nc24 engine wiring probs

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rusty1210
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nc24 engine wiring probs

Post by rusty1210 » Fri Dec 21, 2012 11:38 pm

i recently brought a nc24 as a project and i have not done to bad on getting it back together, but i have a problem with some of the wiring i think its got a nc21 engine in, on the right side at the back and bottom is a unit held in with two bolts and has 5 wires coming out with a plug on that wont fit anywhere, also i have no neutral light but i have the wire in with the pick ups and oil switch but no ware for it to go i have looked on here and someone had this problem back in 2009 but i cant find any fix for this other than try and match up the wires by color, also it seams to be firing a bit all over the place this might have something to do with this part of wiring if its a crank sensor ??
i am a bit stumped can anyone help bring some life to my nc24 please
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Re: nc24 engine wiring probs

Post by thunderace » Sat Dec 22, 2012 2:31 pm

The 5 wire lead will be your stator. Should be red, black and three yellows. If you've nowhere to plug it into chances are that someone has removed the plug from the loom and used crimps. It's common due to the connectors getting a pretty rough life and a hive for corrosion. Find the wires on the loom and re-connect. It doesn't matter which order you connect the three yellows (or they could be white sometimes) but the red and black must be connected correctly.

What colour is the other wire you mention? The one that lurks with the pick ups? The neutral light wire should be on the opposite side of the engine coming out just above the front sprocket.
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Re: nc24 engine wiring probs

Post by Neosophist » Sat Dec 22, 2012 5:04 pm

The neutral light plug / pickups plug is different on the NC24 and NC21 and wont fit you will need to re-wire the plug

I think this is your problem.

You will have an extra wire

You can see the neutral light circled in this picture and the wiring block for the pickups (green plug)

this plug is different on the NC21 (and the NC21 loom of course)

Image
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rusty1210
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Re: nc24 engine wiring probs

Post by rusty1210 » Thu Jan 10, 2013 9:54 pm

yes that picture you put up is spot on thanks at last someone knows what i am trying to do
my bike is nc24 1989 and it has the cdi with two plugs not the early one with three plugs and one wire
any how the loom is all wired in ok but on the engine the neutral light switch has five wires that dont go into the loom, now the last time you did say to splice the wires into the loom but i dont know what they do or which wires they are ment to go to.
also i have never had this running to
plus when i try to fire here up she is popping and farting out of the carbs and tail pipe, is this because its a nc21 engine in a nc24 +loom as i have seen people say about 360 timing and 180 timing
someone must have put a early engine in a later bike eg nc21 to nc24 and come across this before
or is it going to end up getting another engine to match the bike and loom and cdi
please help as i am pulling my hair out
thanks rusty

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Re: nc24 engine wiring probs

Post by Cammo » Thu Jan 10, 2013 11:43 pm

rusty1210 wrote:plus when i try to fire here up she is popping and farting out of the carbs and tail pipe, is this because its a nc21 engine in a nc24 +loom as i have seen people say about 360 timing and 180 timing
21's and 24's both have a 180 degree firing order - the nc30 has 360 degree - so I doubt that's an issue.
rusty1210 wrote:someone must have put a early engine in a later bike eg nc21 to nc24 and come across this before or is it going to end up getting another engine to match the bike and loom and cdi
please help as i am pulling my hair out
I just learnt that nc21's use a camshaft position sensor (to trigger firing), so I really doubt that the cdi's from 21 and 24 can be made to work on each model because of this change. Covered here (the 'early' and 'late' model engines discussed are 21 & 24 respectively): viewtopic.php?f=24&t=39739

I think it would be far easier to use the loom and cdi that matches your engine, try a wanted ad in the classifieds.
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Re: nc24 engine wiring probs

Post by magg » Fri Jan 11, 2013 2:46 am

From other posts it would appear that not all nc21 engines used a cam sensor. If yours does then it should be located between the carbies on the front cylinder head with a lead hanging free. May be we need a sticky regarding engine swaps to put all the info.

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Re: nc24 engine wiring probs

Post by magg » Fri Jan 11, 2013 3:00 am

Thinking about it, cam sensor or no cam sensor should not be a problem as nc24 did not have one. Therefore nc24 ignition control unit does not expect a cam sensor signal, just pickup signals. If engine runs but only poorly then the pickup signal wires may be reversed even if the 21 and 24 plugs go together. This would alter the timing being sent to the ignition unit. You could try just swopping the wires to see how it runs. There are betters way to check the signals but you would need specialized test equipment.

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Re: nc24 engine wiring probs

Post by Neosophist » Fri Jan 11, 2013 12:06 pm

It's been a while since I've done this and I am nowhere near an NC21 / NC24 to look. If I could get to one I could show you how to do it but i've forgotton!

You have both engines right?

You have an NC21 engine and your trying to put it into an NC24 bike which is why it doesnt fit.

Instead of the single wire neutral switch you have a a black thing there with 6? wires coming from it which if you remove you will see clicks in and out.

The NC24 has a green multiplug in that place with only 5 wires.

Just a thought but before you do anything further, have you tried starting it with the clutch pulled in.. I suspect it might be cutting the spark due to the neutral light not functioning and the bike thinking its in gear.. (clutch in should allow this to work providin the clutch swtich is ok)

try that while i think over how to fix it
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

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Re: nc24 engine wiring probs

Post by chownsy » Thu Feb 28, 2013 10:42 pm

I had a simular problem when installing my NC21 lump into the NC24 frame. I ended up cheating and putting on the NC21 loom and TDI. I would like to know what wires to swap over as I think my TDI unit is playing up as when the bike is warm it missfires between 9000 and 11000 rpm under load, wont go over 90 at all and wont start well.

Bikes had loads done to it, http://www.repsolhondanc24.co.uk this is the link to the bike restoration with loads of pics and whats been done.

Basically

NC21 engine in NC24
NC21 loom and TDI unit
New Dynatek coils
New battery
New rectifier
New spark plugs
New jets
Cleaned carbs
New carbs to engine rubbers and clamps
New HT leads
New radiator
New silicon hoses
New bearings

Richard

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Re: nc24 engine wiring probs

Post by magg » Fri Mar 01, 2013 6:47 am

Have you measured the battery voltage with engine running at idle and 5000 rpm.


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