2003 GG 280 TXT

Discussion in 'Trials' started by Greebe, Apr 29, 2017.

  1. lineaway

    lineaway Long timer

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    Jim also has one just for the waterpump seal replacement. Biggest issue on the clutch is the pressure plate is not symmetric. It has a notch in one of the spring tower bolt holes and a corresponding mark on the pressure plate. What fun.
    #21
  2. Greebe

    Greebe Been here awhile

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    The guy I bought it from said he replaced the water pump seal, maybe he did not replace the oil afterwards, but I guess it is possible he did not replace the seal. He also told me he replaced the fork seals yet one of them is leaking.
    #22
  3. lineaway

    lineaway Long timer

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    He could have replaced the seal, but the shaft needs replaced too if it get`s a groove worn in it. The shaft is the expensive part. Forks can just leak with temp changes. I went out yesterday and my son`s bike just puked the left one and we have not used tie downs on it in a month.
    #23
  4. Greebe

    Greebe Been here awhile

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    Thanks, I have been looking for the parts to fix this but am not having any luck. Any advice where I can get this stuff online? Thanks.
    #24
  5. lineaway

    lineaway Long timer

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    I already told you where to get it from. You have to wait till tomorrow and use a phone.
    #25
  6. Greebe

    Greebe Been here awhile

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    Yeah I was hoping to find parts online but didn't, so I will call Monday. Thanks!
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  7. Greebe

    Greebe Been here awhile

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    What might be some common parts that I might want to stock up on for the future? I was thinking that I should buy parts that might get hard to find, but that I might need in the future. Thanks.
    #27
  8. laser17

    laser17 Long timer

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    Call Jim Snell and ask him. I would say a rear fender would be a good spare to have along with your clutch and wp parts order. I would stock up on twin air - air filters too - It's just as easy to clean three as one and that way you always have a clean one to pop in.
    #28
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  9. LemmeTry

    LemmeTry Over-thinker...

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    Thrilled for you, Greebe! A trials bike is certainly a fun machine to own.
    #29
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  10. Greebe

    Greebe Been here awhile

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    Thanks guy, just came in from playing some more. Fun bike. I think I need to adjust the carb though. The manual shows the air fuel mixture screws, which the guy I bought it from said the large one was to adjust idle speed? I worked in the logging / tree trimming business and I can tune my chainsaws just fine, but I am not sure about how to do it on this bike. Any videos showing proper adjustment. The engine just kind of bogs down and blubbers when I get up past the mid RPM range. Thanks.
    #30
  11. Greebe

    Greebe Been here awhile

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    Here is a description for the 280txt that I found on the net. Does this sound about right for making the adjustments?

    The screw in the center of the carb body adjusts the slide stop and is to set the tickover speed. Be sure to adjust the tickover with the engine warm, bike in gear and the clutch pulled back normally, which is usually with one finger back to the knuckles (not fully back to the grip). This way you adjust for clutch drag and reduce stalling.

    The other screw is to fine-tune the off-idle response (a "mixture screw" in this case) and there is no absolute correct setting for it, in spite of what some may tell you (that's why it's adjustable and not factory set). The mentioned settings are a starting point only and that screw is used to adjust the carb response under changing ambient weather conditions (the off-idle throttle response is a complicated "procedure" and there are several "circuits" that have an influence on it and they all overlap).

    Once you get the hang of it, it's fairly easy to do. First, very lightly bottom out the screw (screwing it in hard will damage the needle and seat). Turn it out about 3 turns, the number of turns is not critical, you could start with 2, for instance. With the engine warm and in neutral, quickly open and close the throttle ("blip it" as we say in the States) and then adjust the screw in or out to start. When you go too far either way, the engine will start to bog so then you go back the other way until the engine responds perfectly. That is the "correct" setting.

    The "recommended" number of turns-out for the mixture screw will work well in most cases (but not all engines) but if you want your engine to run it's best under a variety of conditions, you'll take the 30 seconds now and then it takes to check the mixture setting.

    Unlike the other forms of motorcycle sport, Trials riding places a huge demand on the carb's ability to constantly adjust the air/fuel ratio in the idle-to-half throttle range.
    #31
  12. lineaway

    lineaway Long timer

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    Yes, but being you just got the bike a little time cleaning the carb goes a long way. Good time to see what jets are in the thing.
    #32
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  13. Greebe

    Greebe Been here awhile

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    Sounds good, thanks. Picked up some carb cleaner, will tear into it tonight or tomorrow night.
    #33
  14. alpineboard

    alpineboard Been here awhile

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    Use a Fuel filter if there is not already one on there. You may have the correct Pilot/Main jet in there , but if it is clogged you will never know. What is the correct Octane for that bike? Use the right fuel first, then tune the carb.
    #34
  15. Greebe

    Greebe Been here awhile

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    Thanks again for the replies. Yesterday I checked the fuel mixture screw, it was 3 turns out, then I tried half a turn either direction, and ended up at 2-1/2 turns out and she is running pretty good. I have another bike up on the stand in the shop that I am in the middle of replacing the shock, once that is down I am going to put the 280 TXT up there and pull the carb.

    One other thing, after changing the oil to the Maxima 75 UT, not only did the sound in the engine go away, but the clutch is releasing properly now and it is easier to shift. Thinking this bike just needs a little TLC and she will be happy again.
    #35
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  16. alpineboard

    alpineboard Been here awhile

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    #36
  17. Greebe

    Greebe Been here awhile

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    Thanks for the link. That looks pretty thorough. Will that apply to the Gas Gas as it was written for a KDX200?
    #37
  18. laser17

    laser17 Long timer

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    Your bike should have a Dellorto PHBL 26 carb. The stock pilot jet was a 36, will run better on a 38. PHBL Dellorto's like a rich pilot. The fuel screw should end up around 3 to 4 turns out. If you find it runs better at say 4 to 4 1/2 turns, run a richer pilot and adjust back to target the 3 1/2 setting. If you're at 1 to 2 turns run a leaner pilot. Of course, as lineaway has suggested, you need to start with a clean carb and as alpine said the proper fuel. Note: 3 1/2 turns is the average bike, each bike SHOULD be fine tuned and yes a 1/4 turn will make a difference on an unusually hot humid day or cold snap during riding season. (Of course, elevation changes everything)

    To set the fuel screw on a PHBL / GG
    warm up the bike

    turn down the idle - a low idle helps resolve the setting. (center screw on left side as low as you can and not have the bike stall).
    NOTE: This will require changes to idle as you make changes to the fuel screw.

    Turn fuel screw all the way in and then back off 1 turn (out)
    Let idle die all the way down and hit a steady state. takes a few seconds so be patient and let it get all the way down.

    Twist the throttle WIDE OPEN as quick as you possibly can.
    You SHOULD get a tremendous hesitation until the needle/main jet kicks in. It will sound like a huge bog -" boo wah sound ", followed by the revs picking up. This is what you want (for now) the reason the motor is bogging is that it's too lean. Hence you have a "lean bog". It SHOULD be very obvious. Learn to recognize that sound. You will now make adjust the fuel screw until the bog "just" disappears.

    Add a turn of richer (out) fuel screw adjustment and repeat above.

    Once you get rid of the lean bog, go back a turn and repeat with 1/2 turn and then 1/4 turn adjustments. Note, all the while the idle will change. Many don't do the super low rev portion at the rough 1 turn stage, but to really hit the threshold of the lean bog, you need to drop the revs down as far as possible IMO. Note: as you approach the bog transition, the severity of the lean bog will get less and less noticeable.

    Once you find the point where the lean bog JUST disappears, and you're on the 1/4 turn adjustment resolution part of the process (This can take a few back and forths to really resolve) you need to add another 1/4 to 1/2 turn out/richer. This is a safety factor and definitely needed. To verify if rich enough, go climb the steepest, longest hill you can find with the engine HOT and hold the bike wide open all the way up. (maybe 10 seconds under heavy load of WOT), at the top, CHOP the throttle. If you hear any knocking, the fuel screw is too lean still. Go another 1/4 richer and repeat. Note: knock can be too low an octane as well. These bike LIKE high octane - like 98 ish.

    Finally, increase the idle speed to normal.

    I always liked the phbl because it was very easy to detect the lean bog threshold. Some carbs, like the Keihin, are a little tricker to find the exact transition, but you can follow the same procedure (except your turning an air screw IN for Richer) and yes, I've found that keihins are more like 1 1/2 turns out on the air screw.

    Hope that helps - it can take time to develop an ear for the perfect adjustment, but if your patient, this should find a very good setting.
    #38
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  19. Fallacy

    Fallacy Been here awhile

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    That's the best explanation I've heard, thanks for that.
    #39
  20. lineaway

    lineaway Long timer

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    Lazer had a great teacher and he explained it well. Most of the bikes came with a 33 pilot, even though the manual states it came with a 30. As everyone has said it is important to know what you actually have in it to make it run the way it should.
    #40
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