spark Posted September 22, 2014 Report Share Posted September 22, 2014 Hi chaps, I bought a 2011 TXT Pro 300 recently with extremely low hours on it. Including the riding I have done it amounts to about 20 hrs. You can still see the square shaped grooves on the tread blocks on the original back tyre. As part of maintenance I drained the gearbox oil to find the usual small bits of metal on the magnetic drain plug, but also this piece as well. I cleaned the drain plug and stuck the shaving back to give a reference for size. These are pics under a low power microscope- Now that I think back I did battle once on Saturday to get the bike into second gear from first. This was with a light lift of the foot, with a hard pull it went in. Then on Sunday I remember thinking to myself that the box felt a bit more notchy than usual. It was not bad but it did catch my attention. The steel is hard and when I tried to flex it between two pliers it broke instead of flexing. My first guess would have been a needle roller cage but then I thought that the cage would be out of a softer metal.... So do you guys have any idea where this piece may have come from? Do you think I should split the engine? Quote Link to comment Share on other sites More sharing options...
crazybond700 Posted September 22, 2014 Report Share Posted September 22, 2014 (edited) Looks a bit like one of the thin rings which can be between the kickstarter shaft or something. Would defenitly open the clutchside to see if its not part of a bearing, and try to find what it is. Shouldn't mean extreme trouble, but could be something which definitly needs attention. I had: Broken bearing on the gear between the kickstartgear and the clutch. Also some broken clutch bearings, and some bearings in the tranny that broke. (multple (OLD) bikes) But its difficult to see what it exactly was. If you cant find anything there, you will probably have to search elsewhere ... /read the last part of your post now, could mean you have to split the engine yes... but like I said first look at the other side. Edited September 22, 2014 by crazybond700 Quote Link to comment Share on other sites More sharing options...
smalley250 Posted September 22, 2014 Report Share Posted September 22, 2014 I had similar piece on a 300 07 and it turned out to be a roller needle cage from the gear shaft in the gearbox. I was at the time told by gasgas uk i was lucky as the gearbox could of self destructed if i had continued using it. I stripped and replaced numerous bearings due to the metal fillings damaging them. Dont use the bike until you locate the issue as it wont go away but only cause fatal damage in the long run. 1 Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted September 22, 2014 Report Share Posted September 22, 2014 Not sure what it is but it does look to have been hammered about inside the case. Hopefully that is the only piece and it has not damaged other parts. For sure I would pop off the clutch cover and use some of the oil passage holes to go in with one of those small "magnet on a stick" tools to see if there are more that will come out easily. Great reminder for everyone. If you don't have a magnetic drain plug, get one! Quote Link to comment Share on other sites More sharing options...
dadof2 Posted September 22, 2014 Report Share Posted September 22, 2014 Split the crank cases and thoroughly clean and examine everything. Wherever it came from bits have obviously ended up in the gearbox. You could be looking at quite a bill already, if you don't clean it out and repair properly you will be looking at a very very big bill. Quote Link to comment Share on other sites More sharing options...
lineaway Posted September 23, 2014 Report Share Posted September 23, 2014 It is MT280236162 on the primary shaft. Replace all needle bearings on the primary. Much cheaper than a complete tranny. Quote Link to comment Share on other sites More sharing options...
spark Posted October 13, 2014 Author Report Share Posted October 13, 2014 Hi Chaps, just an update on what I found. The culprit was split needle roller bearing MT280236161 on the secondary shaft. I flipped the one half over so you can compare the good cage side to the bad side. There is no real reason this should have happened that I could find. I micrometered the shaft and bore and both are spot on. It was the ends of the splines that ate the side of the cage away. All I could really do to help prevent this in future is chamfer the ends of the splines and give the ends a polish with 1000 grit water paper. I also found that the primary shaft was tight. I could turn it by hand if I grabbed really tight. With the paper center case gasket squishing when bolts are tightened it made the cases too close together, or perhaps the distance from the circlip groove to the shoulder on the shaft was a bit over spec. I ended up grinding 0.05mm off the circlip on the surface grinder and that gave it 0.02 clearance. Also gear 5 that ran on the damaged needle roller was really tight with it's circlip on and you could see how it had worn the washer. I used an oil stone to take off 0.04mm from the circlip and it runs sweet now. I do not know how they even assembled it like that, the circlip should not have even gone on without some serious force. All in all after working on this motor I am impressed with the engineering behind it, but I can see they have made some compromises to make it this light and compact. It is also evident that they do not take care to ensure everything is perfect when assembling either. However I love these gassers so I am willing to put up with it. Thanks to all who gave advice! 1 Quote Link to comment Share on other sites More sharing options...
crazybond700 Posted October 13, 2014 Report Share Posted October 13, 2014 Great you found the problem. And its true the tolorances on those engines are quite high... Quote Link to comment Share on other sites More sharing options...
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