Carb needle position idle problems....

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borntofli

Member
Jul 27, 2012
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Ht 66, nt carb......

I have a 66 jet and have the needle on 2nd from top... Bike idles perfect and runs well w/ some 4 stroking up to 3/4 throttle....

I move the clip to the top and it runs smooth thru the whole throttle range except it idles very high....Idle adjustment has no effect..... No air leaks...

Plug chop on both positions gives same color...

Is the top clip position just too lean while idling but ok for all other rpms????

Maybe I need a 65 jet and then the second position would be right.....
 
biknut

biknut

Well-Known Member
Sep 28, 2010
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Check to make sure your throttle cable still has some slop after you adjust the idle screw. It could be the cable holding the slide up a little. If that's not it then a 65 would be good to try. If that doesn't help and you're sure there's no air leaks, I would recommend a Speed carb. I've found them to have a much better idle than a NT, and they're not nearly as touchy about 4 stroking. Jetting is about the same, but where the NT seems to like the next to top needle clip position, the Speed seems to like the top position better.
 
crassius

crassius

Well-Known Member
Sep 30, 2012
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Idle adjustment has no effect
Click to expand...
if the slide is going all the way to the bottom, the motor has to stop

your cable/slide is stuck or too short, or there is an air leak
 
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borntofli

Member
Jul 27, 2012
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I thouight about the cable problem, and took it apart and tried several times but idle still stayed high... as soon as i moved to second needle position it idles great......

I will get a speed carb (so cheap) and give it a try......

Im sure i need a new cable too..... I have about 2000 miles on this setup...

You guys are great w/ your answers..... I'd be lost without this forum.........
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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I cuncur with the other guys... if the carb slider can go 'down' far enough, the engine will slow down until it shuts off... period.
There has to be some adjustment left somewhere in the cable to be able to lower the slider a little more. :/

Let us know how it goes. :)
 
crassius

crassius

Well-Known Member
Sep 30, 2012
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you don't need to take the carb apart, just take off the air cleaner & look - or, take out the idle screw and listen for the slide to hit bottom
 
maniac57

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
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There's a thread in here somewhere about a mod to make the idle better on these carbs. Mods? A little help?
 
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borntofli

Member
Jul 27, 2012
306
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tx
It turns out hte cap on top of the carb, the the adjustment screw wa\s sheared offand the cable wobbled around....

funny thing is.... Needle on second position It idles fine... move the clip to top position and idle is racing... no other changes.... doesnt make sense to me...... shouldnt have any effect......some times you just have to say hhmmmmmmm.........
 
maniac57

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
borntofli said:
It turns out hte cap on top of the carb, the the adjustment screw wa\s sheared offand the cable wobbled around....

funny thing is.... Needle on second position It idles fine... move the clip to top position and idle is racing... no other changes.... doesnt make sense to me...... shouldnt have any effect......some times you just have to say hhmmmmmmm.........
Click to expand...
I sacrifice a chicken to the two-stroke Gods every chinese winter solstice....
*mumbles and makes gestures*
It never hurts to be careful!
 
crassius

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
usually, if it idles faster at one setting, then it likes the mixture better at that setting

check how it runs at other throttle positions across the range
 
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