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Carbs spitting petrol. NC29
Posted: Sun Nov 20, 2011 2:46 pm
by CBR_2009
Still trying to get the bike fired up. Baisically it starts spitting petrol out of the left tube that's inbetween the two left side trumpets of the carb (pic below).
Any idea why it would be doing that and how would I sort it out.

Re: Carbs spitting petrol. NC29
Posted: Sun Nov 20, 2011 5:29 pm
by tanuki
That's an overflow so I'm guessing stuck float.
Have you cleaned the carbs?
Re: Carbs spitting petrol. NC29
Posted: Sun Nov 20, 2011 5:34 pm
by CBR_2009
Took them apart and gave them a goodish lil clean. Not cleaned carbs before, so it was a first. Is there a specific way to check/clean the floats? And would I have to use specific carb cleaner or could I use summit like WD40?
Oh yeah, Are the overflow pipes supossed to be attatched to anything? Haynes manual says nothing about connecting/disconnecting them and I find it weird that they would spit the petrol over the electrics and engine.
Re: Carbs spitting petrol. NC29
Posted: Sun Nov 20, 2011 9:19 pm
by yeurman
Hi overflow pipes should route back into the air box... and if you get some carb cleaner from Halfords and strip the carbs so you can get to the float chamber, remove the float valves and seats and give a good squirt with the cleaner, its prob best to buy a new set if you can see some wear on the float neddle rubber tip.. wont cost much. If you take pics and lay out all the parts, its quite easy Cheers Col
Re: Carbs spitting petrol. NC29
Posted: Sun Nov 20, 2011 9:58 pm
by CBR_2009
yeurman wrote:Hi overflow pipes should route back into the air box... and if you get some carb cleaner from Halfords and strip the carbs so you can get to the float chamber, remove the float valves and seats and give a good squirt with the cleaner, its prob best to buy a new set if you can see some wear on the float neddle rubber tip.. wont cost much. If you take pics and lay out all the parts, its quite easy Cheers Col
How do they connect to the airbox? The only connections I can see on the airbox are for the two tubes the connect at near the headstock end.
Re: Carbs spitting petrol. NC29
Posted: Mon Nov 21, 2011 8:10 pm
by cbr400rrn
Not sure if they do go into the airbox, will have to look at the Haynes manual as i can't remember connecting mine to the airbox last time i took it off but i could be wrong
Re: Carbs spitting petrol. NC29
Posted: Mon Nov 21, 2011 8:46 pm
by tanuki
They don't go into the airbox Col was getting his ram aired knickers in a twist.
They lie flat against the carbs and if they did leak fuel it wouldn't go over anything that wo t get piss wet through when it rains anyway.
Re: Carbs spitting petrol. NC29
Posted: Wed Nov 23, 2011 1:13 am
by yeurman
sorry, my flatsides overflow route into my airbox on my race bike... not having not owned a road going CBR I assumed this was also the case... my apologies... :)
Col
Re: Carbs spitting petrol. NC29
Posted: Wed Nov 23, 2011 1:53 am
by Pleiades
tanuki wrote:They lie flat against the carbs and if they did leak fuel it wouldn't go over anything that wo t get piss wet through when it rains anyway.
Is the fuel leaking into an airbox? My NC29 doesn't have an airbox, and when this was happening to me, there was a lot of fuel flowing onto the very hot exhaust. Nothing went bang, but surely it's a possibility? It was exacerbated by the belly pan filling up with fuel (it's a race bike), thus soaking the exhaust in a 98RON bath!
Re: Carbs spitting petrol. NC29
Posted: Thu Nov 24, 2011 7:59 pm
by CBR_2009
Gots me some new carbs. Floats were abit green from stale petrol. Gave them a quick clean. Engine now sounds like it wants to start for a split second but the exhaust just ends up banging instead. Oh, and the last time I tried the airbox shock from where I think it blew back some flames through the carbs :p
Reckon I should just keep trying to start it and hope it just needs to clear out the system a lil bit?