72' CB750 four

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72' CB750 four

rookie
Hello fellow CB enthusiasts! i just picked up my first project bike. So far i've cleaned the carbs, replaced the jets with one size bigger (from 15's to 18's i think?), fresh premium gas, changed the oil/filter, ordered a new seat, and cleaned the bike up a bit. It was running well, except for the occasional bog out were it sounds like its flooded or just not igniting all the fuel, then it would die. After changing the oil it ran good (except for the same occasional bog out problem), then i accidentally ran it with the choke open, the next day it barely ran. i replaced the plugs even though the old one's didn't look fowled. Still no improvement. Ended up killing the battery trying to start it. Borrowed a trickle charger from a friend, hooked it up this morning and started to smell burning. Then i realized the +/- wires coming out of the charger were melted and touching. My questions are: 1) would that ruin the battery? 2) What is happening/Why won't it run?
I really appreciate having a forum like this to learn from you all, thanks in advance!
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Re: 72' CB750 four

seestheday
I don't think cross the wires alone would have ruined your battery, but if it's old you might want to take it to an auto parts shop and get it load tested - most do it for free where I am, just know that it can take a while to do.

Do you have an inline fuel filter in place?  Crap from your tank might have gotten in and clogged your carbs somewhere.  When you say you cleaned the carbs, do you mean that you soaked them and put them back on, or meticulously cleaned every hole with a very thin wire.

Did the 72's have accelerator pumps on the carbs?
1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals

My wife's recipe website that I'm trying to help promote: Strawberries for supper. Yes, I am a lucky man.

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Re: 72' CB750 four

shinyribs
Administrator
Welcome to the forum!  A '72 model probably has the roundtop style carburetors.  That do not have accelerator pumps. Because of that there is an inherent bog. It shouldn't be enough to kill the engine every time, but they wont tolerate a quick flick to wot from idle.  Always a good idea to run an inline filter. There is a lot of things that could cause a bog. Mainly a dirty low speed jet.
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Re: 72' CB750 four

rookie
In reply to this post by rookie
Good call! I took the battery in to autozone and they charged it for free. I put some fresh gas in it and it fired right up. no fuel accelerator, probably just needs a more meticulous cleaning on the carbs. I have to keep in mind this baby is 40 years young. Thanks again guys!
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Re: 72' CB750 four

rookie
In reply to this post by shinyribs
I will be installing an inline filter and give the jets a thorough cleaning. New seat came yesterday, will post an updated picture soon. Thanks again gentlemen.
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Re: 72' CB750 four

shinyribs
Administrator
We're all about some pictures!