choke idle speed

[wikreigs]

I got my 81 running good but I do have a question. When I start it cold with choke either half out or all the way out it idles way up to 3500-4000 rpm. Once it warms up and I can push the choke in it idles down to about 1200 rpms and runs great. Is there some way to adjust this? It sounds too high to me.

 

[JARichmond]

I managed to adjust it using my idle screw down underneath the carb. It was a trial and error experiment, but I found the sweet spot within a few minutes.

 

[OliverB]

I guess you could play around with your idle speed screw but that screw is really just to adjust warm engine idle. Yes, the rpms will go up kinda high on full choke but should be a little lower on half choke. A lot of folks aren't use to engines like ours that rev up pretty high on choke but that is pretty normal. I don't remember the exact rpm for mine on full choke but it is a little above 3k.

 

[bcware]

High rpms on choke is completely normal; don't adjust your idle for it.

 

[bentwrench]

Yeah, that sounds normal to me.

 

[domains]

set when motor is warm.

 

[xs400neophite]

I think my bike is slightly above 2000k at full choke and slightly below 2000k at half in choke. I will look next time. Nowhere near 3000k-4000k though.

She is cold hearted and takes her a while to heat up. If I dont let her warm up she is slugo at initial throttle.

 

[HoughMade]

if the bike idles at about 1200rpm when warm without any choke, sounds like it is properly adjusted. The only thing I would say is that the idle mixture may be a bit lean, but if it is running fine and there is no hesitation upon acceleration, I'd leave it as-is.

My bike will idle closer to 2000rpm on full choke and then as the rpm increases to around 3000rpm, that's the sign to cut it to half choke, and when it rises again, no choke.

 

[FUBAR]

does jetting have an effect on how the bike will idle with the chokes on vs. off?

 

[HoughMade]

Yes,but only the low-speed jet and I am really referring to the idle mixture screws, and not the jet. Generally, leaner will run faster than richer, at least until you get so lean it can't run or so rich it can't run.

 

[FUBAR]

so if the bike idles well at full choke and 1/2 choke, it should idle well with no choke as long as things are clean?

 

[HoughMade]

I would think so.

 

[bcware]

I wouldn't open that can of worms. That's just my advice! Tuning can be a pain and I certainly wouldn't do it for choke. When my bike surges up with choke, I go to half choke; when that starts to surge I turn choke off and ride away. I have 3 bikes that all behave similarly and none have any issues.

If it ain't broke...

 

[xs400neophite]

Ok when my bike starts to heat up in full choke, she lets me know she is ready for half choke because the rpms drop she starts to run crappy and stalls. Is that normal?
When that happens, I push the choke in to half choke and she keeps on warming up at high-ish revs. After a while I push the choke all the way in and hit the throttle.If there is no sluggish response, she is ready to rock.If not, I let her keep on warming up. Is this normal or is there something wrong with this routine?

 

[bcware]

Normally revs will climb on choke over time, not drop. If it's working for you I wouldn't try to fix it. Spend your time out riding instead

 

[vectra]

i dont know if i done something wrong or not when i start the old girl
i can have choke open full and she starts and revs around 5000
put choke to 1/2 and still revs at 5000
no choke and still revs at 5000
but drops some when she warms up
thinking my idle mix screws need changed they are 3 turns out now
what way do i need to go in out out more

 

[JARichmond]

I'd say have a look at your jetting to make sure it's set up for your intake setup. Also, have a quick look around for any leaks in the intake piping. Too much air and it will run lean. If it's fairly constant, it means that your air volume going into the engine is fairly constant, so I would have a look at your intake boots and make sure there are no prominent cracks. You can also see if the idle screw will make and changes (with the choke out, of course). 3 turns out on idle screws is what I run and I have a decent mixture. No popping, no uneasy revving, but a little rich (which is better than a little lean). Going clockwise will lean your mixture out.
Best of luck!

 

[vectra]

all jets are stock with the stock air box setup
going to spray the intake boots with starter fluid when running see if there is any diferance in the revs
by the eye they look like no cracks but you never know

update:-
yep revs went up even more when i sprayed the boots with easy start
so dose anyone think spraying the boots with flex seal will work or just pay for new boots ????

 

[bcware]

A seal of some kind may hold up for a while, but for reliability's sake I would replace the boots. Under the right (or wrong) conditions you could end up stranded because the goo fails. Spend the $30 or $40 for the peace of mind.

 

[wikreigs]

I had good luck with Seal-All. Mine are holding up after a year.