NC24 coolant leak

chownsy · Post by **chownsy** » Sat Jul 02, 2011 12:00 pm

I have a NC24 with a horribly annoying water leak.

It dont leak much, The radiator has dropped by 1" it total capacity but there is no smoke, no steam and no water in the oil.

No leaks from any where like water pump or thermostat.

Has anyone got any ideas?

My idea is a pipe could be perishing and slowly leaking off but not that muchto see visibly.

Post by **Neosophist** » Sat Jul 02, 2011 12:29 pm

Theres a water transfer pipe in the middle of the V thats chromed steel, this is sealed with an O-ring at each end.

A minor leak on here and you wont' see it as the heat will evaporate the water.. I have seen two fail.. one the o-rings perised and the other had a hairline crack that was letting out a fine mist.

Had to make my own pipe as there not available anymore

chownsy · Post by **chownsy** » Sat Jul 02, 2011 12:47 pm

Neosophist wrote:Theres a water transfer pipe in the middle of the V thats chromed steel, this is sealed with an O-ring at each end.

A minor leak on here and you wont' see it as the heat will evaporate the water.. I have seen two fail.. one the o-rings perised and the other had a hairline crack that was letting out a fine mist.

Had to make my own pipe as there not available anymore

Thank you for that reply.

As I will have to remove carbs for that area, can you let me know if there is anything i need to check with the carbs and engine as under full load it missfires and lurches and i took it down a private peice of land and it wouldnt get anywhere over 90mph and missfired a lot.

ROll on in top gear will replicate the problem from 30mph to 50mph it missfired and lurches when opening full throttle.

Post by **Neosophist** » Sat Jul 02, 2011 5:18 pm

that pipe can be inspected with teh carbs on, the only way I found it was with the engine running upto temp, i put a kitchen towle in there and it came out wet.

Your problem sounds carb related, not setup properly.

There are other things like damaged plugs / faulty electrical system but the roll on / full whack issue sounds like fuel related very much so.

I'd test the electrical system and perhaps replace the plugs if you dont' know when they were last done (I cant see it making any difference replacing the plugs but cheap and easy to isolate and you'll need them anyway even if the old plugs are ok as part of the next sevice, testing the electrical system is free)

My money is on carbs.

Sounds like your flooding the engine, the excess fuels making its way into the exhaust and burning or its killing the plug temporarily.

What color are the plugs? Any photos?

chownsy · Post by **chownsy** » Sat Jul 02, 2011 5:23 pm

I will get pics of the plugs later but they are virtually brand new, Done less than 300 miles on them.

Carbs are running 115's now after your last advice. The bikes a hell of a lot less fuel hungry now than when it was on 120's.

Ill sort all this out tomorrow if i can. If i got to take the carbs off ill do that pipe with out checking as its worth doing it anyway for the future.

Forgot to say that starting on choke is now a pleasure to do.

Also a quick questions, do these engines cool down really fast as i can leave it at my mates for 30 mins and it will need ot be put on choke again to get her to idle well. Riding down the road she will idle at 3000rpm, but put a bit of load on her when stationary and she will settle down to idling at 1500rpm again.

EDIT: Coould this also be down to unbalanced carbs? I still to get them balanced right. I have the vacumm gauges but cant sus out the balancing. Im so used to cars with fuel injection than bikes and carb setting up.

Post by **Neosophist** » Sun Jul 03, 2011 7:11 am

That sounds like classic air-leak symptoms.

The idle is hangs at 2-3000 rpm before eventually returning to idle.

When the bike has cooled a bit the rubbers might not be sealing properly, hence needing choke to start (as it is overly lean) and causing the idle problem.

When a bit warmer it might seal and the problem goes away.

You definatly have carb related troubles with the bike.

Which carbs do you have on there? If I remember rightly you swapped them around or something?

I'd be tempted to bin the carbs and the rubbers, put a known good set of NC24 carbs on there with new carb rubbers and the correct jetting and you shouldn't have any problems, make sure the airfilter is stock and the airbox is on properly.

chownsy · Post by **chownsy** » Sun Jul 03, 2011 8:56 am

NC21 engine - very clean, tappets done, new spark plugs
NC21 wiring loom
NC21 coils
NC21 clocks
NC21 oil cooler
NC21 air filter - clean and fits well.

NC24 carbs cleaned really really well and jetted to 115 all around. (these were a very very good set of carbs just jetted to 120's before i got them)
NC24 Frame
NC24 radiator
NC24 bottom coolant hose

Carb rubbers are hard so i will look into these being replaced (do NC30 rubbers fit?)

EDIT: would a pipe like this http://www.ebay.co.uk/itm/RED-Silicone- ... 19b5e23ff5 cut to length work instead of the carb rubbers, they should last longer as silicone is a good material for heat disipation.

Also if i want to replace the main coolant tubing, would straight hose with right angle joiners be a okay decision to go down?

chownsy · Post by **chownsy** » Thu Jul 07, 2011 8:29 pm

what do you suggest i check when i next set my carbs up? Im hoping to balance them this weekend too.

Post by **Neosophist** » Fri Jul 08, 2011 12:11 pm

Ah.. brainwave.

NC24/30 carbs are 32mm..

The NC21 had 30mm carbs.

Your carb rubbers maybe wrong..

chownsy · Post by **chownsy** » Fri Jul 08, 2011 12:26 pm

I measured the OD of the NC24 carbs they are 38mm

NC24 coolant leak

NC24 coolant leak

Re: NC24 coolant leak

Re: NC24 coolant leak

Re: NC24 coolant leak

Re: NC24 coolant leak

Re: NC24 coolant leak

Re: NC24 coolant leak

Re: NC24 coolant leak

Re: NC24 coolant leak

Re: NC24 coolant leak