Yoshimura rings

[ka-ja]

Hi,
     Any out there know of the where-abouts of any piston rings that would fit the old (458cc) yoshimura pistons, I have compression readings of 140,125,125,142 psi 1 to 4 cyls. and the two low ones come up to 145psi after oiling the bores, it seems to affect the centre two pots carburation!

[paul G]

Ka-ja
              Try giving IMD pistons a ring he has loads of stuff.
Something might fit. If you google him he has a web site.

Regards,

[ka-ja]

Cheers Paul-will do.---Ken

[Dave_Canada]

Are you positive you have the 458 pistons? Every Yosh kit I have come across actually used the 466 pistons intended as a possible repair overbore from 458.

[ka-ja]

Hi Dave,
            The piston kit was bought and fitted in 1985, pistons are full skirt pistons have "yos" cast near the gudgeon pin, were sized as 458cc ( 50cc over standard)and the box was labelled as "For Racing Use Only"-Ken

[Dave_Canada]

Denoon (in Canada) has 54mm rings, I don't know if they fit the Yosh pistons though. You could ask him...
http://www.denoonsp.com/omt-catalogue.htm

[ka-ja]

HiDave,
            Thanks-I have sent of a query, but reading between the lines, he has partially backed out of the parts supply business and concentrating on information supply, the listing for the yossy rings is dated 1983? from a different company, now defunct.
            I have also tried IMD in the UK, but they haven't any 54mm rings, but may have some later in the year ( apparently a popular "dirt bike" size)----Ken

[Dave_Canada]

MC-Again in Japan have also been selling kits but they now have their own brand but I don't see 458. They used to have Yosh kits and parts, I bought a couple of head gaskets that came in Yoshimura packaging (probably fake but still good gaskets).

[ka-ja]

Hi Dave,
             It would appear that I can forget yoshi rings although I would prefer to use the pistons I have because of the 10.5 to 1 compression ratio, most other big bore kits are 9.5 to 1 or lower, below is the original yoshy parts list from 1983/4, I can get hold of non yoshy 466cc rings from America, but although they can be "gapped" to fit, there is no guarantee they are the correct thickness or depth until I buy them and see. I may well have to buy the alternative forseti pistons and hone the bore out to 54.5dia---Ken
             PS. Rick in Canada is a very helpful fella!

           
1223 458cc PISTON KIT with head gasket, no resleeving necessary
1224 466cc PISTON KIT with head gasket, no resleeving necessary
1273 Piston, 458cc, 54mm, 10.5:1
1274 Piston, 466cc, 54.5mm, 10.5:1
1313 Piston Rings, 458cc, 54mm
1314 Piston Rings, 466cc, 54.5mm
1343 Wrist Pin, 458cc & 466cc
1362 Circlip
1386 Head Gasket