Replaced Small end bearings - still probs.

Jammy-G · Banned Joined: 17 Mar 2004 Karma :

Having stripped down the engine under the impression that the small end bearings had gone (knocks in the engine while under breaking), have found there is very little play at all to what was expected.

Looks like it is the big end, is it worth replacing all that gear on a bike worth that much, or should I just put the new piston kit, small end bearing in and ride it?

The old piston looks very scoured, while the cylinder looks ok, would this have contributed to the knocking?

Hmm opinions please !
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kev · I Hump Things Joined: 07 Oct 2002 Karma :

First of all what engine is it?
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20:02:36 Jammy-R6: any holes a goal
20:02:48 kev: even if its a hairy mans arse
20:02:56 Jammy-R6: hell yes

Jammy-G · Banned Joined: 17 Mar 2004 Karma :

RXS100, single 2 stroke.
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RooRoo: just like the time i stuck my finger up my arse with no lube at all and she didnt talk to me for hours

kev · I Hump Things Joined: 07 Oct 2002 Karma :

It will be far cheaper to just replace the engine.

If you do decide to fix it for a start your going to need a new crank and rod and maybe a piston as well if you say its a bit on the buggered side.
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20:02:36 Jammy-R6: any holes a goal
20:02:48 kev: even if its a hairy mans arse
20:02:56 Jammy-R6: hell yes

Jammy-G · Banned Joined: 17 Mar 2004 Karma :

I have a spare new piston kit, would it be ok to fit this into a slightly scoured cylinder? I know its not ideal, but I don't want to spend too much on it.

And the knockong coming from the engine under braking, is this a sign its about to fall apart or shall I put up with it?
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RooRoo: just like the time i stuck my finger up my arse with no lube at all and she didnt talk to me for hours

kev · I Hump Things Joined: 07 Oct 2002 Karma :

When big ends start to go they will get worse really as time goes by then they will just give up.

Your best bet really is to get another crank for it then put it back together and hope for the best.
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20:02:36 Jammy-R6: any holes a goal
20:02:48 kev: even if its a hairy mans arse
20:02:56 Jammy-R6: hell yes

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Is there any vertical play in the big end bearing?

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

Jammy-G · Banned Joined: 17 Mar 2004 Karma :

No vertical play, horizontal a little bit. I read that the horizontal play should be 0.3mm but i think there is more than that.

I think I will take it to get rebored, my friend knows a guy that can do it for 12.50 and I think it needs it as the piston is discoloured where the gases have gone past.

After I found the small end didn't have much play in it, I am assuming its the big end, but not sure. The knocking I hear when I brake or let off accelerating, would this occur when there is not a noticable amount of play in the small end?

Cheers.
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RooRoo: just like the time i stuck my finger up my arse with no lube at all and she didnt talk to me for hours

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

If the bore is well worn, could it not be piston slap?

Main bearings OK?

You said it yourself though, if you can get it rebored for that sort of price then go-ahead. If it is still clattering then just keep riding it 'till it lets go and get a new engine.
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Sounds like the big end bearing is fine. You can check the mains for play but they normally whine instead of knock.

New over size piston and a rebore might be required, or get someone to accuratly measure the barrel first possibly.

From experience stick to original pistons.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

Jammy-G · Banned Joined: 17 Mar 2004 Karma :

Thanks guys, put my mind at ease a little.

Still unsure to as why it would knock though if the bearings are fine. As for the slap in the piston and barrel I doubt there is enoug play to casue that.

Taking the engine into a bike mechanic tomorrow so he can have a poke around.

Thanks for your help Very Happy

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RooRoo: just like the time i stuck my finger up my arse with no lube at all and she didnt talk to me for hours

Jammy-G · Banned Joined: 17 Mar 2004 Karma :

Took the engine in today, and he said the big end bearing is fine, thank god.

he said it was caused by piston slap and it would definitely require a rebore as it was scoured to hell, probably due to the time my choke seal broke, and I didn't know, so was flushing all the oil out the cylinder.. doh !

Thanks for all your replies, appreciated Thumbs Up

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RooRoo: just like the time i stuck my finger up my arse with no lube at all and she didnt talk to me for hours