Motorcycle Repair: reboring a motorcycle engine., stroke engine oil, piston rings

Question
Sir i am parched a new herohonda  spender+ at 2.5year back now i gating a white smoke in silencer  total running of the bike is 30000.

Answer
I had to look that one up on the Internet! I had never heard of that model before. Based upon the fact that it is only 100cc and you have put 30,000KM on it, with smoke coming from the engine, it must be time for new piston/rings in an overbore size.

Because it is an air-cooled engine, I am guessing the smoke has some bluish tint and that you are having to add oil to the engine regularly. Actual white smoke would be from a liquid-cooled engine with a bad head gasket or similar cooling system issues. The light blue smoke is engine oil burning (like a 2 stroke engine). Oil burning can come from both the piston/rings and from worn valve stems/guides and valve stem seals.

Removing the piston and checking the fit into the cylinder bore will tell you if the cylinder can just be honed (cylinder clearances should be around 2-4 thousandths of an inch) or rebored. If you have had difficulty keeping the air filter cleaned or have changed it to a less efficient design, then the ingested dirt will wear the internal engine parts much quicker than normal.

Have the valves removed, cleaned and checked for excess wear in the guides and at the valve sealing surfaces. Replace valve stem seals and put it back together with new gaskets and seals. Always change the oil regularly to minimize wear in the rest of the engine.

Bill Silver