Torque Settings for Head

[marty]

the point of that post is, i would have thought about 50ft/lbs would be plenty for 80cc's

[Ryaz]

Did anything let go?
Is the cylinder surface damaged at all?
If there's no obvious damge you'll prolly not need to replace more than rings.
Take the barrel, piston and rings into your dealer and get him to measure gaps.

Nope, nothing let go as far as I know, and the barrel looks fine. I have to at least replace the rollers, do I need to replace anything else?

[Ryaz]

the point of that post is, i would have thought about 50ft/lbs would be plenty for 80cc's

Just been told it uses about 20ft/lbs Cheers Marty

[Oscar]

Nope, nothing let go as far as I know, and the barrel looks fine. I have to at least replace the rollers, do I need to replace anything else?

Strictly speaking no.
As it's in bits, I'd replace at least the rings and check the piston for wear.

Are you talking about replacing the big end bearing?
Or the gudgeon (piston) pin rollers?

[Ryaz]

Strictly speaking no.
As it's in bits, I'd replace at least the rings and check the piston for wear.

Are you talking about replacing the big end bearing?
Or the gudgeon (piston) pin rollers?

Well I'm not exactly sure what the right name for the rollers are, but its when the conrod joins the crankshaft, the bearings that keep it smooth. That explains why when I started it up it sounds really rattly.. How much is a new set of rings worth? And for a piston? Cheers

[Oscar]

Well I'm not exactly sure what the right name for the rollers are, but its when the conrod joins the crankshaft, the bearings that keep it smooth. That explains why when I started it up it sounds really rattly.. How much is a new set of rings worth? And for a piston? Cheers

Ahh, the big end bearing.
You're prolly going to need expert help.
If it was mine and I had it apart to that degree (and assuming it's done a bit of work), I'd be replacing piston, rings and the piston pin and small end bearing.

[Ixion]

Ahh, the big end bearing.
You're prolly going to need expert help.
If it was mine and I had it apart to that degree (and assuming it's done a bit of work), I'd be replacing piston, rings and the piston pin and small end bearing.

yep, tis no job for a beginner. You will usually need to replace at least the crankpin, the rollers, and the conrod. New little end bearing is a given. Might as well do the gudgeon pin.

But why did the big end fail? Are you sure your lubrication system is working ? Apart from the unlamented Ariel two stroke , it's not that common. Usually the mains go first, so you might want to check/replace those too.

[Ryaz]

Yep, the only problem is money I can't really afford anything, so I need to put in as less as possible, just the bearings if thats possible..

[Oscar]

yep, tis no job for a beginner. You will usually need to replace at least the crankpin, the rollers, and the conrod. New little end bearing is a given. Might as well do the gudgeon pin.

But why did the big end fail? Are you sure your lubrication system is working ? Apart from the unlamented Ariel two stroke , it's not that common. Usually the mains go first, so you might want to check/replace those too.

12 year old bike.
Get one owner who don't know what an aircleaner is and you've got a rumbly big end...

[Ixion]

12 year old bike.
Get one owner who don't know what an aircleaner is and you've got a rumbly big end...

Ah, that's getting long in the tooth for tuned two smoker. So being, I'd pick the mains will also be toast, or well on the way.

Might be cheaper to source another engine ?

[Ixion]

Yep, the only problem is money I can't really afford anything, so I need to put in as less as possible, just the bearings if thats possible..

Unfortunately, there's no cheap out on this one. Labour cost is the same regardless of what you replace beyond the roller and cage. And if the big end's gone usually (not always) the hardening on the crankpin and conrod eye will be shot.

Cheapest out might be to source a secondhand crank assembly. That would save all (or most all) the labour cost, and maybe be cheaper than just a new big end set.

[Oscar]

Ah, that's getting long in the tooth for tuned two smoker. So being, I'd pick the mains will also be toast, or well on the way.

Might be cheaper to source another engine ?

It's so long since I worked on a two stroke I dunno what parts cost.
The last one I worked on of my own was my 1989 RMX250, and that was in 1990....

[Ryaz]

I'm getting my KX80 repaired, is it absolutely essential to balance the crankshaft? I'm not racing, just trail riding. Cheers