Topic: Do all bikes NEED choke?

[Scott S]

 '71 CB500

 Got the bike back together and running pretty well. I'm sure there's some minor tuning and nit-picking left to do, but...
  I have noticed that the bike starts and warms up best WITHOUT using the choke. It will idle a little low at first, but if I give much of any choke at all, it just stalls. It won't even start with the choke full on.
  It's a tad rich at first. I can see some rich smoke from the exhaust pipe when I rev it up and clear it out. But once it's warmed up and on the way, it no longer loads up or smokes.
 Rebuilt carbs, floats set, idle mixture screws 1.5 turns out (more that the manual says, but I was trying to lean it out some), MAC 4-1 exhaust, stock points, etc.

 I guess I really don't have a problem with it and it's pretty warm here in SC right now. Just curious if all bikes NEED to use the choke to start and warm up properly?

[TwoTired]

Choke is used to compensate for poor fuel atomization when engine is cold.  Cold is a relative term.
Morning starts usually need choke, whose depth and duration varies with the temp extreme.  In summer,  the second start of the day can often be made with out choke.  I notice the 77 and later models always seem to need choke upon start up.

The 550s have a smaller pilot jets (#38 vs. #40) than the CB500.  Makes me wonder if Honda made a correction along with the model change.

Is your air filter clean as new?  Have you tried a UNI NU-4055?  The later may alter the carb throat pressure "just enough".

Cheers,

[Scott S]

 I am, in fact, running a brand new Uni filter, NU-4055. Tried it again this afternoon. Just doesn't like choke.
 Rode it around for 15-20 minutes, including some low speed stuff through the surrounding neighborhoods and a 7K+ blast through all 5 gears. Got it home and had to adjust the idle slightly (too high), but otherwise OK. Some low speed stumbling, which I guess is to be expected at 2K or less in 2nd gear. Very slight hesitation (like it's rich ) in first gear when leaving from a stop or a slow roll, but if I keep the revs up a bit, it's fine and pulls hard.
 Very slightly hesitant to re-start when warm. Hit the button twice and she didn't fire right up. Kicked it once and she did.

 I know there's some slop in the 2/3 points and the 1/4 are at max advance. I have plans for a points elimination system, but I feel like at least SOME of the performance issues (if you can call them that) are related to the points/timing.

[dave500]

if you have any doubts with your ignition sort them out first,going no points or honda man is a great idea,good plug caps,mine will start with no choke,its winter here and about 15 c outside so not really what you might get,itll start a little easier with the choke but as soon as its fired off goes the choke,it wont idle till warmed i use the throttle lock whilst putting on my jacket and helmet,,after a high speed fang itll idle higher for a minute then drops again so i dont adjust it back.

[Scott S]

 Yes, that was my plan: Get the timing sorted first (all the rest of the ignition system is new: plugs, wires, caps, coils). The points were adjusted and timing set, but it's just worn out.
  Sounds like what I'm experiencing is somewhat normal and may improve with the ignition fixes. Never thought about using the throttle lock. I just hold the throttle by hand for a few seconds until it'll idle close to 1,000 rpm, then off I go.

 This is only my second day of shakedown runs. Maybe 15 miles on the bike since pulling it out of a barn where it sat for almost 30 years!

[dave500]

yeah the old stay close to home shake downs,,it sounds like it runs ok,look at leaks etc,get that igniton sorted then youll be sure its something else if something else gets funky,you can buy complete ignition plates with condensors and points,,if you stick with your old plate replace all the little adjustment and hold down screws with stainless allen heads and washers,,just dont over tighten them,nothing worse than fiddling with a fiddly screw that wont turn properly because its chewed out in the slots.