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Coil replacement
- Thread starter gph118
- Start date
kirky
CB750 Addict
one of my coils split like that and the bike was fine , once i had seen the split i replaced both coils but the bike starts and runs just the same.
Thanks for the information. Your experience deepens the mystery. This bike won't start cold. Good compression, sync'd carbs, new plugs, fresh gas, new petcock. If I goose it with gas or starting fluid, fires right up and will start when hot and runs great.
Your experience puts me back to thinking carburation (totally rebuilt, new everything).
Thanks again,
also now thinking cheap coils, just because of the damage.
Your experience puts me back to thinking carburation (totally rebuilt, new everything).
Thanks again,
also now thinking cheap coils, just because of the damage.
kirky
CB750 Addict
you have the same symptoms as mine suffers from . with the old split coil she didn't like cold starting and with the new coils she still didn't like cold starting and with a mates spare original old coils if shes been stood for a week. i have also done carbs etc. i did notice the old battery was dying and put a new one on and she fired up no problem. i thought i had cured the bad starting when shes left to stand , but i hadn't , she loves it when the suns out she fires up straight away even if left. she also fires up well when hot , but the cold starting after shes been stood has me playing with the choke until she fires on a couple and then brings in the other two, it is frustrating at times with all the work and expense on new leads , plugs and carbs set up.
bluecoolpa
CB750 New member
My immediate thought is that when cold you're not drawing fuel into the engine, because it might be possible have an intake air leak. When the engine cools down gets cold if the intake rubber tubes isn't seated real good (the rubber tubes on the engine side of the carbs), there could be an air leak the prevents the vacuum getting created by the engine at starting time from drawing fuel into the cylinders. When it gets warm the aluminum expands from heat and seals the rubber intake tubes, so you don't see it then. just a thought. Mine starts every time on the first kick from cold, when not using the electric start, if I prime the motor with ignition off, by slowing rotating the engine 2 to 3 times with the kick starter.
And 1 other thing to try, is to loosen the gas cap (break the seal), in case the cap vent is starting to fail when cold and holding a vacuum on the fuel in the tank from preventing gravity to work feed fuel into the carbs.
And 1 other thing to try, is to loosen the gas cap (break the seal), in case the cap vent is starting to fail when cold and holding a vacuum on the fuel in the tank from preventing gravity to work feed fuel into the carbs.
Last edited:
No kickstarts on my DOHC.
plantguy
CB750 Enthusiast
Should put a sticky on my post in this thread. These bikes have weak ignition systems what I did completely cured the isues I was having.
https://www.cb750.com/threads/cdi-ignition-module.9296/
