Carb needle setting and idle problem...

Put a few sqirts of lub into the throttle cable before you connect the carb back up.

I got a carb from Dax that behaved just like that and I isolated the problem to the cap on top by swapping with other carbs. Duane sent me a replacement immediately which worked fine. I never did figure out exactly what is wrong with that top but it's definitely bogus.

PS All the carbs I got from him say NTCC instead of NT and seem to have somewhat crooked and cross threaded tops but except for that one the others work fine.

Be cautious to not let the cleaner spray get sucked into the air cleaner. This will cause a false reaction.

your cable might be too tight, also. try messing with the adjuster at the carb while you pull lightly up and down on the cable till you get hardly any freeplay. then take off your air filter and make sure when you turn the throttle it opens the slide up all the way.

Its really strange. I've had the top off again and have made sure theres no restrictions and i've even ptfe'd around the thread. I thought i'd cured it but all of a sudden the revs rose skyward again. I can feel that the slide is still working when i use the throttle.

I noticed that when i rock the bike from side to side (like you do to feel how much fuel you got left) - this causes the revs to rise dramatically. Literally went from tickover to 3/4 revs in a second or two.

I'm wonderin if i should just get a replacement carb whilst i strip this one down???

Gonna take my air filter off first and get it running for a short while while i look to see if i can see it sticking or anything.

I was talkin about the fuel filter bein a paper element not the air filter.
I bought some Lucas 2cycle oil and it advertises no more clogged filters...must be a common problem for them to put that on the label.

Just out of curiosity, is the little pin that guides the throttle slide actually long enough to engage the groove that runs the whole length of the slide?
I have had similar issues as you are having when the pin was either worn down too short or it fell out alltogether. These conditions can let the slide spin around in the slide bore and wreak havoc with any and all throttle positions, especially idle speed.

These little carbs are a pain in the rear. I have had a few that will not fetch up at all. As the bike breaks in it will usually settle down, then again it will sometimes go the other way. I am the one that started adding the air bleed to the float chamber in order to add some fuel to the idle. This carb is missing an idle circuit all together. You can try this and see what you think, I will not run any of my bikes unless the hole is in there. Have fun, Dave

Stock carb mod

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FIXED!!!


It was an air leak. Got it running today and sprayed carb cleaner around various parts - as soon as i sprayed near the inlet manifold, revs rose and when i sprayed on the engine side of the inlet, it cut out. Turns out there was no gasket left top or bottom - only the remains of the gasket around the bolts.

The most shocking part of this is that the intake and exhaust sides of my grubee engine have nice wide ports but the exhaust and intake flanges are roughly half the size.

I got my dremmel out and widened the intake pipe - took about 3mm off each side but none off the top or bottom as there is only roughly 3mm alloy to make a seal with the engine.

Didn't use a gasket either - just put on some gasket paste instead.


Well its running better than ever now. No air leaks etc and has a nice throaghty sound to the intake - deffinately has more power low down now too. The carb got a complete strip down and clean too - i was shocked to see how much cr@p had gotten into the air filter housing and around the choke area.

I used sealant to seal up the intake to carb and also around the slide to slide top.

No more air leaks and running sweet.

Cheers for all the help guys. Lots of helpful hints here in this thread,



Gav.

congrats.

you might have problems further down the road if you're not using a gasket on the intake. any auto parts store will have sheets of gasket material for cheap that you can make your own out of.