Right... Been told by the bike shop that my bikes big end has gone:(

As I had to spend

yes its simple enough ,1st id like to know how they know the big ends gone without going into the engine , 2nd if it has gone who missed it when the piston and cylinder was off ,( are you sure its not the mains that has gone ) any way back to removal get some freezer bags and masking tape tape up any cables or wires you might forget and wright on the tape what it is put parts in bags and label bags take pics whilst removing ,drain the oil before removing ,it could be fiddly the actual dropping down of engine so get a hand and dont let it drop on the floor ,keep work erea tidy so any dropped parts can be found ,power washing so everythings clean can make life easier

The thing is though this knocking sound that goes up in speed of the engine happened when I accidentally tried to start the bike while it was running as I could no here it running due to other bikes around me!

There was a clack which I think was a tooth breaking off the kickstart gear? They are saying its the big end though. This noise started after the clack of the kickstart. I some how don't believe them.

They are saying the new piston put too much pressure on the big end .

never hear such crap

That's what iam thinking

you need to check the kickstart gears idler cog and clutch basket teeth

I will tell them to check that then

you dont need the engine out to check for this ,, and if they are filling you full of crap id go somewhere else

They are saying the new piston put too much pressure on the big end .

I wouldn't dismiss what they are saying - the extra compression from a fresh piston and rings could put more on the bottom end of an engine. why not take the head and barrel off and see if there is up and down play on the rod? this will tell you if the big end has gone.

It is only a 125 and it still has very little compression compared to bigger bikes.

Ben

Have a look at the kickstart idler gear, which is the one that the kickstart gear meshes with when you start the bike and runs continuously behind the clutch basket. You will find that some of the teeth have been damaged when you operated the kickstart with the bike running resulting in it rattling like a bag of spanners.

Steve

Ben

Have a look at the kickstart idler gear, which is the one that the kickstart gear meshes with when you start the bike and runs continuously behind the clutch basket. You will find that some of the teeth have been damaged when you operated the kickstart with the bike running resulting in it rattling like a bag of spanners.

Steve

Thanks I'll get them too check that too

Ben,

I totally agree with members zerorev3rev4 & chylowen. I would certainly pull the clutch off and look at the back side of the kickstart idler gear. I am basically chasing the same demons as you; you described the exact same problem I'm having with my 2010 Pro 280: The clattering noise that gets faster in frequency as the revs go up, and then slows down in frequency as the revs drop. Also, the fact that this happened (as did mine) right after a poor statring technique (not being critical of you; this is more aimed at myself. You already know you don't try to start a bike when it's already running, I'm bettin'....) would steer me towards a problem with the k/s mechanism somewhere.

FWIW, here's what the back of my bike's idler gear looks like:

Basically, those 2-3 chipped teeeth are enough to make that noise, Ben.

It's actually pretty easy to get to this to look at, Ben (I think you've already done some of this before, haven't you?). You pull the Kickstart lever, then the clutch cover, and then the clutch itself. This makes the idler gear visible, but you have to pull a circlip off for the gear (and a washer or two; watch out for those!) to come off, to be able to look at the back side. I suppose if that gear is seriously "grenaded", you may not have to pull it off to see the damage. Look at your kickstarter shaft's gear also, as well as the gear on the back of the clutch that the idler gear meshes with, for any chips, chunks, or other carnage. At any rate, doing this first is much easier and cheaper to check out than yarding the engine out, and then taking it to have it looked at & repaired. Hope this helps some!

Jimmie

It can be hard to find. As it now has been smashed into the teeth and sounds just like a bad rod. ( To give the shop some credit it does sound like a bad rod bearing, but it`s not!!!!) You might even need a magnifying glass and go tooth by tooth to find it!