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NC700X Hard to Start Intermittently

treybrad

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Ok, I have a bit of an issue and figured I could use some more heads brainstorming causes. My NC has become hard to start, at seemingly random times -- I've not detected a pattern anyway. Sometimes it's first thing in the morning when it's 'cold' (it's June in TX, it only drops into the 70's at this point). Or today it was fussy when I started it after work, sitting in the 90°F heat.

Video from the other day, morning start up:

[video=youtube_share;0mcAmm-iMco]http://youtu.be/0mcAmm-iMco]NC700X Hard Starting - YouTube[/video]

A little twist of the throttle and it'll usually fire up. This happens maybe 40-50% of the time. Some mornings it starts immediately. :confused:

If I remember right, this started right about the time I finished my Iron Butt ride. Portions of that were into a nasty West Texas headwind, and I had the throttle literally pinned for a few hours at a time. I didn't think much of it really, this was standard procedure on my little WR250R and TW200 and neither seemed to mind a bit.

Thinking maybe all my WOT exploits fouled a plug or something, I replaced the spark plugs this weekend because they're easy to get to, and OCR found a cheap NGK substitute for the Iridium stock plugs. No change in the way it runs afterwards. It fired right up this morning, but gave me trouble this afternoon like I said. OEM plugs looked just fine (~23k miles) and still had proper gap.

14146740017_82b23fe6ba_c.jpg


My next thought is to check the valves again. I checked them at just shy of 20k miles and adjusted a couple to spec, but I'd be shocked if they moved in 3k miles. Valve noise is the same as always, I'd think if I didn't torque down an adjuster they'd loosen up very quickly and be noisy. Not sure what else I could screw up there.... My 10k and 20k inspections they've barely moved, and I only adjusted them to put them back to the middle of spec.

You can see the voltmeter on the dash, battery seems healthy to me. Maybe something with the fuel pump? I'm going to start 'priming' it twice and see if that helps -- ie, turn the run switch on, let it prime. And then cycle the run switch off and on again. Maybe the fuel pump is going, or the priming time is being cut short? Seems the same as it always has to me (you can hear it in the video).

So, any other ideas? It's been doing it for a few weeks now, quite a few tanks of gas have gone through it, so I don't think it's bad gas. Once it starts it runs great. I intentionally did quite a few full throttle, all the way to rev-limiter pulls today on the way home from work and it runs great. This is my daily commuter and weekend warrior, it doesn't sit for more than 48 hours, ever. Cruising around the hill country this weekend I got my best fuel mileage ever, 82.5 MPG. Previous best was ~75 MPG.

Does anyone know how the EFI choke/enricher works on these? It has never failed to start right away once the engine is fully warm, so maybe there's some temperature sensor that's out of whack? No CEL or anything (that'd be too easy :p). This started in late April, about the time it stops getting cool here at all, or I'd try and see if it's consistently better or worse when cooler out.

Any help mucho appreciated.

trey
 
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Is it just me or is the starter motor turning over a bit slow? Is it possible to have normal voltage but insufficient amperage? (What I know about electricity you could stick in your eye with your optometrist's complete blessing).
 
Is it just me or is the starter motor turning over a bit slow? Is it possible to have normal voltage but insufficient amperage? (What I know about electricity you could stick in your eye with your optometrist's complete blessing).
The first thing I thought was the starter sounds "different" than mine -Mike, you hit it, it does sound slower than mine.
Don't know if that's the problem, though -sorry.

Good original post! So many people are very vague in describing the problem. You've done your slutheing!
 
Mine always fires right up, even in the dead of winter. On the extremely rare occasions it goes a second or so before catching, the starter seems to be more energetic than that in the video. The only time it has sounded like that was when the battery got waaaay down one time. A few hours hooked up to the Optimate 4 tender cured that.
 
Interesting, maybe the battery is going, it's just been such a slow death I haven't noticed the gradual weakening. I know there are others who have had some premature battery issues.

Will be interested if others agree the battery sounds a little weak. Anyone want to post a video of their NC starting up for comparison??

trey

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I dunno. :confused: I always like to start with the simplest and cheapest possible remedies. I'd run some SeaFoam or injector cleaner/engine treatment of your choice through the system and see if there's any improvement after a tank or two of fuel.
 
Check for loose battery connections.

Check battery voltage while cranking. If it drops too far replace.

A fuel system cleaner (techron is recommended) would not hurt.
 
I think your battery is fine. It showed 10.9V while cranking. You could do a load test on the battery to confirm before you change it. Because its intermittent your going to have to get a scanner on it and see if there are any codes present. I'm not sure if the NC's have a self diagnostic procedure. My best guess would be a the coolant temp sensor. You could ohm it and see it in specs before seeing your Honda dealer to get the system scanned.
 
I had a similar problem this morning. First time in 2 years.
Difference is I plugged in the GPS (empty so it drew amps from the battery straightaway), and I had to crank say 4 times and then the bike started.
Other times, it is always 1 turn 1 startup.

I also think it is a battery amperage problem which can lead to non-start.
Check your battery and disconnect unnecessary assessories or make a on-off switch for them (they remain off til bike is on).
:D
 
I think your battery is fine. It showed 10.9V while cranking. You could do a load test on the battery to confirm before you change it. Because its intermittent your going to have to get a scanner on it and see if there are any codes present. I'm not sure if the NC's have a self diagnostic procedure. My best guess would be a the coolant temp sensor. You could ohm it and see it in specs before seeing your Honda dealer to get the system scanned.

This is kind of along the lines I was thinking. Because of the intermittent nature of it I was leaning towards some sensor giving false info to the ECU.

Here's my thought process on something like this. The bike reads the sensor and it says it's hot out, so don't 'choke' it too much. Well, what if that sensor is reading 20°F too high? Instead of 95°F when I got out of work yesterday, it thinks it's 115°F? It might not trigger the enricher system at all... it wouldn't have mattered so much in winter, 50°F or 70°F is most likely within the threshold for the enrichment.

I could also be full of crap, and that's not how the system works at all, I really don't know. I'll have to hunt around in my service manual for the temp sensors and how to check them.

I also think it is a battery amperage problem which can lead to non-start.
Check your battery and disconnect unnecessary assessories or make a on-off switch for them

A good suggestion, but there's nothing on my bike that stays powered once the key is off. There's a GPS plug, 12v socket in the frunk, heated grips, heated jacket plug, and that voltmeter -- none of it should be pulling any amperage when off. I will check for current draw with the bike switched off to double check.

Shouldn't the battery voltage be reading a wee bit higher than 13.9 when bike running?

I really don't know... at idle, is that low? I'll have to pay attention to what it's reading at stops and while cruising on the way home. I only pay attention to the volt meter during winter when I'm running my heated gear for long periods.

if the battery does have drop in voltage this could interfere with the starting it requires 11.5v to run the ECU and components to start the engine

11.5v while cranking? I thought the 11.1v shown while cranking seemed sufficient, Googling around 9.5-10v seems to be 'normal' for cars.

Started up fine this morning when I 'double primed' the fuel pump. I'll keep trying that, and I'll check the current draw when the bike is off and see what I can find.

Thanks for the suggestions so far!

trey

*edited to add.... the temp sensor things fits also with my better than expected fuel mileage recently. Not that 82 MPG is out of question for this bike, but I've done rides just like that before and never cracked 75 MPG. Could be coincidence, or it could be the bike thinking it's hotter than it actually is outside and leaning out the mixture to compensate for the less dense air....
 
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FWIW, I Watched the voltage meter on the way home. 14.1v at idle and 14.3-14.4v at any other speed/RPM. Seems normal, but doesn't mean the battery isn't on the way out either.

trey
 
Easy way to do a quick check to see if the battery is causing the issue. When you first go to start the bike turn the key on but don't start it. Let the battery drain down so the voltage on your meter shows just under 12V. Turn the key back off then on again and try to start the bike. Were you able to duplicate the starting issue with the slightly drained down battery? Have a charger handy to recharge the battery, don't rely on the bikes charging system to do this for you. The charging system is designed to maintain battery voltage and not charge the battery, that's what a battery charger is for.

For your information. To do a load test on a battery take half of the CCA of the battery and and use that number (amps) to load the battery for 15 seconds. Battery voltage must be above 9.6V after 15 seconds with load applied to pass. So a 200 CCA MC battery would be tested at 100 amps for 15 seconds and must have a voltage greater than 9.6V under load.
 
Check for loose battery connections.

Check battery voltage while cranking. If it drops too far replace.

A fuel system cleaner (techron is recommended) would not hurt.

X2! I recently had an issue like this with my car, except it would start at all. It turned over real slow like the battery was dead, and then nothing. So, thinking my battery was toast I took it to my local auto parts store to get a new one. The people in front of me in line had a dead battery issue also. They had the guy at the counter test the battery, it was found to be low, so he offered to charge it for them. So I though, maybe I should have mine tested first before I jump the gun and just get a new one. The guy tests it and it's PERFECT!! It is actually showing more CCA's than it is rated for. Whew, that saved me some coin. Then I thought, damn, must be the starter. But while talking with the guy at the counter I had mentioned how I tried jumping my car off my wife's car with cables and it still wouldn't start. So he says must have been a bad connection. Then the light bulb goes off!! I go home slap my old battery back in the car, clean off the battery posts and the connecters with a wire brush made for battery terminals, and BAM!! The car fired right up!

So, in summary check your connections, make sure they are CLEAN and SECURE. There may be some resistance building somewhere in the circuit, by either a loose connection or corrosion.

Hope this helps. If not hope you get the root of the issue and get it fixed soon. I hate intermittent vehicle problems that leave me worried I'll get stranded somewhere.
 
I don't understand the concerns with the bike's alternator charging the battery. If the alternator voltage is higher than the battery voltage current will flow to the battery and charge it. If a battery is low charge the running motor / alternator will charge it. It takes time whether with a charger or alternator so don't expect a 15 minute ride to charge it. I have had motorcycle batteries too low to turn on the dash lights, jumped the bike to start it, gone for a ride and never hooked up a charger and no more problems with the battery if I didn't forget to turn the key off again when I got off.
 
As a mechanic you learn that the charging system is designed to maintain the battery, not charge it. Charging a low battery with the charging system will make the system output max amps for long periods of time which will shorten stator/alternator life.
 
As a mechanic you learn that the charging system is designed to maintain the battery, not charge it. Charging a low battery with the charging system will make the system output max amps for long periods of time which will shorten stator/alternator life.

Not true on a permanent magnetic alternator.......it's output is 100% all the time and the excess power is sent to ground when not used to run the vehicle and charge the battery. No extra strain is put on the alternator or regulator in this type charging system.
 
Easy way to do a quick check to see if the battery is causing the issue. When you first go to start the bike turn the key on but don't start it. Let the battery drain down so the voltage on your meter shows just under 12V. Turn the key back off then on again and try to start the bike. Were you able to duplicate the starting issue with the slightly drained down battery? Have a charger handy to recharge the battery, don't rely on the bikes charging system to do this for you. The charging system is designed to maintain battery voltage and not charge the battery, that's what a battery charger is for.

For your information. To do a load test on a battery take half of the CCA of the battery and and use that number (amps) to load the battery for 15 seconds. Battery voltage must be above 9.6V after 15 seconds with load applied to pass. So a 200 CCA MC battery would be tested at 100 amps for 15 seconds and must have a voltage greater than 9.6V under load.

Excellent info, thank you. I'll let the battery drain itself a little and see if that doesn't at least make it consistent.

So, in summary check your connections, make sure they are CLEAN and SECURE. There may be some resistance building somewhere in the circuit, by either a loose connection or corrosion.

Another good idea. I don't guess I've had a reason to even take off the inspection panel to look at the battery in months. It's possible the connections are a little corroded.

The past two days I've done my 'double prime' and it's started up instantly every time. Could be complete coincidence, or not. I'll keep doing that until it doesn't work, to at least debunk that idea.

I'll have time to really mess with it this weekend, thanks for all the ideas -- keep 'em coming!

trey
 
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