Gas Gas TXT Pro 300 2013 Gearbox rumble

[betatractor]

Hi everyone, I have recently bought a low hours bike which I am happy with coming from a four stroke, the only concern is that the gearbox seems rough in lower gears 1-4th smooth above that, on removal of the oil there is a little metal sludge on the magnet sump plugs. I have heard that the gearboxes are constructed differently, so is this normal, engine runs nice as pull the clutch in it's smooth. Any info would be appreciated.

[sirdabalot]

Any suspicion of a defect and the gearbox needs inspection via engine removal/stripdown. They are a bit fragile, but ignore warning signs at your expense. 

[cabby]

Gasser boxes don't like being shifted through at speed in my experience, best pop them up to 3rd if you're going flying between sections but they are made of chocolate. 

[chappo]

Is it a Gas Gas.

I had one in 2013 and there was always small metal traces on the magnetic sump plug when changing the oil.

 

[betatractor]

Hello everyone who commented, I have changed the oil again and there seems to be little amounts of metal in but not as much. 

[crazybond700]

Most often the metal parts come from the kickstarter gears.

Problems with gearboxes (with gg) are solveable, however the question is wether you want to put the effort and money in. You can take it all appart, notice some small fragments missing on some gear, but will you buy a new one?

The gg have a design of gearbox were gears are used in multiple gears, so one ''worn'' gear can cause noice in multiple gears.

The sound can also come from one of the bearings of the gearbox.

The conclusion is a little sound is ''normal'' most of the times, and if you want to solve it you have to exchange the parts, but a lot of bikes get old with a little sound. (disclaimer, we dont know your sound it could be something important).

Edited June 11, 2017 by crazybond700

[lineaway]

 I gave a guy that same advice on his 10 month old 2010. He eneded up buying the whole transmission.

[betatractor]

I hope that it does not come to that 

[still trying]

If I've understood your last sentence right, you pull the clutch in and it sounds nice.  

Could be and indication that there is rubbing until the side load on the clutch pushes things apart.

Time to inspect, You could be risking selecting two gears at the same time, which never ends well. 

Go looking for side play. Something loose, or a bearing worn or loose in its housing. missing shim , or shim in the wrong place, etc.

A good opertunity to improve the clutch action. Check the clutch basket edges and plate drive faces, (this is a likely source of metal bits, you may need a magnifying glass to see the true wear face properly). There was an article on setting up a clutch to reduce stiffness that covered this sort of thing, but I can't remember where I saw it.

They talked about getting all the fingers on each plate to contact the basket lugs evenly, make the faces flat,smooth, and square to the face, also add small rads on the edges. Checking all the basket lug load faces were smooth and had small rads on the edges as well,  They also checked that the lugs are parallel to each other, and square to the plate face.

 The result of the clutch work was better operation and reduced noise and effort on the lever ,so worth doing if you strip the box

Good luck