NC24 ENGINE REBUILD

[pagan1001]

Right neo got them stripped and boy has this guy buggered it the two carbs on the left are 115 and the two on the right are 112 so it looks like he has taken them out but mixed them up so I have changed them around the right way so I will see if that makes any difference. If not I might just try your way 115's all round

[Neosophist]

ok.

Thats not right

Take the emulsion tubes out too.. these are the tubes the jets screw into.. come out with a 7/8mm spanner.

Get them all out and inspect that the holes are all clean.

Two of the tubes should have MORE holes in them.. these go in the rear cylinders.

Also get all the pilot jets out and clean them up too. (There the small #35 recessed ones)

I've checked my parts book.

The early NC24's (Depending on carbs used) have 112 jets in the FRONT and 115's in the rears. (didn't know that )

None of the NC24's ever had 110's in there.. that was purely NC21's.

So put your 112's in the front two and the 115's in the rear.

Check float heights etc.

No point upping to 115s all around until you have it running properly and find it's lean at top end (unlikely) changing jets wont affect your idle at all.

[pagan1001]

Yeah cheers changed them round and a big difference it runs so smooth now and the idle is even a bit better now it is just wavering from 1300rpm to 1500 rpm so huge difference but will check the emulsion tubes tomorrow as totally forgot about them.
And you were right Neo I pin pointed the noise and it is the starter clutch so will get in there tomorrow and check it all.

[Neosophist]

Cool coo, getting there then.

When your in there get the pilot jets out and make sure there spotless.

If there all clean theres probably still an airleak somewhere causing the idle to fluctuate.

You could do with a can of brake / clutch cleaner / easy start etc from halfords (needs to be flammable)

and spray it on the rubbers and see if the RPM changes.

Other possible leak points are.

The screws that you put the balncing gauges in..

there is 1 screw per cylinder head that has a flat aluminium washer on it, you unscrew these to put the carb balancers in, make sure there all still there. The on on cylinder 4 is behind the thermostat and can be hard to see.. the other 3 are directly below the carb rubbers more or less.

theres also the spiggot the vaccum pipe for the tank connects to, make sure this isn't leaking air.

[pagan1001]

There are no washers on these screws!!!!!! but they are very,very tight just broke my screw driver getting them out. Also what are the tubes next to to float right at the back of the carb chamber?????? I cant see how to get the emulsion tubes out as there is no way of using a spanner on them they are solid ......... please help
When you say spay on the rubbers you mean the rubbers connecting carbs to engine and do I spray it around them or into them????

[superlite]

Also what are the tubes next to to float right at the back of the carb chamber?????? I cant see how to get the emulsion tubes out as there is no way of using a spanner on them they are solid ......... please help
When you say spay on the rubbers you mean the rubbers connecting carbs to engine and do I spray it around them or into them????

Sounds like either the pilot jets (flat head screw driver), or the non-removable brass tubes in there. A 7 mm socket should do the job to get the emulsion tubes out - ditch the spanners for carb work.

Spray around the rubbers conneting the carbs to the engine when it's running - if the rev's change, the carbs aren't seated properly.

[Neosophist]

Pictures of the carbs please.

The MAIN jets screw into the emulsion tubes with a flat head. Sometimes unscrewing these removes the long brass emulsion tube too.



This is an emulsion tube.. notice the hexagonal head on the top.

The MAIN jet screws into there.



Your pilot jets are next to the main jet and look like this



You need to make sure that all the little tiny holes are clean and clear and that the hole at the top is also clean and clear.

[pagan1001]

yeah guys have done!!!!, checked it all now and a okay!!!!! going to change the clutch pates tomorrow as these ones look old, very old so got new ones to fit but my starter motor is the thing that jams so fitting a new one tomorrow also.
But Neo i have emulsion tube in all four carbs????
anyway big difference now burt will try that with the rubbers!
Even top speed is smoother to reach you guys are the shit!!!............in the good way!!! Bike runs like a dream cheers

[Neosophist]

Yeah theres emulsion tubes in all 4 carbs.. it's what the main jet screws into.

There differnet though.. two of them will have more holes in than the others, they go at the rear cylinders (with the 115 jets)

[pagan1001]

cool getting there now!!! big improvement now so will do that tomorrow as well as change the clutch plates. put it is so much better already so a big thanks to you Neo You figured it out no problem........... very impressive!!!! cheers