Topic: 1976 cb750F idle/choke problems.

[beks82]

Hey guys, for the life of me I can't seem to get the bike to idle properly. What's really strange is that with choke off (completely down) the bike fires up but idles roughly around 6000rpm.  When choke was engaged the bike would not start at all.  I assumed that the bike was running way too rich, so with the choke on it was dumping fuel and smothering the engine.  So I turned the choke off, and set the idle to around 2000rpm.  Even with choke off and idle set to 2000, the bike stumbles and dies after about 30seconds, if choke is applied, the same thing bike stumbles and dies.  I looked in the manual and I saw that the carburetor has a screw called the "throttle stop" but I couldn't find an idle screw.  I don't know why but my '76 F has the throttle stop screw in front of the carb not on the right hand side.  I'm thinking that this is the same as an idle screw, correct?  What should be my next course of action?  I don't think it's a carb related problem as it starts right up when the starter is engaged, the only problem is it won't idle at low rpms without dying  .  I did read that the slow jets need to be thoroughly cleaned, I used fishing line to clean out every hole, it worked well if you give the jets a thorough flossing with the line, so it leads me to believe that it's not an slow jet issue.  it's strange that the bike almost behaves like the choke is reversed....any help or suggestions would be much appreciated.

[flybox1]

tell us more about the steps you took to clean/service your carbs.

[beks82]

the carbs were taken off the bike, each carb was torn down and each jet removed

[flybox1]

that dont help much...its all in the details, man!  
did you..
set your float heights, and then verify fuel level?
inspect and clean passageways and emulisifer tubes?
bench synch your slides?
have you been able to attempt a vacuum sync??
what is your jetting? mains/pilots
what is your A/F mixture screw setting?

do you have pods or airbox?
if you have an airbox, is your filter new/clean?
what kind of exhaust sytem do you have.

what other maintenance/mods have you done to your bike to get it to run better?

[kenolds]

Just because the jets are clear doesn't mean the engine is getting fuel.  The fuel level in the float bowls must be correct and the internal passages throught the carb body must be clear.  Did you try squirting carb cleaner and/or compressed air through all of the carb passages?  Have you checked your actual fuel level - not just the float level?  I would suspect that it is in fact a carb issue..But I am no expert.

_Kenolds in Alpharetta

[beks82]

hey sorry, yeah i had posted regarding what i had done with the carbs earlier.  so to put into further detail, bench syncing was done using the drill bit method, float levels were tuned and checked.  vacuum sync was not performed, but i figured if i could get it to idle rough then i could always get it done afterwards.  air screws were turned out 1.5 turns from seated position and everything was cleaned.  hmmm if i missed something let me know.  but the main and slow and emulsifier were pulled and cleaned, they were actually in pretty good condition prior to cleaning as it was....hope that gives more info, thanks

[beks82]

hey ken that was a great tip about checking the fuel level in the floats.  turns out my reserve on my petcock is crap dribbles fuel.  turned it to on and ran fine.  which reminds me, i remember you saying you had the rotor and starter clutch out, was it a pain to remove?  I hear that there's a tool to remove the rotor, or was it not necessary?