AllanB Posted January 26, 2014 Share Posted January 26, 2014 (edited) Still struggling with my NV400 hot stall/start problems and high rpm misfire and read that the culprit could be a shagged stator. Most tests i have read about on other bikes say all phases to earth should be open circuit, but I am getting 19.5 ohms. All readings across phases bell out at zero so no broken wires, but what do you think about those earth readings? The stator casing has been damaged and repaired, so that may be the problem, if not do Honda use a common stator type, as my bike is very rare? I haven't done a dynamic test yet which is a little difficult on my bike. Also does the stator have to be disconnected to test, I couldn't make this out and don't want to cut wires unless I have to? Edited January 26, 2014 by AllanB Link to comment Share on other sites More sharing options...
VocalNeal Posted January 27, 2014 Share Posted January 27, 2014 Allan, This may help. https://www.electrosport.com/media/pdf/fault-finding-diagram.pdf RSstator in quebec can also rewind it for you. Just a thought there is a motor rewind place near me, next time you come to Bangkok? Link to comment Share on other sites More sharing options...
AllanB Posted January 27, 2014 Author Share Posted January 27, 2014 Allan, This may help. https://www.electrosport.com/media/pdf/fault-finding-diagram.pdf RSstator in quebec can also rewind it for you. Just a thought there is a motor rewind place near me, next time you come to Bangkok? Thanks for that Neal, my battery output ranges from 13.8 to 14.14v (and a little unstable) when the engine is running circa 1-5krpm, which as far as the chart is concerned means all is well. Besides I don't have a charging problem at all and wonder whether this chart refers specifically to charging, rather than powering the CDI. The bike cranks and starts fine, needing a little choke on colder mornings, but when I have ridden for a while that's when the problems start. I think my next move is to check earth leakage of the stator, this means cutting all three yellow wires to be sure and soldering them back together afterwards along with shrink sleeving, then I have completed another check. This fault is driving me nuts, as the bike otherwise drives so well. Link to comment Share on other sites More sharing options...
seedy Posted January 27, 2014 Share Posted January 27, 2014 Ignition coils can fail when they get hot, and the symptoms can be intermittent. Have you tried a replacement coil / coils ? Link to comment Share on other sites More sharing options...
AllanB Posted January 27, 2014 Author Share Posted January 27, 2014 Ignition coils can fail when they get hot, and the symptoms can be intermittent. Have you tried a replacement coil / coils ? That was my first assumption, bought a Steed coil, made no difference, then two NV400 coils, no difference. The chances of 5 S/H coils all having the same fault are low. We can probably dismiss fuel problems, due to all the cleaning and checks..... Link to comment Share on other sites More sharing options...
Spoonman Posted January 27, 2014 Share Posted January 27, 2014 allan. what fuel are you using ? from my SR thread you know I had issues and purchased new coil/cdi/rectifier but to no avail. I put 95 benzine in it for the run the Ban Seang on the weekend and it ran fine. Because of small tank I had to fill up to come home and all I could find was gasahol and the "miss" returned. Link to comment Share on other sites More sharing options...
mimi9000 Posted January 27, 2014 Share Posted January 27, 2014 Cdi. Replace it. Sent from my iPhone using Thaivisa Connect Thailand 1 Link to comment Share on other sites More sharing options...
AllanB Posted January 27, 2014 Author Share Posted January 27, 2014 Replacing the CDI may be difficult on this rare bike, but will try the benzine as I have been using 91 gasahol, although did try 95 gasahol which made no difference. When I get back from a truck trip will test the stator earthing first. ....thanks Link to comment Share on other sites More sharing options...
paz Posted January 27, 2014 Share Posted January 27, 2014 I doubt that your problem is due to stator or anything related to the charging circuit. Since you have ruled out HT coil already, it can be faulty CDI box or sensor. Link to comment Share on other sites More sharing options...
Garry Posted January 27, 2014 Share Posted January 27, 2014 Also make sure your plug leads aren't deteriorating. Are they carbon impregnated fiber or a wire type core? Sent from my SM-T211 using Tapatalk Link to comment Share on other sites More sharing options...
AllanB Posted January 27, 2014 Author Share Posted January 27, 2014 I doubt that your problem is due to stator or anything related to the charging circuit. Since you have ruled out HT coil already, it can be faulty CDI box or sensor. As I understand it the ignition system is powered by the charging circuit and any malfunction, or fluctuations will affect it adversely. I read on another forum that a guy with the same problem changed the stator and rectifier and the problem disappeared. As I said i will change to petrol, test the stator, after I get back and publish my findings. Link to comment Share on other sites More sharing options...
paz Posted January 27, 2014 Share Posted January 27, 2014 (edited) I doubt that your problem is due to stator or anything related to the charging circuit. Since you have ruled out HT coil already, it can be faulty CDI box or sensor. As I understand it the ignition system is powered by the charging circuit and any malfunction, or fluctuations will affect it adversely. Everything is powered by both the charging circuit and the battery, working in parallel. Proof, disconnect one or the other for a very short time, bike still runs, except on some modern bike that have protection circuitry that prevents it to run with one component disconnected or failed. I read on another forum that a guy with the same problem changed the stator and rectifier and the problem disappeared. I will be glad to say that I was wrong once you report. Edited January 27, 2014 by paz Link to comment Share on other sites More sharing options...
VocalNeal Posted January 28, 2014 Share Posted January 28, 2014 Alan, What haven't you done? Do you know which cylinder? Valve clearance? Spark plug boots are really connected to the wire? Changed the spark plugs (again) Is it missing a heat insulator between the manifold and carbs? Vacuum leak? Spray the whole think with WD-40 and look. Is it missing at idle or when riding? Cut the ignition and remove the plugs see if one is different? Link to comment Share on other sites More sharing options...
ll2 Posted January 28, 2014 Share Posted January 28, 2014 this bike has never ending problems Allan! We told you to buy a second hand bullet proof honda cbr250 Link to comment Share on other sites More sharing options...
seedy Posted January 28, 2014 Share Posted January 28, 2014 As I understand it the ignition system is powered by the charging circuit and any malfunction, or fluctuations will affect it adversely. I am not familiar with your bike model, but on my HD I had the battery fail while riding. The charging circuit could not / would not keep up with the ignition circuit. After new battery installation, things back to normal. In the above the charging circuit was between 13.8 and 14.5 V DC Agree with you - seems to be electrical problem. If you were close by CNX I would run over and give you a hand. You'll get it - just a process of elimination, which is what troubleshooting is all about. Nice to see someone running something other than cookie-cutter bikes. Kudos !! Link to comment Share on other sites More sharing options...
yankee99 Posted January 28, 2014 Share Posted January 28, 2014 the best way to check your stator is a incandescent light bulb. Link to comment Share on other sites More sharing options...
AllanB Posted January 29, 2014 Author Share Posted January 29, 2014 this bike has never ending problems Allan! We told you to buy a second hand bullet proof honda cbr250 It is the same problem...yet to be solved. CBR250 boring, sounds like a knitting machine.......... and too small for me anyway. I think how good I will feel when I have it fixed (hopefully in my lifetime), 43bhp, bags of torque, unique looks, good handling and great sound. We shall see. Bought for 65k with book, spent about 10k on it so far. ....oh and nothing is bulletproof. 2 Link to comment Share on other sites More sharing options...
AllanB Posted January 29, 2014 Author Share Posted January 29, 2014 (edited) Alan, What haven't you done? Do you know which cylinder? Valve clearance? Spark plug boots are really connected to the wire? Changed the spark plugs (again) Is it missing a heat insulator between the manifold and carbs? Vacuum leak? Spray the whole think with WD-40 and look. Is it missing at idle or when riding? Cut the ignition and remove the plugs see if one is different? Suspect both cylinders??? Tappets done, now quiet, but fault remained. Spark plug leads checked swapped and working and it is twin spark anyway, so the chances of both not working unlikely. Twin spark plugs all NGK, so can rule out plugs. Possible vacuum leak, but doesn't explain hot start problem. Only misses at circa 5000+rpm under full load. What do you mean by "heat insulator" has rubber bushes between engine and carbs. ...The plug leads are copper multi-strand, had some spares, swapped them around, trimmed the ends, belled them out, nothing made any difference. Edited January 29, 2014 by AllanB Link to comment Share on other sites More sharing options...
VocalNeal Posted January 30, 2014 Share Posted January 30, 2014 If you bike is 100% original then it has them already. If it has been "worked on" before they may not be there.A thicker gasket-like piece between the manifolds and the carburettor. Link to comment Share on other sites More sharing options...
furyrider Posted January 30, 2014 Share Posted January 30, 2014 the best way to check your stator is a incandescent light bulb. MMMMM incandecent light bulb ??? What? Link to comment Share on other sites More sharing options...
yankee99 Posted January 30, 2014 Share Posted January 30, 2014 the best way to check your stator is a incandescent light bulb. MMMMM incandecent light bulb ??? What? Its not complicated as the stator output is ac. Just need about 100 watt incandescent not led our fluorescent. This test the stator for voltage with a load. I am guessing 50-60 vac at about 3000 rpm Link to comment Share on other sites More sharing options...
AllanB Posted January 30, 2014 Author Share Posted January 30, 2014 If you bike is 100% original then it has them already. If it has been "worked on" before they may not be there. A thicker gasket-like piece between the manifolds and the carburettor. I see what you mena. No the carbs don't fit like that, they are two rubber sleeves, held on by four hose clips. So an inherent heat isolator. Link to comment Share on other sites More sharing options...
seedy Posted January 31, 2014 Share Posted January 31, 2014 (edited) Its not complicated as the stator output is ac. Just need about 100 watt incandescent not led our fluorescent. This test the stator for voltage with a load. I am guessing 50-60 vac at about 3000 rpm Good point - have you checked the rectifier ?? This changes AC to DC to charge the battery. And of course - all wiring and connectors in the charging system. Edited January 31, 2014 by seedy Link to comment Share on other sites More sharing options...
AllanB Posted January 31, 2014 Author Share Posted January 31, 2014 Its not complicated as the stator output is ac. Just need about 100 watt incandescent not led our fluorescent. This test the stator for voltage with a load. I am guessing 50-60 vac at about 3000 rpm Good point - have you checked the rectifier ?? This changes AC to DC to charge the battery. And of course - all wiring and connectors in the charging system. No, not yet, another thing to add to the list, but it doesn't look that easy on my bike, how do you do this? I have fiddled with the various connections and cleaned a few, but access isn't that easy. One reason I suspect the stator is that the ally casing has been damaged and welded up, so there could be an earth leak as a result of the damage. When I get back home I have a list of stuff to check and recheck in some cases and try to get to bottom of this, so please keep the suggestions coming. I have a feeling that the fault is something very simple and I may feel a bit of a fool for not thinking of it earlier. C'est la vie. Link to comment Share on other sites More sharing options...
BSJ Posted January 31, 2014 Share Posted January 31, 2014 "I have a feeling that the fault is something very simple and I may feel a bit of a fool for not thinking of it earlier. C'est la vie." Don't be to hard on yourself. I've spent hours on searching out why I have bike electrical problems only to have a mate come over and fix it in 5 minutes! Link to comment Share on other sites More sharing options...
seedy Posted January 31, 2014 Share Posted January 31, 2014 (edited) I have fiddled with the various connections and cleaned a few, but access isn't that easy. Good place to start. Whenever I found something that someone 'Fixed' it is an immediate suspect. I hear you. Access can be a Real B*tch !!! Have had good luck with dielectric grease. Keeps junctions nice and clean. Edited January 31, 2014 by seedy Link to comment Share on other sites More sharing options...
AllanB Posted January 31, 2014 Author Share Posted January 31, 2014 This is the offending bike, not a great photo. Built specifically for home market between 1983 and 1985, (mine is 1983, judging by chassic number) a 398cc v-twin, twin spark, 6 valve, liquid cooled, engine similar to Honda Steed, but 43bhp at 9000rpm and shaft drive. Link to comment Share on other sites More sharing options...
seedy Posted February 1, 2014 Share Posted February 1, 2014 Nice looking bike. Should have good performance with 43HP I see now the trouble to access wiring. If it was me, and I had exhausted all simple solutions, I would remove the fuel tank and any other body parts to expose the wiring harness. Remove, clean, grease, and replace all junctions. Watch for corrosion where the wire goes into the solderless terminals. Don't know about that bike, but earlier Japanese bikes were notorious for having all the charge current go to the headlight first, and then elseware on the bike. If you follow the main charging wire from the stator you can see if this is true or not. I would re-route the main charge wire to a bus bar fitted as close to the battery as you can get. From there take power where needed. This will also allow you to install circuit breakers and / or fuse holders using modern ATO fuses. Best possible scenario on an old bike - complete new wiring harness with mods as you see fit. But first - let's get it running good !! Link to comment Share on other sites More sharing options...
AllanB Posted February 4, 2014 Author Share Posted February 4, 2014 Allan, This may help. https://www.electrosport.com/media/pdf/fault-finding-diagram.pdf RSstator in quebec can also rewind it for you. Just a thought there is a motor rewind place near me, next time you come to Bangkok? Just back from showing my sister around Thailand and first thing this morning disconnected the stator wires and checked the earth leakage. First of all I thought all was okay, with zero resistance between the yellow stator wires and earth, then I set the DVM to 0-20M ohms and got a reading of 1.43M ohms. Do you have the phone number of this guy as I want to check if this is acceptable as a zero reading in terms of this problem. With 100% continuity of the 3 phase wires, it doesn't need a rewire, just re insulating. The other problem I found is that it was very difficult to tin the 6 wires with solder prior to rejoining, this is usually because of heat damage...any comments? Link to comment Share on other sites More sharing options...
yankee99 Posted February 4, 2014 Share Posted February 4, 2014 You are wasting your time and money imho. If you enjoy doing this which i do then its your time and money. If your stator is putting ac out around 50-60 vac at 3000 rpm close her up and go back check your compression and your ignition system. My money is on a ignition system issue. What wires are you trying to solder? If they have some tinning already they may not be solderable. Why not use proper crimps and a plug? Was it soldered from the factory? 1 Link to comment Share on other sites More sharing options...
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