+2019 GPX FSE250E Air Cooled Modern MX Mountain Goat

Discussion in 'Thumpers' started by Navin, Feb 5, 2019.

  1. ChiefOshkosh

    ChiefOshkosh Been here awhile

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    Thanks for the feedback - at least I know I not crazy! Agree - suspension is great on MX track.

    I can search the fleabag...what WP forks and shocks will fit? Year etc.?
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  2. bark sampler

    bark sampler Been here awhile

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    I used a shock off a 2018 KTM SFX 250: perfect fit. I think forks have even more options as KTM used the same tube diameters and axles since like 2003/4 depending on model. [edit: see @Navin post below as there was a caliper change I forgot.]

    I wanted to make the stock stuff work, but with some searching I had new take-off forks and a nice shock both with appropriate springs for not much more than a professional revalve and springs. Too easy. And it saved a few pounds and parts are as simple as any KTM shop.

    If I sell the bike I can split the suspension and recover much of it too. Stock stuff is fairly serviceable but not WP quality, parts just aren’t interchangeable with anything. Last I talked to Gary he had a lot of parts coming in, so it may be easier now.
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  3. Navin

    Navin Long timer

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    +2016 SXF/FC and +2017 any linkage bike shocks. If you go back further for the forks you need the bigger axle too and the brake caliper changed also (Maybe around 2011? 2013?) where the new stuff everything bolts on.

    Big axle AND wheel spacers too!
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  4. Navin

    Navin Long timer

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    I forgot you need a KTM shock bolt at the bottom shock mount as the threads are different pitch.

    The nice thing about the WP, anyone can tune it for you and its pretty inexpensive in new take off or freshly built condition. Plus if you get them to your liking you can keep putting them on your new/next bikes. My WP forks have been on like five different bikes now, I bought them in 2016.
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  5. ChiefOshkosh

    ChiefOshkosh Been here awhile

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    Ok, I have three options.
    1.) check w/Pro Tune
    2.) find used WP suspension
    3.) check w/Gary

    Plenty to work on over the winter. Thanks again.
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  6. bark sampler

    bark sampler Been here awhile

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    Here’s a snapshot of the shock piston. Note the thick stack of face shims on the rebound and limited space for flow on the compression side. Both were single stage, so some shuffling can give you more compliance if you turn a smaller one into a cross over.
    D8378297-77ED-4E42-B40E-F1C570F04703.jpeg

    I added some base shims to the compression side to center things better and make sure there weren’t flow limits with that small gap to the base plate. I looked all over for shims and eventually found some I could use on McMaster. My goal was to make the adjusters work in a useful range instead of all the way out.

    That photo was taken right after I opened it up. All those black pieces were from the top-out bumper disintegrating. I think there were only a few that had this problem and GPX fixed us up.
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  7. Navin

    Navin Long timer

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    Depending on what WP stuff you find you might still need a revalve/spring so factor that into anything you might buy.
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  8. oldie230

    oldie230 Adventurer

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    Are the specifications on the GPX website are correct for the engine???

    It says the 2021.5 (due to arrive in September) is 71mm bore and 62mm stroke.

    That does not sound like the 172FMM 3A engine at all which is 72mm bore and 61.something stroke

    Joe Henner says that the 172FMM 3A engine shares very little, if anything, in common with the 165/169FMM ZS engines.

    BUT, if this engine is 71mm x 62mm it just might be a slightly bored version of the ZS 169YMM engine in the AJP.

    If that is the casem it would have a two peice head (seperate rocker cover) and CFR230 type cams can be adapted (a bush rplaces the roller bearing on the non drive sprocket end). No only that, but that engine has a substantially wider barrel stud spacing and could be re-sleeved to take pistons up to 75mm, pssobly 76mm. The AJP toye engine also has a couple of mm larger intake and exhaust valves which should feed a bigger bore easier. With 62mm stroke and 74mm bore you get 268cc. if it can go to 76mm it would be 281cc.

    But this all hinges on what the new engine actually is.

    In any case, I have a project underway to bore my AJP engine to 72mm - which is the limit for the stock the stock sleeve - for 253cc, with changes to compression, cam, carby, intake and exhaust. Stage 2 dream would be to change the crankshaft and stroke it to get 300cc, but that will take a while to get around to. :evil

    My point is, which engine the new GPX has will have a huge impact on what mods are practical.

    But I REALLY like the 6 speed GB! :jump
  9. oldie230

    oldie230 Adventurer

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    To further add to my confusion, GPX advertise the 69mm x 62.2mm 169FMM engine on their 'Crate Engines' section of the website, This is the same engine in the AJP (but without the oil cooler fittings). I also notice they have the same 71mm x 62.2mm bore and stroke specifications for the small wheel FSE250S. ?? is the new FSE250E really getting the 172FMM 3A engine???
  10. Navin

    Navin Long timer

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    @Chadzu or @Pitster would know for sure. My understanding is the E engine was a fresh sheet from Zong. The air cooled stuff hasn't inspired me to learn all the variations.

    The missing 6th gear was all I felt it was lacking. A better counter balancer is icing on the cake. At all but high revs its already smooth in the previous gen.
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  11. Chadzu

    Chadzu Lost In Space

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    You need to take everything on the GPX website with a grain of salt. The new 3a engine is significantly different from the older 169 engine that actually has 65.5mm bore in GPX guise. Gary has said that the new bigger engine will be in the GPX bikes both the E and the S. I haven’t seen the new counterbalanced 6 speed version. When the container shows up with the new bikes we will know for sure what engine is in them.
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  12. oldie230

    oldie230 Adventurer

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    Yeah. I wish they could get their S@$t together. I agree. The only way we will know for sure is when they actually arrive. But there are versions of the 165FMM and 169FMM engines on the Zongshen website in both 65.5mm bore and 69mm bore that are counterbalanced. Fingers crossed it is one of those. :-)
    http://zse.cc/Upload/motor/CBB250-09475597408.jpg
  13. Navin

    Navin Long timer

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    Careful, you might spook him away and then get nothing! :lol3

    E0EB122A-C93D-4B76-A865-141F66541944.jpeg
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  14. oldie230

    oldie230 Adventurer

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    Huh?
    I think the bikes are probably on the water, so I am guessing they will arrive eventually.
  15. Navin

    Navin Long timer

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    Izz joke. :muutt
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  16. oldie230

    oldie230 Adventurer

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    Ahhhh... OK.
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  17. Bitingdog

    Bitingdog That's not my dog

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    Ah humor. I recognize it
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  18. BUNK657

    BUNK657 Adventurer

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    I contacted GPX on Thursday inquiring about the VIN's for the 250E and 300R I have ordered. Mardi said to call back on Tuesday or Wednesday about it. She said that they should have the VIN's by then. Maybe they'll be able to answer your questions about the engines by then as well. Either way, the arrival of the new bikes is getting closer!
    Bitingdog likes this.
  19. crackerguy

    crackerguy Been here awhile Supporter

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    I ordered one of these over the web last weekend after following this thread for a while.

    Have been looking for something used for my teenage son to ride, definitely a seller's market around Austin for decent used dirt bikes right now, couldn't find anything that I liked for him for a decent price.

    I bought a "cheap" 2007 KTM 300 for myself that I am in the process of (lovingly) throwing time and money at so 4k at my door for something new looked pretty good and I like the unique combo of a real chassis with a good old air cooled thumper.

    They called me today and told me the bikes are at the port and will hopefully ship out in the next week or so.
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  20. Pablogordo

    Pablogordo Been here awhile Supporter

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    yeah seems like a sellers market for used bikes, but the reality is, are they actually selling for those prices?? Smart move on ordering the 250E...