250cc w/ng cylinder sleeving/new piston

[doug.pearce]

Cylinder bore on max dia with corresponding piston +060".
Coned and fit new rings and oil seal compression back, but some 500 miles later losing compression.
Carried out dimension check at max, now looking at re-sleeving back to orginal bore size with new piston etc.

Can anyone reccommend where I can get the cylinder resleeved inc new piston and rings.

Regards.

[admin]

You shouldn't need to fit another piston/rings/rebore to regain compression .. certainly not after 500 miles.
Have you checked the other possible suspects such as tight valve clearances holding open a valve, the valve lifter holding open the exhaust valve, head blowing at barrel/head joint (or my personal favourite the gudgeon pin circlip coming adrift and grinding two massive grooves in the barrel.)

do the stuff that doesn't cost money first....

[nevhunter]

Like checking the oil pump output. Are you in a dusty environment?....Also Confirm 250 cc. The W/NG is 350 cc.
the 350 cc barrells are not overly thick at the base. When used competetively they are a bit prone to breaking off. IF you resleeve, don't go too big on the O/D or you will weaken it unnecessarily. Nev

[tony.barnett]

350cc barrels are as common as muck - your friendly (sometimes) Single Spares person should be able to help. There really is no need to sleeve. They are quite common at autojumbles too.