Hi all, I recently purchased a 1987 NC24 from a guy who says that he just rebuilt the whole motor, and redid the wiring, for a very good price. I took delivery and drove the bike back home for about 25km, the bike started instantly and settled into a 2k idle purring perfectly along, I hooked 1st and off I went, slowly at first as she was ice cold, went through all the gears shifting at 5k, then 6k, then 7k... had a scare when I looked down and saw a red "Speed" light come on, at the same time a sudden flat spot, so I let off and hooked 6th, but the light remained. (have since learned this is a non-issue - just a speed warning for jap market)

Pushed through the flat spot and hit redline in every single gear and it was the most fun I've had since i met my wife.

Soooo.... it starts and idles perfectly, runs strong and smooth up to about 6000k and then very flat and rough up to about 7500k and then steam trains through perfectly till redline.

Why?

According to the bloke who sold it it's running a rec/reg from a gixxer400 and I can confirm it is not stock as its silver and has lots of fins, its quite large also, could it cause a 1500rpm odd flat spot?
I am scared to pull the carbs off as I've read nightmarish tales, but I do realize I might have to clean them and check locations of emulsion tubes etc..

The tank has a lot of loose rust in it and there was no filter what so ever, even the screen on the tap was missing, I have since installed a pingel cleanable one inline, but the bike has not been started since so I hope I don't restrict fuel. (Rust inside carbs would surely affect more than just a little ole flatspot at a specific rev range?)

There was some very fine glitter in the oil when I drained it, but I have heard it could just be run in wear from new parts.
Plan on changing oil and filter this weekend..

I haven't checked plug color but zero smoke from exhaust even when cold, so I assume its not too rich, It was running quite hot at one stage when i sat at the lights in quick succession, so it could be a bit lean, not sure. (Coolant was some flush additive and was a little low, so hopefully the new coolant I put in will solve this issue..)

The vacuum valve on the tap has been bypassed, I ordered a kit and got the big and small diaphragms and screws and a spring but I think I need something else to restore this as I could not figure out the assembly, and just installed back the bypass parts.

So whatcha guys think?

It's my second "big" bike, and the first multi cylinder one I've had to work on, but I have been building and modifying bikes for years and am very comfortable with working on them, any suggestions will be executed.
Thanks in advance!!

Anybody? Is Neo still around?

I am, and I saw

"Location: South Africa / NC24"

This is a combination for world of hurt / money pit, most abused bike in the world ever, throw it away and run a million miles away don't get involed kind of deal.

I think it's easier to find aliens than to find a good VFR in SA, the hunt is on between NASA and greybike to see who makes the first discovery.

I'll reply to your above post in a second but before I do my best advice would be to sell it and get something more modern / easier to work on more parts, like a CBR600F jellymould, faster, cheaper, better handling, better gearing, better everything, easier to work on and made for a lot longer.

NC24 was made for only 2 years as a Japanese only bike...

After reading this at least do yourself the honour of riding a decent cbr600f, you'll not go back to the vfr..

Anyhow. Lets break it down.

Eben007 wrote:Hi all, I recently purchased a 1987 NC24 from a guy who says that he just rebuilt the whole motor, and redid the wiring, for a very good price. I took delivery and drove the bike back home for about 25km, the bike started instantly and settled into a 2k idle purring perfectly along,

These bikes shoulnd't idle at 2000, 1300rpm is the correct idle speed. More worringly, why was the whole motor rebuilt (what does this even mean?) what parts were changed, many parts are no longer avaiable either so can't be replaced.

What happeend to the wriring for it needing to be re-done?
Soooo.... it starts and idles perfectly, runs strong and smooth up to about 6000k and then very flat and rough up to about 7500k and then steam trains through perfectly till redline.

Why?

Becuase most likely your fuelling isn't setup right.. What altitude is the bike at? Are the jets and tubes in the right place, float heights ok? Pilot screws ok? Air filter upto stock spec and airbox not changed?

The NC24 doesn't have a typical midrange dip during the transition from needle to main that the NC30 had so setup as stock it should run smooth from idle to red-line through all gears.

According to the bloke who sold it it's running a rec/reg from a gixxer400 and I can confirm it is not stock as its silver and has lots of fins, its quite large also, could it cause a 1500rpm odd flat spot?
I am scared to pull the carbs off as I've read nightmarish tales, but I do realize I might have to clean them and check locations of emulsion tubes etc..

No it shouldn't cause a flat spot.. a broken charging system can over-charge the battery and kill your ignition box as well as upset the running, just as an undercharging system can but this is often shown at idle.. an aftermarket reg/rec isn't sign of a working charging system so i'd want to do a full test of the charging system to make sure everything is working as it should.. connectors corrode and parts do burn out if not kept on top which is why its probably had the reg/rec changed.

The tank has a lot of loose rust in it and there was no filter what so ever, even the screen on the tap was missing, I have since installed a pingel cleanable one inline, but the bike has not been started since so I hope I don't restrict fuel. (Rust inside carbs would surely affect more than just a little ole flatspot at a specific rev range?)

Depends whats plugged up but rusted tank and no filter means its been bodged about before and neglected, who knows what the rest of it is ilike.

There was some very fine glitter in the oil when I drained it, but I have heard it could just be run in wear from new parts.
Plan on changing oil and filter this weekend..

This is metal in the oil and is classic sign of knackered engine. When this guy says he rebuilt the whole motor, what does he mean by that? Many parts to rebuild one of these are unavaiable and rebudiling them propelry is SO expensive that a second hand engine, even shipped from Japan is usually cheaper.. Even just to sort out leaking valve seals in an old engine (which is somethign you should do as part of a major rbeuild on a V4 anyway is going to cost 3000 rand if you can get the parts). Not dispting it hasn't had some engine work but anytime somebody sells a cheap V4 that has had the whole motor rebuilt is very suspicuos as parts are expensive / not commonly available / time consuming.

I haven't checked plug color but zero smoke from exhaust even when cold, so I assume its not too rich, It was running quite hot at one stage when i sat at the lights in quick succession, so it could be a bit lean, not sure. (Coolant was some flush additive and was a little low, so hopefully the new coolant I put in will solve this issue..)

These bikes unlike the NC30 don't get very hot usually, even riding one in a Japnese 40c super humid summer at town pace the bike temp doesn't get much above cold... if it's getting that hot it sounds like its not running too well. I'd want to check that (after everything else) inpection water pump / blocked passaged and thermostat opening ok

So whatcha guys think?

It's my second "big" bike, and the first multi cylinder one I've had to work on, but I have been building and modifying bikes for years and am very comfortable with working on them, any suggestions will be executed.
Thanks in advance!!

As above, ditch it and get a cbr600f, much more foriginvg to ride, easier to work on and theres a reason why courieres all over the world use them, run forever with minimal of love... nc24 too old and too muhc of a hooligan bike, will have been abused and neglected to an inch of its life.

Wow. Thanks Neo. While I do really appreciate the in depth response, I am not a rich man.. and I have taken a loan from the bank to get the bike. It wasn't dirt cheap but it was a lot more than a months salary.

I fully intend to try my hardest to make it work out good. I have 2 spare engines and a spare set of carbs. And enough parts to build another bike including a complete rolling frame. I have found fork seals, service parts and the odd gasket sets, piston kits, etc. I have a colleague who drives one to work and back daily for the past 2 years with no problems.. had a bad reg once I think. I don't intend to make it a daily drive either. It was running what I believe to be healthy ie. No strange noises, zero smoke, no bad vibes, easy to start, no water in oil, no leaks, no issues really but the slight flat spot.

The guy just said he rebuilt the engine, he also gave me the old parts and it looks like the old crank had a big end knock. So while he was in there he replaced the oil pump, pistons, rings, small ends clutch etc.

If I could afford a 600 I would have bought one but the little viffer is mine and I'm gonna try it. Thanks neo reallappreciate the input.

Go well

no worires fella, but seriously, sell the lot and save for some time and get a 600 best or differnet bike... i still have one, my best one, that was really mint when i bought it, only 14000km, but i spent 50,000 rand / 2500 uk pounds to make it super reliable.

they really not cheap, and while it is fun and ok its no where near comparable to an nc30 and woth much less and compared to other bikes really not that great eiehtre.

if it really is your only option then i dont mind and no doubt other will to helkp you sort any trouble but many other bikes offer so much more for less money and chepare maintance.

but it will cost a fortune to make reliable for even part time use, everyone ive owned always has, and at best they will always be a v1 NC30, ie poorer brakes / chasis / frame and wheels..

nice bike for what they are but cost an arm and a leg to put right and spares / extras are getting more and more hard to find making them really pricey.

I hear you, and appreciate what you're saying Neo, when you say you had to spend 2500 quid to get yours reliable, what were those costs going toward? Just so I know...

Before I bought the bike, I read up on it quite a bit, and everyone was saying that they're reliable bikes except for the charging system, I know they're not as good as a 30, but I'm very new to road bikes, always played in the dirt, so I'm in my limited experience very happy with handling and brakes.

I'm sure I would be blown away by a 30 or a 600, but they're double the price. I have a good set of mechanical skills, all the tools and a s#itload of parts (even have 2 good collector boxes), I feel quite confident I can keep it on the road for a while, it's only done 25k km, and the engine has only about 1000 since the rebuild, I've found all the service parts, filters, brakes, etc. available locally for decent prices, a set of fork seals is 5 pounds, that's cheaper than the seals on my chinese pitbike, which are so common you can almost buy them at the grocery store. Honda also sells a lot of the parts still and I AM willing to spend money on the bike, don't want you to think I bought it thinking I can thrash it and it would last forever.

I have read a lot of your comments on South Africans, and while the majority of SA bikers are a rough lot, who bike because they cannot afford better transport, I myself am a highly educated guy, with 2 very reliable cars I use day to day, I take very good care of my vehicles, I change the oil in my car every 5k instead of every 15k, I have never had a vehicle give up on me, I don't rev them to death, or burn out tires, the chain on my 250 gets washed and dried and lubed after every ride, even if I was only out for an hour. And to date I have never had to change it or the sprockets.

My vehicles are my children, because I don't have any actual kids, and they get treated as such. I'm meticulous is what I'm saying.

Do you really think I won't be able to make the 24 work out for me Neo?

Not knocking your ability at all fella just reminding you that it has probably had of load of the rough owners before you.

And they are reliable bikes, its just they are old so things wear out.

Copy fork seals are junk too, they last about 500km and need to be replaced, genine honda ones are only fork seals worth entertatining.

And things I spent money on.

Chain / Sprockets / Cushdrive rubber / fuel tap rebuild / carb gasket set including all orings / new generator / new reg/rec / swingarm bearings / rear hub bearings / front wheel bearings / head bearings / fork seals / valve stem seals / associated gaskets and shit that goes along with that / water pump / rear shock / fornt fork bushes, engine respray paint

using them everyday stuff does show up due to age, rear hub bearings are expensive. everything is do-able but cheap parts do cost time and money.

I ride a 50 year old 2t scooter most days and it starts and runs on the button and i regulalry take it jounreys of 120 miles each way non stop... but only reason its still reliable is I replaced everythigg on it. Suspension, all bearings on bike / wheels and all bearings inside engine as well as new piston rings etc, full carb rebuild, all hoses and cables, so even though its old its like a new motor.

Its a toy compared to the 24 though as its a lot more cumbersome to work on a v4 than a small single.

they just at the age where things are more likely to go wrong. dont let it put you off though, espeically if you wnt to keep it.

if you hadnt have bought it id have adivsed against it but you have it now right, unless it starts costing money all the while worth at least seeing how you get on with it right.

I really appreciate that Neo, my problem is, I've fallen in love, and love makes us blind ya know? haha.. Seriously I think I'm rather going to go through all the shit, than to try sell her because she's old, she's younger than me by 2 years so that's a good girl in my book

Just for interest sake:

Chain NEW / Sprockets NEW / Cushdrive rubber WILL CHECK / fuel tap rebuild DONE / carb gasket set including all orings HAVE NOT STRIPPED CARBS YET... / new generator CHARGES FINE / new reg/rec AFTERMARKET/ swingarm bearings WILL CHECK / rear hub bearings WILL CHECK / front wheel bearings ZERO PLAY/ head bearings ZERO PLAY/ fork seals NEED DOING/ valve stem seals DONE/ associated gaskets and shit that goes along with that HAVE A LASER AT WORK, CAN CUT MY OWN/ water pump WILL CHECK/ rear shock FEELS GOOD/ fornt fork bushes SEEM OK, engine respray paint NEED DOING.

I really feel I have one of the good ones here, I went to look at a bunch before I bought, and this one was by FAR the cleanest and best looked after example.

Touch wood...

I'm curious, does anybody know what the black plastic box between the battery and the rear heads is? I assume it's a toolbox? It has a water drain and an easy to remove lid, from the right side of the bike. but mines empty so not 100% sure, I thought it could be a fuse box but no holes for wires or such? Cannot find even 1 picture on google or any info on the forum here either... suppose I should post a pic yes?

My parts bike doesn't have that or the battery tray either..

Eben007 wrote:I'm curious, does anybody know what the black plastic box between the battery and the rear heads is? I assume it's a toolbox? It has a water drain and an easy to remove lid, from the right side of the bike. but mines empty so not 100% sure, I thought it could be a fuse box but no holes for wires or such? Cannot find even 1 picture on google or any info on the forum here either... suppose I should post a pic yes?

My parts bike doesn't have that or the battery tray either..

tool kit holder.

I have the tool kit in mine!

fuse box is on the tripple clamps at the top