Hi everyone

I have bought a used xt660x 2006 model about 30000 km and i am the 3rd owner now...
The problem i have is when i want to make a fast acceleration 0-100 i start at high rpm with fist gear and then i try to shift at second gear but some times its hard to shift at high rpms and i can hear the gears from 2nd to scratch.And some times again with high rpm trying to shift from first to second gear,i can shift second and then it downshift its own to first gear and bike goes to revlimit...at normal ride i have no problem with shift....Anyone have the same problem? Please help

I'd be inclined to point an accusing finger at the clutch first before blaming the gearbox. Is the clutch correctly adjusted? Too much free play? Where's the bite point? Is it a fair way through the lever's travel?

If the clutch is dragging even a little bit (not disengaging fully), gear changes at higher engine speeds will be clunky, particularly first to second.

Incorrect grade oil (too viscous) will cause similar clutch drag and subsequent gear selection problems.

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My clutch lever is almost full travel from top so it makes full pull.
I have change oil to Castrol power1 15-50..and i dont notice any dragging at clutch (how i could notice if there is any dragging).

I think you've found at least two factors that will not help a smooth gear change!

The clutch bite point should not be at the full extent of the levers travel. If it is, there's a good chance the plates will not be disengaging fully. There should be no more than 10-15 mm of free play measured between the levers tip. I would consider adjusting your clutch.

As for the oil, whilst you can use 15/50, it is at the thick end of what's acceptable. 10/40 is more than adequate for the Greek climate and will make the clutch less likely to drag.



Effectively what happens is a thick oil in a wet clutch acts a bit like a viscous coupling or a torque converter in an automatic gearbox when the clutch is disengaged. The oil rotating between the plates will cause "drag" between them and some torque (power) will be transmitted through the clutch even when its disengaged. I would seriously consider going back to the standard issue 10/40 grade.

How do you spot clutch drag? Well for a start your symptoms are typical - clunky gear changes. Other things you'll notice are more clunkiness when cold, particularly engaging first at a standstill and in the worst cases the bike will "creep" when held on the clutch on level ground. If you put the bike on a centre of paddock stand and run the engine with first selected and clutch pulled you should easily be able to stop the rear wheel rotating by hand with very little or no effort if there is no drag. If the clutch is dragging, for a start you'll notice the wheel will start rotating more easily and quickly, but it will need much more effort to stop it turning.

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Thanks for the advices.I will start with the clutch adjustment,as for the oil i have done only 500km with the new oil so i have to wait some time.
Would it help if i open the clutch cover and messure one by one the thickness of the clutch plates as the manual says?

Not at this stage. If the clutch plates are worn you're more likely to see clutch slip rather than clutch drag.

Shame you've just changed the oil. Did all this start happening after the oil change by any chance?

Just start with the easy things first like adjusting the clutch. Try and get the biting point somewhere in the middle 50% of the lever's travel. Ideally the clutch should fully disengage two fingers on the lever and the other two between the lever and grip.

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I adjust the clutch and i went out for a ride and the same think happen but..i had 3rd gear at high rpm i was about to shifting to 4rd and it downshift its own to 2nd gear
I had this issue 1 time before change the oil.Now is more offen

An oil that's too viscous for the conditions can cause similar drag issues between rotating components in the gearbox too. As you say the situation has worsened since changing the oil, it is probably worth spending the �35 to try a 10w40 grade oil before looking into mechanical issues (which are going to be a lot more expensive and time consuming).

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Yes i will change the oil to 10-40 it costs only 22 euro and its worth the try...i had change the oil filter last time should i change now? its only 500km
and what oil do you recommend

I always use Motul 5100, which in its rebranded form is the Yamalube that any Yamaha main dealer would use as the default oil during a service.

Any decent quality motorcycle specific (look for JASO-MA spec) 10w40 semi-synthetic will do the job.

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