GPX TSE250R 2T Enduro

Discussion in 'Thumpers' started by Navin, Dec 3, 2017.

  1. JDUBinCO

    JDUBinCO Q-bald

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    Whereabouts in Colorado? I used to ride a KDX220 (I'm told its a very similar feeling engine, designed in the same time frame) at altitude from Denver to 12,000 ft. I try to not be too picky on jetting but always switched to one size smaller on the main at 9,000 ft and above where it became a boggy turd. I'd use the 17 mm float bolt on the bottom and reach up in there blindly with a 6mm socket to get the main out. 7 minute procedure for a better running bike!
    Just a guess, but it seems like your main jet is off, possibly in combo with the needle position - I assume the needle position is adjustable?

    When in need of jetting, I'd pull the offending jet and take it to the parts store to get a match.

    Regarding Air leak: Get the bike up to temp and idling smooth as possible. Go around the carb, base gasket, and all around the intake with starting fluid. If there is a leak it will suck in the starting fluid and the idle will jump.

    I'd love to take a look at the bike if you're somewhere nearby and don't mind me fiddling with it a bit? :amazon
    I'm sort of interested in owning one and would like a good look before discussion with the CFO!
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  2. andrewgore

    andrewgore Gôremā

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    Look at your carb. the "Kehin" one looks like this.
    [​IMG]

    I don't have a good pic from way back, but if its a "mikuni", you'lll see it cast into the left side:
    upload_2021-3-3_12-54-49.png

    @Navin or the Facebook group may have more info on if GPX has done other carbs, but I believe these are what they rolled with.
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  3. Navin

    Navin Long timer

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    Those are the two OEM carbs I am aware of. If the TSE doesnt start on a whiff of the button, its most likely in need of jetting.
  4. Bitter

    Bitter Been here awhile

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    When sitting for a few days or more, takes 8-9 button pushes before it fires and keeps running. That's with the choke on, not touching the throttle. About the 6th or 7th time it fires/pops but won't keep running. When it does finally fire up it idles very slowly, then after a second or so abruptly jumps up to a very fast idle. Stays at a high idle until I turn the choke off. Then idle comes down as it warms up.
    Once started and warmed up from a cold start, it starts right up on a whiff of the button the rest of the day. But as I said, the idle is inconsistent and lacks punch on low and middle ranges.
    I'm taking the carb off tomorrow to inspect and see which one it is. Also going to change the fuel filter and fuel line.
    In my opinion jetting can't be that far off to cause the issues I have. But, I could be wrong.
  5. Navin

    Navin Long timer

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    The TSE engine will tolerate wide jetting settings but you get things like you describe or massive drool, out the pipe. Id be looking right at the pilot and going fatter, but you could start by raising the needle and see what effect that has.
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  6. Bitter

    Bitter Been here awhile

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    Moving the needle clip down a notch or two? What is the standard position?
  7. Navin

    Navin Long timer

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    Ive not been in your year tse but if there are five slots you can use any of them. Your jetting is wrong no doubt IMO. And yes, clip down raises the needle making it richer.
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  8. andrewgore

    andrewgore Gôremā

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    A Sea Level and the PWK Style carb I had the following Jetting:
    180 MJ
    55 PJ
    NOZF Needle (Middle clip) I believe
    Air screw 1 turn out. Should start like this (cold w\choke):
  9. modette

    modette Rider

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  10. Bitter

    Bitter Been here awhile

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    Took carb off today. It's a Keihin with 160/55 jets. Didn't look to see where the needle clip is set. It's how ever the factory sets it. I haven't changed it. Nothing obviously wrong inside or outside the carb that I could see. Float and float needle seem to work ok. I'm not sure what to do.
    Is that jet combination good for 6500' to 8k' elevation ?
  11. Navin

    Navin Long timer

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    Move. The. Needle.

    Or run the air screw all the way in, then try out 4 turns. You cant go anywhere unless you try something and see how it works.
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  12. Bitter

    Bitter Been here awhile

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    Didn't change anything. Did some research. And the jetting is where it should be for my area. Cleaned it well. Maybe had an air leak at fuel line connection to tank petcock. It was way loose. Also turned air screw to one turn out. It was at two. Started right up, idled and ran well , like it should.
    Last time I'm taking that freakin carb off. I've had it off at least 3 or 4 times. It's a bitch to get off and back on.
    Guess I'll keep it for now. I'd like to have a new KTM or Husky 250 two stroke. But I'm just not going to given them that kind of money for a new one. And not crazy about buying a used one either. Even two to four year old ones are too expensive. Too bad the Japs won't make a modern two stroke enduro.
  13. Navin

    Navin Long timer

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    You dont get too much air in the fuel mix via the fuel hose but whatever makes you happy. Pulling the air filter out, and popping the air boot back into the box an inch makes carb access pretty painless BTW.
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  14. North ride

    North ride Long timer

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    YZ250X and if you want it to feel modern put a aftermarket e starter on it.
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  15. Bitter

    Bitter Been here awhile

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    Yes, having a good air tight system always makes me happy. And I did take the filter out and loosen the air box. Still a time consuming bitch to have to take the carb off that many times on a brand new bike.

    I seriously thought about a YZ250X, or maybe even a 125X. But, I'm not going to buy a brand new bike(YZX) and have to spend more money on it for features it should already have. And I have heard the aftermarket e starters are not very reliable. And they are still 2.5K to 3K more expensive than a GPX which has way more features as standard equipment. I've just had a little bad luck with mine and got frustrated. It's still the best value available for that type of bike. IMHO.
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  16. andrewgore

    andrewgore Gôremā

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    I'm understanding your username. :lol3
    Joking aside.....I sold my tse and bought a new KTM 350exc. No regerts. :thumb

    Hope you enjoy the bike with jetting sorted. :ricky
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  17. North ride

    North ride Long timer

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    Yeah they are what they are Still the best suspension going in a good chassis but a simple bike. But they are priced according to what you get nothing is free.

    * Only features I see missing are E start if you want tu race hard enduro and for some uses a Head light would be nice. Neither are things I have to have so works for me.
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  18. Navin

    Navin Long timer

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    Havent had a two stroke that didn't need jetting changes (for weather at least) in as long as I can remember. The ones that "didn't" need it before that most likely did, but I just did not know enough about it back then. Which meant Id kick my 81 YZ125 till I was exhausted... And then finally shoot ether in it and bump start it to get it running in winter.
  19. Bitter

    Bitter Been here awhile

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    That's another bike I seriously considered. And maybe even the GPX 300. I'm just not a big fan of four strokes. Back in the day, we considered them only good for lawnmowers. But I know the KTM 350 is an awesome bike.
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  20. offroadtoys

    offroadtoys Been here awhile Supporter

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    Well I finally joined the cool kids!
    521A4DA2-222F-41FC-A0FE-633CAFDE49CA.jpeg