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jimcub
27-08-2013, 04:49 PM
We had a go at the nova today at last due to me having to wait for a pair of hands, although I had looked in the throat before this was with a bit of athrottle. Today we noticed on a fast 2000 rpm tick over no fuel going into the barrel, the other side you could see it dripping in and a wet butterfly valve, the near side carb was dry and the butterfly had black marks on it.
Makes me think a service kit might be the best way, with a good blow out of the jets.

letterman7
27-08-2013, 07:01 PM
Normally you wouldn't really see the fuel going in if it's operating correctly. Even at 2K rpm, the fuel should be atomizing as it reaches the throats. If you're seeing dripping into the barrels, then yes, a rebuild would be in order!

jimcub
27-08-2013, 08:36 PM
Dripping is actually a squirt from the main jet, that is the side that fires good the other side has the firing problem. As it is dry until until I blip the throttle and fuel squirts down that carb. Also the butterfly has black marks on it, the firing side butterfly is as shiny as the day I bought them.

MicksRedNova
27-08-2013, 10:25 PM
Jim

Could be that the float height setting is incorrect on one side or the fuel inlet valve is seating badly causing it to flood. The fact that the leaky side appears to be the one that fires properly could be a red herring as the lack of sooty deposits could be excess fuel washing the butterfly clean.

Mick

jimcub
28-08-2013, 09:30 AM
I think a service kit and a good clean might be the order of the day

jimcub
05-09-2013, 09:48 PM
Service kit here just have to get it sorted and back on, have to make a few calls as me fingers not working to well in this damp rain.

Peter
06-09-2013, 06:51 PM
One thing I fully recommend is the extended adjustment screws from alfa1750 on Ebay, makes the job a whole lot easier.
http://tinyurl.com/nx4pfun

jimcub
07-09-2013, 07:54 PM
Peter I have that much room round my carbs I could hold a party :cheers:
Makes a whole lot of easy work when the rear panel comes off in 30 seconds and on in not more

jimcub
27-10-2013, 03:35 PM
Hi all right had some help today with the carbs, fitted and static set up after an overhaul with a service kit.

it fired up and ran rough but there was fuel going in both carbs, the near side which was just fitted had a hell of a lot more suck than the other.

put hand over top and off side carb pulls lightly, the near side carb would suck your hand in also the exhaust on that side was cool.

does this ring a bell as to what's going on, I seem to have more symptoms than cure here.

jim:confused1:

Peter
27-10-2013, 05:00 PM
A engine is just a pump, so suction is relative to the amount of air (mix) being pulled into the cylinders, (about 400cc per down stroke on a 1600cc) and 'should' be equal on all four, if you are lacking 'suck' on one cylinder then you are not drawing in that air/mix.:oops2:

Exhaust valve open so sucking in from exhaust too, inlet valve not opening, can't be much else. If the piston is on the down stroke and ONLY the inlet valve is wide open then you WILL get 400cc of suck, if not, think of what could be stopping that from happening, short of having no piston rings, no plug or a bloody great air gap on the inlet manifold.:whistling:

If ONE exhaust is cool and the other three are HOT then you are not firing on that cylinder, only reasons can be plug/plugs or valves or no mix entering the cylinder. if BOTH cylinders on that side are cool and the spark is good then it IS a carb problem

jimcub
27-10-2013, 05:05 PM
Will have to get the valves checked again, takes so long nowadays to get some one in to do it

Gmacz
27-10-2013, 05:35 PM
Could be many things as mentioned above.
If one is sucking hard, could it be the carb balance that is the problem.
Are both carbs connected and both moving together.
Try manually moving the bad cylinder carb lever and see if it sucks harder.
I would check bad side valve clearances as well.

Peter
28-10-2013, 09:33 AM
Will have to get the valves checked again, takes so long nowadays to get some one in to do it

Why? it is so easy, pop off the covers, wind the crank pulley to TDC, check valve clearances as per book or as I do it for a quick check, inlet a little bit and a little bit more on the exhaust, following the firing order turn 180 degrees do the next pair, 180 do the 3rd pair and 180 do the 4th pair. correct any questionable clearances and pop covers on again.

jimcub
28-10-2013, 09:55 AM
Why? it is so easy, pop off the covers, wind the crank pulley to TDC, check valve clearances as per book or as I do it for a quick check, inlet a little bit and a little bit more on the exhaust, following the firing order turn 180 degrees do the next pair, 180 do the 3rd pair and 180 do the 4th pair. correct any questionable clearances and pop covers on again.

Yes it is easy if you can get down there, body is not as pliable as a healthy adults any more. I can drive ok but am crippled with chronic pain again, so not so easy and have to rely on friends