Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
I dropped the CB250RSA barrel and head off a the engineering shop today. It looks likely a rebore will be required although he is going to try a gentle hone first as there is a lot of melted piston in the top of the bore. If this doesn't work it will be a 0.50 oversize piston (I had it bored 0.25 over previously).The engineer thinks the Haynes Manual maybe incorrect regarding the cylinder to piston clearance. The manual states a clearance of 0.01 —0.04mm. He thinks this is very tight for a 74mm piston? He doesn't want to risk a potential seizure.Does anyone know if the Haynes Manual measurements are correct or is there a Honda measurement or even a 'rule of thumb' for Japanese bikes (Brit bike clearances are much bigger). Dave
Hi Trigger. I haven't bought the new piston yet as waiting to hear what size I need, hopefully it will be 0.50 over. I have seen a IMD oversize piston on flea Bay. I think this is the same make as the 0.25 piston I purchased from DS. I haven't heard any feedback on this make of piston good or bad?Julie, it has one spark plug (that was new at the rebuild, now slightly mangled due to the blow-up......). Ash, thanks for the article reminder, I'll print this at work tomorrow when nobody is looking! You may have guessed I've been delayed sending you the parts manual, it's currently back in use! I'll send it when the re-rebuild is complete!
The manual states a clearance of 0.01 —0.04mm.