I understand that the 5th gear on XT600's wear out after 30'000 (is it miles or km?). I also understand that the 3AJ Engine in the XT600 and latter Tenere's as in the TTR(E) are the same, just the gearbox's are different. Does this mean that the TTR is not prone to the 5th gear wearing out, with the TTR's lower gearing then there would be less strain on the gears them self increasing the life.
All this is leading to my real question, my bike (04 TT600RE) has about 20'000 km/12'000miles and i expect to be covering about 13'000miles on my next trip (trans africa) should I replace the 5th gear before i leave??
Thanks George

Depending on how your TT was driven, the gears might be fine, or not. A lot of cruising at low engine speeds and / or accelerating hard from low engine speed might have damaged the gears.
No way to tell except to take the engine apart. Or, with road tires, drive along a concrete wall. If your bike makes the sound of a dive bomber, your gears are finished. No nobblies, as they make the same sound :-)
The gears on 3AJ and later models indeed were better, but not bomb proof.

If your bikes behaves normally I would not worry. Just start thinking about replacement of the gears if the noises start. And, change oil regularly, choose your sprockets to have a reasonable engine speed at cruise speed, ie abt 4200 rpm / 100 km/h.
Search this forum, lots of facts and opinions to be had.

Auke

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Auke
http://aukemarieke.blogspot.com

cheers Auke I willl try the wall trick, I don't think there is anything wrong currently but was wondering if it would be wise to change before I leave. I think I will open her up-so to speak(!) and see what it is like
George

Just opened a 2KF motor at 52.000 km. Fifth gear clearly shows signs of pitting and needs replacement. Metal parts have damaged oil pump that needs to be replaced too. Motor was running well and there were no clear audible symptoms.
I have to admit that the motorcycle has often been driven at 100-110 km/h (4000 rev/min) in 5th gear.

Guy