Scooterotica

A friend of mine decided to strip his top end down after hearing an unusual clattering in the barrel area. There was quite a bit of play on the piston / gudgeon pin area, so thought his little end bearings had gone kaput......After some grunting and hammering, we managed to get the pin out and noticed the wear on it. I have never seen wear like this, so thought I would ask on here as to why it would happen.

Cheers
Bizz

i think i have the answer;- it was made in scunny using scunny steel!

sorry couldn't resist that! come over to selby this saturday i'll give you a new one,
regards
joe

joespeed wrote:i think i have the answer;- it was made in scunny using scunny steel!

sorry couldn't resist that! come over to selby this saturday i'll give you a new one,
regards
joe

LMAO Its been in 4 year without a checkup

was there lubrication holes in the piston?

camel wrote:was there lubrication holes in the piston?

No....rapido I think Asso piston, 2 holes in rod to small end bearing.

Is it run on decent oil and at what ratio?

Also, what sort of quality was the small end? Was a 20mm small end fitted when it needed a 22m? (length of small end between piston not diameter).

nelson pk wrote:Also, what sort of quality was the small end? Was a 20mm small end fitted when it needed a 22m? (length of small end between piston not diameter).

He's not sure what make the small end bearing is, as he put it in about 4 year ago, but the roller bearing was the same width as the small end on crank. He also uses Rock oil fully synthetic at 4%.

If the piston has got a 22mm gap or very slightly over between where the small end fits, a lot of tuners advise the use of a 22mm long small end regardless of weather this pokes out a bit either end on the eye of the rod because if you use a shorter small end, the small end can move along the gudgeon pin and then only a proportion of the conrod eye is making contact with the small end if you see what i mean, and therefore you are getting uneven pressure on approx half of the bearing.
I would measure the gap where the conrod sits on the piston and if its 22mm or very slightly over get a 22mm long bearing. MBD used to do them and camb lam do them as well. I think they come out of a Yamaha but i dont know which one.

Thanks nelson much appreciated