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Rough running NC30 - help!

Posted: Fri May 09, 2014 11:59 pm
by DoktorMandrake
Threw my bike back together after a little fettling, but she's not running right.

I bought her month ago after she had been sat. I heard her running and she didn't sound like this! She's now really loud. Sounds like something mechanical/top end. She sounds fierce like a chainsaw. Something is definitely not right.

I did not touch the top end, except to re-seat the rocker cover gasket that was leaking.

I changed oil, filter and coolant and cleaned carbs.

The clutch was sticking/did not work when I fired her up at first yesterday, so I wonder if that has anything to do with it?

I thought it might have been the fuel, as the bike had been stood for a year or more, and I could hear the pinking sound, so changed the fuel, but still sounds awful. That smooth sewing machine sound of the V4 is absent.

Has a standard, OEM exhaust but is jetted to 122/120. Originally the front cylinders were richer, so I swapped the jets - could this have caused it to run lumpy/knocky/shitty? I know the rear cylinders are supposed to be richer so thought by putting the 122s in the back it would improve things.

Other than that, not done anything I can think of to cause it to run like a dog. Fitted new carb rubbers, sorted out the vacuum hose for the fuel tap and given her a bit of love, but the old girl is having none of it.

I know it's hard to diagnose over the internet, but any suggestions greatly appreciated.

Thanks

Re: Rough running NC30 - help!

Posted: Sat May 10, 2014 3:27 pm
by GeeTee
122/120 is too big for OEM exhaust

115/118 is stock spec

Re: Rough running NC30 - help!

Posted: Sat May 10, 2014 3:36 pm
by DoktorMandrake
I know. But it ran with 122/120 when I bought her. Thinking this is mechanical. Might play with jets but don't think it will make much diff :(

Re: Rough running NC30 - help!

Posted: Sat May 10, 2014 9:51 pm
by Dynamohum
Is it firing on all 4 a v3 nc30 sounds awful a bit like your describing with knocking noises etc ..

Re: Rough running NC30 - help!

Posted: Sat May 10, 2014 11:18 pm
by DoktorMandrake
I did wonder about that. What is the easiest way, isolate the plugs and check they are sparking?

Re: Rough running NC30 - help!

Posted: Sun May 11, 2014 12:52 am
by jpete41996
mine was 118/122 when i first bought it, and was OK, but quickly went downhill...after a complete carb go-thru using Cam's guide and some Rick O tips about cleaning float needles, seats, and setting the floats...it runs right as the mail (not royal mail, however, lol ;) )

Re: Rough running NC30 - help!

Posted: Sun May 11, 2014 10:54 am
by DoktorMandrake
http://youtu.be/zpNl12UPNDM


http://youtu.be/rlwZRNIVEok


Hopefully these videos work. Think it sounds mechanical, but would love for it to be something other than engine trouble. Would be nice if it was sumat easy ti fix as sge is ready for MOT :(

Re: Rough running NC30 - help!

Posted: Sun May 11, 2014 12:14 pm
by Dynamohum
It's hard to tell from the video but it sounds like its running on all 4 there's definitely a nasty mechanical sound there , exhaust leaks can sometimes give knocks n clattering but might be best to get the opinion of some of the more knowledgeable on here. .

Re: Rough running NC30 - help!

Posted: Sun May 11, 2014 1:13 pm
by arsey30
Check all 4 cylinders are working by ex temp warm up time from cold.

Nothing to do with main jets, the rattle is not relative to revs, much slower, more like a vibration induce metal to metal contact. Speed up the engine slowly until rattle is audible to try to locate the area of the noise [top end left or right side]

What was touched after it ran quietly, re check those.
Cam cover, how was the clutch freed off, fuel tank fitting/mounting.

Re: Rough running NC30 - help!

Posted: Sun May 11, 2014 1:26 pm
by Neosophist
As above, somethings resonating at a certain rpm. Check usual supects, exhaust headers, anything youve unbolted and not reseated properly.

Messig with the carbs might cause it to run shiitty but shouldnt cause that noise.