NC21/NC24 Differences

[Neosophist]

Would you gain any performance advantage by putting an nc30 motor in the nc24 chasis? I suspect not as the nc30 and the nc24 both have around 60bhp.

No, just the awkward gearing of the NC30.

You'd be better doing it the other way around if you wanted an oil-cooler, and better carbs. would make a better starting point for tuning

But you'd loose that weird 360 degree idle of the 30

[bantam_dave21]

Still no sign of the engine number perhaps its a T.W.O.C - gutted !!!!

Thanks for the clutch info - the rod withdraws without any major stripping so i'm in no rush, I'll just keep an eye out for the slave, rod, master & hose then when they're all painted and polished I'll get them fitted.

Don't suppose you've still got that link pipe and can that exits on the left that I read on a post you had have you?

Thanks again though for all your advice - lost otherwise

[Neosophist]

Can exits in the normal place..

I'll have a look in the garage, last few weeks been taken over by kawsaki bits..

[Vfr400KM]

This i weird, my nc21 seems to have a cable clutch lever at the bars to however it does have a push rod that comes through to the sprocket cover later on?
Its a KM model made for learners and jap police as far as i know. Its most notable oddities are the large crash frame over the exhaust and its single round headlight also minus most of the usual fairings.

[Xeloraul]

Hola buenas tardes sr. Neo o amigos del grupo. Quiero hacer una pregunta sobre el tablero de la NC24. Mi tacómetro está malo y instale uno de una NC 21 funciona todo pero el tacómetro solo llega a 7000 RPM será que está malo igual o no son compatibles y por eso marca menos RPM y está haciendo el doble de RPM. Gracias por su atención esperando respuestas

[Xeloraul]

The frames are the same (apart from the frame numbers!) so all the drillings are present.

The NC21 has a hyrdaulic clutch, this needs the matching sprocket cover and pushrod, as well as some longer bolts for the sprocket cover, like wise, if your fitting the NC24 cable clutch you'll need the sprocket cover and shorter bolts.

Collectorbox is differnet between the two as the 21 has a low-level exhaust.

The 24 subframe has a hanger for the rear exhaust and uses different rear-pegs.

The NC21 has a different Reg/Rec but same connector.

There are subtle differences between the wiring looms too, some of the plugs are different shapes.

The NC21 has a twin piston rear-caliper, the NC24 has a single piston rear caliper.

The NC21 has fixed discs the NC24 has floating discs.

Internally, the NC24 had revised camshaft profiles, you'll notice that a lot of the parts end in 720, as opposed to 000 of the NC21, indicating a revision.

The clutches are different, the NC24 basket is the same part used on the NC30, I theorise that you could drop an NC30 internal in there (yet to test this)

Depending on your NC21 there were two clutch baskets fitted, the plates are the same so i'm not sure what the changes were.

Generators are different, the NC21 uses a smaller genny and flywheel ,some early NC24's use the smaller genny too, i'd stick with the later 350watt type across all models if you need to change it, though this might require the later-type flywheel.

An interesting point here is that the only flywheel available for the NC24 is the MR8 NC30/35 version. The NC21 still has listed the old ML0 type, although I can't see a problem fitting it as the genny covers are the same between both models so it'd fit.

The carbs have different jetting / internals between the models. The NC24 has the richest jetting (115's), the NC24 came with two revisions of the slides. After / Before VDE-2F, the NC21 has different slides to both, along with different needles too.

The fork internals are different, springs have different rates, the NC24 has air adjustable valves while the NC21 doesn't.

Likewise the rear shocks have different internals / springs.

There are differences internally between the gearbox too, I think the affects the ratios too, I'm at work at the moment and dont' have the information to hand.

If you think of the NC24 as a refined NC21 you should get the idea, things were smoothed out / improved over the 21.

Most things will bolt straight in, but if your going for engine work it's best to stick to the 21 stuff for a 21 engine or vice-versa when it comes to gearbox parts, carbs / cams. Chopping and chaning might lead to some really weird running engine.

Expansion bottles differ.

Pistons / Crankshaft / are different between the models.. NC21 has KT8 PCN's in there (I'm sure KT8 is a CBR400 Aero), NC24 has two revisions of piston depeding on year.. but there both ML0 and end in 720 / 721

Interestingly though the rods are the same.

There all NC13E engines anyway, even in the later 30 / 35. I can't see why you could transfer a 30 internals to a 24 case (you'd get a nifty oil cooler too).

Obviously if you went major like this all the bearing shells, cam journals etc would need to be re-checked. Major work and not for the feint hearted.

But I would't chop and change cranks without pistons etc.

However, If theres anything your thinking of fitting and are unsure just ask :-) I'm at work at the moment and will have more info later.