d2w

Hello, I don't have direct experience with your model of bike, but I found that the clutch drag on my 2008 GG TXT300 was particularly sensitive to the clutch lever freeplay (or lack there of). On one ride in particular the clutch progressively "slipped" as the system heated; a quick back-off of the clutch free-play adjustment screw restored my clutch operation. So I suggest you check your clutch master cylinder for correct and full operation. And in reading your above post it seems odd to me that you would find rust on the clutch plates. Perhaps the water pump seal was leaking and that would also contribute to the grey (milky (?)) oil you found? Could something else in the clutch mechanism be rusty and its correct operation compromised? Dale

I have two similar bikes; I have a 2008 TXT300 and my son has a 2008 TXT280. Both were bought used. We are just recreational riders. I've had no issues with either bike. Just respect that the bike is 11 years old and treat/maintain it accordingly. I found that the linkage (aka "dog bone") bearings were in poor shape and needed replacement. So just be prepared to strip in down and lube surfaces/bearings and tighten fastners. Replace all fluids. One issue which you may experience is that unless you religiously follow the starting ritual - second gear/clutch out/roll back until compression/clutch in/kick firmly - you'll hate it. Dale

If I may, I have a question for drca related to the situation; how do you ensure that your fixed frame will align with the engine? Do you simply make the weld with the engine in place? Or do you just "eyeball it", and then open up the mounting holes later if required (say with a file)? Thanks. Dale

Is this possibly helpful? ClutchCoverRookieCadet.pdf

Forward facing piston? I think you want the arrow facing to the left if you're in Europe and to the right if you're in North America. It may be a struggle to do so though.

How badly is your cylinder scored/grooved by the pins? Can this damaged be honed-out and still leave you with the bore plating? Since you have the cylinder off the bike perhaps you should show a machinist and get their opinion? I like to think that GG would have an assembly process which ensures that pistons are installed with the correct orientation. But, as you say, you'll never know and it doesn't matter. But now you do know what was the likely cause of your troubles and that you have corrected it.

My understanding is that the cylinders are plated and that one does not want to bore them. Rather the cylinder surface is lightly honed if not too worn or damaged. You would then install the next larger piston (A to B to C to D). I have no experience when it comes to changing the big/bottom end bearing.

Any chance the piston was in backwards (i.e, the orientation arrow was facing backwards)? I ask because two items in the picture catch my eye (but I apologize it's kinda difficult for me to see clearly): 1) It appears that the top ring opening "notch" is toward the front (and what I see is not the result of a broken ring), and 2) It appears that I see what could be the ring retaining pin in the area of the fracture. Over time a piston will develop a fore/aft "rock" and an incorrectly oriented ring could eventually snag on the exhaust port. And then things go south very quickly. So perhaps carefully clean the top of your piston and try to determine how it was oriented. And do try to find the missing piece lest it lie in your crankcase waiting to ambush you. Dale

I routed my lines into the airbox. Originally the lines exited near the linkages, but I had a bad experience where they sucked up water and fine sand on a ride. Yes, they are vent lines and allow the pressure in the float bowl to be at atmospheric. I guess since the fuel is being drawn up through the main jet there can be a slight vacuum on the lines (maybe until the float needle opens and refills the bowl (?)). And when the bike goes on its side the gas may drain out the lines but it then runs down the airbox sides and eventually out the airbox drain. Also that little plastic plate above the airfilter helps to keep the gas from dripping on the filter. To date I have not experienced issues with the filter being damaged by gas. And the airbox on my 2008 TXT was not too well sealed to the seat plastic. I ended up dismantling the lot and reassembled it with a generous portion of RTV/Silicone. As a test I filled my airbox with water and it didn't leak! Dale

Any chance that you compared the OEM and the "new" spindle and noted what was the difference? Overall length? Thread length? Head shape (I seem to recall that the spindle on my 2008 TXT300 has a small flat on it)? But happy to hear that you resolved the issue. Dale

I'm sorry that I can't contribute a solution to the problem at hand, but can anyone say which years(s) and which model(s) of GG had Ducati ignitions and which had Kokusan? And I too had an issue with a faulty tank breather valve; the valve failed and a vacuum would develop in the tank and starve the engine of fuel. And in debugging the problem I'd check the fuel level by removing the cap and unknowingly temporarily "correct" the problem. Doh!

Actually, I had a more careful look at the exhaust of my 2008 TXT 300, and I realize that the pipe "header" is welded to the "parallelogram" flange which contains the holes through which the hex-head bolts secure the assembly to the cylinder/spigot. Phew. I suspect there's a gasket between the flange and the cylinder. I believe the gasket is a deformable/soft metal. So if there's a leak it would be between the flange and the cylinder and not in any area in your photo which is rusty. Perhaps the assembly process/weld simply made the join area more susceptible to rusting? And I don't see any signs of exhaust "leak" on the cylinder.

I'm only a novice trials/trail rider, but I've always felt well-planted on my Pivot Pegz. https://www.pivotpegz.net/ Don't know how a good trials rider would feel about them.

I still see rust and possibly baked-on dirt/mud. I would have expected to see soot/blackness/oily residue around a leak, but I don't see that in your picture. Yes, if it's not broken don't fix it! Those rusted flange nuts with what appears to be a hex-key head would be easy to round-out. But in that event you could always grind them off and then replace them with something more suitable.Soak the area with a penetrating oil first and lightly tap the head to break any rust joins. Any chance there's a leak and what you hear is air being sucked into the pipe? Consider simply running a bead of high-temperature silicone/RTV around the flange/pipe junction and see if anything changes noise/cleanliness wise.

I second the simple rust theory. And note how the lower rad guard nuts are rusty and/or covered in what might be mineral deposits. Any chance your rad is leaking and dripping on the exhaust spigot?

The 180 degree rotation would be "interesting" ... you'd tap up for first and tap down for all higher gears.

If it's not a contravention of the site rules, I found a source for a "cyclops"-type LED headlights (as used in my 2008 TXT) for a very reasonable price. The unit is a "Vision" from N2MOTO as listed on Alibaba. https://www.aliexpress.com/store/product/Dirt-bike-Motorcycle-Universal-Vision-LED-Headlight-as-GASGAS-TXT-PRO-280-125-Racing-motorcycle-head/1735717_32311456492.html The unit contains all parts and a light for < $20 (including shipping). I will be using this light on my son's TXT 70, and I'll report on the build quality and operation when it arrives. Thank you. Dale

Hello, I hope this is the correct sub-forum to post this question. I'm the mechanic for my son's 2007 Gas Gas TXT 70 trials bike. The engine is kind of a one-off in that it was made by Franco Morini. The engine is 72cc (47mm x 40mm stroke) liquid cooled with a hydraulic clutch. I believe the engine derived from the Franco Morini MC65. The cylinder is an iron bore unit from Metrakit. I could not ID the piston. I am hoping to over-bore the cylinder to 80cc (50mm x 40mm stroke). One piston which "looks" reasonable is the Polini 204.0829A. This piston is compatible with something called a "Derbi Senda", and when cylinder kits were available for that bike (Italkit used to make the CK.22.750.g) they were noted as being compatible with the Derbi Senda. Hence my "compatible by association" theory. Can anyone suggest how I might be able to obtain detailed specs for the Polini piston? I would need to verify ring pin positions, piston pin to edge measure, dome height, etc. I've written to Polini in Italy but have heard nothing back so far. Does anyone have a piston from a Derbi Senda which can be measured? Can you suggest another forum/sub-forum I should try my query (not being part of the scooter crowd)? Your suggestions as to how to find a compatible piston for this bike will be greatly appreciated. Thank you. Dale

Thanks for the link. But I don't see the model of engine I have in my TXT 80. I believe it may be a GG engine with a Morini cylinder. The cylinder looks like the one on the Morini M65-C engine, but the bore is 47mm (with a displacement of 74cc). So close but no cigar. Other links I've tracked-down imply that the cylinder (or engine (?)) may be a Gilardoni. And I've also seen a reference to Gilera. Thinking about Spain and Italy and Europe made me recall this Canadian joke about what's Heaven and Hell: Heaven: British policemen, German mechanics, Italian lovers, French cooks, all organized by the Swiss. Hell: German policemen, French mechanics, Swiss lovers, British cooks, all organized by the Italians.

Howdy Rob474. Dale here in Summerland. Learning and loving trials. I'm just beginning but having great fun. FYI there's an informal event this weekend in OK Falls. Where about are you living? Dale

Hello from the Canadian side of the 'pond'. My son has a 2006 TXT 80 and I'm thinking of "refreshing" the top end. The OEM cylinder is a Morini and is made with iron (and is not Nicosil (sp?) coated). As a result I am considering a complete kit from Italkit (model CK.22.750.G). Anything I do will be an improvement to the (lack of) power output. Does anyone have any experience with Italkit and/or this particular kit? At the moment I'm trying to determine if the kit is available and from whom I could order it. Scooters and their support shops are not very popular here in N.A. Your help is appreciated. Dale

Howdy. I just repacked the muffler on my son's TXT80 last night and thought I'd add my experience to this thread: 1) I choose to use the FMF Four-stroke packing rather than the two-stroke packing; the four-stroke packing is semi-rigid and I find it's easier to roll and form and it keeps its shape. 2) When pushing the packing into the canister and the pipe I use a sheet of thin plastic (Mylar) to form a "cone" so that it better slides; the cone helps to compress the packing so it doesn't get hung-up on the edges. Dale

I too had a difficult time understanding what I was seeing in the photo. If the rim is cracked why not just weld the crack (after cleaning and prepping the surface)? I'm not a welder/metallurgist so I'm asking just to learn. Dale

I have a 2008 TXT PRO 300 and the (non-) starting ritual was initially frustrating me to no end. But then I read a hint which now consistently works for me; put the bike in second gear with the clutch out, roll back until you stop (as the piston rises and you form compression in the cylinder), pull in the clutch, and kick with a firm/strong stroke from the top. This technique will light my bike up in one or two kicks tops. The throw of the kick start lever is so short that you can't afford the energy/time to spin the piston to compression. Rather you have to be there already when you kick.Clearly having a bike/carb in tune is equally critical. And I did find that if the kick lever was too far forward/advanced on the spline it didn't work well as I'd often drive the lever down/forward rather than down and around. Just remember that you only have about a quarter circle of "kick time" before you hit the peg and so you need to make the most of it. Good luck.

Would anyone know if the Contact tank would fit an older 2008 PRO? I believe my PRO frame is built with rectangular tubing, but the coil is mounted between the frame up near the steering head. And I see that there is a factory clear tank for the 2008 PRO on the GG web site (?), but I believe it's ~4x the cost of the Contact tank. Thanks. Dale