Topic: Hard to start

[duc750f1]

Hi, I picked up a '73 cb750k3 which had been sitting for a year or so. Anyway, cleaned out the carbs, reset points, timing, new plugs, checked valves etc. Problem is, its a #$%* to start. I've tried with full choke, no choke and everything in between. There's fuel flowing out of tap, tank is clean inside, fuel is fresh, the plugs arent wet after I've tried to start it. Fuel comes out of the carb bowls if I undo the drain screws. Got it started today by having full choke and throttle wide open. Once its been started, it starts first kick even after an hour of sitting. And it revs out fine and runs nice. But if I go to start it the next day, I go nuts. Could it be the float levels? I havent had the bike long, and everytime I try to start it, I'm using a different technique. What can I check, or is it my starting technique? thanks guys.

[KingCustomCycles.com]

Good morning,
First, a properly working SOHC should start almost instantly hot or cold, winter or summer.  Honda did good on these years.  My DOHC is a pain if it sits more than 2 days, anyway, I suspect you are lean on the idle circuit due to some obstruction in the jets or passages.  Does your choke close all the way? Have you got stock airbox and exhaust?  Are your rubber carb isolators in good condition and installed properly?  I am certain it is fuel related as you alluded to.  I hope this helps.

[duc750f1]

Choke close all the way, you mean when the lever is up, the choke should fully close the intake side of the carb? Also, have stock airbox, exhausts and new intake rubbers.

[KingCustomCycles.com]

You have narrowed it down my good man.  Take the carbs off (I know, ugh.) and verify float level and idle passage cleanliness. 

[duc750f1]

Oh well, there goes my day. Thanks for the info, will pull off carbs and recheck them. So when the choke is on, the height of it should be 0.5mm from the bottom of the carb intake? And is the float level that critical for starting the bike?

[KingCustomCycles.com]

Oh well, there goes my day. Thanks for the info, will pull off carbs and recheck them. So when the choke is on, the height of it should be 0.5mm from the bottom of the carb intake? And is the float level that critical for starting the bike?

Yes.