2003 GG 280 TXT

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

  1. Greebe

    Greebe Been here awhile

    Joined:
    Aug 6, 2010
    Oddometer:
    152
    Location:
    MN
    Yeah that is how it is when you take photos in a shop without lights. Hehe! Took the dirty one in the dark with a head lamp and the clean shot during the day time. :D
    #61
  2. Greebe

    Greebe Been here awhile

    Joined:
    Aug 6, 2010
    Oddometer:
    152
    Location:
    MN
    Put the 38 pilot in and have the 118 still in with the needle clip at the second from the top. When adjusting the mixture screw it seems like it wants to be around 2-3/4 turns out and runs pretty well. Still at the very low rpms it seems like it is not quite right. Kind of makes a "putt putt putt" sound when in idle and when you give it just a fraction of power. Once you give it the throttle maybe 5-10 degrees of twist it sounds pretty good. Maybe this is just normal for this engine, as I am not used to a 2 stroke bike. However the bike responds instantly to throttle, and sounds pretty good up to the high rpm range. I do not have a video camera right now, but I do have a digital voice recorder. Not sure if I can upload an audio file here though.
    #62
  3. Greebe

    Greebe Been here awhile

    Joined:
    Aug 6, 2010
    Oddometer:
    152
    Location:
    MN
    Last night I put in a 115 main and have the 38 pilot. Putting the 115 seemed to clear things up. The fuel screw is out 3 turns. The needle clip is on the second to top.

    It still is not running great at the lower RMP's. seems like it is four stroking, if I am using that term correctly. The engine is kind of jerky when going slow and corresponds to the way the engine is running and pop pop poping away. Once I give it a little gas it clears up in the mid RPM Range.

    Not sure what to do. Any input would be appreciated.
    #63
  4. laser17

    laser17 Long timer

    Joined:
    Mar 6, 2008
    Oddometer:
    1,252
    Location:
    Boston,Massachusetts
    Pop pop is a PHBL trade mark. Have you tried the bike with the fuel screw at 3 1/2 turns out with the 38. The PHBL likes a rich pilot setting. The other thing that effect this is incorrect float height. Should be level.
    #64
  5. Greebe

    Greebe Been here awhile

    Joined:
    Aug 6, 2010
    Oddometer:
    152
    Location:
    MN
    Here is a video that might help for you guys to see how it is running. The video makes it sound much better then in person. It also is worse under load with me on it.

    [​IMG]
    #65
  6. Greebe

    Greebe Been here awhile

    Joined:
    Aug 6, 2010
    Oddometer:
    152
    Location:
    MN
    Thanks. I will try another half turn out. Also how would I check the float height?
    #66
  7. laser17

    laser17 Long timer

    Joined:
    Mar 6, 2008
    Oddometer:
    1,252
    Location:
    Boston,Massachusetts
    #67
  8. Hoss Cartright

    Hoss Cartright Been here awhile

    Joined:
    Oct 23, 2016
    Oddometer:
    131
    The bike looks really clean!

    The plastic supply is dwindling down now. It seems that the molds are no longer in existence so there may never be anymore seat base pieces or rear fenders. Most of my remaining rear fender stock is going to the UK for some time now. Seems these rear fender and seat parts are completely gone in Europe for some time.

    I've got everything in stock that was talked about in this thread including the viton o-rings for the exhaust.

    We sold thousands of these bikes in the USA with this engine. I've got an incredible supply of engine parts. And these engines are as reliable as a stone. transmission and crank bearing failures are extremely rare.
    I cover the clutch in detail in my videos and yes, the most common error there is not knowing the indexing of the pressure plate to the center hub.
    A bike that old should have the brakes and clutch hydraulics flushed.

    It takes a lot less time to get the right parts from me when using the telephone than spending hours Googling to buy on-line or buy from some dealer in the UK and get the wrong parts and have no clue about the tricks to installing them.

    The worst part on these 1999 2003 TXT bikes (not the Pro) is the "HEBO" brake calipers. They are problematic and there are no longer rebuild kits available. And they tend to seize the pistons hard... I have alternative front calipers that are an easy change-out and we have a kit for the rear that includes a disc rotor to convert it to a two-piston AJP/Braktedc caliper that is quite nice, works better and is a permanent fix. Don't worry about the calipers until they are broken, then call me and we will get you going on the right track.

    Here is the Dellorto video. It's long but I explain everything.
    #68
    ADVCoop, Fallacy, dave_d and 3 others like this.
  9. motobene

    motobene Motoing for 46 years

    Joined:
    Mar 9, 2013
    Oddometer:
    3,697
    Location:
    Wichita Mountains SW Oklahoma
    Love the Snell videos! Very educational to help visualize what's going on.

    I wanted to emphasize something again due to a comment that was made above about the bike running a bit rich sounding at idle and partial throttle. That something is the Newtonian action-reaction aspect of jetting. Specifically, fuel utilization with respect to loading.

    The idea that there is one set of recommended jets for all misses the huge variable of how the bike is being loaded; how the rider loads the engine.

    I've been puzzled about why my Sherco 250s keep coming with a ridiculous 42 low-speed jet, when a 52 or 55 is much better for smooth power. The answer dawned on me yesterday that perhaps even the Factory 250s are assumed to be for the putt-putt rider market? Those folks who don't want the power of a 300?

    Yet I and many others with higher skill levels riding such levels as local Expert specifically want 250 power characteristics over a 300. And we make deep use of the potential power.

    Then again, the factories will fit a 45 to 300s, which isn't that far off from a 42, so my theory may be hooie, and too lean is just a repeat plague, 250 or 300.
    But the smaller displacement motors often need a larger, not smaller low-speed jet, so the 250 may be an anomaly. Here are the stock low-speed jets for 2017 Sherco-Scorpa:

    300 has 45
    250 has 42
    125 has 50

    My throttle style to outside observers has them often commenting on just how well whatever bike I'm riding runs, and they often assume my 250s are bigger displacement because I use heavy throttle at times in the lower rpm range.

    I've handed bikes that sound and run awesomely under me to riders for eval and watched them stall the bike right off several times, then float around in a putt-putt style with the 2 stroke engine constantly 4 stroking. Meanwhile I watch and hope vainly the rider will actually open the throttle more than a crack!

    A recent incident of this really drove the matter home for me. I can recommend jets or jet a bike excellently for power, but I can't make a rider make Fuller use of the potential power. If a rider has not advanced beyond a putt-putt throttle style (carburetor slide kept just above the throttle stop almost always), a too-lean-for-optimal-loaded power is the jetting the rider is probably going to prefer, even if it causes problems like more difficult cold starting, a long warm-up, and some hunting of idle when the bike gets hot. He will comment, "I tried your such-and-such jets and the bike was too blubbery."

    I've been mulling around how to describe the jetting process succinctly, and these significant variables keep intruding. The goal: describe how to jet on one page! That's probably asking too much :-0
    #69
    LemmeTry and jonnyc21 like this.
  10. Iffykid

    Iffykid Been here awhile

    Joined:
    Jul 3, 2015
    Oddometer:
    783
    Location:
    Blaine,Mn
    From a Shindig post you indicated north central Mn are you anywhere near Gilbert OHV Park? There is usually a 2day club event over there about every other month.
    #70
  11. Greebe

    Greebe Been here awhile

    Joined:
    Aug 6, 2010
    Oddometer:
    152
    Location:
    MN
    Gilbert is not too bad of a drive for me. Much closer then the UMTA location in Thielman. Where would I find more info about the Gilbert events? Thanks.
    #71
  12. Iffykid

    Iffykid Been here awhile

    Joined:
    Jul 3, 2015
    Oddometer:
    783
    Location:
    Blaine,Mn
    Looks like only one event at Gilbert this year, There are a couple of UMTA guys with nearby cabins that ride up there most weekends.

    https://umta.org/pages/schedule
    #72
  13. Huzband

    Huzband Team Dirt

    Joined:
    Oct 4, 2006
    Oddometer:
    5,891
    Location:
    Cowford, Fl.
    I broke the front wheel down last in prep of having the cracks welded. I was shocked at how feather light it is and made me wonder. Are the rims on the Pro magnesium? I had already thought they have a different appearance than most aluminium rims I've seen.
    #73