Honda NSR 125 Engine don't Stop

[Mauy]

Hello to everyone this is my first post.

I apologize for my English but I'm Italian and I do not speak often in English

I have a problem with my Honda NSR 125 F '92 JC20, about a month ago one morning the engine doesn't start, I've checked everything and I finally decided that was the cdi unit CI572, fortunately a friend had an identical unit and gave it to me.

Once mounted the new unit the engine is started immediately without any problem, but now it will not turn off!

If I take the key the lights go off and all the instrumentation too, the tachometer goes to zero but the engine remains on, the only way to turn it off is put the first gear and drop the clutch.

It not turn off even with the kill switch

according to you is another unit fails or is something else.

Thanks to everyone for the advice

[Vincent]

This might be a pre-ignition or "pinking" problem. If you have a build up of carbon on top of the piston and/or the cylnder head, it can glow red hot and ignite the fuel. One way to tell is to carefully remove the spark plug cap and see if that stops it - if it doesn't, it's time for a decoke

[Mauy]

ok I try this evening

but before I replacing the cdi unit I never had this problem and I use the bike every day

[Vincent]

[Mauy]

The problem is always even when the engine is cold, practically I started the engine and immediately try to shut it down but remains on

I do not think the unit could be wired incorrectly because the unit is like my original that has done for 17 years and to link it you just put the plug in

[Vincent]

Very strange Does the ignition key feel like it is turning properly?

[Mauy]

https://img63.imageshack.us/img63/8018/img3475b.th.jpg

https://img692.imageshack.us/img692/5145/img3471o.th.jpg


These are the two cdi unit that i've tryed

[Mauy]

the ignition key seems to be working correctly because when I put it in the off position turn off everything except the engine, then the engine does not stop even with the kill switch on handlebars

[Vincent]

Hhhmmm - different numbers on those CDIs. Hopefully, Alain will be along, he is the resident NSR125 expert and should know more.

[Mauy]

I have already sent a pm to Alain
He told me that lets me know something tomorrow

[Mauy]

last night I started to check again and I noticed that with the ignition key in off position the bike stays on because it continues to get power to the spark plug if I remove the spark plug cap I see the sparks, and if I unplug one of the ignition coil wire the engine turn off immediately.

And the bike turns on with the kill switch in off position.

Give me some ideas I'm almost desperate

[Mauy]

Alain's suggestion I checked all the connections of the CDI unit block of the lock and the kill switch but nothing has changed the bike never shuts down.
while doing various tests, however, is a strange thing happened at some point the starter has been entered and continued to run also with the key off position so I disconnected the wires from the battery I had to push start the bike and returned normal.
I remounted the bike and I went home I did about 40 km, got home the bike still does not turn off, but I noticed that at hot engine if I get it low rpm (as in a roundabout) and then open it acts as a vacuum and tends to fade.
This morning I took the bike going to work I walked another 40 km I stopped at the bar and miracle the bike turn off with the key, I tried for 4 or 5 times and was always off with the kill switch and key . Then I went to fill up the bike is off with the key but then doesn't start with the elettrostart lit I really struggled but I managed to turn it on push, and once I get to work I tried to turn on and off more times it works fine and turns on and off without problems.
the defect that did not turn on when I went for gas is like when I have the old cdi unit.
now I think is a problem of a bad contact somewhere or the starter.
Someone has no idea what the problem might check to solve them

[Mauy]

News

now the bike is almost always on and off

but when engine is hot it turn off at lower rpm, for example, if I stop at a traffic light if I not keep accelerated the engine turn off and then makes it hard to turn on or when I arrive at a roundabout, alwayas at lower rpm, the engine trying to shut down but when I open the gas it takes over and begins to push again.

dispersion??
bad contact??
Bhoooo

[sumpgard]

try checking the earth connections to the battery and frame there is one by the coil if one of these are lose the bike will continue to run hope with the ignition on or off hope this helps .

[alains]

i am pretty sure that your problem is oxyded terminals and the main ground which comes from the starter (big green wire) . you should also check all the loom especially where it's clipped on the frame . your erratic idling comes certainly from your choke piston , when you put it off the piston base close has a convex rubber which close a hole . if this hole is not completly close the engine will idle very low and sometimes cut off . to cure , change piston with the spring and eventually the cable . also a sharp bend or a stiff cable do the same bug
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the worst day fishing is better than the best day working

[Mauy]

alains I did not understand what you mean you can re-explain more simply I use google translate to understand what you say and honestly I doesn't understand more or less anything in your last post

[alains]

send me a pm with your mail , i'll give you some picts
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the worst day fishing is better than the best day working