New nc30 fouling plugs (again!)

Icemaestro · Post by **Icemaestro** » Fri Feb 20, 2015 4:07 am

Hi,

Another bike this time, another NC30, sitting for 14 years. have replaced carb rubbers with ones from rick o, cleaned teh carbs out 3x with carb cleaner, fuse wire and a toothbrush. Bike starts and idles, but rear two cylinders don't seem to be firing much, and is very hard to get started from cold? pipes are warm to hot, but not scalding, and didn't change when I kept it at 4000rpm for about a minute? it hasn't been out on the road yet as it is just finalising the registration process again (failed on needing a footpeg replaced due to previous scraping!!!!).

Took the plugs out (plug chop at 4000rpm, hit kill switch) (which were new and replaced about a month ago when I went through replacing everything, and this is what it looked like compared to another new one...second pic is when I wiped what I could off with a rag...

It looks like carbon fouling to me, would someone on here agree? which therefore means running too rich, is that right? given that, what should I do?

settings are as per stock exhaust and no changes to anything except 115 front 118 rear, 2 turns out on the idle screws as per cammo's guide.

Pulling spark plug caps off each of the rear two cylinders (one at a time) doesn't change the exhaust note. front one causes it to die. I have good spark....

Does it just need another clean? or just a good ride? or are my settings wrong?

Post by **lukemillar** » Fri Feb 20, 2015 4:53 am

What is the air filter like? Are the float heights all good and float valves not sticking etc?

Icemaestro · Post by **Icemaestro** » Fri Feb 20, 2015 6:27 am

Good point on the air filter, it looked okay to me I thought, but haven't replaced. I checked and set the float heights :-) as per the guide..float valves are good now (prev weren't)..how would they affect my plugs?

Could it just be cause it hasn't had a good run on the road at speed, with air etc?

Icemaestro · Post by **Icemaestro** » Fri Feb 20, 2015 6:27 am

And then maybe idle jets? It has been a couple months since I last cleaned them and did the plugs, at that point it was running on 4 with good acceleration...(but didn't check plugs)

Post by **hunter** » Fri Feb 20, 2015 9:44 am

I would get the carbs ultrsonically cleaned,It sounds like your pilot circuits are blocked, 14 years idle is a long time.
Not a lot of point doing plug chop at 4000 rpm,You need to get it on the road in a high gear at around 12000rpm kill engine then check.

Post by **Neosophist** » Fri Feb 20, 2015 3:11 pm

if the pipes are not burning after a minute at 5000rpm then something is up.
/
is it firitng on those cylinders? the rears share the same set of coils. tried swapping front and rear coils?

start bike with full choke and no throttle until its running and after 20 seconds or so back chock in and warm up

That kind of revs is way off the idle / pilot circuit which is the most liekly to block up, you are into needle / main jet territory there so you should get four equally roasting pipes, even if the carbs are way off balance and all the idle circuits are blocked up.

Icemaestro · Post by **Icemaestro** » Fri Feb 20, 2015 4:53 pm

Exactly neo, hence why I thought to raise the revs up that high, to make sure main jet part working fine and tell me 'hey you need to clean the idle circuit again'

Can anyone tell me what the carbon on te plugs mean? Google says too lean or too cold - is that reflective of not getting up to operating temp enough maybe?

Neo - I don't think it is firing on those cylinders due to the lack on engine note change when I pull a rear plug out. I haven't tried swapping the coils, but I do have a nice big spark? Which again makes me think I've probably just got crap in the carbs...is there anything that could block or be set wrong that would limit main jet/needle running too?

Post by **Neosophist** » Mon Feb 23, 2015 11:08 am

Icemaestro wrote:Exactly neo, hence why I thought to raise the revs up that high, to make sure main jet part working fine and tell me 'hey you need to clean the idle circuit again'

Can anyone tell me what the carbon on te plugs mean? Google says too lean or too cold - is that reflective of not getting up to operating temp enough maybe?
Neo - I don't think it is firing on those cylinders due to the lack on engine note change when I pull a rear plug out. I haven't tried swapping the coils, but I do have a nice big spark? Which again makes me think I've probably just got crap in the carbs...is there anything that could block or be set wrong that would limit main jet/needle running too?

no fuel aha.

if the pipes are not hot it isnt burning fuel

stuck vaccum sliders? can you lift them up with finger and do they slide back down nice and smooth

if you opent the drian screws to rear carbs do you get fuel coming out? float valves could be stuck shut.

spark is a good sign.

only other things coul dbe some cam / valve issue but likely the engine owuld explode so look at everything else first unless you had all the cams and stuff out