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Re: NC21 still not running right
Posted: Sun Aug 29, 2010 11:43 pm
by Viffer77
No good.
After changing the overpriced rubbers and yet more tweaking. Still has the problem!
I agree that this is an air leak problem, but just don't know where from!
It's really pissing me off!!!
Any suggestions?
Help.
Re: NC21 still not running right
Posted: Mon Aug 30, 2010 11:15 am
by Neosophist
Hmm,
So what's it doing now, the revs hanging on the way down?
Any other problems?
Re: NC21 still not running right
Posted: Mon Aug 30, 2010 8:55 pm
by Viffer77
Exhaust way too hot and flat spots once you've pinned the throttle for a few gears. If I cruise for a bit it then runs ok.
WOT seems to cause it some serious problems!
Re: NC21 still not running right
Posted: Tue Aug 31, 2010 12:40 am
by Neosophist
Viffer77 wrote:Exhaust way too hot and flat spots once you've pinned the throttle for a few gears. If I cruise for a bit it then runs ok.
WOT seems to cause it some serious problems!
Vaccumn pipe is to be suspected if WOT is killing it.
Weak ones leak / collapse in on themselves at full vaccumn which shuts off the flow of fuel until you back off. have you replaced the smaller fuel vaccumn pipe?
Hot as in glowing?
Re: NC21 still not running right
Posted: Tue Aug 31, 2010 1:42 pm
by Viffer77
If you spit on the end can, it doesn't sizzle. It flies off.
I haven't changed the vacuum hose.
Re: NC21 still not running right
Posted: Tue Aug 31, 2010 4:11 pm
by Neosophist
Standard end-can or aftermarket?
They do get hot.
Are your downpipes 'glowing' (this would indicate a really lean mixture)
Change the vaccumn hose and see if that solves your fuel starvation issue.
I can't remember what jets you have in the carbs.. 110 / 112's?
Re: NC21 still not running right
Posted: Wed Sep 01, 2010 10:08 am
by Viffer77
Hi Neo,
Standard can. Haven't noticed the downpipes glowing, but the power loss induced by fuel starvation would obviously lean up the mix quite a lot.
110's & 112's.
I will have a look at the vacuum pipe. Is there an easy test that you know of other than putting my lips round it and sucking.
Cheers.
Ben.
Re: NC21 still not running right
Posted: Wed Sep 01, 2010 11:47 am
by Neosophist
Take it off and stretch it, weak spots will snap the pipe, it generally dies where it connects to the engine.
Re: NC21 still not running right
Posted: Mon Sep 06, 2010 8:35 am
by Viffer77
Tried it, no good! The hose seems alright. I've given it some real suction and stretched it it nearly twice it's size.
I am at a loss now!
Any more suggestions (other than putting a match to it!).

Re: NC21 still not running right
Posted: Mon Sep 06, 2010 10:32 am
by Neosophist
Have you had a look at the fuel tap, theres a gauze filter inside the tank attached to the fuel tap.
If you remove the four screws from the tap you can inspect the diaphram too and make sure it doesn't have any holes in it.