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Question NC700X won't turn over...?

670cc

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Update: remounted the cleaned starter motor. The engine turns over without any suspicious noise or sign if the spark plugs are out. Still somehow it feels to me slower than usual (I'm not sure about that, it's just a feeling). If I put back one plug, it sometimes fails to turn, if both plugs are in, it fails almost every time, a few times it gets one or two revolutions, and then gets stuck at the next compression stroke. I checked and cleaned the connections, I tried to feed the starter motor directly from the battery with jump cables, same result. Any ideas?
It sounds, at this point, like the starter motor is bad, or current to the motor is being limited by an as-yet undiscovered resistive connection. However, I believe you said you connected a battery directly to the starter motor and it could not crank well, which would eliminate all electrical connections and the starter relay. From the exercises you have performed on the engine, it does not appear that the engine, transmission, or clutch has a mechanical problem.

It’s always a tense moment when you try the new part. Swapping the starter motor with a new one may lead to a celebration, or “oh crap, now what do I do.”
 

lootzyan

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If the starter motor switch is eliminated and you have a reliable source of power then you only have two components of the electric circuit: the starter motor and the electric wires. Checking the connections is quite simple so you have only the starter motor as a suspect.
 

lootzyan

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There is something I'm not familiar with: the starter clutch.
Could a faulty clutch cause a reduced engine speed under load when trying to start the engine?
 

itsmenc700

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If a car battery that has over and above current needs for the bike cant turn it over correctly the only thing it can be is the starter motor,
I say that because you stated when it did start it ran fine, and you hooked a car battery directly to the starter and it didnt spin correctly.
 

spark82

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There is something I'm not familiar with: the starter clutch.
Could a faulty clutch cause a reduced engine speed under load when trying to start the engine?
I think before I buy a new starter motor I'll get familiar with the starter clutch first. All the more that my bike has a low mileage (15.000 miles or so), the starter motor should not die this early. A faulty clutch may have damaged to starter motor or prevents it from getting up to speed, so I would like to sort that out before mounting a new motor anyway. Well, it seems I have to dig into this a little deeper. I'll update when I'll have something.
 

TNHoosier

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I think before I buy a new starter motor I'll get familiar with the starter clutch first. All the more that my bike has a low mileage (15.000 miles or so), the starter motor should not die this early. A faulty clutch may have damaged to starter motor or prevents it from getting up to speed, so I would like to sort that out before mounting a new motor anyway. Well, it seems I have to dig into this a little deeper. I'll update when I'll have something.
Do you have a shop near you that repairs electric motors? They should be able to test it for proper torque, etc.
 

lootzyan

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After a quick search I found one YT example of a bad clutch but it is a BMW.
If the design is similar then you should hear "strange" noises. So the clutch is probably not the cause.
An experienced mechanic could find out.
 

MZ5

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I've never heard of a starter clutch causing drag on the starter system. I've only heard of them semi-failing (or failing outright), which means that _mostly_ the starter spins fine but doesn't get engaged to the crankshaft and so does not turn the engine over.

I happen to think this is a starter motor problem, but I definitely don't know or have really high confidence.
 

itsmenc700

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I have to agree with the above.
The clutch is just a mechanical piece between the actual starter motor and the flywheel.
Cant see this having any drag on the system.
AND since you had it apart you'd have seen if it was broken, ect...
 

670cc

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For reference, in the case of the NC engine, the starter clutch is apparently a one way device that allows the starter to engage with a still crankshaft, but does not allow the turning crankshaft to spin a still starter. When starting, the clutch would disengage the starter once the engine speed reached a certain point relative to the starter motor speed. See photos from the service manual.

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bigbird

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Will a failing sprag clutch not turn the engine over properly, or not disengage the starter properly?
From what I know, as long as the bearings in the sprag are not seized, the sprag clutch should have no impact on the turnover rpm of the starter.
I would be looking at the starter motor, not the sprag clutch.
 

TNHoosier

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For reference, in the case of the NC engine, the starter clutch is apparently a one way device that allows the starter to engage with a still crankshaft, but does not allow the turning crankshaft to spin a still starter. When starting, the clutch would disengage the starter once the engine speed reached a certain point relative to the starter motor speed. See photos from the service manual.

View attachment 48017
View attachment 48018
View attachment 48020
I can't get past the thumb bend in the picture!
 

TheIronWarrior

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Did you get a voltage read at the starter motor contact? It should be close to battery voltage.
I'd measure battery voltage while trying to start, and then motor voltage while trying to start. A significant drop suggests a circuit fault, little to no difference suggests bad starter motor or mechanical failure (though I expect you'd have other symptoms if it was something mechanical).
 

spark82

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Did you get a voltage read at the starter motor contact? It should be close to battery voltage.
I'd measure battery voltage while trying to start, and then motor voltage while trying to start. A significant drop suggests a circuit fault, little to no difference suggests bad starter motor or mechanical failure (though I expect you'd have other symptoms if it was something mechanical).
I tried to connect the battery directly to the starter motor contacts to eliminate everything else. Same thing happens. Measured the voltages, too, nothing abnormal. It's freezing around here, couldn't persuade myself to work in the cold garage yet, maybe I'll try to inspect the clutch somehow without disassembling the whole thing but I think I'll get a used starter motor from ebay from a reliable source and give it a try. A new starter motor costs a bit too much for my taste. I could hook up a 4,5HP Briggs to start my engine for that price. :)
 

spark82

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Hmm. Always assume more than one problem until you eliminate it down to one.

Keep in mind, that I am not too bright.

Things that matter:
Kick Stand Switch
Battery
Starter Motor
Engine internal electricals
Engine external electricals (Computer)
Spark producing electrical device
Switches such as ignition

You get the idea. Testing for spark is pretty easy.

Test the easy stuff first.

I had to short out my kickstand switch to make my DCT run. If this is faulty, all sorts of weird stuff happens.

Check what is easy access. Battery terminals and all that. Have the battery professionally tested using a HONDA battery tester. I have purchased bad batteries.

When your computer fails, it might fail when it is hot, then cool down and work again

Spark usually works or it does not

Wanna test stuff fast? Start unplugging whatever you do not need to get the bike to work. Then force the bike to work,

If you cannot pop-start the bike, you cannot eliminate the battery and the starter.

Such diagnosis is a process of elimination. And you need solid facts. Start with the battery.

If the bike pop-starts, then it is clearly not seized.

The starter motor can be burned out, jammed and frozen. So there are ways to check that.

I usually ask myself how old are things? When were they last replaced or touched? Was something unplugged recently?

I fix super complicated stuff. When you do that, you need to make a big problem small. Focus on that.
Since the engine cannot get to the point where the spark would even matter, I'd leave that out until it does. :) The starter starts to move and when the piston starts to compress, it stops and only keeps it there. When I release the starter button it moves back to the starting point (compression pushes the piston back). Same when applying voltage directly to the starter.

Got an idea from the Yamaha forum tho, there are types that use similar starter motors. I'll take a look at it, and report back.
 

TheIronWarrior

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Since the engine cannot get to the point where the spark would even matter, I'd leave that out until it does. :) The starter starts to move and when the piston starts to compress, it stops and only keeps it there. When I release the starter button it moves back to the starting point (compression pushes the piston back). Same when applying voltage directly to the starter.

Got an idea from the Yamaha forum tho, there are types that use similar starter motors. I'll take a look at it, and report back.
I had a small airplane with an old battery. The battery would not produce enough juice to get past compression to start the engine if it had sat for any length of time (hours, even). What I had to do to get it started was to turn the key, let go of the key, let the propeller bounce back from the compression, and then time the next turn of the key so the momentum of the engine turning was added to the starter push to get past compression and start the engine.

Based on that experience and your troubleshooting so far, I'd suspect either battery (though you said it seems good) or starter motor (worn brushes or windings maybe).
Did you get a voltage read on the battery while cranking as well?
Can't eliminate something mechanical in the engine either. When you try a start, do you have it in N, or in gear, stand up, and clutch pulled in?
The cold will make the oil drag on the moving parts a little more, and will also affect battery performance, so either of these could be contributing.

I doubt anything "engine" electrical where you have a manual version and your problem seems to be getting enough starter motor output to turn the engine. There's nothing really electrical that would come in to play except the start circuit.
The interlocks should all be simple on/off switches grounding relays, plus you eliminated the start circuit entirely, so that rules that out to me.

From the service manual, the listed options for "starter motor turns slowly" which I think best describes this issue is:
Low battery voltage [you mentioned voltages looked good]
Poor connections (battery or start motor terminal) [likely eliminated where you juiced the motor from the battery directly)
Faulty start motor

I think they oversimplify and "forget" that the engine mechanicals can cause an issue, so don't necessarily take this as gospel.
Have you tried unmounting the starter motor to see if it seems to turn fine with no mechanical load? I think the motor has a ground cable instead of only grounding through the case, so you should still be able to power it with it "removed". This may (or may not) help point to a bad motor.

It could also be possible that the starter motor has some "debris" from the brushes. As they wear down, the bits of brush that get worn off can build up and affect the function of the start motor. Have you tried disassembling and cleaning the motor itself?
 

670cc

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I had a small airplane with an old battery. The battery would not produce enough juice to get past compression to start the engine if it had sat for any length of time (hours, even). What I had to do to get it started was to turn the key, let go of the key, let the propeller bounce back from the compression, and then time the next turn of the key so the momentum of the engine turning was added to the starter push to get past compression and start the engine.

Based on that experience and your troubleshooting so far, I'd suspect either battery (though you said it seems good) or starter motor (worn brushes or windings maybe).
Did you get a voltage read on the battery while cranking as well?
Can't eliminate something mechanical in the engine either. When you try a start, do you have it in N, or in gear, stand up, and clutch pulled in?
The cold will make the oil drag on the moving parts a little more, and will also affect battery performance, so either of these could be contributing.

I doubt anything "engine" electrical where you have a manual version and your problem seems to be getting enough starter motor output to turn the engine. There's nothing really electrical that would come in to play except the start circuit.
The interlocks should all be simple on/off switches grounding relays, plus you eliminated the start circuit entirely, so that rules that out to me.

From the service manual, the listed options for "starter motor turns slowly" which I think best describes this issue is:
Low battery voltage [you mentioned voltages looked good]
Poor connections (battery or start motor terminal) [likely eliminated where you juiced the motor from the battery directly)
Faulty start motor

I think they oversimplify and "forget" that the engine mechanicals can cause an issue, so don't necessarily take this as gospel.
Have you tried unmounting the starter motor to see if it seems to turn fine with no mechanical load? I think the motor has a ground cable instead of only grounding through the case, so you should still be able to power it with it "removed". This may (or may not) help point to a bad motor.

It could also be possible that the starter motor has some "debris" from the brushes. As they wear down, the bits of brush that get worn off can build up and affect the function of the start motor. Have you tried disassembling and cleaning the motor itself?
The thread has covered the battery health possibility. A car battery was substituted with the same no-crank results. Also, the conditions for starting, like clutch position, gear position has already been defined. It was reported that during the onset of the symptom, that the engine ran normally even though starting was difficult. It has already been stated that the starter motor has been disassembled and cleaned. It has already been stated that the starter motor has been run with no load on it.

Please review the thread from the beginning. You are asking questions that have already been answered, or proposing possibilities that have already been investigated.
 

TheIronWarrior

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The thread has covered the battery health possibility. A car battery was substituted with the same no-crank results. Also, the conditions for starting, like clutch position, gear position has already been defined. It was reported that during the onset of the symptom, that the engine ran normally even though starting was difficult. It has already been stated that the starter motor has been disassembled and cleaned. It has already been stated that the starter motor has been run with no load on it.

Please review the thread from the beginning. You are asking questions that have already been answered, or proposing possibilities that have already been investigated.
Apologies, I've been responding to a few threads on a variety of forums for starter issues and mixed this one up with another one where none of this was tried.
 
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