hey everyone,

i used to hear that sound since i got the bike (over a month now) but didn't realise how serious it can be. now, after reading a lot about how "different" the gearbox/engine construction on K`s is from the japanese bikes i come to a conclusion that it might be pretty serious and involve dying splines.

so ok, let's start with the symptoms:

it's only heard on 1st gear (very rarely on 2nd) - when i start moving very slowly and add throttle and close it while hitting the clutch at the same time, i hear a loud knock in the gearbox. then when i add the throttle again (in gear) and do the same thing, the same sound comes out. it get louder with time i guess... may it be the spline dying?

also, when i put it on a central stand, put in 1st gear and hit the brake suddenly for a moment, the same sound is heard.

any ideas?

cheers!

The splines being dry and therefore worn excessively would make noise regardless of which gear you've selected. Also, there are splines between the engine and gearbox (at the centre of the dry, automotive-type clutch), as well as splines on the back of the gearbox to driveshaft, and driveshaft to final drive. All three spline areas need lube somewhat regularly.

How's the gearbox oil itself? Look for a lot of metal shavings on the magnetic oil drain plug. Change it to GL5 rated Hypoid gear oil if you don't know what's in there now. If you have the original tool kit use the shock absorber pre-load spanner to check the oil level, at least. There is a mark across the tool that is the fill line. Remove the fill plug and dip the tool into the oil to check its level.

Is the clutch adjusted correctly? There should be some cable freeplay at the hand lever as well as the release arm down at the back of the gearbox. The Haynes manual download here will give you a tutorial on how to properly set it, and it's not difficult with a few basic hand tools.

Try a few of these things first to eliminate the simple things, then we'll have a go at it on a different level of understanding. Good luck with it.

did everything you said - the oil is new, changed 2kkm ago to a good one, just like it should be.

the cable has freeplay. i also have the haynes (printed;)).

the sound definately comes from the bearbox/engine connection and is clearly heard.

i think it may be pretty serious...

Measure the rotational free play of the rear wheel in each gear, that is how much the wheel will move in each direction without any real force. First will probably have a little less but not by much the rest will probably be much the same but maybe increase a little as you go up the gears. 80mm is not uncommon or around that.

Also put the bike in 5th gear and try to force the rotation just by hand and try to feel if there is any give past the free play point, this will test your overload mechanism to find if it is a broken spring in it.

Then put the bike in each gear in turn and give the rear wheel a good shake in either direction to find if you can replicate the noise, this may give an indication of the spline condition by picking up a rattle.

Bear in mind these gearboxes are not exactly a quiet thing at the best of times.

You may also be getting a backlash noise because of a poorly adjusted throttle position sensor.

thanks for those instructions K freak - what i did:

i checked the wheel's freeplay - 1st gear - around 70-80mm and getting smaller with higher gears (i went up to 3rd)

i didn't do the rest of the tests as i didn't have much time today but will do it tomorrow.

ps. it definately has nothing to do with the throttle because as i said - when i started the engine once, put the 1st gear in and started hitting the rear brake, the noise was easily heard.

i'll check the 5th gear's giving past the freeplay point.

big thanks,
peace