Which bore size?

Post by **southerly95** » Mon Jun 18, 2007 6:06 pm

Have taken the head off our 1098 to put an unleaded one on and checked the bores - fine no lip. Not sure which bore size it is though, i.e. whether it's been rebored or not. Pistons are stamped MOWOG with a 2 above that and a two lines joined at about 130degs (like wide arrow). Can't see anythind else, thanks, John

Post by **bmcecosse** » Mon Jun 18, 2007 9:30 pm

Sounds like standard bores then - the '2' is a grade mark - and should be inside a diamond mark of which I think you are seeing the two top lines. If oversize they would not have the grade mark - and would show 10/20/30 etc oversize marking. Check the rockers before you refit - look for excessive wear as detailed on other posts near this one ! Where did you get the 'unleaded' head ?? And take this chance to fit a new NON CORRUGATED bypass hose while the head is off!

Post by **Dominic** » Tue Jun 19, 2007 11:54 pm

Where did you get the 'unleaded' head ??

I think this is the head that I sold on ebay a while back. Was bought from MGM in Oct 05, newly reconditioned and converted to unleaded, has done about 10k miles, then had 2 new guides fitted after an exhaust valve burnt out due to worn cylinder bore allowing an excessive amount of oil to burn. As I bought a new engine, was no longer needed.
Dom

Post by **bmcecosse** » Wed Jun 20, 2007 7:44 am

Exhaust valves don't burn because of oil! I was just curious because many unleaded heads are ex Mini with smaller inlet valves and subsequent loss of power if used on a 1098 - but ok on a 948.