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Question NC700X won't turn over...?

...I must apologize to you for one thing I overlooked, you were right: the regulator will not fry, the fuse will go first anyway....
This is a joke, right? Not very funny though.
You apologize in advance for what you say next? What would have to be done to burn the 30 Amp fuse? And why would this happen? It's hard to imagine.
 
This is a joke, right? Not very funny though.
You apologize in advance for what you say next? What would have to be done to burn the 30 Amp fuse? And why would this happen? It's hard to imagine.
I apologized for me being wrong and you being right (as in the regulator will not fry as I falsely stated).
I also thought through your input and I think I found the source of our disagreement: on older bikes (mostly kickstarters) which I am more familiar with, the order was alternator-rectifier-regulator-battery. The battery voltage was regulated which was simpler to do and needed less semiconductors, also the delicate, smaller alternator was not regulated by shunting, instead the battery was (and the power was much smaller anyway.) For example on older Ducatis there is an additional sensing input for the battery voltage, and there's the regulated, high power line.
On newer bikes, as on the NC, there's one more rectifier between the battery and the regulator, and the battery is only sensed for reference voltage - you were right again.

So yeah, I stand corrected.

In other news, my starter problem may be mechanical after all, as in the resistance of the engine is somehow bigger. I was able to find another NC and had a feel for the force needed to turn the main shaft and mine definitely needs more force/torque. There's no defined point where it is obstructed but overall it is harder to turn than on the other bike. That may be a failed bearing or something else, which the engine was able to overcome but the starter cannot. I was not able to notice it while riding, so here's hoping that it's not that serious.
 
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If the door between us is closed no matter how terrible you are. If I can't see you, I'm not afraid of you.
Yes, this is why I said "NOT THE ALT/R/R ... PRESUMABLY THE DIODES IN THE RECTIFIER CAN HOLD BACK THE VOLTAGE"
As long as your door is sturdy, me kicking at it won't break it down, but a battering ram might. The values we are talking about are likely in the "kicking" range, not the "battering ram".
But, if I'm already inside your house (jumper cables to the battery terminals, already "past" the regulator), the front door being closed isn't going to keep me from smashing your dishes.
 
In other news, my starter problem may be mechanical after all, as in the resistance of the engine is somehow bigger. I was able to find another NC and had a feel for the force needed to turn the main shaft and mine definitely needs more force/torque. There's no defined point where it is obstructed but overall it is harder to turn than on the other bike. That may be a failed bearing or something else, which the engine was able to overcome but the starter cannot. I was not able to notice it while riding, so here's hoping that it's not that serious.
Thinking about what could put a drag on the engine that the starter couldn’t overcome, the water pump comes to mind. The NC engine was designed with the fewest number of rotational parts as possible to reduce friction losses. The oil pump runs off the balancer shaft, if I recall correctly, and the water pump runs directly off the end of the camshaft. All rotating parts moving when you try to start the engine in neutral are running enclosed, in engine oil, except if there is a bushing or bearing in the water pump that is not engine oil lubricated.

I have no idea the likelyhood of a failed water pump causing drag, or whether it could even cause your starting symptoms, but the idea just popped in my head so I wrote this post.
 
Thinking about what could put a drag on the engine that the starter couldn’t overcome, the water pump comes to mind. The NC engine was designed with the fewest number of rotational parts as possible to reduce froction losses. The oil pump runs off the balancer shaft, if I recall correctly, and the water pump runs directly off the end of the camshaft. All rotating parts moving when you try to start the engine in neutral are running enclosed, in engine oil, except if there is a bushing or bearing in the water pump that is not engine oil lubricated.

I have no idea the likelyhood of a failed water pump causing drag, or whether it could even cause your starting symptoms, but the idea just popped in my head so I wrote this post.
Thanks for the input, I was thinking about that too. I'll start to demount things and see what happens. Hopefully I won't have to split the crankcase... I've done that on other bikes a few times but the NC being that "cramped" engine-wise, I'm not looking forward to doing it...
 
...my starter problem may be mechanical after all, as in the resistance of the engine is somehow bigger...
If you can notice unusual resistance to manually turning the engine with the spark plugs removed, it is time to consult an experienced mechanic. I could give you the address of a good repair shop, also in the Schengen Area ;), but with your many years of experience with motorcycles, I'm sure you have a trusted repair shop. Good luck.
 
If you can notice unusual resistance to manually turning the engine with the spark plugs removed, it is time to consult an experienced mechanic. I could give you the address of a good repair shop, also in the Schengen Area ;), but with your many years of experience with motorcycles, I'm sure you have a trusted repair shop. Good luck.
I don’t see why getting away from servicing an electrical problem and switching over to a potential mechanical problem automatically justifies hiring outside services.
 
I don’t see why getting away from servicing an electrical problem and switching over to a potential mechanical problem automatically justifies hiring outside services.
In fact, I'd even argue that in lots of cases, a mechanical problem is more within the realm of a DIY than an electrical problem.
But maybe that's just because I'm a mechanical guy with a little bit of electrical knowledge instead of the other way around.
 
I don’t see why getting away from servicing an electrical problem and switching over to a potential mechanical problem automatically justifies hiring outside services.
It is relatively easy to make the right decision. Finding an electrical problem in starting of engine is incomparably easier than finding a mechanical problem. Electrical components are readily accessible for servicing and test equipment is widely available. Mechanical problems inside the engine are very rare and there is a greater chance that an experienced mechanic will encounter such cases more often by virtue of his profession.
Of course, seeking the help of an experienced workshop is not required. I, personally, would not be afraid of such a task. The only question is if I would have liked it. Probably not anymore. A long time ago I already had many occasions to dismantle much bigger internal combustion engines. I don't miss it.
 
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Update, everyone: it seems my compression is higher than expected on startup. There's no dedicated Honda shop near me, so I took my bike to a Yamaha specialized guy, he's good but not necessarily familiar with NC700. We thought about the problem together and the question arose if the NC has some kind of decompression mechanism for starting, ie. some mechanism that opens up an exhaust valve while cranking or something similar. We looked at the service manual but there seems to be no indication of this. Anyone knows if the NC has this kind of thing? The bike can be started by pushing and seems to be working fine, idling and revving well. So there's no indication to take it apart fully if it can be avoided...
 
Update, everyone: it seems my compression is higher than expected on startup. There's no dedicated Honda shop near me, so I took my bike to a Yamaha specialized guy, he's good but not necessarily familiar with NC700. We thought about the problem together and the question arose if the NC has some kind of decompression mechanism for starting, ie. some mechanism that opens up an exhaust valve while cranking or something similar. We looked at the service manual but there seems to be no indication of this. Anyone knows if the NC has this kind of thing? The bike can be started by pushing and seems to be working fine, idling and revving well. So there's no indication to take it apart fully if it can be avoided...
There is no decompression system (to aid in starting) on the NC engine.
 
Sorry if I am back tracking....

How long have you owned this motorcycle?
Was it starting fine for some period of time?
If so, how long?
What were the compression measurements?

I am having trouble understanding what could cause a sudden INCREASE in compression. I guess a significant buildup of carbon on the piston or head could be the issue. It would be a gradual change over time. If so, what caused such a buildup of carbon?

This is certainly a head scratcher, I am interested in the root cause.
 
Sorry if I am back tracking....

How long have you owned this motorcycle?
Was it starting fine for some period of time?
If so, how long?
What were the compression measurements?

I am having trouble understanding what could cause a sudden INCREASE in compression. I guess a significant buildup of carbon on the piston or head could be the issue. It would be a gradual change over time. If so, what caused such a buildup of carbon?

This is certainly a head scratcher, I am interested in the root cause.
I bought it new in 2013. I used it for 2 years, after it was in storage for 5 years (family issues). I used it again for 2 years, no problems. It only has 10000 miles. Last autumn there were starting problems, I thought it was a dead battery, so bought a new one. After that it seemed better but looking back there were a few cases where I felt the starting was a bit difficult.
No carbon buildup, checked it with endoscope camera, piston, cylinder and head is clean. Compression was not measured the conventional way, because if the compression meter is screwed in, the starter won't turn the engine over, so you cannot measure it as usual. It was done by spinning the main shaft and measuring the torque. I don't remember the exact values, it was compared to another NC700 and the torque needed was significantly higher. With the plugs out, the torque values were similar, that's why we thought it's about compression and hence the idea came of a possible decompressor malfunction - which doesn't exist so, yeah, here we are. :)
 
If compression pressure is higher than expected, my thoughts would be pointing to some kind of extraneous material like fogging oil being introduced into the cylinder, but a dead giveaway to that would be excessive smoking on startup.
A blown head gasket could allow coolant into the combustion chamber, causing that nasty sludge produced from engine oil and coolant mixing.
Is your coolant overflow level low?
Is your oil milky looking?
Are your spark plugs looking OK?
Any excessive anti seize used on your spark plug threads?
 
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You don't know if compression is increased because you can't measure it. It is practically not possible to increase the compression ratio without changing the combustion chamber. So you have to check what is causing the difficult cylinder stroke. First try to inject some oil on top of the cylinders. Plug the spark plug holes with rags and turn on the starter for a few seconds. Repeat this several times.
 
I do not understand where the idea came from that there is something like a "decompression mechanism for starting". The principle of operation of an internal combustion engine is to compress the fuel mixture. It would be difficult to start the engine without proper compression.
 
I do not understand where the idea came from that there is something like a "decompression mechanism for starting". The principle of operation of an internal combustion engine is to compress the fuel mixture. It would be difficult to start the engine without proper compression.
Decompression devices can be found on manual start (kick, hand crank, etc) engines. Never seen one on an electric start engine but it does not mean they do not exist.

@spark82: When you say the torque was "similar" with the plugs out, how similar? Within 5%, 10%, ?
 
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