Nc30 poor run off idle, foul 1x plug

[Icemaestro]

Nc30 just had a new set of reconditioned carbs put in my a mechanic friend as old ones were leaking fuel from every orifice.

Riding now is fine above about 2.5k and any throttle, however Reving from 1/1.5k and it bogs down, worse the more throttle you give it. It could do with a new set of plugs but the right rear is the problem one with it looking like this:[IMG]http://img.tapatalk.com/d/14/02/05/
e3u4ypet.jpg[/IMG]

And doesn't seem to be firing at idle (exhaust is near cold until a little bit of throttle then starts to heat up). Looking at the plug would I be right in saying the idle jet might be blocked (despite ultrasonic clean, can happen I hear) +/- idle mixture is rich? I never checked the jets or the idle mixture before putting them back on the bike...or is there anything else you reckon I should check/do?

I tried to clean the plug a bit, this helped the idle which was previously all over the place, but it still searches a little between 1200 and 1600 every couple of seconds

[Icemaestro]

Pic attached again, and before I go playing with things - is this a stock exhaust system cut and a Yamamoto end can put on?

[arsey30]

The plug gap looks big, but may be an optical illusion as the plug body is small.

Does it run OK on choke? [If so pilot circuit suspect]

Set all pilot screws to standard setting then check the carb balance.
New plugs the next bet.

[CMSMJ1]

and it is a Yamamoto half system

[royster81]

Read the last post on this topic.

viewtopic.php?f=62&p=333153#p333153

[Icemaestro]

not sure about if it runs better on choke when it's warm, I know these bikes love to foul plugs at a mention of choke so hadn't tried.

With the Yamamoto half would you still recommend standard pilot screw setting and jetting (I didn't look at the jets before I put it in, I assume standard, stock air box and filter)

Thanks for the link - my search didn't show that up. Coils I would think be okay, we don't have salt on our roads here, and it's been garaged since being in nz, they looked all right when I had a quick look. So I think I'll get a new set of plugs, clean the idle jet and if someone can suggest re the jet sizes and screw setting and I'll do it all al once :-)

I wondered about he plug gap - pulled the left one to see if it was different but didn't look like a bigger gap to me (but left rear plug looked better)

[arsey30]

Run it on choke when cold to see if it runs/picks up on all 4.

Set pilot screws to 2 turns out, 35 jet size.
Plugs 0.6 to 0.7mm

If only 1 cylinder is faulty, then it narrows it down to carb/inlet , plug, lead/connexion, cap [or cylinder compression, but not common, check valve clearances if all else fails ]

[Icemaestro]

Right, have replaced the rear two plugs (given that one looked rubbish) this has improved it somewhat, now it idles well when warm, and doesn't really hang at 4/3k rpm, just slow to return to idlehttp://youtu.be/G86ozeoRCZ8

Using choke possibly makes it drop even slower?

Haven't had the carbs off to check jets etc yet, given the half system (id thought it was stock pipes with exhaust) it might need playing with yeah?

[Cammo]

Hanging revs is usually caused by incorrect pilot screw settings.

[Icemaestro]

Excellent that's what I was hoping!:-) hadn't ever heard of needing to change idle jets, I'll whip them off in the next week and play with the screw setting as above, cheers!:-)