have been trying to get my 225 to idle a little better ( I know thats not always possible ) have been chasing a possible air leak in system, can't seem to find any problems, so I started over with my linkage, timing synchronizing, I noticed when I pull just a little on the linkage wich advances the timing (without opening the throttle it runs so much better, is there any bottom end setting on the timing or only wot setting ? can't find anything in service manual.