Neosophist wrote:If you went with the 24 head you'd need the NC30 cams so you'd have to make sure journal clearances were within spec.

An easier option might be to use the NC24 valve gear.. (rocker-arm etc and put them in the 30 head)

I've heard that Neo. The problem I have is tracking down used parts locally (within NZ) or paying the postage form overseas, which is hammering the budget. I got quoted US$180 to ship a rear shock the other day! They include postage costs to the total for import duty so I'd have paid an additional NZ$100 (55quid) there too.

Have you (or anyone else) ever compared heads, side by side? Are the valves and ports the same size? I'd be concerned about the reduction in material between the ports and plug hole, especially with a higher compression ratio.
The boffins at Honda will have gone to 8mm plugs for a reason I reckon.
I'd love to see dyno results of the two different heads on the same bike though.

I've heard of many NC30's being Helicoiled to 10mm plugs, never seen one though.

The Valve Seat Width is the same (1.7 - 2.30mm)

The NC30/35 uses the same valve stem seals as in the 24 and the same valve collets.

Cam lobe heights are higher on the NC30.. 32.x as opposed to 31.x on the NC24.

I know the NC21 has much fatter valves than the NC24 (Stems are too big to fit)

Don't have any off hand to measure i'm afriad.

The Compression Ratio on the 24 is 11.3:1 same as on the 30.

Both made 59ps when they left the factory.

The NC30 has an Overlap of 20.00 degrees and has in Intake Duration of 230.00 degrees. The Exhaust Duration is 220.00 degrees. The Inlet Cam has an Installed Centerline of 100.00 degrees ATDC. The exhaust cam has an Installed Centerline of 105.00 degrees BTDC.

I don't have the NC24 cam specs on hand, these were from memory (Will have to check)

The NC24 has an Overlap of 43.00 degrees and has in Intake Duration of 255.00 degrees. The Exhaust Duration is 250.00 degrees. The Inlet Cam has an Installed Centerline of 104.50 degrees ATDC. The exhaust cam has an Installed Centerline of 105.00 degrees BTDC.

From memory Neo!?! I can hardly remember my own whatsit at times.
It’d be an interesting exercise to play pick and mix with a variety of bits and a dyno.
Maybe throw NC35 cams into the mix?

My wife’s just had a read to see what I find so interesting and has stated that I am in fact one very sad individual.

Mananon wrote:Thats $400 NZ, not US but if you remember who you got the set off please let me know! I've seen full gasket kits on ebay uk (about NZ$200) but I worry about quality and not sure it they include stem seals. I'll mail them and ask.

Might be worthwhile asking for a price from RB Imports in Oz also.

They probably fall somewhere in between the cost of your NZ dealers and the UK providers, but shipping cost will be better and they have most items in stock.

Good thinking Cam.
I'll give them a bell.

Those might be ZXR angles actually.. but i think the ZXR has more like 60 degrees of overlap.. hence the high reversion at idle but the increase (65ps) in power...

Erm

I'll have to dig my service manual out.. it would deffinalty be worth checking bits out though and throwing different things at it while it's apart.

You can't use 24 cams though as there 180 order and you'd need the matching crank and pickup gear as well as some extra coils and CDI.

Dont' see why 24 rocker-arms wouldn't fit though, they have locknut adjusters on the tappets. Could keep your 30 head then.

Never really had enough time to build my ideal 400 VFR.. it's on the cards, maybe next year or the year after :-)

Roughly thinking

35 motor / frame / suspension / wheels
30 bodywork
24 carbs / oil cooler / heads

Ignitech box

Possiblly FCR33's too depending on what I decide it'll end up as.

It's just finding time and space! :-)

Anyway.. back to your thread.

To save me a few hours of searching and reading Neo, can you give me a breif rundown on the differences between the NC24 carbs and later types? I've read quite a bit on 30 and 35 carbs but nothing about the 24's yet.
I've also read a few bit's about 35 pistons being better but not why.
The Keihin carbs I'm not even going to think about.
I'll def be going ignitech though, if RO ever replies. 3 weeks now and no reply
Cheers,

Mananon wrote:To save me a few hours of searching and reading Neo, can you give me a breif rundown on the differences between the NC24 carbs and later types?

I've had several sets of nc24 carbs in the past (to use their slides - same as nc30 hrc), the main difference is that that they're a lot easier (less parts required) to get to hrc tune. This is because the air jet is much smaller than nc30 carbs, so there's no need to restrict it (which you need to do if you run hrc carbs - the nc30 hrc velocity stack does this normally but is now hard to find). They also already come with needles that are very similar to nc30 hrc...

Mananon wrote:I've also read a few bit's about 35 pistons being better but not why.

A much more recent, better design. They're interchangeable between nc engines, the compression ratio remains the same. Check this: viewtopic.php?f=24&t=18447&hilit=nc30+piston&start=10

Mananon wrote:The Keihin carbs I'm not even going to think about.

Good idea...!

Mananon wrote:I'll def be going ignitech though, if RO ever replies. 3 weeks now and no reply

Persevere, the man is well worth it!

As cammo said.. :-)

Give him a ring :D

The NC24 carbs apart from needles and sliders being very close to NC30 HRC items with the smaller air-jet it's not so flakey when you remove the airbox so easier to set up for an open air-tray / ram air etc.

Just need to put some bigger mains in there :D

Thanks for that guys. Good of you to take the time.
A set of 24 carbs I think I can find. Quite a few in the breakers, being a bit older.

Montsta off here is about 2 hours north and thinks he may have RVF cams so I'll see if he'll part with 'em.

I doubt I'll change to RVF pistons as mine look pretty mint and I'm not keen on touching the bores at this stage.

Got to draw the line somewhere or the money will run out before I get it half way back together.

I'll be keeping the airbox as this bike will run on the road.

I'll come back to carbs when I get a bit nearer.

Want to get the heads sorted first and still got heaps to buy and pay for: welding the plastics, decals from Brooky, RC30 style single seat unit, paintwork, powder coating, carb bits, fork internals, rear shock, ignitech unit and exhaust system are all to pay for in the next month or so. Once the weather improves and the market picks up I'll have to sell the Hornet to fund this.

I've been wanting to build a good V4 for years though so I can't say I mind.

Thanks again for the help guys. Very much appreciated.