NC24 ignition pick-ups / 2 cylinders not sparking

[EvanTate]

Hi guys,

Having a recent issue with my NC24. Was riding home about 3 days ago when the bike lost all power and refused tor rev up. Had it open and have come to the conclusion that there is no spark on cylinders 2 and 3. Plugs are good, as are the coils and plug leads and wiring. Which leaves my fault at either the pick ups or CDI.

Problem is, I have no clue on how to go about check the pick ups as I don't even know where they are, nevermind what could be wrong with them. Apparently I'd notice any faults such as a crack or anything.

Another possibility occured to me, I thought maybe it was the Jap restriction that was faulty. Unfortunately none of the gauges work at the moment so I can't tell you the top speed (+-80km/h according to my friend behind me) or the revs. Could very well be maxxing at around 6000rom though, I took the speedo apart and checked everything. The limiter seems to work with a disc that runs between two magetic pick ups. When you hit 180km/h the disc moves out from between the magnets thus engaging the limiter. I read here somewhere that a direct line of power to the wire could solve it. Tried that with no luck.

Any help would be greatly appreciated.

[thunderace]

The pick ups are under the right hand engine cover.

There is no restriction on the NC24, just a lamp that lights up to politely tell you that you are exceeding a certain speed (80kph IIRC).

[Neosophist]

As above, there is no speed restriction on the NC24.

On the NC30 and NC35 the disc engages at 180km/h and cuts the spark to the cylinders to prevent further speed.

On the NC24 this disc engages at 80km/h and lights up the warning lamp.

Why don't your gauges work?

There could be many reasons why it isnt sparking.

The NC24 has 4 seperate coils. 3 and 4 are right rear and right front cylinders.

First thing is to double check they are sparking, hold the plug threads on a metal part of the engine to earth it and crank the engine, check the kill switch isnt on.

Best to remove all the plug caps to stop the engine starting on the other cylinders.

[EvanTate]

The pick ups are under the right hand engine cover.

There is no restriction on the NC24, just a lamp that lights up to politely tell you that you are exceeding a certain speed (80kph IIRC).

80kph yes that's correct. Apparently some NC24 imports were restricted but I had no clue so I double checked anyway.

And thanks for the location, I'll check them tomorrow.

As above, there is no speed restriction on the NC24.

On the NC30 and NC35 the disc engages at 180km/h and cuts the spark to the cylinders to prevent further speed.

On the NC24 this disc engages at 80km/h and lights up the warning lamp.

Why don't your gauges work?

There could be many reasons why it isnt sparking.

The NC24 has 4 seperate coils. 3 and 4 are right rear and right front cylinders.

First thing is to double check they are sparking, hold the plug threads on a metal part of the engine to earth it and crank the engine, check the kill switch isnt on.

Best to remove all the plug caps to stop the engine starting on the other cylinders.

Temp gauge needs new sensor, rev counter is totally dead as far as I can tell. Tried giving some power but no needle movement. And the speedo used to work but the speedo drive on the wheel itself has worn out. I have a spare to put in when I get a chance though.

1 and 4 spark. 2 and 3 don't. I swapped the no. 1 and 3 coils around and same thing. The coils are receiving power however I am not sure it is receiving the pulse signal. That's why I want to check the pick ups.

[thunderace]

80kph yes that's correct. Apparently some NC24 imports were restricted but I had no clue so I double checked anyway.

The only NC24s that will have restrictions are those with washers in the carbs for our A2 licence @ 33BHP and done over here. No 24s left Japan with any kind of restriction.

[Neosophist]

Yes, no NC24 came from Japan with any kind of restriction, even then the 33bhp carb washer restictors wont stop a plug from firing.

If you look at the right hand (when sitting on the bike) engine cover you will see a lead coming from it, this is the pickup lead, check that and the plug is ok before you take the cltch cover as you will need a new gasket.

the haynes book has some specs you can measure the resistance of the coils from by testing the plug

[EvanTate]

Haynes manuals for the NC24 are non existent in SA I'm afraid. I can't order online as I don't have a credit card.

The pick ups are measuring 388ohms and 387ohms. Seems ok to me, if both weren't working then there should be no spark at all. I am trying to find out what the resistance should be though.

The workshop said I can take the bike in tomorrow moring and they will swop the cdi out to see if it isn't maybe that causing the issues.

EDIT: I have part of an NC30 manual in PDF. According to that the NC30 pick ups should be 450 - 550 ohms.
Is that maybe the cause then?

If the cdi doesn't work tomorrow can I safely buy pick ups and be confident in the problem being resolved?

[Neosophist]

Haynes manuals for the NC24 are non existent in SA I'm afraid. I can't order online as I don't have a credit card.

The pick ups are measuring 388ohms and 387ohms. Seems ok to me, if both weren't working then there should be no spark at all. I am trying to find out what the resistance should be though.

The workshop said I can take the bike in tomorrow moring and they will swop the cdi out to see if it isn't maybe that causing the issues.

EDIT: I have part of an NC30 manual in PDF. According to that the NC30 pick ups should be 450 - 550 ohms.
Is that maybe the cause then?

If the cdi doesn't work tomorrow can I safely buy pick ups and be confident in the problem being resolved?

The Rear of the NC30 Haynes manual lists all the specs and figures for the NC24 and NC21 under the section NC21 / 24 specifications. Some of them are wrong like jet size settings for NC24 but the pick up coil resistance is right.

The NC24 is listed as between 400 - 500 ohms and the NC21 between 350-430 ohms.

Since your ignition coils are pretty much the same resistance then that does't look likely to be the problem.

Only a technical point but the bike doesn't use CDI ignition it uses TCI, which is a different technology.

The unit could be faulty. But I have not yet come across that issue before. Have you checked the electrical system out of curiosity, if the reg/rec has failed it could have over-volted the system and burned out the ignition box.

[EvanTate]

Just checked the voltage now. Hadn't thought of that. The bike is charging at 18.5v... Pretty sure that shouldn't be higher than about 14v - 14.5v?

Possibly the rectifier that's gone as well then?

[thunderace]

Reg/rec is fried. You may want to check the stator output on all three phases too.

Best replacement reg/rec is an R6 5EB/5SL or R1 4XV unit