NX250 Thread -- official ADV owners manual

Discussion in 'Thumpers' started by valvecrusher, Mar 17, 2008.

  1. larry31

    larry31 Back Roads Explorer

    Joined:
    Mar 24, 2011
    Oddometer:
    356
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    New Hampshire
    Sakone
    Quote: Nice condition. 22k miles. Street tires. Included was lithium grease sprayed on the chain and tire. Using this bike primarily for street. Decided to change a few things.



    Are your wheels stock size? If so, what tires do you have for street?

    I have a 1990 NX with original wheels ( 16" & 19" ) and would like to try street tires, but can't find a size to fit.
  2. IheartmyNx

    IheartmyNx Ihave2draft

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  3. IheartmyNx

    IheartmyNx Ihave2draft

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    No, not the jetting... At least mine is still SUPER super lean... It's cold natured and needs to warm up even in the mid to upper 70's.

    Runs like a bat out of hell when it's cold and dry though.

    I'm itching to see what it's like jetted. (3rd gear wheelies?:D) I bet it's good for another 1 or 2 h.p on the Butt Dyno.

    Take your trap door (of the muffler) off unless you're running around federal lands. It might be a placebo but I think mine runs better.

    There are two posts on this site that previous owners say THEIR bikes were slow or ran out of steam over 55. Mine has plenty of roll-on at 55 even in 6th... I do not even have to downshift.


    The Husky guys say the SMR450 gets like 5 more hp when they shorten the can by 4-5 inches... There's plenty of that to spare on the NX's...

    I wonder if that E3 plug would help...

    EDIT: Plus, advancing the fuel pump in the carburetor...
  4. SAKONE

    SAKONE one cylinder

    Joined:
    May 12, 2012
    Oddometer:
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    los angeles
    The DNA air filter by itself seems fine, just bought it so I don't have to buy a new filter for awhile. Exhaust upgrade, and new sized jets and some dyno time should take care of my performance upgrades.




    My rear is a 120/90/16 the front is 100/90/19 both Kenda challengers. Still getting used to tire sizing for motorcycles. Off the shelf tires from a store around this area. Fairly cheap.
  5. tntmo

    tntmo Been here awhile

    Joined:
    Jan 31, 2012
    Oddometer:
    544
    Location:
    San Diego, CA
    14,292 miles and the NX250 is dead.

    I sold my NX250 to my neighbor and friend when his Baja Bug broke down for about the fifth time. He had been renting cars while he repaired his VW, so he was happy to have reliable and cheap transportation in between breakdowns.

    Yesterday he called me at work and said that the bike made a bit of a grinding noise and then lost power and wouldn't start. My wife rescued him with the truck and when I got off work I took a look at the bike. Pulling the valve cover showed no immediate damage, but as I turned over the engine I saw that the exhaust valve buckets stayed depressed after the cam passed over them. I checked the timing and it was off by quite a bit, looks like the timing chain skipped and the exhaust valve are probably bent. No telling what other damage has occured until I get the head off.

    So much for reliable, less than 15,000 miles isn't that impressive.
  6. tntmo

    tntmo Been here awhile

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    Cam chain was stretched a bit, not all the way loose though. Teeth all stripped on the cam drive gear on the crankshaft, chain slipped and piston hit the exhaust valves. Cam gear is integral with the crankshaft, so I need to buy an entire crank. Piss poor design.

    [​IMG]
  7. Gebogen

    Gebogen Been here awhile

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    Okay what is the process for using the vynal? Heat gun? Any prep involved? That came out very nice.
  8. IheartmyNx

    IheartmyNx Ihave2draft

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    If you fill in your location, someone might be able or inclined to want to help you more... If you're in or around middle TN, PM me.


    Otherwise, PM (Preventative Maintenance) or how the bike was treated, is a bitch....

    I got mine at 13k, have not rode it ONE day where it hasn't been in the red and it has over 26,000 on it.

    I havent so much as adjusted the chain tensioner.

    I beat it like a red-headed rented mule daily and have not had so much as a hiccup.

    When the horn starts sounding weak or dead, that's my que vibes have loosened the positive battery terminal and I need to tighten it.

    If I ever get the Valvoline oil out of it, it will NEVER EVER EVER go back in it again (twice now; the clutch sticks and it takes FOREVER to warm up on cold days, shifting is VERY poor unless it's at operating temps, and the lever had to be adjusted after the change so it would stop rolling in gear.).

    Otherwise, rear tires are the worst part of my bike... If I can stop backing-it-in EVERYWHERE, EVERYDAY I ride it, I might can get over 3,000 miles out of one.

    Hopefully the spoons I just bought will end all my screwdriver innertube punctures:D
  9. clanbree

    clanbree Adventurer

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    Mar 31, 2012
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    D/FW
    I'm starting to think I'd better replace that timing chain tensioner on my 4,100 mile 1988 NX.
  10. tntmo

    tntmo Been here awhile

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    The tensioner seems like it worked fine, and it wasn't extended all the way. If I had checked it the day prior to the engine crapping itself, I wouldn't have been overly alarmed at it. Maybe it did fail, but even then I don't know how all the teeth on the crankshaft got stripped out.
  11. SAKONE

    SAKONE one cylinder

    Joined:
    May 12, 2012
    Oddometer:
    7
    Location:
    los angeles
    This was my first try at this vinyl wrap. Clean the surface as if you were going to paint it. Just basically have a section of vinyl ready cut for a section of plastic but have 2/3/4 inches overlap of vinyl. Then just peel and stick, using a heat gun to basically get the curves correct along with a plastic scraper to smooth out the vinyl. I did mine around 11pm-1am since I had other projects to finish and it shows in my work. At 30mph it looks great, and 0mph you can tell its vinyl because of the edges. It takes some patience. Just careful with the heat gun. You can actually remove and re apply it if you get bubbles/creases.

    I didn't sand the old sticker glue off all the way down and it shows up on the vinyl. I just did this because I had no time to shoot paint and would hate it if I were to scratch paint. Vinyl is forgiving and it shows when you apply the material. Cost about $120 for the bike. If you want something besides flat black and doesn't need to be maintained this would be it for appearance upgrades.
  12. thirstybuck

    thirstybuck Adventurer

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    Jun 14, 2011
    Oddometer:
    82
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    USA
    Sorry to see this. I'm in the same boat, but my crank cog is ok so I found a used top end.

    On that note, is there a way to determine if the tensioner is functioning properly? I want to be sure when I put everything back together.
    Thanks.
  13. tntmo

    tntmo Been here awhile

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    I think the tensioner must have failed on mine.

    Does anyone know if this crankshaft can be pressed apart? I may have found a deal on a used crankshaft but the connecting rod bearing is questionable.
  14. scrambler66

    scrambler66 Been here awhile

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    Oct 5, 2011
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    352
    Location:
    Germany
    For some time I was thinking of boosting the power of my Nixie – AX1 cams did not lead to more ponies. In Brazil Honda is selling the XRE300, which engine is basically taken from the NX without the water cooling.


    [​IMG]


    XRE300 tuning parts such as piston, cams or even a forged connecting rod are available https://www.hjmotos.com.br/forged/534-forged-connecting-rod-honda-xre300.html , for even reasonable prices. So now we have to find out more about the XRE300, for instance technical data or parts lists, to make sure that the parts will fit :D

    Apprently a french guy already used a XRE310 piston in this NX, he calles it NXR310. Since the stroke of the NX is longer, we will even get 310 cc out of it

    [​IMG]
  15. IheartmyNx

    IheartmyNx Ihave2draft

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    What would help out tremendously in the power department is if we could get the specs off the liquid cooled NX400.

    The NX is already a stroker compared to MOST 250's... I don't need anymore STROKE. Bore, is another story.

    [​IMG]
  16. IheartmyNx

    IheartmyNx Ihave2draft

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    Yes, but any word on the compression ratio?

    If it's lower, depending on how you look at it, it might be counterproductive...




    Some time on Google searching all Honda Single-Cylinder engines with 60mm stroke and 92mm bores might turn fruitful...

    Might not...


    Check THIS out for inspiration.

    Using a KTM piston!!!

    http://www.supermotojunkie.com/showthread.php?123232-Cr(m)250-supermoto-build


    While this guy (follow the links) had major problems finding parts. http://www.johnnystoybox.com/piston_comparison.htm
  17. IheartmyNx

    IheartmyNx Ihave2draft

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    Ok ok... Hiccup!


    Bike won't start.

    Runs, but won't start.

    Why: Left... Or should I say, "found", the bike with the key in it and on. Battery, dead.

    Ran it off, fired right up. (4th gear fellas)

    Decided to ride thinking it'll charge the battery... No.

    Couple of down-hills I killed it and tried the starter... Nothing.

    Battery Terminals: Tight.

    Runs with the light half dead and yellow, horn worked the first time but later sounded like a dying animal...



    Is a diode open, shut or $%it, I don't know... I hate electricity-fyed things....

    What could it be???

    I'll put it on a charger sometime running it off gets to be too much of a pain:D My guess is that'll fix it though.


    Wonder what a battery and starter weighs... :D
  18. clanbree

    clanbree Adventurer

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    Mar 31, 2012
    Oddometer:
    45
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    D/FW
    It sounds like it may be as simple as a sulfated battery. A sulfated battery will niether accept nor hold a charge without some coaxing. Our charging system needs a good battery to work properly, so it may seem that alternator isn't working. Trust me, it is. If it had not been, the bike would not have continued to run until you shut it off.

    If a battery is left standing in a discharged condition the lead sulfate on the plates inside will become hard and have a high electrical resistance. The lead sulfate may become so hard that normal recharging will not break it down. Most charging sources, engine alternators and battery chargers, are voltage regulated. Their charging current is controlled by the battery's state of charge. During charging, battery voltage rises until it meets the charger's regulated voltage, lowering the current output along the way.

    When hard sulfate is present, the battery shows a false voltage, higher than it's true voltage, fooling the voltage regulator into thinking that the battery is fully charged. This causes the charger to prematurely lower it's current output, leaving the battery discharged. Charging at a higher than normal voltage and low current may be necessary to break down the hardened sulfate.

    The way to salvage a sulfated battery is to charge it at a high voltage rate (2.5 ~ 3.5 volts above it's rating) until the sulfates start to break down. The battery will start to off-gas and the electrolyte will bubble. Once it starts doing that, turn the charger down to a lower setting and let it trickle charge over night.
  19. IheartmyNx

    IheartmyNx Ihave2draft

    Joined:
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    Location:
    Nashville TN, no chit, police state.
    Clanbree.... Thanks a ton. Will try ASAP...



    Big Bore...

    I've wondered, for some time now, at the similaritys of the jugs off this bike...

    I swear they look familiar:D

    Via Google... NT650 Bore x Stroke: 79mm (Hmmm) x 66mm.

    EDIT: Quick eBay search says no way, Jose...

    [​IMG]
  20. gforcephuket

    gforcephuket n00b

    Joined:
    May 24, 2012
    Oddometer:
    2
    Thanks for your nice comments fikse and plz do excuse my late reply, been pretty wrapped up with work and other things so not spending much time online recreationally.

    Regarding a couple of your questions below I must first say that I'm hopelessly inept mechanically, insofar as skills and knowledge. :scratch While I've been riding for over 30 years it's just a fact of my life I can't change. I know when a bike is working properly or not and can certainly point mechanics in the right direction but that's about where it ends. So I get everything done at local shops here in Thailand. The upside is that it's really really cheap to get stuff done here; the downside is that most local mechanics speak very little or no English and my Thai is lame, so more than half the time I don't know exactly what they do to my bikes or how they do it -- I just can know if something is right or wrong after a few minutes of riding the bike. I know that sounds a bit iffy but it's been working for 12 years I've been here, knock on wood.

    So I'm sorry that I can't tell you exactly how they got in the DZR shock but it's in there and works fine, much stronger than the stock, though yes it's A LOT higher (but I have a 36-inch inseam, so no problem) and not sure how much compared to the SV650's (though yes, I'm sure it's softer given the DZR's off-road inclination.

    Because the seat height was much higher and was forcing me forward toward the tank too much, I had to have the seat re-done (which I had already made quite higher than stock). So for just $10 I had the seat completely re-scultped recently (into a nice 2 level jobby) and it's just about perfect, but I have to take take it back and have him add a bit more height as he took off too much (making it about normal AX-1 height, which is too short for my long legs). I'll take a pic after I get the seat re-done again soon.

    Regarding brake lines, I forgot to mention in my mod list that my master brake cylinder is also not stock, (frankly I'm not sure what bike it's from, a case as per above of little communication with my mechanics, but it works :evil. But yes you are correct, it's a straight line from the reservoir down to the brake.

    The master brake cylinder I have on there now is pretty good, especially with the braided lines and good pads, but I'd like to put on something even stronger -- can anyone recommend something that would work. I asked the guys at one shop if an XR 250 mbc would go on there but they weren't sure and said they'd actually have to get one and try it. Any advice about this would be appreciated.

    I'm quite sure the Supertrapp isn't specifically designed for the NX/AX-1, in fact I'm personally not aware of any aftermarket exhaust specifically for these models, though there could be. I'm not sure what bike this Supertrapp was originally designed for, perhaps an XR?? It works good and sounds great but I can't really say for sure I'd recommend it. Frankly since I've had that on, the bikes peformance (I ride it hard like all my bikes) has not been as consistent compared to the stock, though I'm not sure if that's related to the Supertrapp or to not just having the carb properly tuned (which mechanics aren't super great at here compared to back home).

    Thx for the advice about the KTM made in India! I've been thinking a bit about getting a new 690, but I'm pretty sure the KTM we'd get in Thailand here would be made in India....And you're right, overall you just can't be Honda quality, I love my little gixxer and Ninja 650 too but at heart I'm a Honda guy.

    Good luck with the NX re-build -- it'll be worth it! :ricky Again I'm not Mr. Mechanical but anything general or not too complex I'll be glad to help if I can.