Ah well time on my balance shaft i think

[admin]

I noticed after the oil change and 2 sessions in to the track day that there was a distinct roughness coming from the lower part of the engine.
it starts, goes and runs just as well as it always has - but sounds a bit - well rumbly to be honest
i dont think it's mains as the flywheel has zero play on the gene side and feels smooth to turn as best as you can feel without a strip. so i am thinking its the balance shaft and bearings.

i did 4 more sessions on it and it didnt sound any different so i wonder if the change from cheap 10w40 oil to fully synth motul transoil has played havoc.

I got cadwell on it next weekend i reckon fill it back up with cheap glug and see what happens.

[fallenmikethebike]

Balance shaft bearing are quite small and the noise is generally a mechanical whirring sound, like mine has done for a couple of years .
It's not normally a heavy mechanical noise, so perhaps the big ends started complaining, but I stand to be corrected.
Mike

[knackeredMk1]

FMtB +1

[admin]

yep it is a whiring sound you are correct, it does sound like a worn bearing noise that increases with revs
i would have said piston slap - but without the slap lol

[admin]

also it came from nothing to whiring within 1 session of hard use - i do seem to recall it got fired down the gears a bit hard to may have over revved - oops

anyway its only got to do cadwell this coming weekend for 2 days on track and then it can be retired / rebuilt

i had a go on a KTM660 - wow what a bike, the vibes were stunningly bad though.
I think CRF450X and motard that is the next logical step for me.

[gregorious77]

When mine went it sounded like i high pitched whine/whistle type noise a bit like blowing across the top of a beer bottle at high revs and rumbly at idle.
Did you check for play of the balancer shaft when you checked the geni? its that side that dies as its a needle roller down a hole that leads to a pants oil feed.
Mine died due to lack of oil change I think. I now change the box oil every 200 odd miles and am using ATF.
I still have my old balancer shaft as LT only give you £20 back and I couldnt be assed to send it back. (might need it again sometime).
Parts were in stock, Balance shaft £96 plus £20 return on old balance shaft, Needle roller bearing £28.75, Ball bearing £13.99 and Seal £4.95, no nut available. Clutch basket Nut £7.90 and Clutch cover gasket £14.29.
That was in Feb

[admin]

Good to know thanks pal
i look forward to tearing it down in a couple of weeks and investigating.
now if i could just find another 5bhp from it

[gregorious77]

I have a spacer if you want to disconnect it but the vibes are mucho!!
P.S. Don't buy a piston yet as I may be getting 2 by mistake!! ordered from Wossner direct and offroad only and both went through as far as I am aware!
If its all good I will sell you my spare.

[fallenmikethebike]

The old subconscious got to work on this last night.
Changing the oil in the gearbox would not affect the mains or big/small end as they are oiled via the the 2T lubrication.
The theory about the oil change from mineral to semi synth might well be correct if enough mineral oil was still hanging about in the gearbox to create an emulsion when mixed with synth oil, I.M.O..The primary culprit is probably the needle roller bearing.
Mike

[Spokey]

"the theory about the oil change from mineral to semi synth might well be correct if enough mineral oil was still hanging about in the gearbox to create an emulsion when mixed with synth oil, I.M.O."

You wont get any emulsion mixing mineral with semi or full for that matter as they will all be compatible. Emulsion normally comes through water, only need a very small amount ( around 0.3% ) to make oil hazy - 0.5% will turn it milky. Engine oils are designed to hang on to water as it burns off at normal working temperatures.

Also, lots of talk of ATF being used in gearboxes - bear in mind that the main purpose of an oil is to keep 2 metal surfaces apart under load and pressure - if the oil is too thin then you can get metal to metal contact and wear.
Most gear oils are SAE 80W ( this equates to a 30 grade engine oil - hence the 10W-30 multigrade being a popular choice for bike gearboxes ) ATF is around SAE 10 so quite a bit thinner so less fluid film between the gear teeth - and many are friction modified too ( Dexron spec ) which could affect wet clutch performance ( Que lots of " I use ATF and never had a problem " posts ) . Its a bit like deciding whether to wear leather trousers, or chinos ...

cheers

[fallenmikethebike]

Chino's for me.
Mike