Engine knock when giving it some, normal or uh oh?
 

Hi all,

I have had this bike a week (xtx, 32,000 ks) and am wondering if a knocking noise when getting up in revs and throttle is normal or something I should be concerned about.
I have read about and heard the final drive nut knocking noise on Youtube but mine is relatively quiet at idle and only makes this noise when under load.
It has a good service history every 5,000k... well a stamp in the book anyway and I have no idea how it was treated before I got it.
I have watched various videos and they do sound similar to mine, quiet as until you open the tap and then gets all snarly.
Doing 100ks on the open road is quiet but I can hear it when doing ^110. No noise when engine braking at high revs which is where I thought bad big ends made themselves known. I see they have a roller bearing big end so it may be how they are?
Appreciate any thoughts or comments. Cheers Mike

For peace of mine I would get a mechanic to have a listen to the motor, to determine if it is a problem or not.

yep...+1 on paying a mechanic to look at it.

or post video clip up ..

I have just done the tappets which were loose, not that they will make a knocking noise. I'm off the dealership to get some cush rubbers and a filter so might see if they can have a listen. Will report back

Had the mechanic at Yamaha have a listen who said it was normal, said he has done a few primary drive nuts over the years so I have ordered all the parts necessary to do the job. Should be here in a couple of weeks so will save that one for a rainy day.
will let you know if the nut is loose.

So riding home today this noise did my head in so I put it in the garage and took the clutch cover off. Sadly the final drive nut was tight.
Looking through the crankcase at the big end bearing there is visible play when I rock it back and forth on the down stroke. Looks like I need a new crank pin and rod and a whole lot of time to sort it out :(
Has anyone else heard of big ends going at 32,000 ks? Googling only comes up with loose primary drive nuts.
Found this also... with the water pump removed you can get a good look at the drive nut and gear without having to take the whole clutch cover off. Also instead of jamming rags and bits of soft metal in the gears to tighten the nut which I have read about you can put a 1/2” rod through the hole in the crankcase which lines up perfectly on the crank web as it comes around to lock the crank. Seemed far safer than loading the gears to take the torque load.
Anyway I’m not sure if I should pull it down, fit a new crank and ride it forever or chuck it together and get better ear plugs....

I understand the bit about locking up the counter weight of the crank shaft but that may rely on your rod jamming against some part of the aluminium engine casing, I guess, which wouldn't be advised as that potentially loose shaft nut needs to be torqued to 80nm (manual's spec, I think) but is often torqued to 120nm by those of us that have done this job.....twice on two engines in my case. I know you don't like the sound of using rags but it seems to be the least aggressive way of locking the transmission beyond obtaining the correct tool.

The casing is quite beefy at the crank vent hole, I used an aluminium drift with no damage to the casing as the end result.
The concern I had with jamming the gears is the bending force on the clutch shaft as the gears try to move apart. It�s obviously been done many times before with success so probably not an issue.