ultrasonically cleaned and synced, timing set, fuel flows freely from tank to carbs, SOS taken off, advance timing checked on 2 and 3 (figured 1 and 4 would be okay if 2 and 3 were, couldn't check 1 and 4 because their plugs were already fowled and I couldn't get a reading on the light), spark advancer is in great condition and works, 4 to 1 exhaust, stock air box, no vacuum leaks, new regulator/rectifier, air/fuel screw 3 turns out, tried dr8, dr7 and dr8 iridium ngk's, stock jetting (108, 68).
Whats confusing is trying to determine electrical or fuel issue here.
I'm thinking new point plate? Also when I open the cover for the point plate everything is covered in like a frothy oil... I guess this is normal and will not affect the spark? Help!