Front Sprocket (with photos)

[Dead Eye]

[quote author=Wookee link=topic=11851.msg130211#msg130211 date=1393495258]


The first thing you want to do before cutting the chain is to get the front sprocket nut off. If it isn't loose due to the 9mm problem then you are probably going to need something heavy duty to get it off. The torque settings in Haynes say it should be 70nm, but something clearly happens to them with heat or whatever because it is easily the hardest nut I've ever had to get off, this includes the hub nuts on my 40 year old car :eek . When I couldn't budge it I checked the torque and it was more than 150nm which is as far as my torque wrench goes!

Excellent write up and photos.


I had a job getting mine off as well and resorted to the method you described.


Mine is a '98 model with the 9mm nut. As yours was torqued up over 150Nm could this be the actual cause of the original 9mm nut problem? Maybe they were overtightened at the factory knackering the thread on shaft and nut leading to the nut coming loose? When you replace with the 12mm nut maybe it's relying on the good thread that's still there on the end of the shaft? I'm new to this bike, so just throwing this in as a possible cause of the problem.
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I believe the official line from Yamaha was a manufacturing fault where the output shafts were cut too thin causing the binding of the teeth on the splines to be too loose - or something to that effect. It's documented around here somewhere including the correct diameter that the shaft should be and at the limit at which you should contact a dealer and have them replace it