Please help not sure what else to do 1975 Honda CB750k

[fastcat1977]

The Bike ran Great one evening, I parked it and it started up and ran very bad then got where it wouldn't run at all . It has hardly no noticeable spark , we have brand new Honda coils installed hoping that would fix it along with new points and condenser from company "4 into 1". I have 12.6 volts at the battery and 11.5 at the black and white primary wire that feeds both coils , soon as I hit the start button the voltage on black and white primary coil wire falls to 8 -10 volts . I have been through every connection, went over everything and not sure what else to check . Tried also a brand new super start battery with 220 CCA and still same thing . Can a failing starter cause an excessive volt drop at the primary coil wire and cause the coils "Not" to trigger , I've literally tried everything, it's so crazy cause bike was literally parked then did this , nobody was near it the overnight that it sat. Please help give me something I can check , but was thinking the starter was caused too much voltage drop , if not that can the voltage regulator or rectifier cause this , didn't think those had anything to do with the ignition side but just asking..? Also tried putting the original condensers back on and still nothing, if I take the boot off the HT leads I'll get a decent spark , but all NGk boots tested just a touch under 5k ohms , only the no 4 cylinder boot tested 5.2 k ohms , anyone please help , I've had this bike just sitting in my way for 2 months now trying to get it running, it's the craziest thing . Please help me , ears are open .

 

[bossboy302]

I have a '75 and in January was having the exact same symptoms. After a ton of testing everything it turned out the battery was bad. Even though it displayed 12.6v, it would not hold it when cranking. One new battery later all is good.

 

[brettp]

Yup, need to load test batteries. Not just bench test them.

 

[fastcat1977]

I have a '75 and in January was having the exact same symptoms. After a ton of testing everything it turned out the battery was bad. Even though it displayed 12.6v, it would not hold it when cranking. One new battery later all is good.

I bought a brand new battery and still did same thing , I'm thinking starter could be robbing my voltage from coil keeping them from sparking

 

[drgnrdr750]

Have you tested the battery draw when starting? Check the starter for battery drain, could be bad windings.Also wondering will it start with the kicker?

 

[fastcat1977]

I tried kicking it but couldn't get it to really fire and get a good kick in but we have a new starter an solenoid to install in the next few days, I have my fingers crossed

 

[72 Blue]

The Bike ran Great one evening, I parked it and it started up and ran very bad then got where it wouldn't run at all . It has hardly no noticeable spark , we have brand new Honda coils installed hoping that would fix it along with new points and condenser from company "4 into 1". I have 12.6 volts at the battery and 11.5 at the black and white primary wire that feeds both coils , soon as I hit the start button the voltage on black and white primary coil wire falls to 8 -10 volts . I have been through every connection, went over everything and not sure what else to check . Tried also a brand new super start battery with 220 CCA and still same thing . Can a failing starter cause an excessive volt drop at the primary coil wire and cause the coils "Not" to trigger , I've literally tried everything, it's so crazy cause bike was literally parked then did this , nobody was near it the overnight that it sat. Please help give me something I can check , but was thinking the starter was caused too much voltage drop , if not that can the voltage regulator or rectifier cause this , didn't think those had anything to do with the ignition side but just asking..? Also tried putting the original condensers back on and still nothing, if I take the boot off the HT leads I'll get a decent spark , but all NGk boots tested just a touch under 5k ohms , only the no 4 cylinder boot tested 5.2 k ohms , anyone please help , I've had this bike just sitting in my way for 2 months now trying to get it running, it's the craziest thing . Please help me , ears are open .

Hi have the points been cleaned , I use 1000 grit sand paper a couple of pulls then clean with a new business card, check the gaps .My 72 oxidizes points every winter, so must be cleaned in spring, stored in side a shed, Try draining float bowls to see if you have water in them and fuel. good luck

 

[fastcat1977]

It was all running fine till it sat over night , all point and everything are brand new

 

[mitchi]

Spray a little bit of starter fluid in the carbs.

If it tries to fire, then you have a fuel issue

 

[72 Blue]

It was all running fine till it sat over night , all point and everything are brand new

its gonna be fuel or ground issue , If it was damp over night then i would look at ground issue, check your bowls for water, and the tank collector.
Water may have got down to the bowls from the lean on the side stand . I hope you find out the issue . please let us know what it was

 

[brettp]

Have you cleaned the starter switch and kill switch?

 

[fastcat1977]

Have you cleaned the starter switch and kill switch?

Yes I did all that , like I mentioned I have voltage at the coils but when I hit the start button it drops too low to trigger the coils

 

[brettp]

Does the starter turn over?