NX250 Thread -- official ADV owners manual

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

  1. valvecrusher

    valvecrusher tractus pro pensio™

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    @spychic

    any NEW tire is going to be 'heavier' than an old worn slick tire....plz keep that in consideration...it's the 'flywheel effect'..,increased by tread material..

    also, the starter button control over time oxidizes, and gets 'dirty' like the Nintendo NES cartridges used to do...i know a few riders(not just NX'ers) that have similar issues..and by repeated squeezing and holding while depressing the button, and moving your thumb all around will re-polish the contacts inside the switch control...
    (or take it apart and use some emery paper)

    I'm not saying that IS your problem, just that you might be over-thinking it<,
    due to the perception of the heavier rear tire, deflection, and the flywheel effect...

    I don't think a bad CDI caused any delays in engagement of the starter, only a non-start when the engine turns over..


    The 'increased vibration' could be from the new tires diameter lifting the rear axle, and putting more weight on the forks,
    increasing whatever vibes by subtle changes in geometry...

    I would check fork fluid condition and levels, check fork tube in the clamps, etc..
    if it's suddenly become excessive?


    The good news, the more you ride, the more wear, the lighter the rear tire !
    And the Duro median is not just bigger, it's a HEAVY tire for it's size...heavier than other models of the same 'size'....


    sorry for any confusing brevity, i broke two cars last week, and i'm hardly making complete sentences after failing to fix one.

    .
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  2. spychic

    spychic Adventurer

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    thanks, valvecrusher, you made perfect sense actually. today, not a single issue with start up and a lot less resistance on gravel and grass, so maybe it was just new rubber stickiness. I am scrutinizing every aspect of the bike since adding the new tire. sucks when machines don't work correctly.

    sorry to hear about your cars. hope something comes through for you soon.

    tires can make or break a vehicles ride, handling and even suspension. for how expensive they are to purchase/install, we kind of have to make the right choices in the first place.
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  3. spychic

    spychic Adventurer

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    thx PTC. sounds like you get it with the tractor issue. sounds like a cheap easy few steps to follow and rule out other things first. would be surprised if it's the CDI given so few miles on the engine. feel free to find the TW40. I can't even find them off NX for sale as parts.
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  4. Kolb Driver

    Kolb Driver Been here awhile

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  5. mattmacklind

    mattmacklind Adventurer

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    OK so I've been enjoying the NX since I bought it in July, its been my first bike. Since then I've bought a 71 CL350 and a 74 CL125 but those are different stories for different forums. Anyway, I replaced the rear shock with the SV650 shock which has been great. I replaced the fork oil with 15w which I thought made little difference but now that I've ridden more it has stiffened it up some but they still dive on braking. I expect to finish my front forks work with the aforementioned auto valve springs and replace the seals also. I replaced the chain, air filter, changed the oil, and it has new tires (Duro Median ear and Vee Rubber front). Now recently I've noticed it stumbles a bit at higher revs but only in higher gears. I can rev up to 7K-8K in 1-4th just fine, once I hit 5th and 6th it starts to hunt, surge and stumble. If it gets through the 5K-6K range, it will get back to normal but there is just that spot under that unique load that causes some stumble. So I;m going to replace the spark plug and go ahead and rebuild the carb. Thought I might just clean it but if Im removing it I may as well rebuild it. I also picked up one of those Coleman Mad dog seats which is OK I guess, softens up the seat some anyway.

    If anyone has any thoughts on the stumble let me know but it looks to me like a carb/jet issue anyway, and thanks for the heads up on those plugs I had one but was missing the other...
  6. Spurlock

    Spurlock Long timer

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    Hey mattmacklind, congrats on your bikes and the work you've done on the NX so far. On the stumbling problem I would suspect either a lean main jet or bad CDI, or both. I've found the stock main jet to be a bit on the lean side, especially for the California model. I switched to a #145 which improved top gear/high rpm power. Ditto for a buddy's NX I worked on which had exactly the symptom you describe. But both our bikes also had the proverbial bad CDI which also caused an elusive high rpm missfire. In my experience Honda CDI modules from the late 1980s/early 90s very often have bad solder joints inside. I've repaired 10 so far and found bad solder joints in all of them. So just to eliminate that possibility I would go ahead and buy a replacement CDI from Rick's Motorsport Electrics and be done with it.

    You can do a barnyard diagnosis on a possible lean condition by holding WOT in 6th gear and gradually closing the choke slightly. If you apply just a very little choke and the stumble disappears, that confirms it's running lean and could possibly benefit from a larger main jet. Of course it could also mean your main jet is OK but passages in the carb are partially plugged. IF slight choke makes the problem worse that might indicate a rich condition, but not likely that would happen unless someone has prieviously gone way too big on the main, or if your air box inlet is blocked off by that extra pair of gloves under the seat.:lol2 If you do change jets, stick with genuine Keihin jets from someplace like PJ Motorsports or Jets R US.

    Good luck!

    -Bill
  7. Spurlock

    Spurlock Long timer

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    So it looks like the Bridgestone TW40 is discontinued in the 16" size, and the only other similar tread tire in the stock 120/90-16 size, the Vee Rubber VRM 163, is out of stock until probably next spring. So I just installed the Duro Median 130/90-16 rear tire and thought I'd report back on fit and performance.

    I estimate the original new diameter of my TW40 in the 120/90 size was 23-11/16". The larger Duro tire measures 25" new which means the gearing is increased by about 5.5%. My gearing is already higher than stock by about 7.6% since I run a 14T C/S sprocket which always worked well for my light weight. With the gearing now even higher the bike still pulls OK in top gear, I just use 6th more as an overdrive when not bucking a head wind or climbing a grade. But I might switch back down to the stock 13T C/S sprocket after more testing.

    Tire width is almost identical at 5" so there is no problem with swing arm clearance, still plenty of space inside the swing arm. But clearance might be tight if someone used a slightly too-short chain and had to have the wheel all the way forward.

    Performance wise I didn't notice anything unusual, the bike rides smoothly and traction seems about the same as the Trail Wing in gravel. So long story short, other than the slightly higher gearing the tire seems comparable to the TW40.

    -Bill
  8. scrambler66

    scrambler66 Been here awhile

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    From Bridgestone the TW202 in 120/90-16 (on the pic to the left) is still available. Good on- and offroad tire - the latter only of course if its not too muddy. To the right the new Bridgestone AX1 Adventurecross in 100/90-19.

    The Adventurecross performs surprisingly well on road, way better than the old Michelin T63 or the overrated TKC80. And offroad it's a breeze.
    its the best dual purpose tire I've ever had - and the exciting news is that the Adventurecross will be available in 90/100-19 and 120/90-16 in Jan 2020 :clap.


    [​IMG]

    [​IMG]
  9. Spurlock

    Spurlock Long timer

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    Good to know, thanks for the review. Unfortunately the TW202 does not seem to be available in the US.

    -Bill
  10. mattmacklind

    mattmacklind Adventurer

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    Thanks for the links-I think I will work my way toward the CDI since I’ve already invested in some other possibilities, but that answers the question as to where to get one. That’s cheaper than I thought, too, and on a bike this old it wouldn’t hurt to just replace it anyway, but we’ll see...
  11. DualSportRider

    DualSportRider Adventurer

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    I picked up a "deferred maintenance" 88 NX250 with 8700 miles on it with the intention to freshen it up and turn over to a new owner...

    Long story short, after spending some time with it, I seem to enjoy it a bit more than I thought I would. Might be a keeper...?

    Currently on the rear, I have just a Street tire on it, and want to get some different treads for adv purposes...Any opinions here on the DUNLOP K460 tire?
  12. Kolb Driver

    Kolb Driver Been here awhile

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  13. Spurlock

    Spurlock Long timer

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    I was looking at that tire, seems to be the only source for the Dunlop K460 available in the US. But it says NOS and from what shows of the date code it appears to say 663. Could that really be the 6th week of 1963? Seems risky to buy a NOS tire unless the actual manufacture date is stated.

    EDIT: I just emailed the seller asking for date of manufacture. Will post back here if/when he replies.

    -Bill
  14. Spurlock

    Spurlock Long timer

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    Yesterday was cool and cloudy for a change so I took the NX on a little 20 mile afternoon escape for more testing of the new Duro Median tire. Heading down off my hill on the way to the high ridge in the distance...

    [​IMG]

    A couple miles down the road I turned off to start a four mile climb up a mostly deserted road, first pavement...

    [​IMG]

    [​IMG]

    then gravel for a while...

    [​IMG]

    then back to pavement for a series of steep twisty switch backs.

    [​IMG]

    Part way to the top I start to get some nice views...

    [​IMG]

    ...then the climb continues and the road turns back to gravel. The Duro was working great floating over fresh gravel that's not yet compacted.

    [​IMG]

    Almost to the top...

    [​IMG]

    Climbing the last bit to the summit...

    [​IMG]

    Just a bit more and I reach the ridge top and lots of communications towers, then ride for a couple more miles before taking a different road back down.

    [​IMG]

    Back on pavement I head back down hill.

    [​IMG]

    [​IMG]

    Heading for home and happy hour, I'm glad I took the afternoon off from chores to share a bit of quality time with the NX! And I have no complaints with the Duro Median rear tire. Hoping it wears better than the Trail Wing.

    [​IMG]

    -Bill
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  15. Spurlock

    Spurlock Long timer

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    UPDATE: just got this reply from the seller: "We have 24 of these. They are at least 20 years old"

    Uh, no thanks. They must be as hard as rocks.

    -Bill
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  16. nxcoyote

    nxcoyote rough and tumble play...

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    Some pics taken on my latest ride.

    20190901_140118-EFFECTS.jpg 20190901_121212.jpg 20190901_140059.jpg 20190901_134033.jpg 20190901_125456.jpg
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  17. valvecrusher

    valvecrusher tractus pro pensio™

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    Don't you think it is odd that both number(not alphanumerics) series from L - R on that sidewall in that picture read....

    ( 6 6 3) 120/90-16 6 63 P

    on that tire...?



    I think the imprint you see is the tire code, some internal something.
    Elsewhere, exactly the same style oval imprint is both

    (Serial number) (date code)


    on one sidewall, or the opposite side.....


    In fact, if you locate the mark in the close-up in the single shot of the full tire, you can see the
    ( 663) just before the 120/90-16

    Ok, counter clockwise 60° or so and you can see either the
    manufacturers serial #, or date code or both inside the

    *(xxxxxxxxx)* oval imprint...


    I can't actually make out what is in that imprint, but i suggest there is a full imprint date code,
    and also manufacturers serial imprinted on the tire on one or both sidewalls.
    These imprints will appear like the ( 663) in shape and form, but that one is not either.
    (imho)


    The seller SHOULD be able to get you pictures of both sidewalls ?
  18. Spurlock

    Spurlock Long timer

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    I think you're right, the date is not actually 1963. Since the seller told me they are "at least 20 years old" I wouldn't buy one though.

    -Bill
  19. Spurlock

    Spurlock Long timer

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  20. nxcoyote

    nxcoyote rough and tumble play...

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    That particular road was built in the comunist era, mainly to exploit natural radioactive minerals. But the mining projects were abandoned for some reason.
    The road leads to the alpine goal, then turns into a hiking trail that leads to Leaota peak. The area is open to the public. There are the usual sheep flocks along the way and you ca also find a lot of wild animals in the area.
    We have a lot of these roads that are still opened here in Romania, but they are slowly closing them down. So I'm taking every chance I get to ride them while I still can.
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