Re: Going for a re-tune....
One simple and cheap fix you could try doin on the valves is a valve lap job.
Here is the run down on the procedure with pictures: http://www.affordablegokarts.com/valve-lapping.php
The materials are fairly cheap and it is an excellent way to get the valves and the valve seats to have a much better contact. If indeed valve sealing is your problem, this might be something you wanna explore to get them to seal better. If your problems are as a result of a bent valve this will not do much for you.
One simple and cheap fix you could try doin on the valves is a valve lap job.
Here is the run down on the procedure with pictures: http://www.affordablegokarts.com/valve-lapping.php
The materials are fairly cheap and it is an excellent way to get the valves and the valve seats to have a much better contact. If indeed valve sealing is your problem, this might be something you wanna explore to get them to seal better. If your problems are as a result of a bent valve this will not do much for you.